Razana Juhaida Johari
email: razana@salam.uitm.edu.my

Md Mahmudul Alam

Jamaliah Said
email: jamaliah533@salam.uitm.edu

Investigating Factors that Influence Malaysian Auditors' Ethical Sensitivity

Keywords: Ethical sensitivity, ethical culture, ethical orientation, locus of control, audit, fiduciary services, Malaysia

Purpose -The primary role of auditors is to offer fiduciary services to the society and users of the financial reporting. With this role, users placed their trust and dependent on the ability and judgment made by the auditors during their auditing works. However, recent financial scandals involving high profile companies frustrated the public's expectations, particularly in Malaysia. It is claimed that auditors are not having ethical sensitivity while executing their task in mitigating the fraudulent financial reporting. Therefore, this study aims to examine the influences of ethical orientation, locus of control and firm's ethical culture on the auditors' ethical sensitivity in Malaysia. Methodology/approach -This study collected primary data based on a questionnaire survey among audit firms in Klang Valley area and registered with Malaysian Institutes of Accountants. Findings -The results showed ethical sensitivity has a significant negative relationship with relativism and some cases have a significant positive relationship with idealism. Moreover, it found a significant positive relationship between ethical sensitivity and ethical culture. Originality/value -This paper provides benefit to the audit firms, professional bodies, policy makers, and academia in understanding the factors that might increase the sensitivity of auditors in dealing with ethical issues that could lead to fraudulent financial reporting in the company.

Introduction

The primary role of auditors is to offer fiduciary services to the society and users of the financial report [START_REF] Sweeney | The impact of ethical culture of the firm and demographic variables on auditors' ethical evaluation and intention to act decision[END_REF]. These fiduciary services create the fiduciary relationship between the auditors and users where the users must trust or depend on the ability and judgment that have been made by the auditors on the true and fair view of the audited company's financial reporting. With this role, users have high expectation of the judgement made by the auditors and that is why the auditors need to balance up their judgment for the benefit of their audit client as well as the public at large. However, nowadays financial scandals involving high profile companies around the world, such as the famous cases of Satyam Corp and Enron outside of Malaysia and PKFZ Berhad, Transmile Corporation Berhad and Perwaja Steel Berhad in Malaysia, had frustrated the public expectation. The number of reported cases of fraud, corruption and mismanagement due to the auditors' unethical behaviour is costly, especially to the employees and society [START_REF] Johari | Auditor's ethical judgments: the influence of moral intensity, ethical orientation and client importance[END_REF][START_REF] Yusoff | The influence of personal and organizational factors on ethical decision making intentions among managers[END_REF]. For example, in Satyam Computers' scandal that happened in India, their auditors of PricewaterhouseCoopers (PWC) were accused due to the failure to detect falsification of the company's accounts. The same issue also happened to Transmile Group Berhad in Malaysia, in which their auditor, Delloite and Touche also failed to detect the accounting irregularities during their audit. Both cases have made the company suffer losses and made the company collapsed.

There is a high possibility that auditors might be involved with unethical judgment when auditors are unaware of ethical issues that are not encountered in situation (Dreike and Mocckel, 1995). For example, after 15 years of Enron's case, it seemed that there are still a lot of companies that collapsed such as Perwaja Steel, Sime Darby Bank and Renong Bhd., even though the rule and regulation on Code of Ethics were being modified and strengthen. The reasons that these big companies collapsed have brought into question the status and credibility of the auditors with allegations of accountants' violations of public trust (Leung, 2006). As a result, public perceived that the auditors are unaware of the ethical implication in their technical decision and all of these financial scandals had caused a high level of accusation and criticism on the auditors. Thus, identifying the factors that influence ethical sensitivity, it may assist practitioners and educators in improving the auditor's judgment as by identifying the intention and behaviour of the auditors.

Based on the ethical decision-making model developed by Rest (1986), ethical sensitivity is the first step in ethical decision-making process. Shaub's (1993) defined ethical sensitivity as ability to recognize the ethical nature of a decision, whereas Butterfield et al. (2000, p.982) defined it as a person's recognition that his/her potential decision or action could affect the interests, welfare, or expectations of the self or others in a fashion that may conflict with one or more ethical standards. It is claimed that moral domain will not be activated unless persons are aware of it or understand that ethical problem exists (Rest, 1986;Shaub, Finn and Munter;1993). Therefore, persons will not use ethical judgment unless they are aware that there is an ethical problem in that situation. Besides that, from a survey in 2007 by Jackling et al., they identified four factors as the top reasons of ethical failure and one of it is lack of ethical sensitivity. However, majority of the previous studies on ethical decision making only focused on the ethical judgement which is the second step in ethical decisionmaking process. Thus, this study is aimed to investigate the factors that influence auditor's ethical sensitivity.

Literature Review and Hypotheses Development

Ethical Orientation and Ethical Sensitivity of Auditors

There are a lot of definitions regarding ethical orientation. According to the Cambridge Advanced Learner's Dictionary (2008), 'ethical' can be defined as "relating to beliefs about what is morally right and wrong"; whereas orientation is "the particular preferences, tendencies, beliefs or opinion that a person has". It can be concluded from both definitions that ethical orientation is an individual's ethical philosophy which describes the beliefs of an individual either it is good and bad or right and wrong. In this study, ethical orientation can be referring as the persons beliefs either it is good or bad based on their individual characteristic's idealism or relativism.

Based on the previous studies on ethical orientation, the results found inconsistent findings regarding ethical orientation on ethical sensitivity. For example, [START_REF] Marques | Ethical ideology and ethical judgment in the Portuguese accounting profession[END_REF] found no relationship between ethical sensitivity and ethical orientation. In contrast, other researchers such as [START_REF] Uyar | The ethical orientation and professional commitment: An empirical examination on Turkish accountants[END_REF] found that relativism affects ethical sensitivity negatively while Shaub et al. (1993) found a relationship between ethical orientation and ethical sensitivity. In that study, they found that auditors who have high relativism and idealism seem to be less likely to detect ethical issues as compared to the auditors who are low in relativism and idealism. Moreover, the study also found that ethical orientations are influenced by the auditors' cultural environment and personal experiences. Besides that, Ismail (2014) also found a significant positive and negative impact of idealism and relativism on ethical judgment that can be related to ethical sensitivity. [START_REF] Johari | Effects of auditors' ethical orientation and self-interest independence threat on the mediating role of moral intensity and ethical decision-making process[END_REF] investigated the influence of individuals' idealism and relativism orientations on the recognition of an ethical issue and ethical intention where they suggest that idealism orientation is associated with increased ethical issue recognition; while relativism orientation is associated with decreased ethical intention. Smith (2009) found a significant positive relationship between idealism and ethical sensitivity, but there is no relationship found between relativism and ethical sensitivity. [START_REF] Ozbek | The moderating role of locus of control on the links between perceived ethical problem and ethical intentions of marketing managers in Turkey[END_REF] supported that individuals with higher levels of ethical idealism are more likely to be aware of ethical issue (ethical sensitivity) during the study involving the marketing managers.

Therefore, based on the previous literatures, the below hypotheses are formulated: H1: Idealism and relativism of ethical orientation statistically significantly influence the ethical sensitivity of auditors

Locus of Control and Ethical Sensitivity of Auditors

The concept of locus of control was first introduced in 1954 by Julian Rotter (Rotter, 1966).

Locus of control is defined as what people's perception of the source of control over their destiny or actions. It is how individuals judge themselves or believe that an external force, such as luck, is related or influence on events in their life [START_REF] Firth | How can managers reduce employee intention to quit?[END_REF]. This definition was supported in the latest article by [START_REF] Chelariu | Education regarding ethics in the accounting professiona literature review[END_REF] where they defined locus of control as the way of a person explains the success or failure of a certain action that can be determined through causes of internal or external nature, controllable or uncontrollable by that person. In this study, definition by Chelariu et al., are used because the objective in this study is to measure whether internal and external influence person actions. Empirically, locus of control plays a significant relationship with ethical sensitivity. [START_REF] Kalbers | Antecedents to internal auditor burnout[END_REF] found that individuals with an internal locus of control are not exposed to stress as compared to an external locus of control that is more in stressful conditions. External locus of control could reduce personal accomplishments and job performance and the probability of making mistakes in the decision could be happening because of the inability to be aware of the ethical issue. Also, [START_REF] Chen | The impact of locus of control on job stress, job performance and job satisfaction in Taiwan[END_REF] found that individuals with high internal locus of control have higher levels of job satisfaction and performance. This in turn gives lower levels of job stress in their workplaces.

Prior studies found that auditors with internal locus of control have higher level of organizational commitment and will report the errors to increase the quality of audit [START_REF] Donnelly | Auditor acceptance of dysfunctional behavior: an explanatory model using auditors' personal characteristics[END_REF] because the action to report the misstatement is related to ethical sensitivity before any judgment can be made [START_REF] Chadegani | The influence of individual characteristics on auditors' intention to report errors[END_REF]. On the other hand, [START_REF] Paino | Modelling dysfunctional behaviour: individual factors and ethical financial decision[END_REF] found that the external locus of control influenced the dysfunctional behavior.

Therefore, based on these arguments, the following hypotheses are formulated. H2: Internal locus and external locus of control statistically significantly influence the ethical sensitivity of auditors

Ethical Culture and Ethical Sensitivity of Auditors

In this study, definition by Ethics and Compliance Officer Association ( 2006) are used were they defined ethical culture as how an organization demonstrates and teaches their staff regarding its firm's values that influence employee's behaviour. The values compromised on three issues, whether employees do the right thing, do what is right and expected and ethics programs such as reward and punishment systems. Ethical culture was found to be important in order to determine the unethical behaviour where [START_REF] Douglas | The effect of organizational culture and ethical orientation on accountants' ethical judgments[END_REF] and [START_REF] Jenkins | Accounting firm culture and governance: a research synthesis[END_REF] found that ethical culture of the firm can influence the ethical decision-making process.

Based on previous studies, researchers found significant relationship between ethical culture and ethical sensitivity [START_REF] Md | The effect of culture and religiosity on business ethics: A cross-cultural comparison[END_REF][START_REF] Shu | Cultural differences in determining the ethical perception and decision making of future accounting professionals: a comparison between accounting students from Taiwan and the United States[END_REF]. However, the result was analysed based on different dimensions. For example, [START_REF] Md | The effect of culture and religiosity on business ethics: A cross-cultural comparison[END_REF] and [START_REF] Shu | Cultural differences in determining the ethical perception and decision making of future accounting professionals: a comparison between accounting students from Taiwan and the United States[END_REF] used ethnicity as the dimension for ethical culture while Jeffry et al. ( 2004) used nation. Jeffry et al. (2004) examined the relationship of ethical culture on ethical sensitivity among Taiwanese auditors and the results showed that ethical culture had a positive influence on ethical judgments. In research by [START_REF] Pierce | Management control in audit firms: partners' perspectives[END_REF], audit partners perceived consequences from junior auditors' actions when junior auditors did not fully perform audit work that should be done by them. These problems occurred due to 'tone at the top' that did not fully emphasise on the ethical culture in which it gave social influence pressures on the decision made by them.

Based on research by [START_REF] Helliar | Taking Ethics to Heart[END_REF], 42% of respondents agreed or strongly agreed that the increasing focus in firm's success such as income aspirations focus has led to a more unethical behaviour. [START_REF] Jones | Auditors' ethical reasoning: insights from past research and implications for the future[END_REF] research focused on the influence of superiors on auditors' ethical evaluations. Based on their finding, the influence of peers has an influence on ethical behaviours of peers. Jones's findings are supported by other researchers, for example, [START_REF] Thorne | the directional effects of discussion on auditors' moral reasoning[END_REF] who found that the improvement in auditors' ethical evaluations can be achieved by encouraging discussion of ethical issue or dilemmas with peers. In contrast, [START_REF] Pierce | Management control in audit firms: partners' perspectives[END_REF] found that time pressure between peers moderated and influenced the relationship between time pressure and quality threatening behaviour.

Considering the influence of peers, accounting profession tends to support that the behaviour of peers has an influence on ethical behaviours. This statement was supported by [START_REF] Thorne | the directional effects of discussion on auditors' moral reasoning[END_REF], because improvements may occur in auditors' ethical evaluations by encouraging discussion of ethical dilemmas with peers [START_REF] Pierce | Management control in audit firms: partners' perspectives[END_REF]. The studies conducted by [START_REF] Trevino | The ethical context in organizations: influences on employee attitudes and behaviors[END_REF] showed that a strong ethical culture creates a positive relationship by lower rates of observed misconduct, increases reporting of misconduct to leadership, greater satisfaction with management's response to misconduct, greater satisfaction with the organization as a whole, lowers exposure to situations inviting misconduct and increases sense of preparedness to handle situations inviting misconduct.

Therefore, by adapting the link between firms' ethical culture and ethical sensitivity, the following hypothesis is proposed: H3: Ethical culture influences statistically significantly influence the ethical sensitivity of auditors

Methodology

Sampling and Data Collection

The focus of this study is auditors' ethical sensitivity. Therefore, the data were collected from the auditors who worked with audit firms in Klang Valley area and registered with Malaysian Institutes of Accountants (MIA). Klang Valley has been selected for the area of this study because this area contributes the largest number of audit firms in Malaysia.

Data for this study is collected through distributing the questionnaires to the selected auditors comprised of five levelssenior, managers, partners, senior managers and audit assistants. A total of 500 questionnaires were distributed and 190 samples have responded. However, only 163 were usable with total response rate of 32.4%.

Measurement of Variables Ethical Sensitivity

Ethical sensitivity is measured through two scenarios. These scenarios were adapted from [START_REF] Cohen | Cultural and socio-economic constraints on international codes of ethics: lessons from accounting[END_REF] that consisted of two ethical scenarios, i.e. (i) under reporting hours, and (ii) noncompliance issue. These issues were used to represent frequently issues occurring practices within auditing firms. All the scenarios contained elements of ethical dimension and were able to measure the level of awareness of participants [START_REF] Dickerson | Ethical decision making in public accounting: investigating factors that influence auditor ethical sensitivity[END_REF].

There were four questions in each of the scenario adapted from [START_REF] Cohen | Cultural and socio-economic constraints on international codes of ethics: lessons from accounting[END_REF] and [START_REF] Gholami | The cultural dependence of the ethical sensitivity scale questionnaire: the case of iranian kurdish teachers[END_REF]. The respondents were asked to read these scenarios and answered the respective questions independently. The two scenarios used in this study have been tested in a variety of subjects including auditors, accounting academics and students [START_REF] Johari | Effects of auditors' ethical orientation and self-interest independence threat on the mediating role of moral intensity and ethical decision-making process[END_REF][START_REF] Dickerson | Ethical decision making in public accounting: investigating factors that influence auditor ethical sensitivity[END_REF][START_REF] Cohen | An examination of differences in ethical decision-making between Canadian business students and accounting professionals[END_REF].

Ethical Orientation

The measurement of ethical orientation was adopted from Ethics Position Questionnaire (EPQ) developed by Forsyt in 1980. The original measurement has 20 items that consisted of 10 items each for idealism and relativism. This study uses the adopted version of EPQ which consists of 14 items for 7 questions each on idealism and relativism. This scale has been verified in [START_REF] Johari | Auditor's ethical judgments: the influence of moral intensity, ethical orientation and client importance[END_REF] and [START_REF] Ismail | Effect of ethical ideologies on ethical judgment of future accountants:Malaysian evidence[END_REF] in their study on the Malaysian respondents. The list of the items is given in appendix.

Locus of Control

This study adopted items developed by [START_REF] Spector | Development of the work locus of control scale[END_REF] to measure the employee's locus of control in an employment situation. [START_REF] Spector | Development of the work locus of control scale[END_REF] observed that it is preferable to use general locus of control scale when investigating behaviours of workers in an organization. The list of the items is given in Appendix.

Ethical Culture

This study adapted the measurement of ethical culture which consisted of 11 items measurement developed by Hunt, Wood and Chonko in 1989. The 11 items being measured were concerning about ethics in organization, the perceived extent when individual acts ethically and the perceived extent either firm will punish or reward for any unethical behaviour [START_REF] Douglas | The effect of organizational culture and ethical orientation on accountants' ethical judgments[END_REF].

Data Analysis

The data are analysed using descriptive statistics through demographic data. Furthermore, inferential analysis was used which comprises of reliability test, normality test, correlations and regression analysis.

Results and Findings

Demographic Information

Among the samples of the study, 46.6% were employed in small auditing firm. Medium size audit firms were the second largest employment with 35%, and only 18.4% of the respondents are from the big four companies. Out of the total respondents, most of the respondents (55.8%) of this study were female, and 46% of the total respondents were Malays, 38.7% Chinese and 15.3% of were Indians.

(Insert Table I here)

In terms of age of the respondents, 55.8% of them were between 21-25 years, 15.3% of them were also between 26-29 years, followed by 22.1% between 30-39 years and 6.7% were 40 years old and above. In terms of job position, 14.7% of the respondents were partners, 12.3% were managers, 22.7% were seniors, and 50.3% were audit assistants. Regarding education. 1.8% of the respondents had diploma, 68.7% had degree, and 29.4 % of them had professional qualifications. Regarding work experience, 54.6% of the respondents had 1-3 years' experience as an auditor, 19.6% had 4 to 5 years of experience, 21.5% had 6 to 10 years of experience, 1.8% had 10 to 15 years of experience and 2.5% had more than 15 years of job experience.

Diagnostic Test

Data Normality Test: To be considered the data as the normal distribution, the skewness must be between 1 and -1 and kurtosis falls between 3 and -3 (Hair, Black, Babin, Anderson, and Tatham., 2006). The value of skewness and kurtosis for each of the variables are within the range (Table II). Therefore, it can be considered that all of the data are normally distributed.

(Insert Table II here) Data Reliability Test: The Cronbach's Alpha is conducted to measure the internal consistency among variables. The Cronbach's Alpha for relativism ethical orientation is 0.947, idealism ethical orientation is 0.956, internal locus of control is 0.723, external locus of control is 0.740, and ethical culture is 0.782. Out of all the figures above, it indicates that all variables are positively contributing to the overall reliability since the Cronbach alpha is higher than 0 .70.

Multicollinearity and Correlation Analysis:

Correlation examines the relationship between two variables in a linear fashion that helps to identify whether one variable is related to another. When variables are considered highly correlated to each other such as the value of coefficient is 0.8 or above, that relationship will cause a multicollinearity problem if [START_REF] Field | Discovering statistics using SPSS[END_REF]. Here, the correlations for all of the variables are below 0.8 for both scenario 1 and 2 (Table III). Therefore, it can be concluded that there is no multicollinearity problem available in the data.

(Insert Table III here) Moreover, multicollinearity problem can be tested if the VIF value is greater than 10, but the VIF value for all of the variables are below 10 in both scenarios (Table II). Therefore, no multicollinearity problem exists among the variables for both of the regression models.

Factor Analysis: Factor analysis is one of the methods used to reduce the large number of variables to a smaller set of underlying factors that contained all the essential information [START_REF] Pallant | SPSS survival manual[END_REF]. This method is used in this study to identify the underlying dimensionality of locus of control, ethical orientation and ethical culture. The Kaiser-Meyer Olkin test indicates all of the value are greater than .6 and chi-square are significant at p<0.000 (Table IV). Therefore, the sample is adequate to be used in this factorial analysis for all of the variables.

Based on the factor analysis, some variables are removed in the measurement when the loading is below 0.5. The value of the loading is given in appendix.

(Insert Table IV here)

Regression Analysis

The regression result shows the goodness fit of the model as the F-test is significant for both scenarios (Table V). In case of scenario 1, only relativism and ethical culture have significant relationships with the ethical sensitivity of auditors. In case of scenario 2, idealism is also found significant as well as relativism and ethical culture on ethical sensitivity of auditor.

(Insert Table V here)

Discussions of Findings

This study is conducted to examine the relationship between ethical orientation, locus of control and ethical culture towards ethical sensitivity among the auditors in Malaysia. The questionnaires were distributed to the auditors who worked with audit firms in Klang Valley area and registered with Malaysian Institutes of Accountants (MIA). In total, 155 respondents participated in this study. Based on the correlation analysis that has been conducted, it was found that ethical sensitivity has a significant negative relationship with relativism. This means that when relativism increased, ethical sensitivity decreased. Besides that, ethical sensitivity also has a significant positive relationship with idealism. This indicated that when idealism in a person is increasing, ethical sensitivity also increases. Whereas, based the regression analysis, it was found that there is a significant relationship only for ethical orientation in Scenario 1. Meanwhile, in Scenario 2, it was found that there is a significant relationship for both idealism and relativism. These findings are supported by [START_REF] Ismail | Effect of ethical ideologies on ethical judgment of future accountants:Malaysian evidence[END_REF] which found that a significant positive and negative impact of idealism and relativism on ethical judgment. Moreover, the result is also supported with the findings from Ozbek ( 2013) who stated that individuals with higher levels of ethical idealism are more likely to be aware of the ethical issue (ethical sensitivity). However, this result is inconsistent with the study from [START_REF] Douglas | The effect of organizational culture and ethical orientation on accountants' ethical judgments[END_REF] that ethical judgment was only affected by ethical orientation in illegal cases only. In another study by [START_REF] Chan | The effects of accounting students' ethical reasoning and personal factors on their ethical sensitivity[END_REF], authors found that there is a significant relationship between ethical orientation and ethical sensitivity, but the relationship is too weak.

From the findings, it is understood that the individuals with relativist normally make non ethical decision more often as compared to idealism individuals. Based on both scenarios, most individuals in Malaysia are more relativist in making their decision. This situation can be seen in the real situation where there are a lot of dishonest practices by the auditors such as in cases of Transmile Group Berhad and PKNZ Berhad. This situation happened as a result from failure of developing ethical sensitivity in oneself. Meanwhile, in Turkey study, they found that most of their auditors are more idealistic individuals as compared to the USA auditors that are more relativist [START_REF] Uyar | The ethical orientation and professional commitment: An empirical examination on Turkish accountants[END_REF]. So, it can be concluded that high or low in both idealism and relativism would defer based on the culture or environment.

Moreover, the results from scenario 1 and 2 showed a significant relationship between ethical sensitivity and ethical culture. The result is consistent with [START_REF] Sweeney | The impact of ethical culture of the firm and demographic variables on auditors' ethical evaluation and intention to act decision[END_REF] and [START_REF] Zakaria | Does organizational ethical climate influence auditors in perceiving ethical problems and forming ethical judgments?[END_REF] whereby it was found that ethical culture had an impact on intention to engage in unethical behaviour. It indicates, when ethical culture is high, auditors' ethical sensitivity can improve the abilities to detect any ethical issue. [START_REF] Fang | Evaluating ethical decision-making of individual employees in organizationsan integration framework[END_REF] found that ethical culture has built up ethical perceptions and indirectly helps individuals in making ethical decisions because individuals are compulsory to follow the code of conduct being enforced in the audit firms.

However, this study did not find any significant relationship between internal or external locus of control and ethical sensitivity for both scenario 1 and 2. This finding contradicted with the finding from the study by [START_REF] Lee | Locus of control, socialization, and organizational identification[END_REF] who used the same questionnaire and the authors found that there was a significant positive relationship. Meanwhile, Appiah and Addai (2014) also found a positive relationship between locus of control and performance. The authors recommended programs of their organizations. In a study by [START_REF] Paino | Auditor acceptance of dysfuntional model using individual factors[END_REF], they also found external locus of control is related to dysfunctional behaviour and it commits more unethical behaviour.

The inconsistency of result may be due to the culture of Malaysia or the target respondents as in this study, majority of the respondents are from audit assistants' level and fresh graduate. Maybe the problem to identify the ethical issue in the questionnaire might be difficult to them due to lack of experiences. [START_REF] Douglas | The effect of organizational culture and ethical orientation on accountants' ethical judgments[END_REF] claimed that any differences in the ethical cases lead to different ethical decision-making process. Therefore, to avoid any ethical issue from arising, the new audit staff especially fresh graduates should join the training on ethics. By joining the ethics training, it can ensure the ethics development among the new auditors after leaving the university.

Conclusions

The financial scandals involving high profile companies around the world had frustrated the public expectations. There are many reported cases of fraud, corruption and mismanagement due to the auditors' unethical behaviour. Therefore, this study investigated the influences of firm culture, locus of control, and ethical orientation on the ethical sensitivity of auditors in Malaysia. It was found that ethical sensitivity has a significant negative relationship with relativism. This means that when relativism increased, ethical sensitivity decreased.

Besides that, ethical sensitivity also has a significant positive relationship with idealism. This indicated that when idealism in a person is increasing, ethical sensitivity also increases. Moreover, it was found a significant positive relationship between ethical sensitivity and ethical culture. Therefore, this study recommends developing good ethical culture in the organization to increase the ethical sensitivity among the auditors. By having strong ethical sensitivity, it is believed that auditors could help in mitigating the incidences of fraudulent financial reporting from happen or re-occur [START_REF] Singh | Humanise corporate governorseradicating accounting fraud by augmenting ethical sensitivity and religiosity in accounting education[END_REF]. At the same time, proper monitoring and establishing rules, guidelines and penalties for any auditors that are involved with unethical actions may improve the ethical sensitivity of the auditors.

This study has been conducted with several limitations such as the target respondents were auditors' who worked in Klang Valey that were selected randomly. Therefore, the selection of the respondents from the big four audit firms is small. For the future study, it should attempt to replicate and use larger and more varied samples of target respondents that focus on all auditors in Malaysia with a variety of different audit task conditions and scenario that is more relevant. This would enhance the external validity of the findings. Other limitation is regarding the distribution of the questionnaire. In this study, questionnaires were distributed via mail, which caused a lot of problems compared if it had been conducted in person such as giving them by hand. When the questionnaires were sent by mail, it was hard to ensure that the targeted subjects answered the questionnaires, there was no guarantee that the mail was forwarded back and no guarantee that the answers were truthful. Finally, it is also recommended to further investigate the issue in broader context to generalize the findings of the study.

Appendix 1 :

 1 List of the items under each variable and related loading factorMany auditors within my firm will often place 'business pressures'(e.g. getting the audit done within time constraints or satisfying the client management etc.) ahead of the quality of the audit work.On some occasions, I have been either explicitly or implicitly pressured by supervisors in my firm to place the profitability of the audit firm ahead of the quality of audit work done.

				EC Q2	In my firm, I sometimes perceive that senior auditors engage in behaviours that I consider to be unethical.	0.54
	Variable Ethical Orientation Relativism		Item # EC Q3 Relativism Q1 EC Q4 EC Q5 Relativism Q2 EC Q6 Relativism Q3 Ethical beliefs cannot be compared in term of their "rightness". Item Name In my firm, I sometimes perceive that junior auditors engage in behaviours that I consider to be unethical. In my firm, unethical behaviour is promptly reprimanded when discovered if it results in personal gain. A code of ethics in an organization cannot be standardized because what is right and wrong depend on individual In my firm, unethical behaviour is promptly reprimanded when discoveredif it results in gain to the firm. perspective. Moral standards are based on individual judgment; one ethical In order to succeed in my firm, it is sometimes necessary to compromiseone's ethics. action might be seen as unethical by others. Relativism Q4 EC Q7 Top management in my firm has let it be known in no uncertain terms that unethical behaviours will not be tolerated. My ethical belief about what is right or wrong is only Often I feel that my firm's stance on ethics is just 'window applicable for me, and it cannot be compared to others. Relativism Q5 EC Q8 dressing' to maintain their public image and has no real I have no right to judge other people's action because my moral principle applies only for me. substance. Relativism Q6 Individuals should be allowed to form their own standards because ethical considerations vary from one person to another. EC Q9	0.70 Factor Loading 0.66 0.87 0.70 0.90 0.75 0.87 0.11* 0.85 0.49* 0.88 0.86 0.57
		Idealism Ethical Orientation		Relativism Q7 Idealism Q5 Idealism Q6 Idealism Q4 Idealism Q1 Idealism Q3 EC Q10 Idealism Q2 EC Q11	No standard of ethical action can be formulated; it depends upon the situation surrounding the action. An action that could harm other people should never be considered. The dignity and welfare of other people is my major concern. One should not perform an action which might threaten the dignity and welfare of other people. People should make certain that their actions never intentionally harm other people even to a small degree. The existence of potential harm to other people should always be avoided. My firm is known as a leader in promoting professional ethics within the profession (reversed). Risks to other people should never be tolerated, irrespective of how small the risks might be.	0.88 0.91 0.90 0.89 0.93 0.88 0.41* 0.86 0.18*
				Idealism Q7	It is never necessary to sacrifice the welfare of other people.	0.86
				Internal Q1	A job is what you make of it.	0.55
		Control		Internal Q2 Internal Q3	On most jobs, people can pretty much accomplish whatever they set out to accomplish. If you know what you want out of a job, you can find a job that gives it to you.	0.74 0.64
		of Locus		Internal Q4 Internal Q5	If employees are unhappy with a decision made by their boss, they should do something about it. Getting the job you want is mostly a matter of luck.	0.66 0.54
		Internal		Internal Q6 Internal Q7	Making money is primarily a matter of good fortune. Most people are capable of doing their jobs well if they make the effort.	0.58 0.59
				Internal Q8	In order to get a really good job, you need to have family members or friends in high places.	0.49*
				External Q1	Promotions are usually a matter of good fortune.	0.58
		Control of Locus		External Q2 External Q3 External Q4 External Q5	When it comes to landing a really good job, who you know is more important than what you know. Promotions are given to employees who perform well on the job. To make a lot of money you have to know the right people. It takes a lot of luck to be an outstanding employee on most jobs.	0.69 0.73 0.77 0.38*
		External		External Q6 External Q7	People who perform their jobs well generally get rewarded. Most employees have more influence on their supervisors than they think they do.	0.34* 0.61
				External Q8	The main difference between people who make a lot of money and people who make a little money is luck.	0.34*
	Ethic	al Cultu	re	EC Q1	In my firm, I sometimes perceive that managers and partners engage in behaviours that I consider to be unethical	0.60

* indicates the removed item where factor loading is below 0.5

Appendix 2: List of Scenarios Scenario 1:

A public accounting firm has recently acquired a new client with a very low bid. The partner suggests the audit hour budget for inventory-related items will be 100 hours. The senior's experience with similar clients suggests that in order to have reasonable assurance of no material errors or irregularities, the audit will take a minimum of 150 hours. Performance evaluation is based in part on efficiency.

Action:

The senior accepts the budget as is. The senior's plan is to do all necessary work to provide reasonable assurance but to underreport actual hours worked.

Scenario 2:

An audit client who also receives considerable tax services has a difference of opinion with the auditor as to when to recognize certain revenue transactions in which there is some uncertainty regarding the collectibility of the receivables. Recently a competitor soliciting auditing and tax services has approached the client. The firm has been a client for 20 years but has recently had a change in management.

Action:

The partner in charge of the engagement accepts the client's interpretation of the receivables Both of the scenarios followed with below questions: Are the issues within the scenario likely to have a significant impact on the financial statements: 4

How important are the issues in the scenario?


Maelig Marquet

W Ben Hania

Chantal Thorin

Laurence Guilbert-Julien

Helene Quinton

Jean Michel Pol

Philippe Escouflaire

Ludivine Chevrier

Julie Gard

Pascale Chavatte-Palmer

Are antibiotics still truly needed in bovine embryo collection media? A preliminary study

niveau recherche, publiés ou non, émanant des établissements d'enseignement et de recherche français ou étrangers, des laboratoires publics ou privés.

Are antibiotics still truly needed in bovine embryo collection media ? A preliminary study

The aim of this study was to evaluate whether or not the removal of antibiotics from collection media leads to an additional risk compared to the standard procedure @oniris

PURPOSE MATERIAL AND METHODS

80 prim'holstein donors (12.9 months average age)donors were divided into two groups, a control group, batch A: n=40; collected with Euroflush ND with antibiotics (ND IMV technologies, 61300 L'Aigle France with antibiotics) and a second group, batch B: n=40; collected with Euroflush without antibiotics, IMV technologies, 61300 L'Aigle France) without antibiotics. The rest of the procedure was identical in both batches, the embryos underwent ten washes containing gentamicin 0.05g/L and kanamycin 0.1g/L. 80 Prim'holstein donors (12.9 months average age) were divided into two groups, " Batch A (control group) : n=40; collected with Euroflush ND with antibiotics (IMV technologies) " Batch B: n=40; collected with Euroflush without antibiotics (IMV technologies).

All the embryos underwent ten washes containing gentamicin 0.05g/L and kanamycin 0.1g/L before transfer (fresh or frozen).

The sample from the last wash was tested for bacterial count (<100 CFU/mL considered free from pathogens) , the sample from the collection medium was tested for mycoplasma .

The size of this study was determined considering a logistic regression model, with a probability of non-infection of 0.99 for the standard procedure (with antibiotics) and of 0.95 for the batch without antibiotics, a power of 0.8 and a significance level of 0.05.

RESULTS

@ Escouflaire

Batch

CONCLUSION

The removal of antibiotics from the collection medium does not induce additional bacterial contaminations.

These first results are very encouraging, further studies with more samples are necessary to confirm the results.

! Bacterial contamination: no statistical differences between A and B (exact Fischer test, p-value = 0,3467).

1

  Marquet 1 , Wajdi Ben Hania 2 , Chantal Thorin 1 , Laurence Guilbert-Julien 2 , Helene Quinton 3 , Jean Michel Pol 4 , Philippe Escouflaire 4 , Ludivine Chevrier 5 ,Julie Gard 6 , Pascale Chavatte-Palmer 7 , Lamia Briand-Amirat 1 Oniris, 44300 Nantes, France ,2 LNCR Maisons-Alfort, France, 3 Evolution 44240 Sucé sur Erdre, 4 Embryovet, 44115 Haute-Goulaine, France, 5 IMV Technologies, L'Aigle, France, 6 Auburn University, USA, 7 D-Breed, INRAE Jouy en Josas, France . ! The OIE recommends the addition of antibiotics to bovine embryo collection media (OIE Terrestrial Code, Chapter 4.8.6), ! Embryos undergo 10 baths of IETS regulatory washes containing antibiotics. ! A pressing demands for veterinarians to decrease the use of antibiotics.

!

  Mycoplasma: not found ! Number of viable embryos : no significant differences (n=196, p-value=0.42 Wilcoxon test), ! Success rate of embryo transfers: not significantly different ( p-value=0.84 χ² independence test) CFU: Colony-forming unit

Table 1 : Results for microbiological controls. Table 2: Results for embryo transfer succes rate.

 1


Céline Burel

Omar Ibrahim

Emanuele Marino

Harshit Bharti

Christopher B Murray

Bertrand Donnio

Zahra Fakhraai

Rémi Dreyfus
email: remi.dreyfus@cnrs.fr

Tunable Plasmonic Microcapsules with Embedded Noble Metal Nanoparticles for Optical Microsensing

Keywords: microcapsules, nanoparticles, plasmon coupling, emulsion, silica 2 ToC

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Introduction

In the last decades, inorganic, organic and carbon-based nanoparticles (NPs) have become prominent components in the development of new technologies due to their unique physical, chemical and biological properties. [START_REF] Ealias | A Review on the Classification , Characterisation , Synthesis of Nanoparticles and Their Application[END_REF][START_REF] Heiligtag | The Fascinating World of Nanoparticle Research[END_REF] In comparison with bulk materials, and because of their small size and larger surface area to volume ratio, NPs show enhanced properties such as reactivity, mechanical strength, sensitivity, stability, thermal conductivity, catalytic activity, light absorption and scattering. [START_REF] Heiligtag | The Fascinating World of Nanoparticle Research[END_REF][START_REF] Daniel | Gold Nanoparticles : Assembly , Supramolecular Chemistry , Quantum-Size-Related Properties , and Applications toward Biology , Catalysis , and Nanotechnology[END_REF] Nanoparticles assembled into two-or three-dimensional architectures offer new collective optical, magnetic and electronic properties. [START_REF] Podsiadlo | Multicomponent Periodic Nanoparticle Superlattices[END_REF][START_REF] Boles | Self-Assembly of Colloidal Nanocrystals : From Intricate Structures to Functional Materials[END_REF] For instance, due to plasmon coupling, closely packed gold (Au) and silver (Ag) NPs absorb light at longer wavelengths than when they are several tenth of nanometers apart. [START_REF] Myroshnychenko | Modelling the Optical Response of Gold Nanoparticles[END_REF][START_REF] Chen | Space-Confined Seeded Growth of Black Silver Nanostructures for Solar Steam Generation[END_REF][START_REF] Feng | Surface Engineering and Controlled Ripening for Seed-Mediated Growth of Au Islands on Au Nanocrystals[END_REF] To fully benefit from these new collective properties, the spatial organization of the NPs often needs to be carefully controlled. [START_REF] Boles | Self-Assembly of Colloidal Nanocrystals : From Intricate Structures to Functional Materials[END_REF][START_REF] Si | Nanoparticle Superlattices : The Roles of Soft Ligands[END_REF][START_REF] Sperling | Surface Modification , Functionalization and Bioconjugation of Colloidal Inorganic Nanoparticles[END_REF] Such spatial organization can be obtained from spontaneous self-assembly of NPs in solution. [START_REF] Boles | Self-Assembly of Colloidal Nanocrystals : From Intricate Structures to Functional Materials[END_REF][START_REF] Yi | Polymer-Guided Assembly of Inorganic Nanoparticles[END_REF] Recently, Pickering emulsions have been used as templates for the self-assembly of NPs into micron-size supracolloidal 3D structures called colloidosomes. 12,[START_REF] Dinsmore | Colloidosomes: Selectively Permeable Capsules Composed of Colloidal Particles[END_REF] In the design of these structures, NPs are used as building blocks. Colloidosomes are then converted into mechanically resistant and less porous microcapsules (MCs) by external locking steps such as particles crosslinking, macromolecules adsorption or interfacial polymerization. [START_REF] Thompson | Colloidosomes : Synthesis , Properties and Applications[END_REF] These MCs can be tailored to several applications and dispersed in a wide range of media, while combining properties directly resulting from the details of the core (size, shape and type of NPs) and shell (thickness, elasticity, porosity…) (see Figure 1). Initially, the intended primary use of these new structures was the encapsulation and the controlled release of active ingredients. [START_REF] Dinsmore | Colloidosomes: Selectively Permeable Capsules Composed of Colloidal Particles[END_REF][START_REF] Thompson | Colloidosomes : Synthesis , Properties and Applications[END_REF] With the development of preparation methods and nanoparticles, the application range has extended to other applications in optics as strong absorbers, [START_REF] Liu | Plasmonic Colloidosomes with Broadband Absorption Self-Assembled from Monodispersed Gold Nanospheres by Using a Reverse Emulsion System[END_REF] in catalysis, [START_REF] Jeong | Fabrication of Stable Nanoparticle-Based Colloidal Microcapsules[END_REF][START_REF] Zhang | Encapsulation of Laccase in Silica Colloidosomes for Catalysis in Organic Media[END_REF] in biomedical engineering for photo acoustic imaging and photo thermal therapy [START_REF] Huang | Biodegradable Gold Nanovesicles with Ultra-Strong Plasmonic Coupling Effect for Photoacoustic Imaging and Photothermal Therapy[END_REF] and in mechanical and chemical sensing (Figure 1). [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF][START_REF] Burel | Plasmonic Elastic Capsules as Colorimetric Reversible pH-Microsensors[END_REF][START_REF] Phan-Quang | Plasmonic Colloidosomes as Three-Dimensional SERS Platforms with Enhanced Surface Area for Multiphase Sub-Microliter Toxin Sensing[END_REF][START_REF] Turek | Self-Assembled Spherical Supercluster Metamaterials from Nanoscale Building Blocks[END_REF] Lately, an increasing research interest has been dedicated to the integration of several types of nanoparticles into multi-functional colloidosomes or MCs. Despite the interest of the scientific community, only few examples of this new type of supracolloidal object have so far been reported.

For instance, Bollhorst et al. reported colloidosomes with two types of nanoparticles (superparamagnetic iron oxide and fluorescent silica) which could be useful in various biomedical applications including biosensing and bioimaging. [START_REF] Bollhorst | Bifunctional Submicron Colloidosomes Coassembled from Fluorescent and Superparamagnetic Nanoparticles[END_REF][START_REF] Wu | Recent Studies of Pickering Emulsions: Particles Make the Difference[END_REF] Additionally, Chen et al. have made permeable TiO2-polystyrene hybrid hollow sphere by emulsion templating which present many applications in the field of drug release and photocatalysis. [START_REF] Chen | Organic -Inorganic Hybrid Hollow Spheres Prepared from TiO 2 -Stabilized Pickering Emulsion Polymerization[END_REF] Recently, we have reported the synthesis of a novel family of multifunctional hybrid micro objects, namely plasmonic-based mechanochromic MCs, [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] and we have demonstrated that they are excellent candidates for microsensing. These MCs made of plasmonic Au NPs and silica polymer, change color under elongation and demonstrate their use as a local optical detector for sensing mechanical strain at the microscale. Though the color-change effect has already been reported, the ability to tune important features of plasmonic MC's has not yet been evidenced. In this manuscript, we show how to improve the properties of these MCs by investigating: the various parameters that can impact the adsorption of nanoparticles on oil droplets, the additional formation of the silica shells around the droplet, and the advantages afforded by using a combination of two types of NPs, which allows further tunability and color variations. This work is of importance as it widens the range of applications of these microsensors (see Figure 1). In this article, we present a comprehensive description of the synthetic conditions that lead to MCs made of hard silica shell, with tunable plasmonic properties. Briefly, the MCs were obtained from Pickering emulsions made of metallic NPs placed at the oil/water interface. Then, a subsequent silanization reaction locks the NPs at the interface and leads to the formation of silica MCs with NPs embedded in the silica shell (Figure 2 (a)). We show that the pH of Au NPs impacts their adsorption on the emulsion and hence the color of the final MCs. We show that the adsorption of Au NPs at the oil/water interface takes several hours to reach a final packing of 52%. Then, we demonstrate how the thickness of the silica crust can be controlled and how it influences the mechanical robustness of the MCs. Furthermore, we show that several oils can be used for the synthesis of MCs and that the relative solubility of the silica precursor and the polarity of the oil phase can also influence the final MC properties. We also demonstrate the synthesis of "monoflavor" and "multiflavor" MCs, with, respectively, a single component or a mixture of metallic NPs embedded in the silica shell. Finally, we demonstrate using a combination of simulations and experiments that the MCs optical properties can be finely adjusted by mixing Au and Ag NPs in different ratios. Controlling the optical and mechanical characteristics of MCs used as sensors is key to significant improvement in microsensing.

Experimental section

Materials: Gold (III) chloride trihydrate (HAuCl4, 99.9%, Sigma-Aldrich), polyethoxyorthosilicate (PEOS, Scientific Polymer Products Inc), hydrochloric acid (HCl, ACS reagent, 37%, Sigma-Aldrich), toluene (Chromasolv Plus, 99.9%, Sigma-Aldrich), 1-butanol (ACS reagent, 99.4%, Alfa Aesar), Poly (diallyldimethylammonium-nitrate -co-1vinylpyrrolidone), (PVP-DADMAN, Solvay®, full structural formula available in Figure S1 of the supplementary information), sodium hydroxide (NaOH, 50%, Sigma Aldrich), ascorbic acid (ACS reagent, 99.4%, Sigma Aldrich), hexyl acetate (99%, Sigma Aldrich), hexadecane (anhydrous, 99+%, Sigma Aldrich). Deionized water was used for all experiments.

Au NPs synthesis: The Au NPs were synthesized by the reduction of HAuCl4 with ascorbic acid and PVP-DADMAN. A solution of 6.10 -6 M PVP-DADMAN and 2.510 -3 M of HAuCl4 was brought to boil. Then, 12.5 mL of ascorbic acid (0.1 M) was added. The solution was protected from light by aluminum foil and stirred for 1 h at 97°C. The Au NPs were then left to rest for one day to remove the largest NPs. The remainder of the dispersion was centrifuged and concentrated into a few milliliters solution.

Ag NPs synthesis: The Ag NPs were synthesized by the reduction of AgNO3 with ascorbic acid. A solution of 6.10 -6 M PVP-DADMAN and 5 .10 -3 M of ascorbic acid mixed with 0.17 mL of sodium hydroxide (0.02 M) was brought to boil. Then, 0.53 mL of AgNO3 (1.2 M) was added.

The solution was protected from light by aluminum foil and stirred for 1 h at 95°C. The Ag NPs were left to rest for one day to remove the largest nanoparticles. The remainder of the dispersion was centrifuged and concentrated into a 5 mL solution.

Au NP-Silica MCs synthesis (pH ̴ 10): PEOS (0.2 g/mL) was diluted in 1 mL of toluene.

The water phase (5 mL) of the emulsion contained a solution of dispersed Au NPs ([Au 0 ] = 0.02 M), butanol (0.22 M) and ammonia (10 -4 M) to adjust pH ̴ 10. The oil and water phases were emulsified together with a Brandson 3210 ultrasonic bath at 30°C for 15 minutes. After 3 days, the silica shell was fully formed. The MCs were recovered, cleaned and concentrated by simple sedimentation.

Au NPs-Silica MCs synthesis (pH ̴ 1.2): 0.2 g of PEOS was diluted in 1 mL of toluene. The water phase (5 mL) of the emulsion contained a solution of diapered Au NPs ([Au 0 ] = 0.02 M), butanol (0.1 mL) and HCl (50 -150 µL) to adjust pH to about 1.2. The oil and water phases were emulsified together (Brandson 3210 ultrasonic bath) at 30°C for 15 minutes. After 3 days, the silica shell was fully formed. The MCs can be recovered, cleaned and concentrated by simple sedimentation.

Ag NPs-Silica MCs synthesis: the protocol used was the same as the one for the Au NPs-Silica MCs (pH ̴ 1.2). The water phase contained Ag NP at 0.6 wt% instead of Au NPs.

Ag-Au NPs-Silica MCs synthesis: the protocol used was the same as the one for the Au NPs-Silica MCs (pH ̴ 1.2). Mixtures of Au and Ag NPs in different wt% ratios were used instead of Au NPs alone.

Electron microscopy: Shape and size of the MCs were analyzed by SEM. Scanning electron microscopy (SEM) was performed on JEOL 7500 HRSEM. The samples were prepared by air drying under ambient conditions a drop of MCs dispersion on an electron microscopy carboncoated copper grid. Environmental scanning electron microscopy (ESEM) was conducted on a FEI Quanta 600 at 1.5 Torr using water vapor. Transmission electron microscopy (TEM) was carried out on a JEOL JEM-1400 electron-microscope. The accelerating voltage was set at 120 kV.

Optical characterization: The color, shape and size of the MCs were analyzed by optical microscopy. Optical microscopy images were acquired on an Olympus microscope in bright field and transmission mode. Images were taken with a 100x objective oil of NA 1.4; no filter was used.

The camera used was a Sony α Nex-7 color camera. The illumination power was set to a third of the Intensity of a 100 W lamp and the acquisition time was 10 ms. For the image analysis, the contour of each capsule on the image was detected and the red level of the intensity on the 8 bits color camera was recorded. The red color is the average performed on a circle of size R/2 by R/2 centered in the middle of the capsule where R is the radius of the capsule. No background subtraction was performed. Optical extinction spectra were recorded in transmission mode using a Cary 5000 spectrophotometer. Single MC extinction spectra were collected using a CRAIC microspectrophotometer mounted on an Olympus BX51 optical microscope equipped with a 40x air objective and a 100W halogen lamp. The spectra start at 450 nm due to the limit of detection of the microspectrophotometer used (Figure S2).

Photo images of vials were taken with a Canon Power shot SX210IS camera (Figure S3). Simulations: to simulate the optical properties of NPs in silica films, we need to generate NPs packing that closely resemble the local packing structures on the surface of experimental MCs.

We note that we are unable to directly simulate entire microcapsules given their large size, so instead, flat layers resembling the local NP packings are generated. One approach to generate these simulated packings is to take experimental SEM images of NPs at the surface of MCs and to identify the perimeter of each NP. This is the first approach that was adopted, NP perimeters were manually identified, and, assuming NPs were perfectly spherical, we were able to reconstruct a packing of NPs. The packings obtained by this method are designated as "SEM packings". This method, though efficient, has one drawback: for mixtures of Au and Ag NPs, we cannot identify whether an observed NP is Au or Ag. To overcome this problem, we numerically generated packings close to the experimental ones.

To generate these packing, we used the DCCP software, available at the url: https://github.com/cvxgrp/dccp. The DCCP software uses an algorithm, which minimized the total surface area occupied by a population of NPs: hence ensuring a tightly packed assembly. This can be done by entering, as an input, a set of NPs (Au and/or Ag) with each NP having a previously assigned diameter. The diameter for each NP was randomly chosen within a lognormal distribution, the parameters of which were measured using SEM images of NPs. More details are provided in the Supplementary information section (Figure S4). Such a method based on the DCCP software allowed us to generate very close packed assemblies of pure Ag or Au NPs and mixture of both NPs. By using parameters that were measured experimentally, we could create packings that are very close to the experimental ones. . These packings are designated as "DCCP packings" and are used for data shown in the last figure. We note that there is a larger potential difference between the DCCP packings and their experimental counterparts, given the larger fluctuations both in size and material type for these packings. As such, these simulations can only provide a qualitative comparison with the experimental data.

To evaluate the importance of the polydispersity of the packing, we generated similar random packing, but with a monodisperse population of NPs rather than a polydisperse population.

The DCCP software is not the right tool to generate such a packing: since the algorithm is based on a minimization of the occupied area fraction, starting from a monodisperse population, it would only generate a very ordered crystalline pattern, possibly with a few defects and dislocations in the crystalline domain. Therefore to create monodisperse packings we used a different strategy. We distributed the monodisperse beads using a Monte Carlo simulation with a hard spheres potential to allow for a level of disorder. This potential was slightly modified with an extra term that harshly penalized touching beads to ensure that the NPs remained separate and periodic boundary conditions were also applied. Ordered monodisperse packings were generated by replacing this potential with an electrostatic potential at 0K. The structures were then imported into a Finite Difference Time Domain (FDTD) simulation package (Lumerical Solutions) for optical analysis. The NPs were embedded at the center of a 60 nm thick silica slab (see the Supplementary section) and NPs larger than the layer, were covered with an additional 3 nm silica coating applied, to ensure that they are engulfed in silica similar to the experiments. Simulations were performed with a periodic boundary in the plane of the NPs to resemble the local microcapsules environment and transmission coefficient was calculated in the normal direction (details in the Supplementary information section, Figure S5). A comparison of the SEM and DCCP packings simulations can be found in Figure S6. The obtained simulated extinctions were compared with the experimental extinction of the MCs.

Results and discussion

Adsorption of NPs

The MCs synthesis by emulsion template using Au NPs is schematized in Figure 2 (a). A solution of toluene containing PEOS, is emulsified in the continuous aqueous phase of the previously synthesized Au NPs. A Pickering emulsion stabilized by Au NPs is obtained. [START_REF] Sperling | Surface Modification , Functionalization and Bioconjugation of Colloidal Inorganic Nanoparticles[END_REF] The Au NPs are further locked at the oil/water interface by interfacial polycondensation of the PEOS giving rise to a silica crust embedding Au NPs. [START_REF] Wang | All-Silica Colloidosomes with a Particle-Bilayer Shell[END_REF][START_REF] Zhao | Microencapsulation of Hydrophobic Liquids in Closed All-Silica Colloidosomes[END_REF] First, Au NPs functionalized with poly(diallyldimethylammonium-nitrate-co-1-) vinylpyrrolidone (PVP-DADMAN ® , full structural formula available in Figure S1, are synthesized by reduction of Au salt with ascorbic acid. [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF][START_REF] Burel | Plasmonic Elastic Capsules as Colorimetric Reversible pH-Microsensors[END_REF][START_REF] Zhang | Shape-Selective Synthesis of Gold Nanoparticles with Controlled Sizes, Shapes, and Plasmon Resonances[END_REF][START_REF] Malassis | One-Step Green Synthesis of Gold and Silver Nanoparticles with Ascorbic Acid and Their Versatile Surface Post-Functionalization[END_REF] The precise synthetic protocol is described in details in the Methods Section. The Au NPs obtained are polydisperse, the mean diameter is δ = 30 nm ± 11 nm and the maximum of their sharp plasmon peak is situated at λmax ~ 525 nm (TEM images, histogram of size distribution, and extinction spectrum of the Au NPs can be found in Figure 2 (b-c)). In this size range, the polydispersity does not affect the position of the plasmonic peak but results in a small broadening of this peak. [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] We have previously shown that the Au NPs adsorption and packing on oil droplets require: i) The right hydrophobic/hydrophilic balance of the NPs, ii) the neutralization of the charges at the NPs surface and iii) the use of rather large quantities of NPs. [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] In contrast, at pH ̴ 1.2, shortly after sonication, the emulsion exhibits an intense pink color (Figure 2 (i)). The silica shell obtained by polycondensation of the PEOS at the interface is fully formed after three days of polymerization at room temperature. [START_REF] Wang | All-Silica Colloidosomes with a Particle-Bilayer Shell[END_REF] The MCs optical microscopy and SEM images are presented in Figure 2 (f-h) and (j-l). At pH ̴ 10, colorless spherical MCs without Au NPs embedded in the silica shell are observed (Figure 2 (f-h Concomitantly both S and V decrease, proving that more light is absorbed by the MCs due to both an increase of the packing of NPs at the interface and the plasmon absorbance due to the coupling between the Au NPs. Additionally, σ (radius of oil droplets normalized by the radius of oil droplets at 0 min) remains constant over time. This demonstrates that the color change of the droplets is due to the Au NPs packing on the droplets' surface through the NPs adsorption over time rather than caused by evaporation of the solvent inside the droplets which would also lead to a decrease of the NPs interparticle distance hence to a change of color. The experimental extinctions of the blue Au MCs were obtained using a microspectrophotometer and were compared with calculated extinctions of closely-packed Au MCs and loosely packed Au MCs obtained by FDTD simulations (Figure 4 (a)). We reconstructed pure Au NPs packing from SEM images and used these packings ("SEM packings") to compute the transmission and extinction E0 (pure Au NP MCs) through a surface of packed NPs embedded in a silica medium. The extinction calculations were performed using FDTD simulations as detailed in the Materials and Methods section as well as in the Supplementary information section.

We use the notation "d" for the mean separation distance between NPs (distance surface to surface). A good agreement between the spectral features of experimental and simulated extinctions was obtained for d = 1.9 nm and φ =51% volume fraction in the case of the blue MCs and for d = 35.9 nm and φ = 9.8% in the case of the loosely packed Au MCs (based on other experiments not shown here, these MCs are pink). For the simulated pink MCs, a sharp plasmon peak was observed at 542 nm corresponding to the extinction peak of well-dispersed Au NPs (λmax ~ 525 nm) red-shifted due to the presence of the silica and toluene. For the experimental blue MCs, a wide plasmon band around 700 nm was observed and a small plasmon shoulder around 535 nm corresponding to the peak of dispersed Au NPs (see Figure S2 for more blue MCs optical spectra).

The simulated extinctions of the MCs as a function of the distance between the Au NPs are reported in Figure 4 (b). As the distance between the Au NPs decreases, the intensity of the plasmon peak of uncoupled Au NPs (530 nm) decreases while the wide plasmon band characteristic of coupled Au NPs is red-shifted and its intensity increases. The maximum of the plasmon peaks around 542 and 655 nm as a function of the mean separation distance between Au NPs ("d") are shown in Figure 4 (c). Both shifts can be reasonably fit to an exponential decay function with a decay length (d*) of about 6-8 nm, which is approximately about 20-25% of the Au NPs mean diameter. This is consistent with previous data reported in the literature for single pairs of NPs. [START_REF] Zhang | Shape-Selective Synthesis of Gold Nanoparticles with Controlled Sizes, Shapes, and Plasmon Resonances[END_REF] The maximum of the plasmon peaks around 542 and 655 nm as a function of the packing of Au NPs (φ) are shown in Figure 4 (d). Interestingly, we found that we can extend the principle of the "ruler equation" described by Jain et al. [START_REF] Jain | On the Universal Scaling Behavior of the Distance Decay of Plasmon Coupling in Metal Nanoparticle Pairs : A Plasmon Ruler Equation[END_REF] derived for 2 isolated NPs to the case of NPs packings. Using the scaling derived by Hoffman and Kevelam, [START_REF] Hoffmann | Model for the interparticle surface separation in mono-and polydisperse suspensions[END_REF] we can relate the mean separation distance between nanoparticles (d) to the area fraction φ. In a 2 dimensional system:

d = 2𝑟𝑟( � φ m φ -1),
where r is the AuNPs' mean radius (15 nm), φm is the maximum area fraction of a polydisperse packing. We find that by adjusting φm to 0.55, and replacing d in the "ruler" equation by the above equation, we can fit with accuracy the position of the plasmonic peaks when it is plotted versus the area fraction φ. This shows that the characteristic d* extracted from the "ruler" equation equates the mean distance between the AuNPs in a random packing. It is important to emphasize the fact that with the same φm, the curves for both peak are well adjusted. This result shows that it is possible to predict the positions of plasmonic peaks when the packing fraction is changed.

Morphology of the silica shell

The brittleness of the MCs has a significant impact on the mechanical and therefore on the final optical output of the MCs used as sensors. A shell more brittle leading to sensing of more minute mechanical deformations for instance. The impact of the concentration of PEOS ([PEOS]) on the thickness of the shell and on the mechanical robustness of the MCs is presented in Figure 5. Based on the SEM images of the crust shown in Figures 5 (a-e) and the graph in Figure 5 The "top half "of the shell fell inside the "bottom half" of the shell (see Figure 5 (f)). Upon increase of [PEOS] (0.2 g/mL), the formed silica shell is thicker (about 61 nm, Figure 5 (c) and(f)). At these concentrations, the MCs retain their spherical shape upon drying as shown in Figure 5 (f)).

For [PEOS] ~ 0.2 g/mL, the obtained MCs remain spherical upon drying (see Figure 5 (f)). The silica shell becomes thicker for 0.3 and 0.4 g/mL of PEOS (Figure 5 (d), (e) and(f)). The thickness of the silica shell had very little to no impact on the optical properties of the MCs. Indeed, the MCs with different shell thickness have similar blue color to the naked eye (Figure 5 ((a) -(e))) and the simulated extinction of Au NPs tightly packed within silica layers of different thickness overlap (Figure S7). The results presented here are consistent for MCs of diameter ≤ 10 µm which constitutes the majority of the samples observed. For the few capsules of diameter above 10 µm, 0.2 g/mL of PEOS was not enough to avoid buckling, which suggests that not only the thickness of the silica shell matters but also the ratio between the size of the MCs and the shell thickness is an important parameter to consider. So far, we have demonstrated the successful synthesis of MCs with toluene; [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] it is therefore questionable whether this approach can be generalized to other organic solvents. The fabrication process of MCs was extended to hydrophobic oils of different polarity. Whilst keeping the exact same formulation ([Au 0 ] = 0.02 M, [Butanol] = 0.22 M, [PEOS] = 0.2 g/mL, pH ̴ 1.2), toluene slightly soluble in water was first replaced by a very hydrophobic oil insoluble in water and nonpolar (hexadecane), and then by a mixture of hexadecane/hexyl acetate (50/50 by volume) to increase the oil polarity of the oil phase. The MCs obtained using hexadecane and hexadecane/hexyl acetate are shown in Figure 6 (a), (d) and (c), (f) and are compared to the ones obtained with toluene (Figure 6 (b), (e)). Simulations presented in Figure S8 show that changing the oil has very little impact on the extinction of the MCs. This is most likely due to two factors: i) the 3 oils studied have close refractive index and ii) the formation of a silica shell for the three oils studied. All the MCs obtained are blue (Figure 6 (a-c)) due to the close packed Au NPs embedded in their shells (see insets of Figure 6 (d) and(f)). In the case of hexadecane, which is the least polar solvent, numerous broken MCs can be seen in Figure 6 (a). Upon increase of the polarity using either toluene or hexadecane/hexyl acetate mixture, the MCs obtained are undamaged (Figures 7 (b-c)). The observed lack of solubility of PEOS in the least polar solvent, here hexadecane (hazy mixture, see Figure S3 (a)), limits the formation of a robust silica shell at the oil/water interface for larger MCs and actually leads to the formation of silica particle (see Figure S3 (b)). Upon increase of the oil polarity, PEOS becomes fully miscible in the oil and permits the formation of the silica shell at the oil/water interface. The polarity of the oil also influences the solubility of PEOS hydrolyzed in acidic condition. Due to its increased polarity, hydrolyzed PEOS is more soluble in polar solvent. Thus, hydrolyzed PEOS is poorly soluble in hexadecane alone. In the presence of hexyl acetate, hydrolyzed PEOS can desorb from the interface due to its increased solubility in the oil phase rendering the interfacial polycondensation more difficult (less robust shell buckle upon drying, Figure 6 (f)). The polarity of toluene is between the polarity of hexadecane and the one of the hexadecane/hexyl acetate mixture. Thus, with toluene, PEOS is fully soluble in the oil phase and hydrolyzed PEOS is "locked" at the oil/water interface therefore favoring interfacial polycondensation and the formation of robust MC shell. A noticeable thicker silica shell can be observed with toluene in Figure 6 (e) as compared to the two other solvents/solvents mixture (Figure 6 hexadecane, (e) toluene and (f) hexadecane/hexyl acetate 50/50 V/V. Insets show the surface of a typical MC for (d) hexadecane and (f) hexadecane/hexyl acetate 50/50 V/V. All syntheses are carried out with 0.2 g of PEOS.

"Multiflavor" microcapsules

So far, only synthesis of MCs with one kind of NPs embedded in the silica crust have been reported. [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] This synthesis fact limits our ability to tune the optical characteristics of MCs used as optical microsensors. To allow such a tunability, NP-silica MCs synthetic method is extended to different types of NPs and mixture of NPs to create the so-called "multiflavor" MCs. Silver (Ag) NPs are synthesized by following a similar protocol to that used to synthesize Au NPs (see experimental section). The obtained Ag NPs are polydisperse as shown by the TEM image and the histogram of the distribution of sizes (Figure 7 (a)). The mean diameter of the Ag NPs is around 33 +/-13 nm. Ag NPs exhibit a sharp plasmon absorption (λmax ~ 417 nm) and a yellow color from pH 0.6 to pH 9 as shown in Figure 7 (b). Zetametry experiments show that Ag NPs are very weakly charged (ζ potential ~ 0 mV) and remain well dispersed in water at pH ranging from 1 to 11. These observations suggest that unlike the Au NPs, the Ag NPs are not stabilized by electrostatic charges coming from ascorbic acid adsorbed at the NPs surface but are instead primarily sterically stabilized by the PVP-DADMAN ® . This result is consistent with previous literature referencing that PVP interact, adsorb and strongly stabilize Ag NPs. [START_REF] Wiley | Synthesis of Silver Nanostructures with Controlled Shapes and Properties[END_REF] Silver-silica MCs are synthesized with Ag NPs embedded in the silica crust by following the same emulsion template process as the one used for Au MCs. Toluene was chosen as the oily phase. We observe that Ag NPs adsorb at the interface oil/water at any pH, which is consistent with the fact that Ag NPs have a very low surface charge, which does not depend on pH (Figure 7 8 (g-i) (see details in the experimental section). Overall, a good agreement between the experimental (Figure 8 (h)) and simulated (Figure 8 (i)) spectra are observed. For pure Au NPs, the extinction curves shows a very wide extinction peaks around 700 nm likely resulting from the superposition of peaks due to the distribution of surface to surface separation in a random packing. The second peak (or shoulder) of absorption is visible at around 525 nm: it corresponds to the regular absorption peak of uncoupled NPs. [START_REF] Zámbó | Optical Simulations of Self-Assembly Relevant Gold Aggregates : A Comparative Study[END_REF] This peak becomes more and more dominant over the coupled Au NPs peak as the amount of Ag is increased. Differences between experimental and simulated extinction curves can be explained by the fact that microspectrometry allows us to measure the optical properties on a scale of the order of about 10 µm, whereas, simulations provide optical properties on a scale of about 300 nm. As such, simulated packings lack heterogeneities in particles size and interparticle distance. Moreover, simulations do not capture the pathway of light through the inside of the MCs.

Our simulations using the DCCP packings (Figures 8 (i), S9 and S10) reveal that for both Au and Ag NPs, a plasmon red-shift is caused by i) the number, position and type of the NPs neighbors; ii) the plasmon coupling between close NPs neighbors and in much larger effect by iii) the presence of toluene inside the MCs or the silica shell embedding the NPs. [START_REF] Jain | On the Universal Scaling Behavior of the Distance Decay of Plasmon Coupling in Metal Nanoparticle Pairs : A Plasmon Ruler Equation[END_REF][START_REF] Jiang | Hybrid Quadrupolar Resonances Stimulated at Short Wavelengths Using Coupled Plasmonic Silver Nanoparticle Aggregation[END_REF][START_REF] Shanthil | Ag@SiO2 Core-Shell Nanostructures: Distance-Dependent Plasmon Coupling and SERS Investigation[END_REF][START_REF] Ghosh | Interparticle Coupling Effect on the Surface Plasmon Resonance of Gold Nanoparticles: From Theory to Applications[END_REF][START_REF] Sheikholeslami | Coupling of Optical Resonances in a Compositionally Asymmetric Plasmonic Nanoparticle Dimer[END_REF] This is because the refractive indexes of toluene (1.5) and silica (1.46 ) are higher than the refractive index of pure water (1.33), resulting in stronger inter-NP coupling. [START_REF] Shanthil | Ag@SiO2 Core-Shell Nanostructures: Distance-Dependent Plasmon Coupling and SERS Investigation[END_REF][START_REF] Rodríguez-Fernández | The Effect of Silica Coating on the Optical Response of Sub-Micrometer Gold Spheres[END_REF][START_REF] Mock | Local Refractive Index Dependence of Plasmon Resonance Spectra from Individual Nanoparticles[END_REF] As Au NPs are diluted with Ag NPs in the packing, we can observe an overall shift towards smaller wavelength of the main extinction peak (̴ 700 nm). These facts suggest that for these mixtures cases, absorption result from both Ag NPs non coupled plasmons and coupled plasmons of Au NPs on the surface. To verify this hypothesis, we have separately "removed" Ag and Au NPs from Au Ag NPs packings and compared the resulting extinctions to the one of the mixture of NPs (Figure S12). Results showed that Ag NPs plasmons are not coupled or are coupled to only a small extent. For pure Ag MCs, a broad peak with a maximum of absorption situated at 520 nm is observed likely resulting from the superposition of peaks due to the distribution of surface-tosurface separation in a random packing. In pure Ag MCs, Ag NPs plasmons remain for the most part uncoupled.

Our experimental data for coupled NPs on MCs gave broad extinction peaks. Interestingly, our simulations (Figure S13) indicate that the optical response of disordered packings of monodisperse Au NPs in MC would likely not be significantly different from the extinction observed experimentally with disordered packings of polydisperse Au NPs. Furthermore, additional simulations show that the extinction band of disordered packings of polydisperse Au

Conclusions

In this work we have presented a simple and versatile approach for the tailored design of plasmonic silica MCs based on the self-assembly of NPs. The MCs were fabricated using o/w Pickering emulsions as templates in combination with a silica precursor PEOS as an interfacial binder for plasmonic NPs. The pH of the NPs dispersion, the solubility and concentration of PEOS in the oil phase, as well as the type of NPs are as many parameters that control the mechanical and optical properties of the final MCs. At very acidic pH, Au NPs closely pack at the emulsion interface, the plasmons of Au NPs couple leading to blue MCs. On the contrary, the plasmons of "loosely" packed Ag NPs do not couple, leading to yellow MCs. Spherical MCs resistant to air drying were obtained with [PEOS] > 0.2 g/mL well solubilized in a polar oil such as toluene. Mono or multi-flavored MCs of different color from yellow to blue were obtained by mixing Au and Ag NPs in different ratios. The simulated plasmonic response of all the different MCs were in close agreement with the experimental results, thus validating our approach. Further simulation findings revealed that the refractive index of the inner oil phase and of the MCs shell have a large impact on the plasmonic response and hence on the color of the MCs. Our emulsion template technique opens new gateways for the design of multi-functional MCs with properties arising from the individual or the combination of the properties of each one of its building blocks. Amongst other, we have shown that the MCs can be used for strain microsensing. [START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] The use of several types of NPs in the crust and the control of the silica shell thickness are gateways toward a finer control of the optical characteristics of MCs used as optical microsensors. Such versatile MCs could also be applied in catalysis for the degradation of dyes, in biology using antimicrobial properties of Ag NPs, and in medicine with the encapsulation of drugs. Due to brittleness of the shell, one can easily imagine the oil-loaded silica MCs to be considered as promising controlled release systems, where the oil soluble actives are released under mechanical force while the plasmonic NPs can serve as optical tracker to localize the MCs within complex matrices. We envision that MCs may be deployed as glucose sensors [START_REF] He | Enzymatic plasmonic engineering of Ag/Au bimetallic nanoshells and their use for sensitive optical glucose sensing[END_REF][START_REF] Zhang | Sensitive colorimetric detection of[END_REF] . Indeed, in aerobic conditions, in presence of glucose oxidase, glucose is oxidized. As a result of this oxidation, H2O2 is produced which, in-turn, oxidizes Ag to

Figure 1 .

 1 Figure 1. Schematic representation of the MCs' properties and applications driven by the

  pH measurements: the pH of the Au NPs solutions was measured with a VWR Scientific digital pH temperature meter (model 8015). Zetametry measurements: The Zeta potential of the Au NPs ([Au 0 ] = 0.57 mM, [NaCl] = 10-3 M, [Ascorbic acid] =0.054 mM) and of the Ag NPs ([Ag 0 ] = 0.005%, [NaCl] = 10-3 M, [Ascorbic acid] =0.054 mM) as a function of the pH was measured on a Zetasizer Nano Serie 200.

  It was demonstrated that condition ii) could be met by adjusting the pH of the Au NPs dispersion below 4. ζ potential results presented in Figure 2 (d) confirm these observations. Two surface potential dependent regimes appear with a sharp transition between pH values 2.1 and 4. For pH ≥ 4, the Au NPs surface potential decreases to about -15 mV whereas when pH ≤ 2.1, the Au NPs surface potential increases to-2 mV. MCs were fabricated at two distinct pH values ( ̴ 1.2 and ̴ 10) corresponding to the two surface potential regimes observed. The impact of the pH on the final MCs coverage by Au NPs is shown in Figure 2 (e-l). At pH ̴ 10, shortly after the sonication, the emulsion droplets are transparent (Figure 2 (e)).

  )). At pH ̴ 1.2, the spherical MCs of diameter in the range of 1 -15 μm present a deep blue color (Figure 2 (j) and (k)) and a monolayer of densely packed gold nanoparticles on their surface is observed (Figure 2 (l)). At pH ̴ 10, the Au NPs are too negatively charged (ζ ̴ -15 mV), and thus cannot adsorb on the oil droplets. Therefore, no Au NPs are observed in the final MCs' silica shell. Conversely, at pH ̴ 1.2, the negative charges present on the Au NPs are neutralized (ζ ̴ -2 mV) allowing adsorption of Au NPs on the oil droplets.[START_REF] Burel | Plasmonic-Based Mechanochromic Microcapsules as Strain Sensors[END_REF] The fabrication of MCs at pH 3.5 (intrinsic pH of the Au NPs dispersion) was also attempted. Interestingly, a pink emulsion was obtained attesting of the Au NPs partial adsorption (intermediate ζ potential) but a silica layer was not formed at the o/w interface. This can be explained by the fact that an acid or base catalyst is needed to polymerize the silica precursor. The fabrication of the plasmonic MCs is an interplay between silica polycondensation and plasmonic NPs adsorption at the o/w interface. Further studies would need to be performed to assess the minimum concentration of acid or base needed for interfacial silica polycondensation. The mean pair correlation function g(r) of Au NPs embedded in the silica shell of the blue MCs was computed by extracting the NPs center identified on SEM images (Figure2 (l)). Results presented in Figure2(m) reveal that the peak corresponding to the NPs first neighbors is shown around 31 nm. Since we estimate the mean radius of the Au NPs to be 15 +/-6 nm, we conclude that the Au NPs are close-packed, as confirmed by the SEM image shown in Figure2(l)), therefore allowing for a strong plasmon coupling of the NPs.

Figure 2 .

 2 Figure 2. (a) Schematic representation of the NP-Silica MCs' synthesis, (b) histogram of sizes of

Figure 3 .

 3 Figure 3. (a-f) Color change of the droplets due to the adsorption of Au NPs as a function of time.

Figure 4 .

 4 Figure 4. (a) Simulated and experimental optical spectra of pink emulsion and blue Au MCs. The

  (f) showing the thickness of the shell as a function of [PEOS], one can see that the thickness of the crust increases with the increase of [PEOS]. Three distinct areas are identified in Figure 5 (f). These areas correspond to the formation of spherical capsules, "hemi-capsules" and totally buckled capsules. Each area is delimited by [PEOS] and the corresponding shell thickness. At low [PEOS] (~ 0.05 g/mL) the shell formed is very thin (Figure 5 (a) shows a translucent shell hard to image) and the MCs totally collapse upon drying as shown in Figure 5 (f). For [PEOS] = 0.1 g/mL, the thickness of the shell increases up to about 40 nm and the dried MCs buckle into "hemispheres".

Figure 5 .

 5 Figure 5. (a-e) SEM images of the shell of the Au-Si MCs obtained with (a) 0.05, (b) 0.1,

  (d) and (f)). From the presented data, we can conclude that the morphology of MCs templated by o/w Pickering emulsions is a delicate interplay between the Au NPs adsorption, oil polarity, and silica precursor solubility and concentration.

Figure 6 .

 6 Figure 6. (a-c) optical images of Au-Si MCs obtained with (a) hexadecane, (b) toluene and (c)

  (b)). Since pH also affects the polycondensation of silica precursor, to remain consistent with previous shell formed, the Ag-Si, MCs are synthesized at the same pH as the one set for the synthesis of Au MCs (pH ~ 1.2). The obtained Pickering emulsion imaged in Figure7(c) has a yellow color. Once condensation of the PEOS at the oil/water interface has occurred, yellow Ag MCs are obtained (Figure7 (d)). SEM images in Figures8 (e) and (f) show the typical aspect of the Ag MCs and the Ag NPs embedded in the silica shell, respectively. The mean pair correlation function g(r) for Ag NPs within the silica shell of the Ag MCs was computed by extracting the NPs center identified on SEM images (Figure7(f)). Results compared to the previously discussed g(r) of Au NPs in MCs are presented in Figure7(g). For Ag MCs, the first neighbor peak is located at 49 nm. The Ag NPs mean radius being 16 +/-7 nm; on average, the distance between the surfaces of the Ag NPs is about 16 nm. This is in contrast with the almost touching Au NPs in the Au MCs leading to strong plasmon coupling (FigureS9 (b)). We believe that the separation is due to the strong PVP-DADMAN ® adsorption on Ag NPs. Under such surface separation conditions, plasmons cannot strongly couple which is consistent with the fact that Ag MCs always appear yellow (FigureS10 (b)).

Figure 7 .

 7 Figure 7. (a) Histogram of sizes of Ag NPs. Inset: TEM image of Ag NPs. (b) Extinction of Ag

Figure 8 .

 8 Figure 8. (a-f) Mixtures of Au and Ag NPs were used to form multiflavored microcapsules. (a)

  Ag + . Over time, the degradation of Ag NPs would produce a change in the optical response of Au-Ag NPs MCs. In this application, the plasmonic multiflavored MCs would translate a chemical input into a clear optical output. Other examples of potential applications include the use of capsules for the detection of species in solution, which could adsorb to NPs and change the overall optical response of the MCs. ASSOCIATED CONTENT Supporting Information. The following files are available free of charge at XXXXXX : Chemical structure of PVP-DADMAN ® (Figure S1), Extinction of blue Au Si MCs of different sizes (Figure S2), Mixture of PEOS with different solvents (Figure S2), SEM image of Au MCs

ACKNOWLEDGMENTS

The authors thank the ANRT, GIE AIFOR, CNRS, and Solvay for financial support. The authors acknowledge the support of the French National Agency of Research (ANR) to the project REACT through the grant ANR15-PIRE-0001-06. SEM imaging was performed in facilities supported by the NSF MRSEC program under award No DMR-1720530. E.M. and C.B.M. acknowledge financial support from the Office of Naval Research Multidisciplinary University Research Initiative Award ONR N00014-18-1-2497. H.B. is grateful for a Master's Scholar Research grant from the Department of Materials Science and Engineering of the University of Pennsylvania. LN2 is an International Research Laboratory (IRL) funded and co-operated by Université de Sherbrooke (UdeS), Centre National de la Recherche Scientifique (CNRS), Ecole Centrale Lyon (ECL), Institut National des Sciences Appliquées de Lyon (INSA Lyon), and Université Grenoble Alpes (UGA). It is also financially supported by the Fond de Recherche du

NPs can be further red-shifted as compared to the extinction band of ordered packings of monodisperse Au NPs [START_REF] Qin | Size Control over Spherical Silver Nanoparticles by Ascorbic Acid Reduction[END_REF][START_REF] Bastús | Kinetically Controlled Seeded Growth Synthesis of Citrate-Stabilized Gold Nanoparticles of up to 200 Nm: Size Focusing versus Ostwald Ripening[END_REF][START_REF] Rodríguez-Fernández | Seeded Growth of Submicron Au Colloids with Quadrupole Plasmon Resonance Modes[END_REF] because a smaller average inter-particles distance can be obtained with polydispersed Au NPs as compared to monodisperse Au NPs (Figure S13) [START_REF] Hastings | Quadrupole-Enhanced Raman Scattering[END_REF] .

AUTHOR INFORMATION

Corresponding Author

* Rémi Dreyfus, Complex Assemblies of Soft Matter Laboratory (COMPASS), UMI 3254, CNRS-Solvay-University of Pennsylvania, CRTB, Bristol, PA 19007, United States.

Author Contributions

The manuscript was written through contributions of all authors. All authors have given approval glucose and cholesterol by using Au@Ag core-shell nanoparticles. RSC Adv. 2016, 6 (41), 35001-35007.