Jonathan Chibois

Inhabiting the Palais Bourbon Together The Democratic Ideals and the Hierarchy of Patterns of Movement in the

Introduction

For more than two centuries, the French National Assembly has been housed in the Palais Bourbon -in central Paris -which was a princely residence before the French Revolution. The Assembly has not left this place since. It has gradually been configured to meet its needs, and even expanded in the 1970s by adding on other buildings in the neighbourhood. Despite efforts to make the Palais Bourbon as functional as possible, it remains a place that was not designed for the use of a state institution. Space is limited and the historical character of the site makes difficult to carry out extensive work. Since the end of the 19th century, many deputies (equivalent to Members of Parliament) have been unsuccessfully calling for the construction of a modern parliament. Not only would the cost of such a project be monumental, but the idea of abandoning this symbolic place is also controversial. The Assembly has little choice but to make do with a place that is fundamentally unsuited to its needs.

To remedy this architectural defect and organise the movement of individuals in the Palais Bourbon, the parliamentary administration works hard. For the civil servants, a crucial question arises: how to welcome all the users of the Palais, how to make them live together in harmony and without giving up the symbolic ambition that this place should embody (Leston-Bandeira, 2016)? I would like to show here that, in order to achieve this objective, the Assembly is now based on a strict policy of the movement of individuals, without which it would simply not be able to carry out the tasks assigned to it. For the anthropologist, studying this policy of movement is a rich opportunity to question the materiality of the parliamentary world beyond its architectural, patrimonial and symbolic dimensions alone and to instead highlight its structuring effect on the daily activities of the individuals who work there [START_REF] Goodsell | The Architecture of Parliaments: Legislative Houses and Political Culture[END_REF].

The work I am presenting here is the result of a PhD thesis in anthropology, which led me to visit the Parliamentary Assembly often for about ten years as an ethnographer [START_REF] Chibois | L'Assemblée du 21e siècle[END_REF].

Throughout this experience, I held several positions in this social world and met a wide variety of categories of users -mainly deputies, staff, civil servants and journalists. I also consulted the archives of the parliamentary administration at length, which allowed me to give historical depth to my field observations when I had to juggle with the different badges and rights of movement to carry out my study. To complete the overview of the background of this work, I should point out that my thesis topic was the Assembly's so-called "digital revolution", and that I therefore became interested in this policy on the rights of movement because of a concern about the massive use of digital technologies for access control and video surveillance in the Palais Bourbon.

I will begin by briefly setting out the historical issues of access and movement in the Palais Bourbon and then explain the upheaval the Assembly experienced in the 1980s and 1990s on this matter. I will then detail the solution that the parliamentary administration has devised to solve the new challenges it faced and what the practical and symbolic consequences of this were.

A recent Upheaval in the Management of Access and Traffic Inside the Palais Bourbon

The history of the French National Assembly is closely linked to the movement of people within the space in the institution. Revolutionary times gave rise to numerous artistic representations showing the people of Paris cheering the debates of the self-proclaimed Assembly, which helped to create the myth of the public as onlookers who were passionate about the verbal jousting of their elected representatives. What these paintings do not show is that the presence of the crowd was soon considered invasive because it was noisy, fickle and impatient, which initiated attempts at regulation from the very first months of the National Assembly's existence. Because of several riots and popular revolts, protecting the deliberations against the crowd became an essential requirement when the Assembly chose to move to the Palais Bourbon in 1798, where it remains today.

Throughout the 19th century, this requirement was further reinforced under pressure from two forces. Firstly, the threats that the executive power posed to parliamentary sovereignty. The coup d'état of 1852 is the best illustration of this, where the army's intrusion into the Palace was literally experienced as "rape" [START_REF] Gardey | Le linge du Palais-Bourbon : corps, matérialité et genre du politique à l'ère démocratique[END_REF]. As a result, the institution started developing its own defences in order to make the area an autonomous zone. Secondly, two attacks at the end of the 19th century made it clear that it was not only the crowds, but also isolated acts that should be feared. This led to the laying of the foundations for a policy of the movement of people in concentric circles. Observers of parliamentary work (first and foremost journalists) were gradually prevented from mingling with deputies and pushed further and further to the periphery (geographically and in terms of relationships).

From the end of the 19th century, with the formalisation of the parliamentary administration into a modern bureaucracy and the arrival of the golden age of French parliamentarism (under the Third Republic), a complementary dynamic emerged as a result of the need to make the Palais Bourbon the "home of the deputies". To that end, it was deemed necessary to erase as much as possible the presence of the administration staff within the walls of the palace in order to bring peace of mind, but also to reinforce the symbolic power of the elected representatives by granting them the privilege of having the place at their disposal. The installation of modern means of communication throughout the 20th century, particularly the telephone, is a typical example of these issues [START_REF] Chibois | The Chamber's Telephonists: Communication Infrastructure and Division of Labor at the Palais Bourbon under the Third Republic[END_REF]. If the parliamentary administration was ever interested in the telephone, it was not for long-distance communications throughout France, but to bypass the messengers to communicate from one point to another in the palace.

After about two centuries of this history, these principles for controlling the movement of people in the parliamentary space have been shaken up by three major changes within the institution. Firstly, in the late 1970s, the Palais Bourbon decided to buy and construct additional buildings to provide personal offices for deputies. Secondly, the status of "parliamentary collaborator" was created in the 1980s to support the work of deputies and groups [START_REF] Phélippeau | La formalisation du rôle d'assistant parlementaire (1953-1995)[END_REF]. Thirdly, the anti-parliamentary discourse reached such a magnitude at that time that the powers that be of the institution have increased the number of initiatives in the project to make the Palais the "people's house" (Abélès, 2011), including the creation of a parliamentary TV channel, a children's parliament and, especially the development of guided tours of the palace on a large scale.

A Policy of "Separation of Flows" as a Response to New Challenges

Thus, within two decades, the Palais, which was a small space reserved for a limited number of regulars, saw its surface area suddenly expand and its level of attendance explode. The rights of movement, as implemented and patiently built since the Assembly was installed in the Palais, was suddenly faced with a paradox. It was necessary to make the Palais both the "house of the deputies" and the "people's house". In other words, the Palais needed to become a private as well as a public place while clearly emphasizing its symbolic and heritage dimensions.

To take up the challenge, the parliamentary administration has set up a policy known as the "separation of flows", consisting, on the one hand, of assigning dedicated entrances to the various categories of users of the palace and, on the other hand, assigning them authorised areas in which they could move. But movement jams appear, especially in central areas such as the "sacred perimeter" where the palace's heritage and architectural heritage is concentrated. This is why, in the most coveted areas, individual patterns of movement vary dynamically, depending on the hours of the day, the days of the week and the weeks of the year.

For instance, on days when the Assembly is not in session, there is no activity around the hemicycle. Therefore, in the so-called "sacred perimeter", there are few deputies and civil servants and no journalists, the place is entirely devoted to guided tours, and some rooms can accommodate public conferences. On days when the Assembly is in session, this "sacred perimeter" is reserved exclusively for deputies, with some places adjacent to the meeting places for deputies and journalists. On these days, guided tours take a different route so that they can only visit the hemicycle from the public galleries. This separation of flows is backed up against an elaborate system of access badges, which not only allows security officers to visually check that everyone does not overstep their rights of movement, but also to take advantage of the automation provided by digital access control technologies. In most functional areas, far from the view of visitors and television cameras, movement controls are carried out automatically by detecting the type of badge each individual is presenting. In the most mediatised or sensitive places, the parliamentary officers carry out the sorting and control by their discreet presence which has, in addition to the flexibility offered by human judgement, the great advantage of making access limits invisible and thus suggesting to the uninformed eye that the place be opened to the greatest number of people.

It should be noted that, since the early 2000s, all staff and visitors have been required to wear their badge visibly in all circumstances in order to make identification and verification possible.

However, there are two notable exceptions to this general rule who do not need to wear badges:

(1) Members of Parliament, whose faces staff have memorised and (2) individuals taking part in guided tours, whose presence is supervised by a guide. The consequence of this double exception is that, from the point of view of these two categories of users, nothing seems to hinder traffic in the Palais Bourbon, making it truly appear as a place welcoming to all. We are therefore dealing with a "exhibition" situation where the presence of the public "is part of the show" [START_REF] Bennett | The Exhibitionary Complex[END_REF], in a operation where visitors come to see the heritage of the Assembly as much as to be seen walking across the Palace, which aims to portray the opening of the institution to the public.

The Control of Interactions Between the Different Categories of Users of the Palais

For those who are neither deputies nor visitors, the parliamentary space is, on the contrary, a very fragmented space, both geographically and socially. For them, the badge does not symbolise the privilege of access to the focal point of the Republic, but rather a stigma that limits their freedom of movement and therefore their freedom of interaction. It is indeed important to understand that in this management of movement, it is fundamentally the control of interactions that is at stake. The two-century-old policy of keeping spectators away from the periphery and dedicating the heart of the Palace to the deputies alone has been transformed into a policy aimed at controlling who interacts with whom in the Palace and, above all, who interacts with the deputies.

In concrete terms, with this new policy, the deputies remain the legitimate protagonists par excellence [START_REF] Heurtin | Architectures morales de l'Assemblée nationale[END_REF] and visitors are only legitimate symbolically. Deputies' freedom of movement is almost total, so that all the other users' patterns of movement revolve around the way they occupy the space of the Palais. For example, parliamentary assistants' badge only authorises them to circulate in corridors where their employer has an office and where their political group is located. Furthermore, journalists' badges only allow them to go to the galleries of the hemicycle, and to the Salle des quatre colonnes (Four Columns Hall) where they are only allowed to interview deputies after the sittings. Finally, civil servants' badges mean that they are only allowed to move about in those areas of the Palais that are necessary for their tasks.

Thus there is a hierarchy of traffic regimes, i.e. a hierarchy of access badges, which is attached to the implicit symbolic hierarchy that organises the users of the Palais according to their degree of involvement with legislative work. From a spatial point of view, this hierarchy of badges means that (deputies and visitors aside) the more individuals are protagonists in legislative work, the closer they are allowed to get to the heart of the parliamentary space that is the hemicycle. The more they are in the official position of observers, the more they are kept on the periphery. From a relational point of view, the more individuals are protagonists, the more their interactions with elected officials tend to be face-to-face; the more they are observers, the more their interactions with elected officials are mediated by communication tools (Le Torrec 2005) such as video broadcasting, telephone, SMS or email.

Consequently, we can see that this policy of "separation of flows" does not call into question the frontal opposition between the figures of the deputy and the public, i.e. between the protagonist and the observer, but reinforces it. Opening up the parliamentary space, in the French National Assembly, does not mean making the public protagonists, nor does it mean getting them to work with deputies. On the contrary, it means erecting virtual glass walls around the deputies so that the public can get as close as possible to the deliberations and become a kind of super-onlookers, in a logic similar to that which led to the construction of the famous dome of the German Parliament [START_REF] Waylen | Space and Symbols: Transforming Parliamentary Buildings in South Africa and Germany[END_REF]. The Assembly's response to the rise in anti-parliamentary discourses, and more generally to the transformation of representative democracy over the last forty years, is not aimed at altering the places of each of these two protagonists (for example, in the direction of a more participatory democracy) but at consolidating the principles of republican elitism and the representative role.

Conclusion

Thus, the main interest of this policy of the "separation of flows", apart from allowing a large number of individuals to share the Palais Bourbon, is to make certain categories of users invisible to each other. In this way, the parliamentary administration is able to demonstrate that this place is, at times, the "house of the deputies" and at other times, the "people's house".

Better still, in doing so, it even manages to show itself to be the emblematic place where deputies and people meet, thus embodying this ideal of an institution that guarantees popular sovereignty. The French National Assembly fully accepts the paradox that access and freedom of movement must be as tightly controlled as possible in order to make open and transparent public life possible.


Michael López Mujica

Yuanyuan Zhang

Fabiana Gutiérrez
email: fabigutierrez@gmail.com

Féthi

Gustavo Rivas
email: grivas@fcq.edu.ar

Non-amplified impedimetric genosensor for quantification of miRNA-21 5 based on the use of reduced graphene oxide modified with chitosan 6 7

Keywords: microRNA-21, Impedimetric biosensor, Biomarker, Graphene 40 oxide, Chitosan. 41 42 1. Introduction 43

We report here an impedimetric genosensor for the quantification of microRNA-21 26 using [Fe(CN) 6 ] 3-/4-as redox probe to transduce the hybridization event. The biosensing

27

platform was built at a thiolated-gold electrode by covalent bond of reduced graphene oxide 28 (RGO) modified with chitosan (CHIT) and further covalent attachment of the aminated DNA 29 probe. GO was used to provide the carboxylic groups for the covalent attachment of CHIT 30 and, once reduced, to improve the electroactivity of the resulting platform, while CHIT served 31 as a bridge between the thiol and the aminated probe DNA. The proposed bioanalytical 32 platform allows the label-free, non-amplified, simple and fast biosensing of microRNA-21,

33

with a linear range between 1.0 x 10 -12 M and 1.0 x 10 -8 M, a sensitivity of (134 ± 4)

34

ΩM -1 (r 2 = 0.996), a detection limit of 300 fM, and a reproducibility of 5.9 % for 1.0 x 35 10 -12 M miRNA-21 and 2.2 % for 1.0 x 10 -9 M miRNA-21. The genosensor was 36 successfully used for the quantification of microRNA-21 in enriched human blood serum, 37 urine and saliva samples.

38 39

  exosomes and the protein p19. Kaugkamano et al. [24] described the fM detection 109 of miRNA-21 through the decrease of Ag oxidation signal at Au modified with 110 polypyrrol/Ag and pyrrolidinyl PNA. Bharti et al. [25] proposed the use of fluorine tin 111 oxide (FTO) properly modified to support the biotinylated probe and the , with 112 transduction of the hybridization event through the decrease of the DPV signal of 113 [Fe(CN) 6 ] 3-/4-. The sub-pM detection of miRNA-21 based on the decrease of the 114 SWV-thionin-redox signal at GCE/MoS 2 -thionine-AuNPs was described by Zhu et al. 115 [26]. Azzouzi et al. [27] proposed the impedimetric detection of miRNA-21 through 116 the increment of the charge transfer resistance of a redox mediator produced by the 117 anchoring of the complex biotin-molecular beacon-AuNPs-hybrid at the 118 GCE/neutravidin. 119 The present work is focused on the development of a non-amplified 120 impedimetric biosensor for miRNA-21 quantification taking advantage of the unique 121 properties of graphenaceous materials in a double role of anchoring support to 122 covalently immobilize the amine-rich polymer chitosan (CHIT) as graphene oxide 123 (GO) and, as reduced graphene oxide (RGO), to improve to electroactivity of the 124 resulting platform. The biosensing supramolecular architecture was built at 3-125 mercapto-1-propanesulfonate-modified gold electrode by self-assembling of RGO-126 CHIT and covalent attachment of NH 2 -DNA probe. The transduction of the 127 hybridization event was obtained from the change of the charge transfer resistance 128 (R ct ) using [Fe(CN) 6 ] 3-/4-as redox marker. In the following sections we discuss the 129 characterization of the biosensing platform and the analytical performance of the 130 mercapto-1-propanesulfonate (MPS), glutaraldehyde (glu), 135 chitosan (CHIT), N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide hydrochloride 136 (EDC), N-hydroxy-succinimide (NHS), and bovin serum albumin (Alb) were 137 purchased from Sigma. Potassium ferrocyanide was obtained from Merck and 138 potassium ferricyanide from Biopack. Ethanol, sulfuric acid (98%) and sodium 139 hydroxide were provided by J. T. Baker. Graphene oxide (GO, aqueous dispersion 140 4.0 mg mL -1 ) was obtained from Graphenea. Other chemicals were reagent grade 141 and used without further purification. DNA and RNA sequences, obtained from 142 Invitrogen Life Technologies, are the following: DNA probe: 5'-NH 2 -TCA-ACA-TCA-GTC-TGA-TAA-GCT-A-3' 144 miRNA-21: 5'-UAG-CUU-AUC-AGA-CUG-AUG-UUG-A-3' 145 Single-base mismatch: 5'-UAG-CUU-AUC-ACA-CUG-AUG-UUG-A-3' 146 Non-complementary sequence: 5'-GGG-GGG-GGG-GGG-GGG-GGG-GGG-3' 147 Ultrapure water ( = 18.2 M cm) from a Millipore-MilliQ system was used for 148 preparing all the solutions. and Ag/AgCl, 3 M NaCl (BAS) were used as counter and reference 152 electrodes, respectively. All potentials are referred to the latter. The gold working 153 electrodes were cleaned before each experiment by successive mechanical, 154 chemical and electrochemical treatment. The mechanical treatment consisted in 155 polishing with 0.05 μm alumina for 6 min, followed by sonication in deionized water 156 for 5 min. Chemical treatment was performed by immersion in "Piranha" solution (1:3 157 v/v H 2 O 2 /H 2 SO 4 ) for 5 min, followed by sonication for 10 seconds in ultrasonic bath 158 and rinsing with ultrapure water. During the electrochemical treatment, the surfaces 159 were stabilized in 0.500 M H 2 SO 4 solution by applying two consecutives step 160 potentials of 2.0 V and -1.0 V for 2 and 4 seconds, respectively. The state of the 161 surface after the pretreatment was evaluated by cyclic voltammetry at 0.100 Vs -1 in 162 a 0.500 M H 2 SO 4 solution.

163

  Electrochemical Impedance Spectroscopy (EIS) measurements were 164 performed with a PGSTAT30 potentiostat (Methrom). The redox probes were 1.0 x 165 10 -3 M [Fe(CN) 6 ] 3-/[Fe(CN) 6 ] 4-and the experiments were carried out in a 0.050 M 166 phosphate buffer solution pH 7.40. EIS parameters were the following, amplitude: 167 0.010 V, frequency range: between 1.0 x 10 -2 and 1.0 x 10 6 Hz, and working 168 potential: 0.200 V. The impedance spectra were analyzed and fitted by using the Z-169 view program.

170UV-

  Vis experiments were carried out with a Shimadzu UV1601 171 spectrophotometer and a quartz cuvette of 0.1 cm path length.

3 .

 3 Synthesis of RGO-CHIT174A volume of 3.125 mL of 4.0 mgmL -1 GO solution was mixed with 6.875 mL 175 of a 2.00 mgmL -1 CHIT solution previously prepared in a 0.100 M 2-(N-176 morpholino)ethanesulfonic acid (MES) pH 5.00 by sonicating for 2 h in ultrasonic 177 bath. The resulting GO-CHIT mixture was sonicated in ultrasonic bath for 2 h to 178 obtain a homogeneous dispersion. After that, the carboxylate groups of GO were 179 activated with 0.100 M EDC and 0.100 M NHS by sonication for 2 hours and 180 overnight reaction until completeness under stirring conditions. The purification of 181 GO-CHIT was carried out by centrifugation for 60 min at 3500 rpm and further 182 resuspension of the pellet in a 0.15 M MES buffer pH 5.00. This process was 183 repeated 4 times to eliminate the excess of CHIT. Subsequently, RGO-CHIT was 184 chemically reduced by adding excess of NaBH 4 and stirring for 24 h. The resulting 185 RGO-CHIT was washed following the same procedure as indicated before for 186 washing GO-CHIT. The characterization of the synthesis was carried out by UV-vis 187 spectroscopy, following the displacement of the GO extinction band at 234 nm 188 (Figure 1-SI).

189 2 . 4 .Figure 1

 241 Figure1presents a schematic illustration of the different steps followed during

FigureFigure 4

 4 Figure2Ashows the Nyquist plots obtained after each step during the

Figure 1 .Figure 2 . 457 Figure 3 . 461 Figure 4 .

 1245734614 Figure 1. Schematic representation of the different steps during the building of the

Figure 1 .

 1 Figure 1. Different steps during the building of the miRNA-21 genosensor.

  2 % of the complementary one, clearly indicating that Azzouzi, W.C. Mak, K. Kor, A.P.F. Turner, M.B. Ali, V. Beni V, An integrated

	262 402	reconstituted human serum samples diluted (1:10 (saliva and urine) and 1:1000 7. R. Rupaimoole, F. Slack, MicroRNA therapeutics: towards a new era for the Detection Using Thionine and Gold Nanoparticles Co-Functionalized MoS 2
	263 333 403	(serum samples)), with 0.050 M phosphate buffer solution pH 7.40 + 0.500 M NaCl) management of cancer and other diseases, Nat. Rev. Drug Discov. 6 (2017) Nanosheet, ACS Appl. Mater. Inter. 9 (2017) 35597-35603.
	264 334	and enriched with 1.0 x 10 -9 M miRNA-21. The recovery values were (96 ± 3) %, (90 203-222.
	265 335 405	± 2) %, and (98 ± 3) % for urine, saliva and serum, respectively. It is important that 8. H. Zhang, M. Fan, J. Jiang, Q. Shen, C. Cai, J. Shen, Sensitive dual functional recognition/amplification bio-label for the one-step
	266 336 406	analogue experiments performed with the diluted samples without miRNA-21, did electrochemical biosensor for MicroRNAs based on duplex-specific nuclease-impedimetric detection of Micro-RNA-21, Biosens. Bioelectron. 92 (2017) 154-
	267 337 407	not show any matrix effect, with interferences in R ct of 1.9%, 2.3 % and 1,0 % for assisted target recycling followed with gold nanoparticles and enzymatic signal 161.
	268 338 408	reconstituted serum, urine and saliva, respectively. These results indicate that the amplification, Anal. Chim. Acta. 1064 (2019) 33-39.
	269 409 410	proposed genosensor can be successfully used for practical applications in different
	270 411	biological fluids.
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	257 281 351 434 435	the genosensor is able to discriminate non-complementary and even one-base possible to quantify miRNA-21 even at fM levels in a simple and fast way, without ECOS-SUD program (A16E02). M. L.-M. thankfully acknowledges CONICET for the ChemElectroChem. 5 (2018) 1380-1386.
	436
	258 282 305 352 437	mismatch sequences. using amplification strategies involving labelling enzymes/redox markers, PhD fellowship. Y. Zhang thanks Chinese Scholarchip Council for providing a three-13. K. Zhang, N. Zhang, L. Zhang, H. Wang, H. Shi, Q Liu, Label-free impedimetric
	438
	259 283 306 353 439 440	Considering that miRNA-21 can be found in different biological fluids and that, endonucleases, special isothermal amplification schemes, different nanomaterials, year scholarship for her stay in France and LabEx MICHEM for supporting her living sensing platform for microRNA-21 based on ZrO 2 -reduced graphene oxide
	284 307 441 442	oligonucleotides with particular structures, and DNA analogues [8-11, 13-19, 25] or expenses in Argentina
	308 443

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depending on the nature of the cancer, it is relevant to use one or other fluid, we 261 evaluate the usefulness of our biosensor to quantify miRNA-21 in: saliva, urine and 271 Table 1 compares the analytical performance of our biosensor with the most 272 relevant miRNA-21 electrochemical biosensors reported in the last couple of years. 273 Among them, most of the electrochemical biosensors based on the use of 274 amplification schemes detection limits (femtomolar to attomolar) than our biosensor 275 (300 fM) [8-11, 13-19, 25] while few of the amplified biosensors present higher 276 detection limits than the proposed biosensing platform [12, 20]. Regarding the non-277 amplified detection, our biosensor presents better detection limits than the strategies 278 reported in references [26, 27] and higher than those described in references [23, 279 24]. In summary, even when our biosensor does not present better detection limits 280 than most of the biosensors reported in the Table 1, it is still competitive since it is

339 9. C. Zhang, D. Li, D. Li, K. Wen, X. Yang, Y. Zhu, Rolling circle amplification-340 mediated: In situ synthesis of palladium nanoparticles for the ultrasensitive 341 electrochemical detection of microRNA, Analyst 144 (12) (2019) 3817-3825. 342 10. W.J. Guo, Z. Wu, X.Y. Yang, D.W. Pang, Z.L. Zhang, Ultrasensitive 343 electrochemical detection of microRNA-21 with wide linear dynamic range 344 based on dual signal amplification, Biosens. Bioelectron. 131 (2019) 267-273. 345 11. L. Tian, J. Qi, O. Oderinde, C. Yao, W. Song, Y. Wang, Planar intercalated 346 copper (II) complex molecule as small molecule enzyme mimic combined with 347 Fe 3 O 4 nanozyme for bienzyme synergistic catalysis applied to the microRNA 348 biosensor, Biosens. Bioelectron. 110 (2018) 110-117. 349 12. M. Liang, M. Pan, J. Hu, F. Wang, X. Liu, Electrochemical Biosensor for 350 MicroRNA Detection Based on Cascade Hybridization Chain Reaction, 354 nanohybrids coupled with catalytic hairpin assembly amplification, RSC Adv.

404 27. S.

Table 1 .

 1 Comparison of the analytical parameters for the most relevant miRNA-21

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electrochemical biosensors reported in the last two years.

Table 1 .

 1 DL: detection limit; LR: linear range; DSN: duplex-specific nuclease; AuNPs: gold nanoparticles; HRP: horseradish peroxidase; DPV: differential pulse voltammetry; ssDNA: single-stranded DNA; RCA: rolling circle amplification; PdNPs: palladium nanoparticles; HCR: hybridization chain reaction; EIM: enzyme-induced metallization; MGCE: magnetic glassy carbon electrode; TMB: 3,3',5,5'-tetramethylbenzidine; MB: methylene blue; EIS: electrochemical impedance spectroscopy; GCE: glassy carbon electrodes; rGO: reduced graphene oxide; CHA: catalytic hairpin assembly; MCF7: human breast cancer cell lines; SPE: screen-printed electrode; SPCE: screen-printed carbon electrode; GO: graphene oxide; SWV: square wave voltammetry; MWCNTs: multiwalled carbon nanotubes; LNA: locked nucleic acid; p19: RNA silencing suppressor; CV: cyclic voltammetry; PNA: peptide nucleic acid; FTO: fluorine tin oxide; CGO: carboxylated graphene oxide; Au-PtBNPs: Au-Pt bimetallic nanoparticles; SA: streptavidin; CP: capture probe; Thi: thionine. Comparison of the analytical parameters for the most relevant miRNA-21 electrochemical biosensors reported in the last two years.

	Technique	Electrode	Platform and detection	DL	LR	Real sample	Ref.
	Amperometry	Au	Hairpin DNA modified-gold electrode, DSN-	43 aM	0.1 fM to 100 pM	Tumor cells	[8]
			assisted target recycling, biotinylated signaling
			DNA/streptavidin-AuNPs to anchor the biotinylated
			HRP.
	DPV	Au	G-rich long ssDNAs generated by RCA to facilitate	8.6 aM	50 aM to 100 fM	Human serum	[9]
			the in situ synthesis of PdNPs .
	DPV	Au	Integration of a dual signal amplification strategy of	0.84 fM	1.0 x 10 -15 M to 1.0 x -8 M	Human serum	[10]
			HCR and EIM, using capture probe (CP H1)
			modified magnetic nanobeads.
	DPV	MGCE	Capture hairpin immobilized at Fe 3 O 4 ,	33 aM	100 aM to 100 nM	Human serum	[11]
			amplification using HCR and detection from the
			synergistic reduction of hydrogen peroxide/ TMB
			system in the presence of a Cu(II) planar complex.
	DPV	Au	Amplification scheme based on HCR, which leads	11 pM	30 pM to 7.0 nM	Human serum	[12]
			to extended growth of DNA chains and higher
			amplification efficiency through MB intercalation.
	EIS	GCE	ZrO 2 /rGO/modified electrode coupled with CHA	4.3 x 10 -15 M	1.0 x 10 -14 M to 1.0 x -10 M	MCF7 cells and	[13]
			signal amplification strategy and detection through			human embryonic
			the change of charge transfer resistance of			kidney cells
			[Fe(CN) 6 ] 3-/4-.
	Chronocoulometry	Au	Triple signal amplification based on target-	6.8 aM	1.0 x 10 -17 M to 1.0 x -11 M	Human serum	[14]
			triggered cyclic duplex specific nuclease digestion
			and bridge DNA/AuNPs; detection from the
			preconcentrated [Ru(NH 3 ) 6 ] 3+ .
	Chronocoulometry	SPE	MoS 2 @AuNPs/capture DNA and detection through	100 aM	10 fM to 10 pM	-	[15]
			the [Ru(NH 3 ) 6 ] 3+ electrostatically bond to the
			surface hybrid.
	Chronocoulometry	SPCE	GO-loaded iron oxide and detection from	1.0 fM	1.0 fM to 1.0 nM	Ovarian cancer	[16]
			[Ru(NH 3 ) 6 ] 3+ catalyzed by [Fe(CN) 6 ] 3-.			and normal non-
						cancerous cells
	SWV	Au	Thiol-modified hairpin capture probe immobilized	0.5 fM	1.0 fM to 1.0 nM	Human serum	[17]

(2018) 16146-16151.

ACKNOWLEDGEMENTS 303

Financial support from CONICET, ANPCyT, SECyT-UNC (Argentina) and

DECLARATION OF CONFLICT OF INTEREST

No authors have any conflicts of interest to disclose. . Other conditions as in Figure 2. M miRNA-21, 1-base-missmatch and fully non-complementary sequences. Hybridization time: 75 min. Other conditions as in Figure 2.