Characterization of self-assembled thiols monolayers on gold surface by electrochemical impedance spectroscopy

Mendes, René; Freire, Renato S.; Fonseca, Carla Polo; Neves, Silmara; Kubota, Lauro T.

doi:10.1590/s0103-50532004000600011

Cited by 71 publications

(60 citation statements)

References 21 publications

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“…After seeding the 3T3 fibroblasts and PC12 cells on the MEA, the changes of the total impedance, including resistance and reactance between the cell-microelectrode-medium interfaces, were recorded at the same measurement condition once every day for 7 consecutive days. Research has simplified this electrode-SAMs interface through the application of a parallel model where the electrode impedance is presumably composed of electrode resistance (R e ) and shunt capacitance (C e ) from SAMs modification (Chidsey and Loiacono 1990;Mendes et al 2004;Chou et al 2003). In our study, additional resistance (R s ) and capacitance (C s ) of the sealing gap, which interpreted the interface between cells and electrodes (Rutten et al 2001;Buitenweg et al 2002), had to be recruited after cells culturing on the electrodes.…”

Section: Impedance Evaluation Of Surface-modified Microelectrodesmentioning

confidence: 86%

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Characterization of surface modification on microelectrode arrays for in vitro cell culture

Lin¹,

Chen²,

Liao³

et al. 2007

Biomed Microdevices

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This study aims to investigate surface-modified microelectrodes on the microelectrode arrays (MEAs) for neuronal interfaces with in vitro cell culture. The polyimide (PI) MEA was fabricated by using micro-electro-mechanical systems (MEMS) techniques. Self-assembled monolayers (SAMs) of 11-mercaptoundecanoic acid (MUA) were utilized to modify the microelectrode surface of the MEA. The SAMs' modified surface of microelectrodes offered a reliable interface to immobilize biological ligands through covalent bonding. To increase biocompatibility, the poly-D-lysine (PDL) was immobilized on the SAMs' modified microelectrodes. Several analytical techniques were used to define the physical structure and functional groups of surface-modified gold microelectrodes on the MEA. Spectra of the Fourier transform infrared reflection (FTIR) were applied to characterize the molecular structure of MUA-SAMs and PDL on the microelectrodes. The spectra, two peaks of amide I (at 1,613 cm(-1)) and amide II (at 1,548 cm(-1)), revealed that covalent amide bonding existed in PDL-MUA-SAMs modified surfaces. The thickness and formation of the MUA and PDL were also observed and quantified by using an atomic force microscope (AFM). The impedance measurement of PDL-MUA-SAMs modified MEA only increased slightly to an average of 524.6 +/- 55.8 kOmega from 352.9 +/- 34.4 kOmega of bare gold microelectrode (p < 0.05, N = 20). In addition, the time-course changes of total impedance resulting from cell sealing resistance and gap reactance were recorded for 7 days for inferring the growth of cell lines on the electrode contact of modified MEA. The experiment of 3T3 fibroblasts, PC12 cells, primary glial cells, and primary cortical neurons cultured on the modified MEAs displayed a good adhesion rate. These biocompatibility assays demonstrated that the neuronal cells are able to grow in a proximity to PDL-MUA-SAMs modified microelectrodes of the MEAs for effective electrophysiological stimulation/sensing schemes and for future implantation purposes.

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Section: Impedance Evaluation Of Surface-modified Microelectrodesmentioning

confidence: 86%

“…5(d)) also indicated that PDL molecules were in a well-ordered distribution, linked through MUA with some pinholes. Pinholes were regarded as defects in a thiol monolayer in another study (Mendes et al 2004). However, pinholes might allow molecules and ions that flow from the medium or electrolyte to reach the electrode surface.…”

Section: Discussionmentioning

confidence: 99%

Characterization of surface modification on microelectrode arrays for in vitro cell culture

Lin¹,

Chen²,

Liao³

et al. 2007

Biomed Microdevices

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“…The degree of penetration of the probe through the monolayer is controlled by the chemical and physical characteristics of the molecule probe and defect sites of the SAM. As in basic media the hexacyanoferrate is negatively charged, it should have a repulsive force towards the deprotonated À COO -of 3 MPA SAM [53], mainly if it is dense and well-ordered. For this reason hexacyanoferrate(II/III) was chosen as the probe molecule.…”

Section: Effect Of Electrode Pretreatment On Thiol Monolayer Self-assmentioning

confidence: 99%

Polycrystalline Gold Electrodes: A Comparative Study of Pretreatment Procedures Used for Cleaning and Thiol Self‐Assembly Monolayer Formation

2005

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The influence of different surface pretreatment procedures on the electrochemical response of a polycrystalline gold electrode was evaluated. Mechanical polishing with slurry alumina (M), chemical oxidation with H 2 SO 4 /H 2 O 2 (C), electrochemical polishing (potential cycling between À 0.1 V and 1.2 V vs. SCE) (E), chemical reduction with ethanol, and combinations among these treatments were employed to change the surface electrode characteristics. The efficiency of the proposed pretreatments was evaluated by electrochemical responses towards the redox couple ferri(II/III)-ammonium sulfate and by the formation of a self-assembly monolayer of 3-mercaptopropionic acid (3 MPA SAM) on gold electrodes. The procedure (C) allowed important gold surfaces activation. Using procedures (C) and (E) the roughness of polycrystalline gold surfaces was significantly minimized and more reproducible surfaces could be obtained. From the profile of reductive desorption of 3 MPA SAM it was possible to verify that reduced gold surfaces generated better packed monolayers than oxidized ones and a comparative study using CV and DPV techniques showed that between the two desorption peaks, the one localized at more negative potential values corresponds to the cleavage of Au-S bond from the chemisorbed thiol. In general, the improvement in the studied electrochemical responses could not only be attributed to an increase in the real surface area of the electrode, but to the chemical surface states set off by the pretreatment procedure.

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“…Although electrochemical immunosensors can reach low detection limits, the electrical and, even more, the electrochemical properties of self-assembled monolayers have not been the subject of many studies. Mendes et al (2004) studied the characterisation of self-assembled thiol monolayers on gold surfaces by electrochemical impedance spectroscopy [11]. Despite previous studies on the topic, it is not yet well understood how the applied potential affects the self-assembled monolayers' properties.…”

Section: Introductionmentioning

confidence: 99%

“…Despite previous studies on the topic, it is not yet well understood how the applied potential affects the self-assembled monolayers' properties. In general, monolayers are known to be unstable under the effect of applied potentials because of their reductive and oxidative desorption [11].…”

Section: Introductionmentioning

confidence: 99%

A Novel Method of Immobilizing Antigens on Gold Electrode for Immunosensing

Uyen¹,

Gajovic‐Eichelmann²,

Bier³

et al. 2015

Comm. in Phys.

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Abstract. An antigen modified gold electrode based on a self-assembled lipoic acid monolayer has been developed. The contact angle measurement and cyclic voltammetry confirm the formation of a dense self-assembled monolayer on gold from 100 mM lipoic acid in ethanol. The electrochemical behavior shows a stable activity in a range of potential from -0.2 V to 0.65 V vs. Ag/AgCl. By applying a potential of 1 V vs. Ag/AgCl the monolayer is completely removed by oxidative desorption and a clean gold surface re-established. This allows for an easy renewal of the gold surface and recycling of modified immunosensor chips. This lipoic acid monolayer was covalently functionalized with a small molecule antigen synthesized from progesterone-3-(O-carboxymethyl)oxime and 4,7,10-trioxa-1,13 tridecanediamine to form a well ordered, low unspecific binding, antigen layer for an antibody-antigen interaction study.The effectiveness of antigen -antibody binding reaction was demonstrated by fluorescence imaging using a fluorescence-labeled antiprogesterone antibody as the binding partner.

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Characterization of self-assembled thiols monolayers on gold surface by electrochemical impedance spectroscopy

Cited by 71 publications

References 21 publications

Characterization of surface modification on microelectrode arrays for in vitro cell culture

Characterization of surface modification on microelectrode arrays for in vitro cell culture

Polycrystalline Gold Electrodes: A Comparative Study of Pretreatment Procedures Used for Cleaning and Thiol Self‐Assembly Monolayer Formation

A Novel Method of Immobilizing Antigens on Gold Electrode for Immunosensing

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