TY - JOUR
T1 - Electrochemical and X-ray Photoelectron Spectroscopy Surface Characterization of Interchain-Driven Self-Assembled Monolayer (SAM) Reorganization
AU - Tricase, Angelo
AU - Imbriano, Anna
AU - Ditaranto, Nicoletta
AU - Macchia, Eleonora
AU - Picca, Rosaria Anna
AU - Blasi, Davide
AU - Torsi, Luisa
AU - Bollella, Paolo
N1 - Funding Information:
Funding: The following funding agencies are acknowledged: Academy of Finland projects #316881, #316883 “Spatiotemporal control of Cell Functions”, #332106 “ProSiT—Protein Detection at the Single-Molecule Limit with a Self-powered Organic Transistor for HIV early diagnosis”; Biosensori analitici usa-e getta a base di transistori organici auto-alimentati per la rivelazione di biomarcatori proteomici alla singola molecola per la diagnostica decentrata dell’HIV (6CDD3786); Research for Innovation REFIN—Regione Puglia POR PUGLIA FESR-FSE 2014/2020; Dottorati innovativi con caratteriz-zazione industriale—PON R&I 2014–2020; “Sensore bio-elettronico usa-e-getta per l’HIV autoalimen-tato da una cella a combustibile biologica” (BioElSens&Fuel); SiMBiT—Single molecule bio-electronic smart system array for clinical testing (Grant agreement ID: 824946); PMGB—Sviluppo di piattaforme meccatroniche, genomiche e bioinformatiche per l’oncologia di precisione—ARS01_01195-PON “RICERCA E INNOVAZIONE” 2014–2020; Åbo Akademi University CoE “Bioelectronic activation of cell functions”; and CSGI are acknowledged for partial financial support.
Publisher Copyright:
© 2022 by the authors. Licensee MDPI, Basel, Switzerland.
PY - 2022/3/4
Y1 - 2022/3/4
N2 - Herein, we report a combined strategy encompassing electrochemical and X-ray photoelectron spectroscopy (XPS) experiments to investigate self-assembled monolayer (SAM) conformational reorganization onto an electrode surface due to the application of an electrical field. In particular, 3-mercaptopriopionic acid SAM (3MPA SAM) modified gold electrodes are activated with a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHSS) (EDC-NHSS) mixture by shortening the activation time, from 2 h to 15/20 min, labelled as Protocol-A,-B and-C, respectively. This step, later followed by a deactivation process with ethanolamine (EA), plays a key role in the reaction yields (formation of N-(2-hydroxyethyl)-3-mercaptopropanamide, NMPA) but also in the conformational rearrangement observed during the application of the electrical field. This study aims at explaining the high performance (i.e., single-molecule detection at a large electrode interface) of bioelectronic devices, where the 3MPA-based SAM structure is pivotal in achieving extremely high sensing performance levels due to its interchain interaction. Cyclic voltammetry (CV) experiments performed in K4 Fe(CN)6:K3 Fe(CN)6 for 3MPA SAMs that are activated/deactivated show similar trends of anodic peak current (IA) over time, mainly related to the presence of inter-chain hydrogen bonds, driving the conformational rearrangements (tightening of SAMs structure) while applying an electrical field. In addition, XPS analysis allows correlation of the deactivation yield with electrochemical data (conformational rearrangements), identifying the best protocol in terms of high reaction yield, mainly related to the shorter reaction time, and not triggering any side reactions. Finally, Protocol-C’s SAM surface coverage, determined by CV in H2 SO4 and differential pulse voltammetry (DPV) in NaOH, was 1.29 * 1013 molecules cm−2, being similar to the bioreceptor surface coverage in single-molecule detection at a large electrode interface.
AB - Herein, we report a combined strategy encompassing electrochemical and X-ray photoelectron spectroscopy (XPS) experiments to investigate self-assembled monolayer (SAM) conformational reorganization onto an electrode surface due to the application of an electrical field. In particular, 3-mercaptopriopionic acid SAM (3MPA SAM) modified gold electrodes are activated with a 1-ethyl-3-(3-dimethylaminopropyl)carbodiimide (EDC) and N-hydroxysulfosuccinimide (NHSS) (EDC-NHSS) mixture by shortening the activation time, from 2 h to 15/20 min, labelled as Protocol-A,-B and-C, respectively. This step, later followed by a deactivation process with ethanolamine (EA), plays a key role in the reaction yields (formation of N-(2-hydroxyethyl)-3-mercaptopropanamide, NMPA) but also in the conformational rearrangement observed during the application of the electrical field. This study aims at explaining the high performance (i.e., single-molecule detection at a large electrode interface) of bioelectronic devices, where the 3MPA-based SAM structure is pivotal in achieving extremely high sensing performance levels due to its interchain interaction. Cyclic voltammetry (CV) experiments performed in K4 Fe(CN)6:K3 Fe(CN)6 for 3MPA SAMs that are activated/deactivated show similar trends of anodic peak current (IA) over time, mainly related to the presence of inter-chain hydrogen bonds, driving the conformational rearrangements (tightening of SAMs structure) while applying an electrical field. In addition, XPS analysis allows correlation of the deactivation yield with electrochemical data (conformational rearrangements), identifying the best protocol in terms of high reaction yield, mainly related to the shorter reaction time, and not triggering any side reactions. Finally, Protocol-C’s SAM surface coverage, determined by CV in H2 SO4 and differential pulse voltammetry (DPV) in NaOH, was 1.29 * 1013 molecules cm−2, being similar to the bioreceptor surface coverage in single-molecule detection at a large electrode interface.
KW - Conformational rearrangements
KW - Cyclic voltammetry
KW - Self-assembled monolayers
KW - Single-molecule detection
KW - X-ray photoelectron spectroscopy
UR - http://www.scopus.com/inward/record.url?scp=85125992326&partnerID=8YFLogxK
U2 - 10.3390/nano12050867
DO - 10.3390/nano12050867
M3 - Article
AN - SCOPUS:85125992326
SN - 2079-4991
VL - 12
JO - Nanomaterials
JF - Nanomaterials
IS - 5
M1 - 867
ER -