Expanding the Monolayer Scope for Nucleic Acid-Based Electrochemical Sensors Beyond Thiols on Gold: Alkylphosphonic Acids on ITO

Abstract

Electrochemical biosensors are a powerful and rapidly evolving molecular monitoring technology. Evidenced by the success of the continuous glucose monitor in managing Type 1 Diabetes, these sensors are capable of precise, accurate measurements in unprocessed biological environments. Nucleic acid-based electrochemical sensors (NBEs) are a specific type of biosensor that employs the target binding and conformational dynamics of nucleic acids for signal transduction. Currently, the vast majority of NBEs are fabricated via self-assembly of alkylthiols on Au electrodes. However, this architecture is limited in scope, as Au electrodes are not universally deployable for all potential NBE applications. Here, to expand the repertoire of materials on which NBEs can be made, we describe the multistep procedure for creating sensing monolayers of alkylphosphonic acids on a conductive oxide surface. Using such monolayers on indium tin oxide (ITO)-coated glass slides, we couple redox reporter-modified nucleic acids and demonstrate signaling of procaine-binding NBE sensors in buffer and human serum. We investigate the operational stability of these NBE sensors to reveal faster signal loss relative to benchmark thiol-on-gold sensing layers, a result that arises due to poor stability of the underlying ITO. Finally, we discuss future directions to continue expansion of NBE sensor materials and applications.

Beyond the Gold–Thiol Paradigm: Exploring Alternative Interfaces for Electrochemical Nucleic Acid-Based Sensing

“…Such monolayers can be modified in a subsequent step with oligonucleotides to create NBEs. Adapted from ref . Copyright 2023 Creative Commons 4.…”

“…(D) Because of the inherent lability of ITO, NBEs fabricated on ITO undergo faster signal loss relative to analogous NBEs fabricated on gold. Adapted from ref . Copyright 2023 Creative Commons 4.…”

“…Although several studies have been published on the fabrication of oligonucleotide-modified conductive oxides, for example in refs and , my laboratory reported one of the first studies specifically investigating the stability of NBEs formed on conductive oxides under continuous voltage modulation . In this study, we created monolayers of alkylphospohonic acids on ITO, which we then functionalized with various oligonucleotide sequences to create NBEs (Figure A).…”

Green Synthesis of Copper Oxide Nanoparticle Decorated Polypyrrole-Chitosan on Pencil Graphite Electrode for Enzyme-Free Glucose Sensors

“…[15][16][17] The use of nanoparticles has also been able to minimize the impact of heavy metals that harm humans and the environment. 18,19 Sensors developed with nanoparticles can eliminate the sensitivity and selectivity problem encountered in sensors obtained with other different materials, making it possible to produce sensors with more selective, sensitive and catalytic effects. [20][21][22][23][24][25] The production of nanoparticles can be by chemical, physical and biological means.…”

Preparation of Electrochemical Sensor for Paracetamol Detection Based on a New Piperazine Substituted Triazole-Coumarin Hybrid Doped PEDOT Modified Flexible HOPG Electrode

“…5 Expensive and time-consuming chromatographic systems and the need for trained personnel are among the barriers to the widespread use of these methods. [6][7][8][9] The development of simpler and faster analytical methods is important for the sensitive detection of pharmaceuticals such as paracetamol. 10 Electrochemical sensors, which can be used as an alternative application, have been frequently used in the detection and determination of pharmaceuticals in recent years due to their ease of preparation, portability, low cost and high accuracy.…”