Survey of Conductive Polymers for the Fabrication of Conformation Switching Nucleic Acid-Based Electrochemical Biosensors

Electrochemical biosensors are a continuously evolving technology with great potential for applications in human health. With the continuous glucose monitor as an example, these sensors are capable of accurately determining molecular concentrations directly in the human body. A specific class of biosensors, termed conformation switching nucleic acid-based electrochemical sensors (NBEs), relies on the affinity of oligonucleotides for molecular recognition and their conformational dynamics upon target binding for signal generation. Currently, most NBEs are fabricated via the self-assembly of alkylthiol monolayers on Au electrodes. However, this architecture is limited in terms of stability and the breadth of supporting materials with which it is compatible. Here, to explore alternative material options for the fabrication of NBE sensors, we form conductive polymers of aromatic amines, thiophenes, and pyrroles on platinum electrodes. Altering many parameters throughout the study, we determine the extent to which the polymers passivate the electrode surface and then couple redox reporters or reporter-modified nucleic acids. We discuss the limitations and benefits of each polymer for the formation of NBE sensors and provide future directions to continue the quest for alternative sensor materials.