Micrometer-thick, porous, nanocomposite coating for electrochemical sensors with exceptional antifouling and electroconducting properties

Abstract

ABSTRACTDevelopment of coating technologies for electrochemical sensors that consistently exhibit antifouling activities when exposed to diverse and complex biological environments over extended time is vital for development more effective medical devices and diagnostics. Here, we describe a micrometer-thick, porous nanocomposite coating with both exceptional antifouling and electroconducting properties that greatly enhance the sensitivity of electrochemical sensors. Nozzle-assisted printing of oil-in-water emulsion is used to create a 1 micrometer thick coating composed of cross-linked albumin with interconnected pores, which also contains electroconducting gold nanowires. Using this approach, the antifouling conductive coating can be deposited only on the surface of the working electrode, and not on the reference and counter electrodes, which greatly facilitates the fabrication and functionality of multiplexed electrochemical sensors. The layer effectively resists biofouling and maintains rapid electron transfer kinetics for over one month when exposed directly to complex biological fluids, including serum and nasopharyngeal secretions. Compared to previously described thinner (nanometer thick) antifouling electroconductive coating made with drop casting or a spin coating of the same thickness, the nozzle-printed sensors coated with this thick porous nanocomposite exhibited sensitivities that were enhanced by 3.75- to 17-fold when three different target biomolecules were tested. As a result, emulsion-coated, multiplexed electrochemical sensors coated were able to carry out simultaneous detection of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) nucleic acid, antigen, and host antibody in clinical specimens with high sensitivity and specificity. This thick porous emulsion coating technology may provide a way to address hurdles currently restricting the application of electrochemical sensors for point-of-care (POC) diagnostic applications, as well as their use in implantable devices and other healthcare monitoring systems.