An Antifouling Coating That Enables Affinity-Based Electrochemical Biosensing in Complex Biological Fluids

Abstract

Affinity-based electrochemical detection in complex biological fluids could enable multiplexed point-of-care (POC) diagnostics for home healthcare; however, commercialisation of POC devices has been limited by rapid loss of sensitivity caused by electrode surface inactivation and biofouling. Here, we describe a simple and robust antifouling coating for electrodes consisting of a 3D porous matrix of cross-linked bovine serum albumin (BSA) supported by a network of conductive nanomaterials, composed of either gold nanowires (AuNWs), gold nanoparticles (AuNPs), or carbon nanotubes (CNTs). These nanocomposites prevent nonspecific interactions while enhancing electron transfer to the electrode surface, preserving 88% of the original signal after one month of exposure to unprocessed human plasma, and functionalisation with specific antibodies enables quantification of anti-interleukin 6 (IL6) in plasma with high sensitivity. Easy preparation, stability, and simplicity of this nanocomposite allow the generation of electrochemical biosensors that can operate in complex biological fluids, such as blood plasma or serum.