An Electrochemical Immunobiosensor Based on PVA/PDA/PEDOT Conductive Antifouling Coating for Direct Detection of CNS Injury Biomarker in Forensic Clinical Sample

Glial fibrillary acidic protein (GFAP) has been recognized as an emerging sensitive marker of central nervous system (CNS) injury. However, there are still few reports of rapid, sensitive, and specific biosensing techniques that can be directly applied to GFAP detection in complex biomatrix samples. In this study, we propose to construct an electrochemical immunosensor based on a ternary polymer nanocoating of poly(3,4-ethylenedioxythiophene) (PEDOT), poly(dopamine) (PDA), and poly (vinyl alcohol) (PVA) that combines high-performance antifouling and electrical conductivity, which could be utilized for the direct and rapid analysis of GFAP in complex forensic clinical samples. PDA and PVA possess abundant hydrophilic groups, which may form a stable hydration layer on the surface of the coating to resist the non-specific adsorption of complex biological substrates, and PDA also confers a stable interfacial adhesion ability. In addition, PEDOT is doped in the coating through hydrogen bonding and physical entanglement effects to fulfill the high electrical conductivity, which overcomes the limitation of high resistance of traditional antifouling coatings. With the above elaborate design, the PPP coating-based electrochemical immunosensor exhibited superior anti-adsorption ability in biological samples such as hemolysis, serum, and urine, and provided a linear response to GFAP in the range of 1 ng mL^-1 to 1000 ng mL^-1, with the limit of detection of 0.5521 ng mL^-1. Encouragingly, the electrochemical immunosensor has been successfully applied to actual forensic clinical samples and accurately screened patients with central nervous system injury with high GFAP expression. Therefore, this novel electrochemical immunobiosensor is expected to provide a powerful technical support for the rapid identification of CNS injury in forensic clinics.