Biomolecule-friendly conducting PEDOT interface for long-term bioelectronic devices

One of the main challenges in biosensing devices is the development of a biocompatible and stable long-term biosensing interface to efficiently convert biological information into detectable electrical signals. Herein, we propose a facile and universal strategy to fabricate protein-encapsulated poly(3,4-ethylenedioxythiophene) polystyrene sulfonate (PEDOT:PSS) materials for signal transduction using the biopolymer chitosan as both the crosslinker of PEDOT:PSS and the bioprotectant of proteins. The solid electrostatic interaction between chitosan and PSS was verified using Fourier-transform infrared spectroscopy (FT-IR) and X-ray diffraction (XRD), which makes PEDOT:PSS curable at room temperature, with good film formability and excellent aqueous stability. Electrochemical measurements revealed a low impedance for electron communication of the PEDOT:PSS/chitosan electrode through the solid-liquid interface. Notably, the bioactivity test using glucose oxidase (GOx) as a model protein encapsulated in PEDOT:PSS/chitosan demonstrated its exceptionally high bioactivity retention (94 % of their original catalytic activity), leading to a biosensor with high sensitivity and stability. Consequently, the developed glucose biosensor demonstrated a broad response range from 0.05 to 36.53 mM and a low limit of detection of 0.02 mM, with favorable long-term stability. To confirm its versatility, the proposed PEDOT:PSS/chitosan platform was successfully employed to detect lactate and epinephrine, which are the main components of biofluids. This work provides a straightforward and effective method for the fabrication of bio-device interfaces, demonstrating significant potential for applications in biosensors, biofuel cells, and other biosensing devices.