Influence of Chitosan Concentration on the Physicochemical and Electrochemical Properties of Glutaraldehyde-Crosslinked Flowable Chitosan Hydrogels for Electrode Coating Applications

Abstract

Recently, chitosan-based hydrogels have gained attention for their biocompatibility, biodegradability and relevance as effective electrode coating for sensors. However, to produce well-coating chitosan hydrogel through a facile process remains challenging. This study investigates the effect of chitosan concentration on the properties of glutaraldehyde-chitosan hydrogels for electrode coatings. Flowable hydrogels were produced via facile chemical crosslinking gelation process under ambient condition, eliminating the need of heating or controlled atmospheres by dissolving chitosan powder with concentrations ranging from 1.0% to 5.0% (w/v) in distilled water, followed by addition of 1.2% v/v of glacial acetic acid and glutaraldehyde as crosslinker to form hydrogels for about 2 hours at room temperature. The hydrogels were characterized by rheological testing, Fourier transform infrared spectroscopy (FTIR), and electrochemical impedance spectroscopy (EIS). Results showed that the 3.0% w/v CS hydrogel demonstrating optimal viscosity of 9.15 Pa·s, while FTIR confirmed successful crosslinking by glutaraldehyde and glacial acetic acid within the hydrogel matrix. Furthermore, EIS indicated superior electrical conductance (3.25 × 10⁻³ S) for the 3.0% w/v CS hydrogel, confirming it as the optimal candidate that integrates physicochemical and electrochemical properties for electrode coatings, which supports efficient and reliable sensor device development.