An enhanced linear range glucose biosensor based on a Prussian blue/glucose oxidase composite with a tailored polyurethane diffusion-limiting membrane

Abstract

Developing robust enzymatic glucose sensors with optimized performance is critical for advancing diabetes diagnostics and continuous glucose monitoring (CGM). This work presents a high-performance glucose sensor featuring a multilayer composite membrane designed to extend the linear detection range while maintaining high sensitivity. The sensor electrode was fabricated by sequentially modifying stainless-steel (SUS) acupuncture needles with a gold (Au) conductive layer, electrodeposited Prussian blue (PB), a glucose oxidase (GOx) biocatalytic layer, and a tailored multifunctional polyurethane (PU) diffusion-limiting membrane. This porous PU architecture effectively balances glucose and oxygen mass transfer; meanwhile, integrated PB nanoparticles within the membrane layers facilitate in situ oxygen regeneration by decomposing escaping hydrogen peroxide (H₂O₂), thereby striking an optimal balance between high sensitivity and an extended linear detection range. Operating at a low potential of −0.1 V (vs. Ag/AgCl), the sensing electrode demonstrates a wide linear range of 0–10 mM, covering the critical physiological glucose spectrum, a high sensitivity of 5.061 µA mM⁻¹ cm⁻², and a detection limit of 100 µM. Furthermore, the sensor exhibits excellent anti-interference capabilities, repeatability, and long-term stability. By offering a simple and reliable fabrication route, this study provides a practical reference for the development of robust, implantation-oriented electrochemical sensors with clinical potential.