Engineering an ionic liquid micro-architecture for stable glucose oxidase enables highly durable implantable sensors

Continuous glucose monitoring (CGM) in interstitial fluid (ISF) is often compromised by temperature and pH variations, hydration–dehydration cycles, and interfering species, which lead to unstable enzyme immobilization and inefficient electron transfer. To overcome these challenges, we developed a hybrid material comprising ionic-liquid–functionalized poly(glycidyl methacrylate) microbeads (ILMbs) with internal immobilization of GOx, interpenetrated with carboxylated carbon nanotubes (CNT). This covalently interconnected ILMbs/CNT framework establishes a dual ion–electron conductive network that maintains enzyme hydration, buffers local pH, and facilitates efficient electron transport. Glucose oxidase (GOx) immobilized within this matrix exhibits high catalytic activity and exceptional stability against microenvironmental perturbations. The resulting ILMbs/CNT/GOx sensor achieved sensitive and reliable glucose detection across physiological pH (6.5–7.5) and temperature (25–40 °C) ranges, maintaining a stable current response during extended operation and under exposure to common interferents. The sensor retained over 94% of its initial current response after 21 days of storage, exhibited less than 5% signal fluctuation over 30 continuous CV cycles and displayed a clear, stepwise amperometric response to glucose concentrations from 0 to 11 mM, demonstrating excellent long-term stability, repeatability, and sensitivity. This materials-based strategy successfully integrates microenvironmental protection with enhanced conductivity, offering a robust platform for fabricating durable, enzyme-based biosensors capable of reliable performance in complex ISF-like environments.