Construction of flexible enzymatic electrode based on gradient hollow fiber membrane and multi-wall carbon tubes meshes.

In this study, we developed a convenient way to construct a flexible enzymatic electrode with excellent stability and electrochemical performance for implanted glucose monitoring. The electrode was constructed through the co-immobilization of the glucose oxidase micro-particles (GOD MPs) and multi-wall carbon nanotubes (CNT) on the inner surface of a gradient-structured hollow fiber membrane (GHM), where CNT improved the electron transport efficiency and GHM controlled the transfer of substances and interferences. GOD MPs showed higher stability under various operation conditions than the free enzymes due to the MnCO template method, which enabled the biosensor to remain relative sensitivity at >86% over 9 days. The GOD MPs biosensor also showed high selectivity, reproducibility, and linear sensing range from 0 mM to 24 mM (R = 0.9993) with a current sensitivity of 25 nA/mM. The combination of porous-structured membrane and the flexible CNT meshes ensures the electrical connections and sensing accuracy of the biosensor under the deformation status. In-vivo experiments showed reliable current responses to variations in blood glucose concentrations that were consistent with tail blood test results. This co-immobilization of enzyme micro-particles in the 3D porous structure method developed a bio-composite platform technology towards the applications in flexible sensing and implantable medical devices.