PVDF-Nafion nanomembranes coated microneedles for in vivo transcutaneous implantable glucose sensing.

We demonstrate that microporous PVDF membranes sandwiched between multiple layers of nanomaterials can be used for continuous monitoring of glucose level in vivo. This is achieved by coating needle electrodes with Polyaniline nanofiber, Platinum nanoparticles, glucose oxidase enzyme and porous layers, successfully fabricated with layer-by-layer deposition. Nanoparticles incorporated into conductive Polyaniline nanofibers resulted in high surface to volume ratio and electrocatalytic activity for glucose enzyme. A composite coating membrane of porous PVDF and nano-sphere Nafion limited the glucose transportation and increased the lifetime of in vivo measurements. The glucose biosensor exhibited a sub-microamperometric output current, fast response time of less than 30s and a sensitivity of 0.23 μA/mM. The linear sensing range in terms of glucose concentration was from 0 to 20mM. Implantable experiments using mice models showed excellent response to the variation of blood glucose concentration while maintaining biocompatibility with the surrounding tissues. The sensitivity was shown to remain within 10% close to initial sensitivity within the 7 days of continuous monitoring, and maintain at 70% of the initial sensitivity within 21 days.