Development of novel glucose sensing capsules with a function of signal enhancement

In order to develop a minimally invasive sensor system for in vivo monitoring of glucose in interstitial fluid, glucose sensing micro-capsules with a function of signal enhancement based on the regulation of transport of enzymatic products across the capsule membranes had been fabricated and their response properties were investigated. At first, a theoretical model describing signal-enhancement functions of the sensing capsule was proposed and experimentally verified. Second, novel near-infrared dyes were designed and synthesized as a sensory element of implantable optical glucose sensors. Finally, a fabrication method of glucose sensing micro-capsules was established. Accordingly, microspheres having amino moieties as immobilizing sites were prepared using an emulsion polymerization method. After immobilizing enzyme glucose oxidase and the dye, the microspheres were covered with five layers of polycation/polyanion using a layer-by-layer method. The thus prepared glucose sensing micro-capsules showed rapid and reversible color responses for glucose.