Design and testing of a fluorescence glucose sensor which incorporates a bioinductive material

One main hurdle in the development of implantable biosensors is that their lifetime is limited by scar tissue formation around the implant. One way to ameliorate this issue would be to use a bioinductive coating to allow normal tissue ingrowth around the sensor. Here, we report design, development and in vitro testing of a prototype fluorescence-based glucose sensor that incorporates a bioinductive material at its tip. Glucose is sensed via a fluorescence-based assay system (Amplex reagent) which is confined to a small chamber separated from the bulk glucose solution by a semipermeable membrane. Excitation is provided by a 530 nm laser, while the emitted light is detected by a photomultiplier tube. In vitro testing of this prototype was done in the presence and absence of a bioinductive material covering the membrane at the sensor/solution interface. In response to a step change in glucose concentration, the output of the sensor increased linearly over time due to accumulation of fluorescent marker molecules as glucose diffused into the recording chamber. The slope of this response increased linearly with increasing glucose concentration, with a sensitivity if 2.1 x 10(-4) V/min per ml glucose/dl solution. The presence of the bioinductive layer did not alter the function of the sensor at the lowest glucose concentrations tested, although responses to higher concentrations saturated, presumably because of depletion of the Amplex reagent within the chamber. In summary, we report that the use of a bioinductive material in an implantable biosensor does not appreciably alter sensor function.