Diffusion of fluorescent insulin from an acrylic derivatised dextran-concanavalin A gel in an implantable closed loop insulin delivery device

The drug delivery mechanism of fluorescently labelled fluorescein isothiocyanate insulin (FITC-insulin) from a glucose responsive gel held in an implantable closed loop insulin delivery device was found to be diffusion controlled. The diffusion coefficient of FITC-insulin in the gel was determined and response to glucose challenges assessed. In response to physiologically relevant glucose challenges in the NP gel, the diffusivity of FITC-insulin increases with increasing glucose concentrations, showing a second order polynomial fit, device thus showing glucose sensitivity and graded response, mimicking pancreas.