Preliminary characterization of a glucose-sensitive hydrogel

We present proof-of-concept studies that display the potential for using a glucose-sensitive hydrogel as a continuous glucose sensor. A study to characterize the swelling ratio of the hydrogel at normal physiological and pathological hyperglycemic glucose levels was performed. The hydrogel exposed to the hyperglycemic glucose solution had a higher equilibrium swelling ratio than the hydrogel exposed to the normal glucose concentration solution. The diffusivity of a small molecule, fluorescein isothiocyanate (FITC), through a hydrogel exposed to a hyperglycemic solution was determined using fluorescence recovery after photobleaching (FRAP). The diffusivity was found to be 4.2 × 10^-14 m²/s, a value approximately four orders of magnitude smaller than the diffusivity of FITC in glucose solution. The permeability of the hydrogel after equilibration in a hyperglycemic solution was found to be 5.1 × 10^-17 m², in the range of 2-4% agarose gels.