Photonic crystal glucose-sensing material for noninvasive monitoring of glucose in tear fluid

Background: We recently developed a photonic crystal glucose-sensing material (Alexeev et al., Anal Chem 2003;75:2316-23), which consists of a crystalline colloidal array embedded within a polymer network of a polyacrylamide-poly(ethylene glycol) hydrogel with pendent phenylboronic acid groups. The aim of the present work was to improve this approach for application to noninvasive or minimally invasive monitoring of glucose. Methods: We used new boronic acid derivatives such as 4-amino-3-fluorophenylboronic acid and 4-carboxy-3fluorophenylboronic acid as the molecular recognition elements to achieve sensing at physiologic pH values. Results: The improved photonic glucose-sensing material sensed glucose in the range of the 100 mumol/L concentrations found in tear fluid. The detection limits were similar to1 mumol/L in synthetic tear fluid. The visually evident diffraction color shifted across the entire visible spectral region from red to blue over the physiologically relevant tear-fluid glucose concentrations. This sensing material is selective for glucose over galactose, mannose, and fructose. Conclusions: These new glucose sensors have properties appropriate for use in such glucose-sensing applications as ocular inserts or diagnostic contact lenses for patients with diabetes mellitus. (C) 2004 American Association for Clinical Chemistry.