Background: We recently developed a photonic crystal

glucose-sensing material (Alexeev et al., Anal Chem 2003;75:2316–23), which consists of a crystalline colloi-dal 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 applica-tion 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-3-fluorophenylboronic acid as the molecular recognition elements to achieve sensing at physiologic pH values. Results: The improved photonic glucose-sensing mate-rial sensed glucose in the range of the 100 mol/L concentrations found in tear fluid. The detection limit