Fast responsive crystalline colloidal array photonic crystal glucose sensors.

We developed new photonic crystal polymerized crystalline colloidal array (PCCA) glucose sensing materials, which operate on the basis of formation of cross-links in the hydrogel. These materials are composed of hydrogels that embed an array of approximately 100-nm-diameter monodisperse polystyrene colloids that Bragg diffract light in the visible spectral region. The hydrogels change volume as the glucose concentration varies.

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

Background: We recently developed a photonic crystal glucose-sensing material, 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-3-fluorophenylboronic acid as the molecular recognition elements to achieve sensing at physiologic pH values.

High ionic strength glucose-sensing photonic crystal.

We demonstrate a colorimetric glucose recognition material consisting of a crystalline colloidal array embedded within a polyacrylamide-poly(ethylene glycol) (PEG) hydrogel, or a polyacrylamide-15-crown-5 hydrogel, with pendent phenylboronic acid groups. We utilize a new molecular recognition motif, in which boronic acid and PEG (or crown ether) functional groups are prepositioned in a photonic crystal hydrogel, such that glucose self-assembles these functional groups into a supramolecular complex. The formation of the complex results in an increase in the hydrogel cross-linking, which for physiologically relevant glucose concentration blue shifts the photonic crystal diffraction.

Photonic crystal carbohydrate sensors: low ionic strength sugar sensing.

We developed a carbohydrate sensing material, which consists of a crystalline colloidal array (CCA) incorporated into a polyacrylamide hydrogel (PCCA) with pendent boronic acid groups. The embedded CCA diffracts visible light, and the PCCA diffraction wavelength reports on the hydrogel volume. This boronic acid PCCA responds to species containing vicinal cis diols such as carbohydrates.