Satyamoorthy Kabilan

Analyte-responsive holograms for (bio)chemical analysis

Analyte-responsive holograms comprise a holographic grating embedded in a smart hydrogel film. The grating acts as a reporter that enables analyte induced changes in the thickness of the associated polymer film to be accurately determined. Interaction of these materials with a specific analyte or stimuli leads to a change in the colour, image or brightness of the hologram and these changes can be visualised directly or quantified using a simple colour reader. Analyte-responsive holograms are inexpensive, robust and have proven suitable for detection of a wide range of clinically and industrially important analytes.

Holographic sensors in contact lenses for minimally-invasive glucose measurements

A contact lens with an incorporated glucose-sensitive hologram has been designed as a system for non-invasive measurement of glucose levels in diabetic patients. The hologram consists of an acrylamide copolymer hydrogel with phenylboronic acid groups acting as reversible glucose-binding ligands, allowing dynamic changes in glucose to be detected. The colour of white light reflected off the hologram changes as glucose binds to the phenylboronic acid groups, and this change is used to quantify glucose concentrations. Holograms containing the ligand 3-acrylamidophenylboronic acid (3-APB) were incorporated into a contact lens. The lens was chemically extracted to render it non-toxic. After sterilization through autoclaving, the system still maintained its ability to bind glucose reversibly.

Selective holographic detection of glucose using tertiary amines

Introducing tertiary amine monomers into holographic sensors containing phenylboronic acids gives greatly improved selectivity for glucose.

Selective holographic glucose sensors [biosensing applications]

A holographic glucose sensor, based on the swelling state of acrylamide co-polymers containing phenylboronic acid groups, has been developed. Boronic acids are known to bind a variety of cis-diols, including glucose and lactate, which are found in physiological fluids. Incorporation of a tertiary amine along with the phenylboronic acid in the copolymer allowed the boronic acid to achieve the reactive tetrahedral state at physiological pH through intermolecular electron donation from the amine. This facilitated the binding of glucose at physiological pH and increased the selectivity for compounds with multiple cis-diol groups. Glucose caused the polymer to contract as it acts as a cross-linker whereas the binding of lactate caused a slight expansion. The sensor is fully reversible and could be used to monitor continuous changes in glucose concentration in physiological fluids.