Abstract

Diabetes is an incurable disease that promotes acute and chronic complications, namely blindness, heart disease or kidney failure1-3. Monitoring the disease marker glucose in blood can prolong life expectancy by allowing diabetics to manage episodes of hypo- or hyperglycaemia, hence providing better control over their condition. Currently, noninvasive-continuous monitoring systems aren’t available1-3. Boronic acids (BAs) are well known for their strong, reversible interactions with diol-containing compounds like sugars, such as glucose. Incorporating BAs in to fluorescent moieties is a common approach for monitoring the BA-sugar binding. On interaction with sugars, a decrease in the fluorescence intensity of the BA sensor occurs with increasing sugar concentrations1-3. Here we present the synthesis and fluorescence study of a novel BA derivative, o-COOHBA, that has been synthesised via a one-step nucleophilic substitution reaction1-2. o-COOHBA was compared in terms of fluorescence, sensitivity to glucose and sensing range with the BA sensor - m-[N-[(3-boronobenzyl)-6-methoxyquinolinium bromide]], which has been previously reported for its sugar-sensing capabilities at physiological pH1-2. Fluorescent measurements of the new BA sensor in response to glucose were taken in various pH buffers in the range of 0.05-5mM, correlating to the ocular-glucose concentration range for diabetics. This approach aims to develop a noninvasive-continuous monitoring device, by immobilizing a BA derivative on to a disposable contact lens. This novel sensing platform will provide personal management of ocular-glucose levels for diabetics in a minimally invasive manner. Consequently, there is considerable interest in using ocular fluid as a sample medium for tracking the disease marker.