Contact lenses for real-time colorimetric sensing of glucose
Bruen, Danielle and Albatal, Rami and Florea, Larisa and Diamond, Dermot (2015) Contact lenses for real-time colorimetric sensing of glucose. In: Advanced Materials World Congress 2015, 23-26 Aug 2015, Stockholm, Sweden.
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Diabetes is a worldwide incurable disease1 known to have acute and chronic health affects2. This disease affects the cardiovascular and peripheral nervous systems, and the kidneys, also known to have fatal side affects1-3, including heart or kidney failure2. Monitoring physiological blood-glucose concentrations is a means of managing diabetes, however few monitoring methods currently exist1-3. ‘Finger-pricking’ is the most common method, although invasive and non-continuous. This method is inefficient because glucose concentrations are measured only at the time of sampling, meaning episodes of hypo- or hyperglycaemia can be missed2, for example while sleeping2. Invasively drawing blood is also an inconvenience to diabetics, due to their rather poor peripheral blood supply. While pricking a finger is quite painless, it requires compliance by affected patients, including children and the elderly3. The use of boronic acids (BAs) for sensing sugars is well-known, as these Lewis acids have a high affinity for diol-containing compounds1, 3. By attaching a fluorophore/chromophore to a BA derivative an optical continuous-monitoring system for glucose-sensing can be created3. In this work, BA derivatives are used for monitoring glucose concentrations in the aqueous humour. Conveniently, a contact lens can be used as the sensing platform, as many diabetics already require a form of corrective vision3. The concept of attaching a BA fluorophore to a contact lens, for colorimetric sensing of glucose, has been introduced before by Badugu et al.3. We attempt to improve this system by using covalent attachment of the sensing element on the convex side of the contact lens, rather than non-covalent doping of the contact lens with the BA derivatives3. This will avoid important issues like leaching and direct contact with the eye, minimizing toxicity effects of these sensor lenses, while allowing diabetics to continuously and non-invasively monitor their glucose-levels in real-time. The smart-contact lens aims to report obvious colour changes providing information on glucose without having to test levels at specific intervals, therefore demonstrating convenience and practicality, combined with easily accessible ICT-technologies. Our ultimate goal is to produce an application for smartphones to track glucose concentrations via contact lens colour changes captured using the phone’s integrated camera. The application will allow data to become available to patients, doctors and careers, which would help contribute to patient compliance and citizen focused management of personal health.
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