2, CEMOP-UNINOVA, Caparica, , Portugal
Diabetes mellitus is currently one of the most serious and prevalent diseases in the world, affecting million people worldwide and the rate of new cases is expected to continue increasing. Therefore, the development of cheap and simple methodologies for point-of-care glucose sensing is of paramount relevance for an effective diagnosis and management of patients, mostly in underdeveloped and developing countries where the access to medical infrastructures is limited and cost-effect and simplicity are of major concerns. Due to its properties, paper represents an alternative in the performance of point-of-care tests for colorimetric determination of glucose levels, providing simple, rapid and inexpensive means of diagnosis. In this work, we report the development of a novel, rapid, disposable, inexpensive, enzyme-free and colorimetric paper-based platform for point-of-care glucose detection. This method is based on the synthesis of gold nanoparticles (AuNPs) by reducing of a gold salt precursor in which glucose is the reducing agent. Different concentrations of glucose present during the reduction process result in the formation of AuNPs of different size, to which colour changes of the sensor are associated. The developed platform was tested and calibrated using different physiological concentrations of glucose from 1.25 to 50 mM and the obtained results were visually examined and digitally analysed through an image analysis software. It was also compared the colorimetric results obtained with a commercial scanner and with a smartphone camera, concluding that both methods are viable alternatives in the digital analysis of the sensor. The colorimetric sensor revealed sensitivity to determination of glucose levels in samples, in a simple, rapid, inexpensive and eco-friendly way.