Glucose Sensing by Fluorescent Nanomaterials.

Diabetes mellitus is a chronic disease and leading cause of death worldwide, affecting more than 420 million people. High blood glucose levels are a common effect of uncontrolled diabetes, which can cause serious health damage. Diabetic individuals must measure their blood glucose levels regularly in order to control glycemic levels and minimize the effects of the disease. Glucose sensors have been used in the management of diabetes for more than 50 years, when Clark and Ann Lyons developed the first glucose enzyme electrode in 1962. Electrochemical sensors have become the leading technology for glucose concentration measuring with most of the commercially available devices being based on amperometric detection. However, the detection of glucose in the blood is still an object of intense research. The development of new fluorescent nanomaterials begins to constitute an alternative for glucose blood quantification. These sensors include carbon dots, quantum dots, graphene quantum dots, gold, silver and upconversion nanoparticles. This paper reviews the last 10 year fluorescent nanoparticles based technologies proposed for glucose monitoring and provide an insight into emerging optical fluorescence glucose biosensors.

3-Hydroxyphenylboronic Acid-Based Carbon Dot Sensors for Fructose Sensing.

The selective fluorescence sensing of fructose was achieved by fluorescence quenching of the emission of hydrothermal-synthesized carbon quantum dots prepared by 3-hydroxyphenylboronic acid. Quantification of fructose was possible in aqueous solutions with pH of 9 (Limit of Detection LOD and Limit of Quantification LOQ of 2.04 and 6.12 mM), by quenching of the emission at 376 nm and excitation ~380 nm with a linearity range of 0-150 mM. A Stern-Volmer constant (KSV) of 2.11 × 10-2 mM-1 was obtained, while a fluorescent quantum yield of 31% was calculated. The sensitivity of this assay towards fructose was confirmed by comparison with other sugars (such as glucose, sucrose and lactose). Finally, the validity of the proposed assays was further demonstrated by performing recovery assays in different matrixes. Graphical Abstract.