Reusable Fluorescent Nanobiosensor Integrated in a Multiwell Plate for Screening and Quantification of Antidiabetic Drugs

A highly stable and reusable fluorescent multisample nano-biosensor for the detection of alpha-glucosidase inhibitors has been developed by coupling fluorescent liposomal nanoparticles based on conjugated polymers (L-CPNs) to the enzyme alpha-glucosidase, one of the main target enzymes in the treatment of type 2 diabetes. The mechanism of sensing is based on the fluorescence turn-on of L-CPNs by p-nitrophenol (PNP), the end product of the enzymatic hydrolysis of p-nitrophenyl-alpha-D-glucopyranoside. L-CPNs, composed of lipid vesicles coated with a blue-emitting cationic polyfluorene, were designed and characterized to obtain a good response to PNP. Two nanobiosensor configurations were developed in this study. In the first step, a single-sample nanobiosensor composed of L-CPNs and alpha-glucosidase entrapped in a sol-gel glass was developed in order to characterize and optimize the device. In the second part, the nanobiosensor was integrated and adapted to a multiwell microplate and the possibility of reusing it and performing multiple measurements simultaneously with samples containing different alpha-glucosidase inhibitors was investigated. Using super-resolution confocal microscopy, L-CPNs could be visualized within the sol-gel matrix, and the quenching of their fluorescence, induced by the substrate, was directly observed in situ. The device was also shown to be useful not only as a platform for screening of antidiabetic drugs but also for quantifying their presence. The latter application was successfully tested with the currently available drug, acarbose.

Automated summary

A stable and reusable fluorescent multisample nano-biosensor has been developed for detecting alpha-glucosidase inhibitors. It can perform multiple measurements in samples containing different inhibitors and is useful for both drug screening and quantification.