Colorimetric detection of glucose in food using gold nanoparticles as nanoenzymes combined with a portable smartphone-assisted microfluidic paper-based analysis device.

Glucose is an important source of energy for the human body, but excessive intake will destroy the body's metabolic balance and increase health risks. In this paper, a smartphone glucose colorimetric detection system was developed in a paper-based microfluidic analytical device (µPAD) using green synthetic gold nanoparticles (AuNPs) as probes for accurate, rapid and efficient quantitative analysis of glucose in food. The AuNPs, acting as mimetic enzymes, were capable of catalyzing the breakdown of HO generated by the interaction of glucose oxidase (GOx) with glucose to OH, which subsequently oxidized the 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS), resulting in a typical green reaction. This reaction was integrated into a µPAD and the color change on the paper chip was colorimetrically analyzed using a smartphone, with UV-Vis verification. Under optimal conditions, the sensor exhibited a linear range for detecting glucose from 0.050 to 5.250 mmol/L and a limit of detection (LOD) of 7.615 µmol/L. The developed approach showed no significant deviation from UV-Vis determination and has good selectivity, as well as proved to be effective for detecting glucose in real samples. This platform for glucose detection combines green synthesized AuNPs, μPAD and a smartphone app, offering features such as intelligence, portability, speed, low cost, high sensitivity and high selectivity. And it holds great potential for broad applications in the field of food analysis.