Ginkgo biloba leaf polysaccharide-modified Cu2-xSe nanozymes for smartphone-assisted colorimetric detection of food additive propyl gallate.

Propyl gallate (PG), a widely used synthetic phenolic antioxidant, has raised health concerns due to its potential risks from overexposure. Traditional methods such as chromatography are typically time-consuming, labor-intensive, and not suitable for on-site rapid screening. In this work, we successfully fabricated ultra-small Cu2-xSe nanoparticles using plant-derived ginkgo biloba polysaccharide (GBLP) as a protective agent and ascorbic acid (AA) as a reducing agent. The generated Cu2-xSe nanoparticles exhibited excellent peroxidase-like activity to catalyze the chromogenic reaction of H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB). The presence of PG could inhibit this reaction owing to its antioxidant properties, enabling quantitative detection of PG with a detection limit (LOD) of 2.25 µM. By incorporating a smartphone and ImageJ software, a portable colorimetric device was developed for visual intelligence detection, achieving a LOD of 6.87 µM. Experimental data of real samples demonstrated that the recoveries of PG ranged from 101.52% to 106.60%, confirming the accuracy and practicality of the method. This work offered a novel nanozyme-based strategy for rapid and intelligent monitoring of PG in food products and provides a reliable, low-cost technical option for PG detection in edible oils, with prospects in the rapid screening of actual food samples.