Use of a smartphone for intelligent detection of cyromazine based on Tween 20 modified gold nanoparticles

In this work, we designed a simple and intelligent method to detect cyromazine. After original citrate stabilized AuNPs were modified with Tween 20, they could remain stable under complex conditions of different pH values (5.5–8.0) and high ionic strength. However, after the addition of cyromazine, ligand exchange occurred with the citrate ion on the surface of Tween 20–AuNPs, resulting in instability and aggregation of Tween 20–AuNPs. At the same time, a new absorption peak appeared near 630 nm, and the color changed from red to blue. This method has been successfully applied to the detection of cyromazine in milk and cucumber. Furthermore, this method was used in conjunction with a smartphone to intelligently detect and analyze cyromazine at concentrations as low as 0.04 mg kg−1.