Biomimetic mineralization-based In situ growth of AuNCs@ZIF-8 on paper fibers for visual detection of copper ions.

As one of the essential trace elements in life activities, copper ion (Cu2+) plays a very important role in human health. However, copper-containing pesticides are usually used for sterilization and disinfestation in agriculture. Thus, the residues of copper-containing pesticides in agricultural samples increase the risk of excessive intake of Cu2+ for human. The development of an effective method for detecting Cu2+ is still an important task. Herein, a detecting system based on AuNCs@ZIF-8 modified paper and smartphone platform was developed for visual detection of Cu2+ in agricultural samples. Herein, a detecting system based on AuNCs@ZIF-8 modified paper and smartphone platform was developed for visual detection of Cu2+ in agricultural samples. In the detecting system, gold nanoclusters (AuNCs) were packaged by ZIF-8 to limit their molecular motion and enhance the fluorescence effectively. In the meanwhile, by ultrasound-assisted biomimetic mineralizing, AuNCs@ZIF-8 composites were uniformly synthesized in situ on the surface of the paper fibers to indicate Cu2+ by fluorescence quenching. A portable visual monitoring system consisted of the prepared Cu2+ paper sensor and a smartphone platform was then successfully built and applied to on site detecting Cu2+ in agricultural samples. The limit of detection (LOD) was 4.57 μM and recovery rate varied from 96.50 % to 121.58 %. The developed detecting system for Cu2+ has the advantages of easy preparation and operation, and is very suitable for the use in agricultural products and farmland.