A water-soluble fluorescent probe derived from fish collagen peptides for multi-targeted detection of Cu2+ and Zn2+ ions via AIE and ESIPT mechanisms

Peptides, which are hydrolysis products of proteins, are commonly utilized as nutritional supplements in food due to their high bio-safety profile. In this study, we present a novel water-soluble fluorescent probe derived from fish collagen peptides, termed Sali-Pep. This probe exhibits light green fluorescence, characterized by both aggregate-induced-emission (AIE) and excited state intramolecular proton transfer (ESIPT) mechanisms, with emission peaks at 480 nm and 522 nm. Furthermore, Sali-Pep demonstrates a high sensitivity towards Cu 2+ ions via a “turn-off” fluorescence mechanism, and towards Zn 2+ ions through a “turn-on” fluorescence mechanism, both in a dose-dependent manner. The detection limits of Sali-Pep were 1.49 × 10 −7  M for Cu 2+ and 4.23 × 10 −7  M for Zn 2+ , respectively. In real environmental and biological samples, the recoveries of Cu 2+ and Zn 2+ ions ranged from 91.14 % to 108.61 %. These findings indicate that Sali-Pep is a promising fluorescent probe for the detection of Cu 2+ and Zn 2+ ions, combining both high biosafety and low environmental risk. Additionally, this study also show that collagen-derived peptides have the potential to serve as AIE sensing platforms for metal ion detection and fluorescent labeling.