Natural collagen peptides-encapsulated gold nanoclusters for the simultaneous detection of multiple antibiotics in milk and molecular logic operations

Abstract

Collagen peptides are primarily obtained from the by-products of fish processing, such as fish skin and scales. The use of these materials is both cheap and environmentally friendly. In this study, we generated gold nanoclusters (AuNCs) using tilapia scale collagen peptides (TSCPs) as reducing and chelating agents. This complex (AuNCs@TSCP) exhibited good photo and thermal stabilities. Meanwhile, AuNCs@TSCP was found to be sensitive to heavy metal ions such as Fe3+, resulting in quenching of the AuNCs@TSCP fluorescence in the presence of Fe3+. Addition of antibiotics tetracycline (TC) and ciprofloxacin (CIP) modified the quenching in a dose-dependent manner. The antibiotics influenced the fluorescence differently: TC decreased AuNCs@TSCP-Fe3+ fluorescence, whereas CIP enhanced it. Based on this observation, we developed an assay for the detection of TC and CIP. The assay was sensitive and specific with detection limits of 32.8 nmol/L and 15.6 nmol/L for TC and CIP, respectively. In addition, the sensing strategy was applied to the construction of an INHIBIT molecular logic gate using TC and CIP as inputs and the fluorescence changes of AuNCs@TSCP-Fe3+ as the output. These findings have potential applications in intelligent multi-analyte sensing systems.