A ratiometric fluorescent probe based on carbon dots and gold nanocluster encapsulated metal-organic framework for detection of cephalexin residues in milk

Herein, we report a ratiometric fluorescent probe based on in situ incorporation of both Gold nanoclusters (AuNCs) and Green emitting carbon dots (gCDs) into zeolitic imidazolate framework-8 (ZIF-8) to analysis of Cephalexin (CFX). Under a single excitation wavelength of 400 nm, the sensor exhibits dual-emissions centered at 520 and 630 nm. The fluorescence of AuNCs (630 nm) is selectively quenched by CFX, whereas the fluorescence of gCDs (520 nm) remains almost constant. The ratiometric fluorescence signal (F-520/F-630) of the prepared composite (gCDc/AuNCs @ ZIF-8) is linearly proportional to the concentration of CFX from 0.1 to 6 ng/mL with a low detection limit (LOD) of 0.04 ng/mL, which is below the maximum residues limit (MRL) of 100 ng/mL set by the Food and Drug Administration (FDA). Moreover, the designed sensing platform was successfully applied to detect CFX in the milk samples. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

A ratiometric fluorescent probe combining AuNCs and gCDs was developed for highly sensitive detection of CFX, with linear detection range and low detection limit. The probe could be applied in the field of food safety for CFX detection in milk samples.