Bimetallic Ag/Au nanoclusters encapsulated in ZIF-8 framework: A novel strategy for ratiometric fluorescence detection of doxycycline in food

Abstract

This study successfully encapsulated the Ag⁺-doped Au nanoclusters (Ag/AuNCs) within the ZIF-8 framework to construct a novel Ag/AuNCs@ZIF-8 ratiometric fluorescent probe for the antibiotic doxycycline (DOX) detection. The incorporation of Ag⁺ contributed to the fluorescence enhancement of the nanoclusters through the "silver effect", consequently improving the stability of the developed bimetallic Ag/AuNCs. Furthermore, the encapsulation of bimetallic Ag/AuNCs within the ZIF-8 framework restricted their intramolecular vibrations, resulting in further amplification of fluorescence intensity at 595 nm. The ZIF-8 also sensitized the restoration of DOX green fluorescence at 515 nm. Within the concentration range of 0.001-20 μg mL^-1, the ratio of fluorescence intensity (F₅₁₅/F₅₉₅) exhibited a favorable linearity for DOX concentration, with a detection limit of 36.8 ng mL^-1. This ratiometric fluorescence approach had the promising potential for accurate and efficient quantitative detection of DOX residue in food and served as a valuable reference for rapid monitoring of food contaminants.

Keywords: Bimetallic Ag/Au nanoclusters; Doxycycline; Ratiometric fluorescence; ZIF-8 framework.