A highly selective ratiometric fluorescent probe for doxycycline based on the sensitization effect of bovine serum albumin.

Fluorescent probes with in-situ visual feature have received numerous attentions for detecting doxycycline (DC), a semisynthetic tetracycline antibiotic widely used in animal husbandry. However, reported fluorescent probes commonly fail to selectively detect DC among tetracycline antibiotics due to their structural similarity. In this work, bovine serum albumin-capped gold nanoclusters (BSA-AuNCs) were ingeniously used as the ratiometric fluorescent probe for detecting DC over other tetracycline antibiotics through the selective sensitization effect of BSA on DC. After adding DC, the red fluorescence of BSA-AuNCs almost remained unchanged, while the green fluorescence of DC also emerged under the sensitization of BSA. BSA-AuNCs showed the highest response toward DC among tetracycline antibiotics ascribed to the strongest sensitization effect of BSA on DC. BSA-AuNCs also displayed the features of simple synthesis, short response time (1 min) and low detection limit (36 nM). BSA-AuNCs were finally applied to detecting DC in fish samples, and further fabricated into test strips for ease of carrying. Thus, this work proposes an efficient strategy to design fluorescent probe for selectively detecting DC among tetracycline antibiotics.