Construction of a smartphone-assisted colorimetric nanosensor with multi-antibiotic response based on silver–ceria nanocomposites mimicking peroxidase activity

Abstract

The improper overuse of veterinary antibiotics in agricultural breeding practices has resulted in their accumulation in food commodities, triggering pervasive concerns regarding food safety. The rapid detection of antibiotic residues is a crucial measure in ensuring food safety. In this study, a nanohybrid of silver and ceria (AgNPs@CeO₂) exhibiting peroxidase-like (POD-like) activity is synthesized and used to construct a colorimetric sensor that can respond to multiple antibiotics, achieving rapid and efficient screening of antibiotic contamination. Nanoceria, exhibiting excellent recognition and adsorption capabilities toward various antibiotics, is chosen as the recognition moiety of the sensor, and additionally, the incorporation of AgNPs enhances the POD-like activity of ceria, thus achieving highly sensitive detection performance. The colorimetric sensing of antibiotics is based on the fact that AgNPs@CeO₂ catalytically oxidizes colorless 3,3′,5,5′-tetramethylbenzidine (TMB) into its blue oxide (oxTMB). However, the chromogenic reaction is inhibited in the presence of antibiotics, and the inhibition effect relies on the concentration of antibiotics. The colorimetric sensor can respond to three common antibiotics, namely, tetracyclines, aminoglycosides, and penicillin. The highly sensitive detection of tetracycline (TC), kanamycin A (Kana), and amoxicillin (AMX) has been proven. In addition, smartphone-assisted digital image analysis is utilized for quantitative detection, enabling rapid on-site detection. The developed sensor is further successfully applied to quantify antibiotic residues in actual samples such as drinking mineral water, tap water, and milk, with gratifying results achieved. This study furnishes a novel alternative for the rapid on-site screening of antibiotic residues and delivers valuable insights into the application of nanozymes in food safety monitoring.