An Easily Operated Signal Amplification Sensor System for the Determination of Chloramphenicol Residues

Misuse of chloramphenicol (CAP) could lead to its residue in animal-sourced food and subsequently harm human health through the food chain. Therefore, it is urgently needed to effectively determine CAP residues in animal-sourced food. Here, an easily operated target recycling strategy for the determination of CAP was developed based on a CAP-specific aptamer. The CAP-specific aptamer was hybridized with a complementary short chain modified with fluorescent and quenching groups at both ends. Upon addition of CAP, the aptamer would be separated from its complementary probe and bind with CAP. The fluorescent and quenching groups labeled on the complementary probe were separated by exonuclease I (Exo I) digestion to release a fluorescent signal. Meanwhile, Exo I also digested the aptamer, and CAP was released from the complex, triggering the determination signal amplification based on CAP recycling. Factors (i.e., NaCl concentration and Exo I digestion time) that would affect the determination performance of this sensor system were optimized. Under the optimized conditions, the developed sensor system exhibited high determination sensitivity toward CAP with a limit of detection of 0.08 ng/mL (linear range from 0.1 to 5 ng/mL). Moreover, this sensor system was applied to determine CAP in real spiked milk, and the recovery rates ranged from 97.2 to 100.0%. Meanwhile, this sensor system also suggested cost efficiency with a determination cost of only $0.29 per sample. Results presented here and the high specificity of the aptamer suggested by the previous work indicated the application potential of this developed aptamer-based sensor system for the determination of CAP residue in animal-sourced food.