The Construction and Application of Aptamer to Simultaneous Identification of Enrofloxacin and Ciprofloxacin Residues in Fish

To detect enrofloxacin (ENR) and ciprofloxacin (CIP) residues in fishery foods, a computer simulation was used to predict and analyze the binding sites existing aptamer specific to ENR and CIP. A new aptamer (SEQ.3) that can recognize ENR and CIP was screened and evaluated, and the dissociation constants (Kd) of SEQ.3 from ENR and CIP were determined to be 210.955 nM and 887.49 nM which are higher than other aptamers SEQ.4 and SEQ.5 by microscale thermophoresis (MST). Colorimetric detection method based on gold nanoparticles (AuNPs) was developed through optimization of temperature, incubation time, aptamer concentration, and other conditions. The results showed that the limit of defection (LOD) of the new aptamer to ENR and CIP were 1.89 nM and 6.84 nM, respectively, which were similar to that of the original aptamer. The recovery rate of the colorimetric method was between 87.8~102.18%. All the results implied that the developed colorimetric aptamer sensor has broad application prospects in food safety detection and environmental monitoring.