Screening of specific aptamers against chlorpromazine and construction of novel ratiometric fluorescent aptasensor based on metal-organic framework

Chlorpromazine is a phenothiazine representative drug that can be used to anesthetize and calm animals. However, chlorpromazine excess may lead to residual persistence in edible tissues, which is potentially harmful to human health and animal production. In this work, high affinity and specificity aptamers against chlorpromazine were screened out based on Capture-SELEX. After ten rounds of screening, the candidate aptamers were obtained. The optimal aptamer of CHL-3 was obtained by isothermal titration calorimetry (ITC) and SYBR Green I (SGI) fluorescence-competition methods. The Kd value of CHL-3 was 69.8 ± 9.81 nM. Subsequently, the Uio-66-NH2 material was prepared, filled with rhodamine 6G (Rho 6G) dye into the pore, and sealed with CHL-3, and fluorescence probes were obtained. The ratiometric fluorescence detection method was established to detect the concentration of chlorpromazine. A linear relationship was obtained in a range of 1-100 nM, with a lower detection limit of 0.67 nM. Meanwhile, a good recovery was shown in spiked food samples, such as eggs and milk. These results indicate that the constructed ratiometric fluorescence strategy can be successfully applied in food detection.