Construction of Aptamer-Molecularly-Imprinted Fluorescent Covalent Organic Framework and Its Collaborative Recognition of Diethylstilbestrol

As a synthetic estrogen substance, diethylstilbestrol (DES) is often used in the aquaculture industry and easily enters the human body and causes health threats. Herein, a biosensing method based on fluorescent covalent organic frameworks (COFs) with aptamers and molecularly imprinted polymers (MIPs) was constructed. TP-COF with stable fluorescence emission was used as a fluorescence signal, coupled with DES aptamer, and further coated with MIPs. The obtained aptamer-molecularly imprinted COFs (COFs-Apt@MIPs) could recognize DES through the cooperation of aptamers and MIPs and induce fluorescence quenching. Dual recognition elements not only significantly improved affinity and specificity but also reduced the interference from complex matrix environments. The sensor exhibited a low detection limit (0.23 mg/L) and a good linear range (0.4–25.6 mg/L) for DES. It was further applied to detect fish samples with a recovery of 98.68%–101.97%, indicating its prospect of application in the detection of various fish drug residues.