Truncated aptamer-regulated Pd@CeO2 NPs nanozyme activity for colorimetric detection of clenbuterol hydrochloride

Clenbuterol hydrochloride (CLB) is prohibited for use in food-producing animals due to its associated health risks, necessitating the urgent development of facile, highly sensitive on-site detection methods. In this study, a truncated aptamer (C40, Kd = 90.29 nM) with high affinity for CLB was obtained via rational truncation guided by molecular docking. Based on this aptamer, a novel colorimetric aptasensor was constructed, operating on the principle of regulating the peroxidase-mimetic activity of Pd@CeO 2 NPs nanozymes through the aptamer. After the C40 aptamer was adsorbed onto the surface of Pd@CeO 2 NPs via electrostatic interactions, its catalytic activity was significantly suppressed. In the presence of CLB, the specific binding between the aptamer and CLB triggered the dissociation of the aptamer from the nanozyme surface, thereby restoring the catalytic activity and generating a strong colorimetric signal in the TMB-H 2 O 2 chromogenic system. Under the optimized conditions, the aptasensor exhibited a wide linear detection range for CLB from 0.01 to 1000 ng/mL, with a limit of detection as low as 8.2 pg/mL, and demonstrated high specificity against structural analogs and other common interferents. In spiked pork samples, the recovery rates of the developed aptasensor ranged from 98.7% to 101%, with relative standard deviations below 4.69%, outperforming commercial ELISA kits. The strategy of “rational truncation of aptamers for regulating nanozyme activity” provided a new avenue for developing high-performance biosensors targeting small molecules.