A PdNC@MIP-Aptamer nanocatalytic probe for determination of sulfadimethoxine based on the RRS effect of AuNPs

Sulfadimethoxine (SDM), an emerging contaminant, poses significant risks to the environment and human health, necessitating selective and sensitive detection methods. This study synthesized highly catalytic palladium nanoclusters (PdNCs) using methionine as a stabilizer and ascorbic acid as a reducing agent. A polyaniline core-shell structured surface molecularly imprinted polymer nanoprobe (PdNCs@MIP-Apt) was prepared using PdNCs as the core, SDM as the template, and aptamer (Apt) as second recognition element. The PdNCs@MIP-Apt nanoprobes exhibit dual recognition of SDM and strong catalytic activity for the Au(III)-HPO₃^2- nanogold (AuNP) indicator reaction, generating AuNPs with strong resonance Rayleigh scattering (RRS) at 370 nm. Under ultrasonic irradiation, the nanoprobe showed high sensitivity, with a detection limit of 0.7 nmol/L SDM. The dual recognition was provided lower detection limits and better selectivity than the single recognition. Applied to milk, the method achieved Relative Standard Deviations (RSD) of 0.90-3.8 % and recoveries of 96.8-106 %.