A new molecularly imprinted nanocatalytic probe for RRS determination of trace enrofloxacin based on covalent organic...

A new nanopalladium surface molecularly imprinted covalent organic framework (MICOF) catalytic probe (Pd@TpPa) for enrofloxacin (ENR) was synthesized by molecular imprinting technology, using 1,3,5-triformylphloroglucinol (Tp) and p-phenylenediamine (Pa) as monomers, ENR as the template molecule, and palladium nanoparticles (PdNP) as the core of nanocatalytic probe. This nanoprobe not only specifically recognizes ENR but also catalyzes the cupric tartrate-glucose (GL) indicator reaction. The amino groups in TpPa replace the tartrate ions, forming a new complex with Cu²⁺. This new complex enhances the efficiency of GL oxidation reaction. The generated Cu₂O nanoparticles exhibit strong resonance Rayleigh scattering (RRS) and absorption (Abs) peaks at 370 nm and 500 nm, respectively. The catalytic and analytical performances of metal nanoparticles including Pd, Pt, Au and Ag were studied. It was found that Pd@TpPa_ENR exhibited the best performance. The RRS response was linear to ENR concentration in the range of 0.01-1.5 nM, with a detection limit of 0.008 nM ENR. The method was applied to analyze river water samples, yielding recoveries of 96.9-106.6 % and precision between 2.33-8.49 %. This nanocatalytic probe-RRS analysis platform is simple, sensitive, selective, and versatile, making it applicable for the determination of norfloxacin (NOR), ofloxacin, pefloxacin, fleroxacin, and ciprofloxacin, with linear ranges of 0.02-6.0 nM, 0.04-6.0 nM, 0.04-6.0 nM, 0.1-15 nM, and 0.1-15 nM, respectively.