Magnetic Fe3O4@Au@PDA core-shell nanoparticle-enhanced SPR detection of tebuconazole

Conventional surface plasmon resonance (SPR) sensor often fails to detect low-concentration small molecules due to insufficient refractive index changes. To address this challenge, we have developed an enhanced SPR sensor utilizing Fe 3 O 4 @Au@polydopamine (PDA) core–shell magnetic nanoparticles as signal amplification tags for the detection of tebuconazole (TBZ). These nanoparticles improve sensitivity through their high refractive indices and enable TBZ enrichment from complex matrices via their magnetic properties. The sensor surface is further modified with PDA, which acts as a reducing agent for Au nanoparticle deposition, enhancing monoclonal antibody (Ab) immobilization and boosting the SPR signal. Our optimized sensor reaches a limit of detection (LOD) at 0.61 ng/mL for TBZ, with a linear response from 1-200 ng/mL, and demonstrates high selectivity and reproducibility, ideal for pesticide monitoring in food samples.