Emulsifier-Free Emulsion Polymerization-Based Copper-Mediated Molecularly Imprinted Polymer for Vitamin B1 Extraction

Here, we present a copper-mediated magnetic molecularly imprinted polymer (Cu-mMIP) as dispersive solid-phase extracting material (dSPE) for fast, selective, and specific extraction of a metabolic biomarker vitamin B1 (VB1) in complex biological matrices. With emulsifier-free emulsion polymerization using styrene and itaconic acid as functional co-monomers, Cu²⁺ as central atom, and Fe₃O₄ nanoparticles (NPs) as core, the resulted Cu-mMIP addresses VB1's structural challenges (conformational flexibility, hydrophilicity) while enabling rapid magnetic separation (< 10 s). The Cu-mMIP demonstrates exceptional specificity for VB1, achieving an imprinting factor of 5.63 and a maximum adsorption capacity of 48.75 mg/g, 2.36-fold higher than non-copper counterparts. Adsorption equilibrium is attained within 20 min, driven by chemisorption via pseudo-second-order kinetics. Competitive binding assays reveal twofold selectivity for VB1 over its structural analog thiamine pyrophosphate and negligible interference from other B vitamins (VB2, VB9, and VB12). When applied to simulated human plasma, the method achieved a detection limit of 9 ng/mL (S/N = 3) with recoveries of 84.3%-90.5% at three spiking levels (RSD < 5%, n = 3), effectively eliminating matrix interferences. This work establishes a scalable, high-efficiency platform for clinical nutrient analysis, combining molecular imprinting precision with metal coordination robustness, and advances separation science by addressing critical challenges in biomarker enrichment and high-throughput sample pretreatment.