MXene-molecularly imprinted polymer composite for enhanced adsorption and enrichment of puerarin and its metabolites

A MXene-based molecularly imprinted polymer (MXMIP) composite was developed for the enrichment and detection of puerarin and its metabolites in complex biological samples. As an ideal substrate material, MXene can make the recognition sites within the MIP matrix more easily exposed compared to conventional MIP. Through the operation of the "dual screening" mechanism, MXMIP combines interaction enhancement with molecular recognition, significantly enhancing the adsorption capacity and efficiency of this material. The successful synthesis of the composite was confirmed by comprehensive characterization of structure and properties. MXMIP achieved a maximum adsorption capacity of 3.70 mg∙g^-1, higher than conventional MIP (2.24 mg∙g^-1) and MXene alone (1.74 mg∙g^-1). The adsorption capacity of MXMIP was 1.65 times that of conventional MIP and 2.12 times that of MXene. In selective adsorption experiments, MXMIP shows excellent specificity toward puerarin, with selectivity factors ranging from 1.33 to 10.4 relative to structural analogs, and achieved an imprinting factor of 6.46. The hydrogen bonding interactions between MXMIP and puerarin were confirmed by ultraviolet spectroscopy, Fourier transform infrared spectroscopy, and density functional theory simulations. MXMIP was successfully applied to enrich and detect puerarin and its metabolites in biological samples. LC-MS/MS analysis showed that the mass charge ratios of MXMIP adsorbed samples were 415.09, 447.13, 253.05 and 255.23, respectively, corresponding to puerarin and its metabolites (dihydroxypuerarin, daidzein and dihydrodaidzein). This study provides a new approach for synthesizing highly selective molecularly imprinted polymers that effectively address the problem of binding site interception.