Highly specific molecularly imprinted microspheres prepared based on dopamine/polyethyleneimine coating and carboxyl-functionalized POSS supports for selective separation of cepharanthine

The high specificity of molecularly imprinted polymers (MIPs) in recognition is pivotal for their practical application. In this study, highly specific molecularly imprinted microspheres were prepared for cepharanthine (CEP) using a shielding strategy to mitigate non-selective adsorption sites within MIPs. Carboxyl-functionalized microspheres (CPMs) were initially fabricated as the support by copolymerizing octavinyl polyhedral oligomeric silsesquioxanes (OV-POSS), methacrylic acid (MAA), and methyl methacrylate (MMA) through suspension polymerization. Cepharanthine, serving as the template molecule,was adsorbed onto the CPMs via hydrogen bonding and electrostatic interactions. Subsequently, a thin imprinted layer was deposited onto the microspheres through cross-linking polymerization of MAA and ethylene glycol dimethacrylate (EDMA). The excessive carboxyl groups within the polymer matrix were shielded by forming an alkaline coating film via the oxidative self-polymerization reaction of dopamine (DA) and polyethyleneimine (PEI). After the removal of the CEP template, the shielded molecularly imprinted microspheres (SMIMs) exhibited a significantly higher adsorption capacity for CEP (330.42μmol g −1 ) compared to the corresponding non-imprinted microspheres, which had an adsorption capacity of only 2.93μmol g −1 . Selectivity studies demonstrated that the SMIMs exhibited superior recognition specificity for CEP and its structural analogs, with an imprinting factor of up to 133.06. Furthermore, the SMIMs were employed in solid-phase extraction for the specific separation of CEP directly from Stephania epigaea Lo extracts. The elution recoveries of CEP were in range of 98.3 %−103.5 % with relative standard deviation (RSD) of below 1.9 % (n = 3).