Enzymatic template removal-enabled fabrication of highly stable magnetic surface-imprinted polymers for selective removal of human serum albumin.

The removal of template proteins by proteases is a viable strategy to improve the structural stability of imprinted cavities in molecularly imprinted polymers (MIPs). Human serum albumin (HSA), the most abundant serum protein, can mask trace biomarker signals and hinder their detection. In this study, HSA was covalently immobilized on Fe3O4@SiO2 via glutaraldehyde, and a thin polydopamine (PDA) layer was formed by dopamine (DA) self-polymerization, yielding magnetic molecularly imprinted polymers (MMIPs). The template was then removed with trypsin and chymotrypsin, and this enzymatic approach was compared with acid elution. The MMIPs reached adsorption equilibrium within 40 min, with a maximum capacity of 63.28 mg·g-1 and an imprinting factor of 4.06. Sips analysis indicated heterogeneous monolayer adsorption, and the MMIPs exhibited selective HSA adsorption in complex biological matrices. After six cycles, acid-eluted MMIPs retained 94.5% of their initial capacity, whereas enzymatically eluted MMIPs retained 96.9% and showed better preservation of PDA functional groups. These results indicate that the developed material is highly promising for repeated selective removal of target proteins.