A general method to improve imprinting efficiency in surface protein imprinting by enhanced pre-assembly

Surface protein-imprinted nanoparticles may replace the expensive and unstable antibodies in biomedical applications but still suffers from a low imprinting efficiency. A main reason may be the insufficient pre-assembly between monomers and template protein in surface imprinting using the conventional surface graft polymerization method. Increasing monomer concentrations enhances pre-assembly, but leads to agglomeration of the particles. To solve the dilemma, here an initiating system consisting of surface-immobilized glucose oxidase and horseradish peroxidase, glucose and acetylacetone was used to synthesize the imprinted coatings. No agglomeration occurs even at high monomer concentrations because of the localized polymerization. When surface imprinting of lysozyme over silica nanoparticles, both adsorption capacity and imprinting factor increase with increasing monomer concentration, because of the enhanced pre-assembly. This strategy was further combined with the "shape-memorable imprint cavity" strategy in which the conventional crosslinker is replaced with a peptide crosslinker capable of undergoing pH-induced helix-coil transition. The resulting surface lysozyme-imprinted silica nanoparticles exhibit high adsorption capacity, high imprinting factor, high selectivity, good reusability, easy and complete template removal under mild conditions, and fast rebinding kinetics. Surface imprinting of other proteins with high imprinting efficiency were also successfully carried out, demonstrating the generality of the strategy. STATEMENT OF SIGNIFICANCE: Surface protein-imprinted nanoparticles have emerged as promising artificial antibodies, but still suffering from low imprinting efficiency, primarily due to insufficient pre-assembly between functional monomers and template proteins. Increasing monomer concentrations enhances pre-assembly but causes particle agglomeration. Here the dilemma was solved by using an initiating system consisting of surface-immobilized glucose oxidase/horseradish peroxidase, glucose, and acetylacetone to achieve localized polymerization. Imprinting efficiency was significantly improved because of enhanced pre-assembly. This strategy was further combined with the "shape-memorable imprint cavity" strategy. Lysozyme-imprinted nanoparticles with high capacity (146.4 mg g^-1), high imprinting factor (13.94), reusability, and fast rebinding kinetics was synthesized. Surface imprinting of other proteins with high imprinting efficiency were also successfully carried out, demonstrating the generality of the strategy.