Synthesis of carbon dots-based surface protein-imprinted nanoparticles via sandwich-structured template pre-assemble and post-imprinting modification for enhanced fluorescence detection

Molecularly imprinted polymers combined with fluorescence sensing show potential application in biological analysis and diseases diagnosis. We illustrate a versatile strategy for synthesis of surface protein-imprinted nanoparticles via sandwich-structured template pre-assemble and post-imprinting modification (PIM) for enhanced fluorescence detection. Carbon dots anchored SiO2 nanoparticles are surface modified with both disulfanylpropanoic acid and vinyl groups. By amide linkage to the carboxyl terminals, protein templates are immobilized to the nanoparticles, and subsequently allowed to bind with functional monomers via strong interactions such as metal coordination and enzyme-inhibitor association. The sandwiched protein templates are surface imprinted by free radical copolymerization with other monomers. The templates are then removed from the imprinted shells by reduction of the disulfide bonds. The derived thiol groups are used for PIM of the imprinted cavities with carboxyl groups capable of electrostatic interaction with the protein rebound. For proof of concept, human serum albumin (HSA) was firstly used as a model template for surface imprinting. It was shown that binding of a Cu2+-chelating monomer to the immobilized HSA and the subsequent PIM could elevate the imprinting factor from 1.6 to 4.1 and further to 7.6, respectively. The final imprinted nanoparticles exhibited a low limit of detection of 9.8 nM and satisfactory recoveries ranging from 98.1 to 102.0% for measuring HSA in diluted human serum samples. This strategy was further confirmed by using trypsin, a typical serine protease, as another protein template, with both the Cu2+-chelating monomer and an enzyme inhibitor monomer binding to the surface coupled template.

Automated summary

Molecularly imprinted polymers combined with fluorescence sensing have potential applications in biological analysis and disease diagnosis. A versatile strategy for the synthesis of surface protein-imprinted nanoparticles is illustrated, using sandwich-structured template pre-assemble and post-imprinting modification (PIM) to enhance fluorescence detection.