Preparation And Application Of Protein Imprinted Polymers

Molecularly imprinted polymers(MIPs)have outstanding mechanical and chemical stability,good selectivity for template molecules and low synthesis cost.MIPs have been considered promising substitutes to natural antibodies.However,proteins have large molecular sizes and complex conformational structures,resulting in reduced mass transfer and permanent template retention in the polymer layers when proteins are used as templates for molecular imprinting.Therefore,protein imprinting continues to face great challenges.Different strategies have been developed for protein imprinting.Among them,surface molecular imprinting is an effective method to overcome the difficulty of template removal and achieve high adsorption capacity.In surface molecular imprinting,the imprinted cavities are mainly distributed close to or at the surface layer,which helps to reduce mass transfer resistance.Compared to traditional molecular imprinting,surface molecular imprinting possesses rapid binding kinetics,higher selectivity and excellent adsorption capacity.In this paper,protein imprinted materials were prepared by surface molecular imprinting,and the preparation conditions,imprinting performance and application were studied.In the first part of this study,lysozyme-imprinted PDA layers(Lyz-MIPs)were fabricated on the surface of titanium dioxide(TiO2)nanoparticles using surface molecular imprinting technique.The effects of polymerization,adsorption and elution conditions on the adsorption capacity of Lyz-MIPs were explored.The results showed that the adsorption capacity of Lyz-MIPs increased with the increase of pH value and the concentration of ion,Lyz and initiator.Adsorption isotherms and adsorption kinetics studies revealed that Lyz-MIPs had adsorption capacity up to 152.4 mg/g,which was markedly higher than the non-imprinted nanoparticles(NIPs);Lyz-MIPs had an imprinting factor of 3.74 and showed the highest selectivity toward Lyz.Moreover,Lyz-MIPs were able to selectively adsorb template protein Lyz from diluted egg white solution,a typical complex protein mixture.In the second part of this study,BMP-2 imprinted polymer layers were fabricated on the surface of chitosan microspheres by surface molecular imprinting technique(Chitosan@BMP-2-MIPs).First,chitosan microspheres were prepared by electrostatic spray ruethod,then heparin was modified onto the surface of chitosan microspheres,and after the adsorption of template protein BMP-2,molecularly imprinted layers of BMP-2 were fabricated by the polymerization of 2-hydroxyethyl acrylate,and finally the template molecules were removed to obtain Chitosan@BMP-2-MIPs.Chitosan@BMP-2-MIPs had adsorption capacity up to 558.59 ng/mL,which was markedly higher than Chitosan@NIPs;Chitosan@BMP-2-MIPs had an imprinting factor of 1.59 and showed selectivity toward BMP-2.Chitosan@BMP-2-MIPs had good biocompatibility and no toxic side effects in vivo,the results of bone defect model repair experiment showed that compared with the control group and Chitosan@NIPs group,Chitosan@BMP-2-MIPs group had higher amounts of new bone.