Evaluation Of Antibody Activity On The Surface Of Silicon Nanomaterials And Surface Construction Of Zwitterionic Polymer

Antibody molecules are widely used in diagnosis,treatment,separation and purification due to the high binding affinity and specificity.However,the randomness of orientation of an antibody during the immobilization and the formation of protein corona in the application environment of biological fluids can lead to the masking of the active site of the antibody,affecting the activity of the antibody.Based on the above issues,this paper used different methods to couple anti-HCG antibodies and studied the orientation of the immobilized antibody on the surface of silica NPs,and the effects of the presence of protein corona on antibody activity were investigated.To avoid the formation of protein corona and improve the activity of immobilized antibodies,polysulfobetaine methacrylate(pSBMA)was constructed on the surface of the NPs,and the anti-protein corona formation ability and biocompatibility were studied.First,3-aminopropyldimethylmethoxysilane(APEs),3-aminopropyl(diethoxy)methylsil-ane(APDEs)and(3-Aminopropyl)triethoxysilane(APTEs)were used to modify the surface of silica NPs to achieve different surface amino densities,which were determined to be0.50±0.01,1.64±0.08 and 2.60±0.05?mol/m~2,respectively.These NPs were further modified with succinic anhydride to exhibit different surface carboxyl densities of 0.11±0.04,0.63±0.03 and 1.41±0.01?mol/m~2.In the presence or absence of protein corona,the enzyme-linked immunosorbent assay(ELISA)was used to investigate the binding capacity of the electrostatic adsorption and covalently bound antibodies of NPs to HCG.The results showed that the binding capacity of the antibody to HCG on the amino surface was better than that on the carboxyl surface,and the binding capacity of covalently immobilized antibody was better than that of the electrostatic adsorption on the carboxyl group.In the presence of protein corona,the ability of electrostatically adsorb antibodies on the NPs surface to bind HCG decreased,while the binding ability of the antibodies to HCG on the covalently immobilized surface was unaffected.It was shown that different surface electrical properties can regulate the orientation of antibody,and covalently coupled antibodies have a more stable antibody orientation compared with those adsorbed electrostatically.The presence of protein corona reduces the activity of electrostatically adsorbed antibodies and has no significant effect on the activity of covalently coupled antibodies.Since the presence of protein corona has an effect on the activity of immobilized antibodies,we subsequently constructed pSBMA polymer brushes on the surface of NPs and evaluate their ability of nonfouling.The SBMA zwitterions were grafted onto the surface of NPs functionalized with APTEs by the electron transfer regeneration activator atom transfer radical polymerization(ARGET-ATRP)method.Bovine serum albumin(BSA)and immunoglobulin G(IgG)were selected as model proteins for static adsorption experiment of protein.The results showed that the adsorption of NP-pSBMA to both proteins was as low as10%compared to nonfunctionalized NPs,proving that NP-pSBMA has good nonfouling capacity.Finally,the cell experiment of NP-pSBMA shows that the survival rate of mouse mononuclear macrophages(J774A.1)incubated at a particle concentration of 50~400?g/mL is higher than 90%.The initial findings suggest good biocompatibility of NP-pSBMA.