Magnetic Nano-materials Modified With The Ligand Of “Sulfuryl-polyethylene Glycol” And Its Function Research On Antibody Separation

Protein A is the most widely used chromatography ligand for IgG purification.However,it suffers from the shortcomings such as high cost of production and storage as well as poor stability.Recently,small molecular ligands are increasingly reported as alternatives of protein A due to their low cost,good stability and easy storage.But the selectivity and binding capacity of these ligands still need further improvement.This dissertation reported a VS_PEG ligand with highly preferential adsorption ability for IgG as well as its application in antibody separation.Firstly,surface plasmon resonance technique(SPR)was employed in the ligand screening using bovine immunoglobulin G(bIgG)and bovine serum albumin(BSA)as model proteins.The results suggested that VS_PEG could specifically adsorb bovine IgG(bIgG)while simultaneously resist the adsorption of BSA.Then,a comparison of VS_PEG and commercial protein A ligand was carried out using biofilm interference technology(Blitz).The effect of IgG species was also investigated,indicating that VS_PEG ligand possessed better adsorption ability for bIgG than ligand protein A.Secondly,the VS-PEG ligand was immobilized on silica-coated magnetic nanoparticles(MPs),forming a new functional material for IgG separation.Using bIgG and BSA as model proteins,the influence of heteroatom and PEG chain length in the ligand molecule as well as pH and NaCl concentration in the binding buffer on the adsorption capacity of protein was investigated.Results showed that the optimized ligand was VS_NH2-PEG2000,and its density on MPs was 190 umol/g.Furthermore,protein selectivity can be improved by controlling the pH and salt concentration of the solution as well as selecting PEG with appropriate chain length for the ligand.An optimized separation process was performed to purify bIgG from BSA containing feedstock,which resulted in bIgG purity of 99%.Finally,the VS-PEG modified MPs were applied in the separation of bIgG from bovine serum,which showed an antibody purity of 88 %.Regeneration,recycle and reuse of particles were also highly successful for five cycles with minor loss of capacity,indicating that,as an antibody separation ligand,VS_PEG could be used repeatedly.