Selective Adsorption Of Proteins On Surface Functionalized TiO₂ Nano-adsorbents

Selective adsorption of a given protein to a given surface has been widely concentrated on in the fields of the separation and purification of proteins.TiO2 have aroused great interest in their application to protein separation and purification due to its good bio-compatibility,large surface area and rich surface hydroxy,which can band with different functional groups for proteins adsorption.In this work,two different types of organic molecules:oleic acid(OA)and 3-glycidoxypropyltrimethoxy silane(GPTMS)were used to functionalize the surface of TiO2 nanoparticles and studied the effects of modification on the surface physicochemical properties in correlation with their selective adsorption toward proteins.The effects of different conditions,including pH values,contact time,ion strength and initial protein concentration on the adsorption activity were investigated and optimum conditions were determined.The same adsorption experiments were also conducted on original TiO2 for comparison.The influence of surface modification were explored and the selective adsorption mechanism was also discussed.Using a binary solution composed of bovine hemoglobin(BHb)and bovine serum albumin(BSA)as adsorption object,the original TiO2 nanoparticles present non-specific adsorption,and both the OA-TiO2 and GPTMS-TiO2 exhibited increased BHb adsorption and decreased BSA adsorption at same time.The higher separation factor(SF)of 2.96 was obtained by OA-TiO2 under optimum conditions.The sodium dodecyl sulfate polyacrylamide gel electrophoresis(SDS-PAGE)was also used to clarify the specific adsorption of BHb by modified TiO2 samples.The structure different between BHb and BSA was responsible for the enhanced chemical interaction between BHb and modified TiO2,and the surface modification caused the surface charge change,that resulted in the electrostatic repulsion was dominant between BSA and modified TiO2.