Synthesis Of Metal Oxide-modified Magnetic Nanoparticles For Purification Of Casein Phosphopeptides

As the binding of metal affinity protein/peptide, metal ion/metal oxide magneticseparation technology becomes a novel separation technology. Metal affinity protein/peptidehave unique physiological function which destine them to have very great economy benefit,outstanding practical significance. Casein phosphopeptides (CPPs) is one of the most widelystudied metal affinity peptide. It is the only promote calcium function of active peptide whichcan be used in food additives in China, so it has the wide practical prospect and hugedeveloping potential. Due to the low stoichiometry of phosphoric acid root from theenzymatic hydrolysis of casein, enrichment CPPs is necessary prior to be applied in infantformula as mineral supplements and other nutritional foods.In this study, functional titania modified (Fe3O4@TiO2) and zirconia modified(Fe3O4@ZrO2) magnetic nanoparticles were prepared，and the effects of process parameterson the properties of the nanoparticles were analyzed. The physical shapes and the crystallinestructures of nanoparticles were characterized by transmission electron microscopy (TEM),the rmogravimetric analysis (TGA), X-ray diffraction (XRD) and Fourier Transform InfraredSpectroscopy (FT-IR). The results indicated the titania and zirconia group covered up thesurface of Fe3O4nanoparticles respectively. The preparation procedure is is simple andfeasible, the materials, with uniform diameter of20nm～25nm, have good dispersion, highmagnetic response, superparamagnetism, and the feasibility of industrial-scale production.Then the adsorption capacity of nanoparticles and the purity of CPPs were analyzed tooptimize the conditions of purification of CPPs, the adsorption kinetics were described bypseudo kinetic model; the adsorption isotherms were represented by Langmuir adsorptionmodel. Meanwhile the unused and reused nanoparticles were characterized by FT-IR andXRD and the purity of CPPs isolated by nanoparticles was analyzed to study the stability ofmaterials after repeatedly used. The final conclusions: relative to Fe3O4@TiO2nanoparticles,Fe3O4@ZrO2nanoparticles showed relatively higher efficiency of purification process withhigher loading amount of phosphoric acid root (6.53mg) and lower N/P (5.94) of CPPs whenpH was4.5, temperature was35oC, initial peptide concentration was50mg/mL; Fe3O4@ZrO2nanoparticles had good stability and high affinity force for CPPs after fifteen repeatedadsorption-elution cycles.Compared with traditional methods, this purification process of CPPs by usingFe3O4@ZrO2nanoparticles has the simpler procedures, higher enrichment efficiency, shorterproduction cycle and lower production cost, just need an external magneticfield, without thedemand on any expensive equipment. The results show that: Fe3O4@ZrO2is a new type ofextraction materials and possesses a wide application prospects in food industry. It canefficiently extract the metal oxide affinity proteins/peptides from real systems, which made itpossible to separate metal oxide affinity proteins/peptides quickly and extend related foodproducts research and development in food industry.