| In addition to greater surface area, size controllable properties and excellent surface effect of the nonmaterial’s basic characteristics, nano-TiO2also has excellent biocompatibility and chemical stability. It will be good adsorbed bimolecular carriers. In recent years, material and heat exchange in the adsorption process and interface characteristics between the carrier and protein have increasingly become the research hotspot. In this study, the TiO2nanoplates and nanospheres were biomimetic synthesized by amino acids. The adsorption better carrier was chosen for further researching of the analysis of isotherm, kinetics, thermodynamics for adsorption and interfacial properties of the carrier and protein.Scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FT-IR) and N2adsorption-desorption experiments were used to characterize the product. The results showed that the size of TiO2nanoplates by biomimetic synthesis were about40-50nm, with lamellar morphology. The phase was pure anatase TiO2. FT-IR spectrum analysis showed that the surfaces contain not only Ti-O-Ti bond, but also O-H bond, which provided-OH for the subsequent adsorption experiments. N2adsorption-desorption experiments analysis showed that N2adsorption-desorption isotherms was type Ⅴ isotherm, which had mesoporous nature. The pore size, pore volume and surface area data of the TiO2nanoplates were56.36nm,0.218cc·g-1and61.42m2·g-1.The size of TiO2nanospheres were about60-80nm, with spherical morphology. In addition to anatase crystalline structure, but also doped rutile structure; the surfaces contain not only Ti-O-Ti bond, but also O-H bond and N2adsorption-desorption experiments analysis showed that it had mesoporous nature, which was the same with TiO2nanoplates; the pore size, pore volume and surface area data of the TiO2nanoplates were59.87nm,0.212cc·g-1and59.87m2·g-1.The adsorption of bovine serum albumin (BSA) onto TiO2was investigated by using anatase TiO2nanoplates as the adsorbent. The results showed that with BSA concentration increasing, the adsorption rate increased in the case of BSA concentration relatively small, when the BSA concentration was1.0mg·mL-1, the adsorption capacity reached saturation. With pH less than the isoelectric point of BSA, the adsorption rate increased quickly, with pH more than the isoelectric point of BSA, the adsorption rate decreased slowly, when the pH was5.0, the adsorption capacity reached the highest point. With the time increasing, the adsorption rate increased rapidly in the range of0-120min and the adsorption capacity of BSA on nano-TiO2reached equilibrium at240mm.The process of mass transfer and energy exchange of interaction between nano-TiO2and BSA was investigated by adsorption isotherm, kinetics and thermodynamics. The results showed that the adsorption phenomena appeared to follow the Freundlich adsorption equation and the pseudo-first-order kinetic model. The adsorption process was the changes of single adsorbate concentration, mainly controlled by mass transfer step, rather than by chemical factors. The adsorption thermodynamics results showed that AH=-29.676KJ·mol-1,△G<0,△S<0, the adsorption process was an exothermic physical adsorption and a spontaneous behavior, with the heat released during the adsorption.The adsorption of BSA on the surfaces of nano-TiO2was investigated by using scanning electron microscope (SEM), X-ray diffraction (XRD), Fourier transform infrared spectrophotometry (FT-IR), N2adsorption-desorption experiments and DTA-TG as the characterization methods. SEM characterization showed that compared to the original particle, the morphology and size of nano-TiO2after adsorbing BSA have no obvious changes. XRD result showed that the BSA adsorption caused XRD peak intensity of nano-TiO2relatively weakened, however a smaller affection on its crystalline structure. FT-IR spectrum analysis showed that Ti-O bond combination with C, Structural stability of the α-helix reduced in BSA, nano-TiO2and BSA were combined to form an adsorption layer by hydrogen bonding and the spatial conformation of nano-TiO2with BSA was changed. N2adsorption-desorption experiments characterization showed that N2adsorption-desorption isotherms of nano-TiO2from Ⅴ type isotherm to Ⅲ type isotherm after BSA adsorption. The adsorption of N2, the specific surface area, pore volume and pore radius of TiO2after adsorption were smaller than what before adsorption, which showed that the crystal structure of nano-TiO2was changed, with the BSA into the pores of TiO2. DTA-TG characterization showed that the adsorption of interface layer BSA was40.2mg·g-1and heat was released continuously with the interface reaction occurs. |
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