超声与光催化作用对大豆蛋白/TiO_2复合膜抗菌特性的影响

采用光催化/超声预处理,结合涂膜法制备大豆蛋白/TiO_2纳米复合膜,分析光催化和超声预处理以及膜中TiO_2含量对复合膜性质的影响。当TiO_2含量低于2%时,扫描电子显微镜观察发现TiO_2纳米颗粒均匀地分散在大豆蛋白基质中,从而有效地改善复合膜的机械性能,降低膜的溶胀变形程度,提高膜的热稳定性,增强复合膜的抗菌活性。荧光光谱分析、红外光谱和X-射线衍射分析证实了大豆蛋白和纳米颗粒间以氢键为主要作用力,且光催化可进一步增强TiO_2颗粒与大豆蛋白链间交联作用,因而光催化复合膜的机械性能、热稳定性和抗菌活性均高于超声复合膜。但当TiO_2含量过高(2%)会加剧TiO_2间的自聚,导致复合膜机械性能下降、溶胀变形程度增大及荧光淬灭。因此光催化大豆蛋白/TiO_2纳米复合膜有望成为新型绿色抗菌包装材料。

Effects of Ultrasonication or Photocatalytic Pretreatment on Antibacterial Properties of Soy Protein/Nano-titanium dioxide Composite Films

Biodegradable soy protein (BSP)-titanium dioxide nanocomposite films were fabricated using a combination of ultrasonication or photocatalytic pretreatment and a solution-casting method, and the effects of ultrasonication, photocatalytic pretreatment, and titanium dioxide content of the film on properties of the composite film were analyzed. At a low titanium dioxide concentration (<2%), the scanning electron microscopy (SEM) results showed that the titanium dioxide nanoparticles were evenly dispersed in the protein matrix, so that the swelling-induced deformation of the film was reduced, and the mechanical properties, thermal stability, and antibacterial activity of the composite film were improved. The data on intrinsic fluorescence spectra, Fourier transform infrared spectra (FT-IR), and X-ray diffraction (XRD) confirmed that the interaction between protein and nanoparticles was mainly mediated by hydrogen bonding, and that the photocatalytic pretreatment further strengthened the cross-linking between protein molecules and nanoparticles, thus the mechanical properties, thermal stability, and antibacterial activity of the composite films prepared by photocatalytic pretreatment were improved as compared with those of the films prepared by ultrasonication. Nevertheless, a high titanium dioxide concentration (>2%) promoted self-assembly of titanium dioxide-titanium dioxide nanoparticles, leading to fluorescence quenching, worsening of mechanical properties, and an increase in swelling-induced deformation. Soy protein/nano- titanium dioxide composite films prepared by photocatalytic pretreatment may potentially become new green packaging materials with antibacterial properties.