Improved mechanical and antimicrobial properties of zein/chitosan films by adding highly dispersed nano-TiO2

Highly dispersible TiO2 nanoparticles were prepared through the hydrolysis of titanium alcohol, and a series of TiO2-modified zein/chitosan (CS) films were prepared through a process involving blending, solution casting and evaporation. The mechanical properties and the antibacterial capacity of the zein/CS/TiO2 films were characterized to explore the effects of different TiO2 nanoparticle contents. Results showed that the addition of nanoscale TiO2 remarkably improved the mechanical properties and thermal stability of the zein/CS/TiO2 film. The tensile strength of the zein/CS/TiO2 films significantly increased (p < 0.05) with the increasing TiO2 loadings in films, reaching a maximum of 28.33 +/- 1.53 MPa at 0.15 wt % TiO2 nanoparticles. The antibacterial effect of the composite films on Gram-positive bacteria (S. aureus) was more significant than that of Gram-negative bacteria (E. coli and S. enteritidis), and the antibacterial effect of UV light was better than that of dark conditions. In particular, the inhibition zones of zein/CS/TiO2 (0.15%) film against E. coli, S. enteritidis and S. aureus under UV light condition increased by 21.78%, 21.45%, and 26.44%, respectively, compared with the control. This study suggested that adding highly dispersible TiO2 nanoparticles is an effective method for improving the mechanical and antimicrobial properties of zein/CS films for various applications, such as medical and food packaging.