Improving the properties of starch-based antimicrobial composite films using ZnO-chitosan nanoparticles.

This work dealt with the antimicrobial nanoparticles and incorporated them into the modified starch matrix to prepare composite films. The ZnO-chitosan nanoparticles with 57.3 wt% ZnO were sol-gel synthesized for formation of hexagonal phase. The absorption peak and average size of nanoparticles was approximately 364 nm and 25 nm, respectively. It was observed that nanoparticles with less than 3.0 wt% were homogenously dispersed in the starch matrix. The increase of nanoparticles in films resulted in a substantial reduction of water vapor permeability from 51.0% to 43.7% accompanied with an increase of tensile strength from 4.11 to 12.79 MPa (p < 0.05). Moreover, higher addition (4.0-5.0 wt%) resulted in aggregation of nanoparticles in films and increased water vapor permeability (p < 0.05). The antimicrobial activity of starch-based films was positively correlated with the loading level of nanoparticles, and these films had stronger suppression in Gram-positive S. aureus than Gram-negative E. coli.