In situ synthesis and properties of Ag NPs/carboxymethyl cellulose/starch composite films for antibacterial application

Carboxymethyl cellulose (CMC) film, one of the biobased materials, exhibited poor mechanical properties. To use CMC film in antibacterial packaging, it was necessary to overcome this drawback and introduce antibacterial nanoparticles. In this article, using CMC and starch (SR) as the reductant and stabilizer, Ag nanoparticles (Ag NPs)/CMC/SR composite (ACS) films were prepared by in situ reduction method. The obtained Ag NPs were uniformly distributed in the ACS films and its diameter was in the range of 8 to 16 nm. The mechanical properties of ACS films were improved by adding SR into CMC. The ACS films exhibited higher tensile strength and lower elongation at break than that of CMC film. When the amount of SR was 4 g, the tensile strength of the ACS film reached the maximum of 9.8 MPa and its elongation at break was 63%. In addition, the ACS films showed an obvious antibacterial activity against gram-positive bacteria Staphylococcus aureus and gram-negative bacteria Escherichia coli via disc diffusion method. The inhibitory effect of the ACS film increased significantly as the increasing of the concentration of AgNO3 solution. Therefore, as-prepared ACS films had potential applications in antimicrobial packaging.