Sodium alginate-assisted route to antimicrobial biopolymer film combined with aminoclay for enhanced mechanical behaviors

Abstract

Considerable attention has been paid to the utilization of eco-friendly biopolymer-based composites in such areas as bioscience, packaging, and tissue engineering. However, the drawbacks of biopolymers, for instance, low mechanical performance and high water absorption, present obvious challenges. In this study, we fabricated a better-performing bio-film from soy protein isolate (SPI) that was modified by oxidized sodium alginate and silver nanoparticles (OSA@AgNPs). Furthermore, synthetic platelike aminoclay (AC) was introduced to form an interpenetrating polymeric network structure in the matrix of the SPI-based films. The appearance and size distribution of the obtained AgNPs were confirmed by transmission electron microscopy (TEM) and dynamic light scattering (DLS). The results of mechanical tests showed that the tensile strength and toughness of the film were significantly increased by 230.3% (to 10.9 ± 0.4 MPa) and 148.1% (to 12.9 ± 0.3 MJ m−3), respectively, with the introduction of 8 wt% AC into the matrix. The antimicrobial properties of the SPI-based films were determined using the disc diffusion method, the results of which suggested that the films had favorable antibacterial activities against both Escherichia coli and Staphylococcus aureus. Furthermore, the SPI/OSA@AgNPs/AC films displayed hydrophobic surfaces and dramatically enhanced water resistance. The effort made in this study for solving the drawbacks of SPI-based films might expand their applications.