Physical, mechanical, and antibacterial properties of Hibiscus sabdariffa L. extract and graphene oxide incorporated corn starch nanocomposite films

The utilization of eco-friendly and biodegradable natural biopolymers is globally expanding due to environmental problems caused by non-degradable synthetic polymers. This study examined the physical, mechanical, and antibacterial properties of corn starch-based films incorporated with Hibiscus sabdariffa L. extract (HE) and different concentrations (0.5, 1, and 1.5 wt% of starch) of graphene oxide (GO). The addition of HE and GO into the starch matrix resulted in increased thickness, moisture content, solubility, and swelling degree in the composite films. FTIR spectrum proved intermolecular interactions among starch, HE, and GO. Moreover, SEM images showed that films presented a continuous surface without cracks and bubbles, without separation of phases between starch, HE, and GO verifying the compatibility of the constituents in the film matrix. On the other hand, the addition of the plant extract and GO significantly reduced the tensile strength of the films (except the film containing 0.5% GO) and increased the percentage of elongation at break. Furthermore, all films displayed strong antibacterial activity against both the Gram-positive and Gram-negative bacteria. Obtained results suggest that the novel antibacterial starch films incorporated with HE and GO are promising to be used as wound dress or food coating.