Modification of starch-derived graphene quantum dots as multifunctional nanofillers to produce polymer starch/polyvinyl alcohol composite films for active packaging

Here we reported a facile and green route to prepare graphene quantum dots (GQDs) by using corn starch as a nanofiller for the preparation of starch-based active films. The aqueous solution of GQDs displayed excitation wavelength-independent emission, stable photoluminescence, and good bio-safety. And the results demonstrated that the starch-derived GQDs have good compatibility with the natural polymer starch/polyvinyl alcohol (PVA) matrix. With the addition of GQDs over 50 μg/mL, the composite film has a very satisfactory UV blocking capacity. Moreover, 100 μg/mL of GQDs significantly increases the elongation at break and tensile strength of the obtained film to 1.79 and 2.94 times respectively, while the water solubility is only 53.9% of that of the starch/PVA film. The maximum scavenging rates of 2,2-diphenyl-1-picrylhydrazyl free radical by the starch/PVA film containing 150 μg/mL of GQDs was 83.3%. As the amount of GQDs added increases, the inhibitory effect of the composite film on Staphylococcus aureus and Escherichia coli becomes more and more significant. The starch-sourced composite film's eco-friendly nature and superior performance make it a promising alternative to traditional plastic materials for active packaging.