Antioxidant and antibacterial lignin nanoparticles in polyvinyl alcohol/chitosan films for active packaging

Binary and ternary polymeric films based on polyvinyl alcohol (PVA), chitosan (CH) and lignin nanoparticles (LNP) added at two different amounts (1 and 3 wt%) were produced by solvent casting. Thermal, optical, mechanical properties, migration, antioxidant and antibacterial activities, as well as morphologies of binary and ternary PVA/CH/LNP nanocomposites, were investigated. Mechanical results revealed that the addition of LNP enhanced the tensile strength and Young’s modulus of PVA, producing also a toughness effect in CH matrix. Higher crystallinity values measured in calorimetric characterization confirmed how well dispersed LNP could effectively provide nucleation effects in PVA. Furthermore, LNP notably improved the thermal stability of the binary and ternary nanocomposite systems. Antimicrobial assays revealed a capacity to inhibit the bacterial growth of Gram negative Erwinia carotovora subsp. carotovora and Xanthomonas arboricola pv. pruni over the time, suggesting innovative opportunities against bacterial plant/fruit pathogens in food packaging applications. In addition, the synergic effect of LNP and CH in the antioxidation response of the produced films potentially envisage their use in many different biomedical applications (drug delivery, tissue engineering, wound healing), where innovative antimicrobial strategies are continuously required.