Green Chitosan Bioplastics: How the Filler Impacts the Biological Activity and the Biodegradability?

The growing environmental plastic pollution triggered research for biodegradable and safe materials, among which biopolymer-based films stand as the most promising. Among these, chitosan has gained significant attention due to its biocompatibility, film-forming ability, and inherent antimicrobial properties. In this context, the use of fillers to design chitosan nanocomposite films has been shown to enhance the mechanical, barrier, thermal, optical, and antimicrobial properties of the resulting bioplastics. However, the fate and destiny of these fillers, as well as their impact on the biological properties and biodegradability of chitosan films, remain underexplored. We herein report a more comprehensive screening of a set of fillers, encompassing three clay variants (montmorillonite, sepiolite, and halloysite) and microcrystalline chitin. The films were systematically characterized to assess their antibacterial performance, cytocompatibility, hemocompatibility, and biodegradability. The highest antibacterial activity was observed for CS@MMT-f film towards Staphylococcus aureus and Escherichia coli. Importantly, all developed films demonstrated negligible hemolytic activity and low cytotoxicity, indicating their safety for potential biomedical or food-contact applications. Moreover, the selected films completely degrade within four to six weeks under soil burial conditions, demonstrating their potential as environmentally friendly packaging materials.