Synthesis and characterization of novel PVA/walnut shell-based composite films: a potential for biomedical...

Novel bioactive composite films based on polyvinyl alcohol (PVA) reinforced with walnut shell powder (WSP) and medicinal plant additives - Lawsonia inermis, Nepeta cataria, and Artemisia vulgaris - were developed using a solution casting method for potential biomedical applications. WSP, a lignocellulosic agricultural waste, was employed as a sustainable reinforcing filler, while the herbal additives were incorporated to impart antimicrobial and wound-healing properties. The structural, morphological, chemical, and thermal characteristics of the composite films were investigated using field emission scanning electron microscopy (FESEM), energy-dispersive spectroscopy (EDS), Fourier-transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). XRD analysis revealed the semi-crystalline nature of PVA, with reduced crystallinity upon filler incorporation due to strong intermolecular interactions. FTIR confirmed effective hydrogen bonding between PVA and the bio-fillers, while thermal analyses demonstrated enhanced thermal stability of the composites. Morphological studies showed smooth to porous surface features depending on the herbal additive used. Antibacterial evaluation against Escherichia coli demonstrated significant inhibition, with the Lawsonia inermis-based composite exhibiting the highest antibacterial activity. Biocompatibility assessment using Vigna radiata seed germination indicated low cytotoxicity and favorable biological interaction, particularly for the Lawsonia inermis formulation. The synergistic integration of WSP and herbal additives within the PVA matrix resulted in multifunctional, sustainable, and biocompatible films, highlighting their strong potential for wound healing, drug delivery, and other biomedical applications.