Nanostructured TPS/PVA/CNC films for sustained copper oxide nanoparticle Release: Toward Advanced transdermal...

The search for biodegradable alternatives to traditional dressings has driven the development of thermoplastic starch nanocomposite films (T) with polyvinyl alcohol (P) and cellulose nanocrystals (CNC). Films were prepared via the casting technique with varying PVA concentrations (10, 20, 30, and 40 % w/v) and CNC reinforcements (2.5, 5.0, and 10 % w/w). The synthesis and characterization of copper oxide nanoparticles (NPCuO) was also carried out. The best-performing films were further modified with NPCuO to study their controlled release. The final material developed (T/P/10CNC/NPCuO) was extensively characterized, with measurements of thickness, swelling capacity in PBS buffer, tensile test, contact angle measurements, thermogravimetric analysis (TGA) and Fourier-transform infrared spectroscopy (FTIR). In addition, solubility, water vapor permeation, NPCuO release by visible ultraviolet spectroscopy (UV-Vis) and the cytocompatibility of the developed films were studied. NPCuO characterization showed hexagonal morphologies, a zeta potential of -32 mV, a hydrodynamic diameter of 122 nm (PDI = 0.5). Mechanical tests revealed that adding 10 % CNC tripled the stress at rupture compared to unreinforced films. Contact angle measurements (62°) confirmed hydrophilicity, a desirable property for dressings. The films showed good solubility in PBS, sustained release of nanoparticles for 8 h. Water vapor permeability increased from 0.9 to 1.75 g.mm^-2.kPa^-1.day^-1 with CNC addition and to 1.88 g.mm^-2.kPa^-1.day^-1 with NPCuO. NPCuO release was low but provided enhanced antioxidant activity: 76 % (24 h), 67 % (48 h), 43 % (72 h), and 38 % (96 h), outperforming T/P/10CNC. These nanocomposites exhibit promising mechanical, permeability, and antioxidant properties, making them suitable candidates for transdermal dressings.