Development of HPMC-modified starch/ZnO nanocomposite films using biodegradable plasticizers for improved...

Biopolymer-based wound dressings offer a sustainable platform for developing multifunctional films with improved moisture regulation, biocompatibility, and protection against microbial contamination. In this study, nanocomposite films were formulated using HPMC, chemically modified starch, and ZnO nanoparticles, with two biodegradable plasticizers (glycerol (H1) and PEG (H2)) incorporated as plasticisers to modulate film performance. The modified starch exhibited increased amylose content (46.80 ± 1.80%) and resistant starch level (36.20 ± 2.10%), while ZnO-NPs showed a hydrodynamic size of ∼95 nm and a zeta potential of -38.44 mV, confirming good colloidal stability. PEG-plasticized films demonstrated the highest hydration capacity (618.42 ± 12.56%), lowest matrix erosion (328.44 ± 14.68%), and superior optical clarity (58.24 ± 2.15%). FTIR confirmed polymer-nanoparticle interactions, XRD verified crystallinity changes, and FESEM/AFM showed uniform nanoparticle dispersion. DSC analysis indicated improved thermal stability for H1 (92.61 ± 0.19 °C) and H2 (88.96 ± 0.21 °C). Mechanical testing revealed the highest tensile strength in H2 (12.0 ± 1.0 MPa), increasing after hydration (13 ± 2.0 MPa) with a strain of 60-64%. PEG-plasticized films also exhibited the strongest antioxidant activity with low IC₅₀ values and produced inhibition zones of 14.8 ± 1.0 mm (E. coli) and 16.0 ± 0.9 mm (S. aureus). High HaCaT viability (135.33 ± 3.11%, 24 h) confirms their wound-dressing potential.