Castor oil/ZnO-loaded quaternized chitosan nanocomposite with multiple antimicrobials, anti-biofilm and pro-healing functions for advanced wound dressings.

A quaternized chitosan-castor oil/Zinc oxide (QCCOZ) nanocomposite hydrogel was developed as an antibacterial and pro-healing wound dressing. The synergistic effect produced a positively charged (ζ = +38 mV) nanoformulation with high colloidal stability and superior encapsulation efficiencies of 89.9 and 80.5% for ZnO and CO, respectively. The successful quaternization and the loading of ZnO into the oil phase was confirmed by FTIR, XRD, SEM/TEM, and DLS techniques. The in vitro release profiles showed prolonged co-delivery of ZnO and castor oil over 72 h without burst effects and diffusional controlled release profiles for a prolonged wound dressing. QCCOZ demonstrated broad-spectrum anti-bacterial and antifungal activity, higher inhibition zones with 2-8-fold lower MIC/MBC values compared to pristine QCS, ZnO or castor oil against Pseudomonas spp., B. subtilis, and C. albicans and disrupted their biofilms. Cytocompatibility studies with human dermal fibroblasts and A375 cells showed >85% viability at therapeutic concentrations, and scratch wound assays confirmed enhanced wound closure where QCCOZ-treated fibroblast monolayers achieved 90% closing compared to 55% within 24 h for controls. Results indicate QCCOZ nanocomposite possesses antimicrobial potency with cytocompatibility and pro-healing functionality, representing a potential advanced hydrogel dressing for infected wounds.