Tuning antibiotic release from gelatin-cellulose nanocrystal hydrogel films

Effective wound dressings that absorb exudate and deliver antibiotics topically can address delayed healing and infection. To this end, we prepared a gelatin-cellulose nanocrystals (CNC) double-layer wound dressing using a casting method designed to tune the delivery of tetracycline hydrochloride (TCH). Specifically, a TCH-loaded gelatin hydrogel was developed, followed by the fabrication of a secondary hydrogel layer via two approaches: direct incorporation of CNC and TCH into the gelatin matrix, and indirect incorporation through a CNC/TCH complex mediated by Mg²⁺ cations. Drug release studies demonstrated that Mg²⁺-mediated complexation enabled sustained release (49 ± 2.1 %) over a period of five days. Moreover, CNC-containing samples exhibited greater swelling, water absorption, Young's modulus, and tensile strength compared to pure gelatin films, indicating improved physicochemical and mechanical properties. Antibacterial tests showed 84 % inhibition of Staphylococcus aureus growth, while biocompatibility assays with L929 mouse fibroblast cells confirmed the films' suitability for supporting cell growth and survival. Notably, the optimized double-layer gelatin film (Gel/TCH + Gel/Complex) exhibited sustained drug release over 48 h, along with enhanced swelling properties, making it highly suitable for applications in drug delivery, tissue engineering, and wound dressing. Overall, these promising results not only demonstrate the synergistic effect of CNC incorporation and Mg²⁺ complexation in improving film performance but also lay the groundwork for future research aimed at developing multifunctional wound dressings. These advanced materials have significant potential to accelerate wound healing, reduce the risk of infection, and improve patient outcomes in clinical settings.