Antimicrobial wound dressing film utilizing cellulose nanocrystal as drug delivery system for curcumin

Diabetic patients with foot ulcer showed 150-fold increased risk of amputation, which is primarily caused by microbial infection. Silver ions are commonly incorporated into wound dressing to enhance the antimicrobial property. However, concerns have been expressed about the development of bacterial resistance to heavy metals. In this study, we evaluate the in vitro and in vivo efficacy of cellulose nanocrystal film to be used as antimicrobial drug delivery system in a diabetic wound dressing. Cellulose nanocrystals were successfully isolated from medical grade cotton fibers. We observe needle-like cellulose nanocrystals with an average length of 159 nm under transmission electron microscope. The developed film with curcumin shows a uniform yellow color, with a thickness of 0.4 mm. The film obtained is soft and flexible, based on the mechanical characterization study of the film. For the curcumin release test, the release reaches plateau condition at 36 h with a total release of 98.9% from the cellulose nanocrystal film. No burst release effect was detected during the test period. The film exhibited significant inhibitory activity on 3 Gram positive bacteria, 2 Gram negative bacteria and 1 yeast. On Hohenstein challenge test, all test microorganisms showed significant growth reduction, with the treatment of curcumin loaded film. 5 of 6 test microorganisms showed 99% of growth reduction relative to growth control. We also notice that the antimicrobial activity of the film sustained even after 15 washes. In the in vivo study using diabetic rat models, a significant reduction of wound size was observed from Day 7 with the topical application of curcumin loaded film. At the end of the study, the lesion was covered by epithelial tissue and the hair started to grow from the skin. A bacterial growth reduction of 99.99% was observed from the skin sample excised from the animal models. The histological examination of skin sample also showed that curcumin loaded film significantly improved the regeneration of hair follicles and sebaceous glands of the skin. Our results indicate that the curcumin load cellulose nanocrystal films can be used for diabetic wound healing applications.