PURPOSE: This work aimed to develop and characterize chitosan (CS)-polyvinyl alcohol (PVA) blended electrospun multifunctional nanofiber loaded with curcumin (CUR) and zinc oxide (ZnO) to accelerate diabetic wound healing in STZ-induced diabetic rats.
RESULTS: In-vitro characterization results revealed that nanofiber was fabricated successfully using the electrospinning technique. SEM results confirmed the smooth surface with web-like fiber nanostructure diameter ranging from 200 - 250 nm. An in-vitro release study confirmed the sustained release of CUR and ZnO for a prolonged time. In-vitro cell-line studies demonstrated significantly low cytotoxicity of nanofiber in HaCaT cells. Anti-bacterial studies demonstrated good anti-bacterial and anti-biofilm activities of nanofiber. In-vivo animal studies demonstrated an excellent wound-healing efficiency of the nanofibers in STZ-induced diabetic rats. Furthermore, the ELISA assay revealed that the optimized nanofiber membrane terminated the inflammatory phases successfully by downregulating the pro-inflammatory cytokines (TNF-α, MMP-2, and MMP-9) in wound healing. In-vitro and in-vivo studies conclude that the developed nanofiber loaded with bioactive material can promote diabetic wound healing efficiently via multifunction action such as the sustained release of bioactive molecules for a prolonged time of duration, proving anti-bacterial/anti-biofilm properties and acceleration of cell migration and proliferation process during the wound healing.
DISCUSSION: CUR-ZnO electrospun nanofibers could be a promising drug delivery platform with the potential to be scaled up to treat diabetic foot ulcers effectively.
Methods: The matrix patches were prepared by using different polymers, with and without silicone adhesive, dibutyl sebacate and mupirocin. The patches were characterized for mechanical properties, drug content, moisture content, water absorption capacity and Fourier transform infrared spectrum. In vitro release studies were performed by using Franz diffusion cell. In vitro disk diffusion assay was performed on the Mueller-Hinton Agar plate to measure the zone of inhibition of the patches. The in vivo study was performed on four groups of rats with bacterial counts at three different time intervals, along with skin irritancy and histopathologic studies.
Results: The patches showed appropriate average thickness (0.63-1.12 mm), tensile strength (5.08-10.08 MPa) and modulus of elasticity (21.53-42.19 MPa). The drug content ranged from 94.5% to 97.4%, while the moisture content and water absorption capacities at two relative humidities (75% and 93%) were in the range of 1.082-3.139 and 1.287-4.148 wt%, respectively. Fourier transform infrared spectra showed that there were no significant interactions between the polymer and the drug. The highest percentage of drug release at 8 hours was 47.94%. The highest zone of inhibition obtained was 28.3 mm against S. aureus. The in vivo studies showed that the bacterial colonies were fewer at 1 cm (7×101 CFU/mL) than at 2 cm (1.3×102 CFU/mL) over a 24-hour period. The patches were nonirritant to the skin, and histopathologic results also showed no toxic or damaging effects to the skin.
Conclusion: The in vitro and in vivo studies indicated that controlled release patches reduced the migration of S. aureus on the live rat skin effectively, however, a longer duration of study is required to determine the effectiveness of the patch on a suitable peritonitis-induced animal model.
RESULTS: The resazurin-based TB assay demonstrated that the L. cuprina larval extract was inhibitory against all tested bacteria, whilst the larval extract of S. peregrina and M. domestica were only inhibitory against the MRSA, with a MIC of 100 mg ml(-1). Subsequent sub-culture of aliquots revealed that the larval extract of L. cuprina was bactericidal against MRSA whilst the larval extracts of S. peregrina and M. domestica were bacteriostatic against MRSA. The GC-MS analysis had quantitatively identified 20 organic compounds (fatty acids or their derivatives, aromatic acid esters, glycosides and phenol) from the larval extract of L. cuprina; and 5 fatty acid derivatives with known antimicrobial activities from S. peregrina and M. domestica.
CONCLUSION: The resazurin-based turbidometric assay is a simple, reliable and feasible screening assay which evidently demonstrated the antibacterial activity of all fly larval extracts, primarily against the MRSA. The larval extract of L. cuprina exerted a broad spectrum antibacterial activity against all tested bacteria. The present study revealed probable development and use of novel and effective natural disinfectant(s) and antibacterial agent(s) from flies and efforts to screen more fly species for antibacterial activity using resazurin-based TB assay should be undertaken for initial screening for subsequent discovery and isolation of potential novel antimicrobial substances, particularly against the multi-drug resistant strains.