Amphotericin B-loaded natural latex dressing for treating Candida albicans wound infections using Galleria mellonella model.

Amphotericin B (AmB) is the gold standard for antifungal drugs. However, AmB systemic administration is restricted because of its side effects. Here, we report AmB loaded in natural rubber latex (NRL), a sustained delivery system with low toxicity, which stimulates angiogenesis, cell adhesion and accelerates wound healing. Physicochemical characterizations showed that AmB did not bind chemically to the polymeric matrix. Electronic and topographical images showed small crystalline aggregates from AmB crystals on the polymer surface. About 56.6% of AmB was released by the NRL in 120 h. However, 33.6% of this antifungal was delivered in the first 24 h due to the presence of AmB on the polymer surface. The biomaterial's excellent hemo- and cytocompatibility with erythrocytes and human dermal fibroblasts (HDF) confirmed its safety for dermal wound application. Antifungal assay against Candida albicans showed that AmB-NRL presented a dose-dependent behavior with an inhibition halo of 30.0 ± 1.0 mm. Galleria mellonella was employed as an in vivo model for C. albicans infection. Survival rates of 60% were observed following the injection of AmB (0.5 mg.mL-1) in G. mellonella larvae infected by C. albicans. Likewise, AmB-NRL (0.5 mg.mL-1) presented survival rates of 40%, inferring antifungal activity against fungus. Thus, NRL adequately acts as an AmB-sustained release matrix, which is an exciting approach, since this antifungal is toxic at high concentrations. Our findings suggest that AmB-NRL is an efficient, safe, and reasonably priced ($0.15) dressing for the treatment of cutaneous fungal infections.

Gentamicin encapsulated within a biopolymer for the treatment of Staphylococcus aureus and Escherichia coli infected skin ulcers.

Skin wound infection requires carefully long-term treatment with an immense financial burden to healthcare systems worldwide. Various strategies such as drug delivery systems using polymer matrix from natural source have been used to enhance wound healing. Natural rubber latex (NRL) from Hevea brasiliensis has shown angiogenic and tissue repair properties. Gentamicin sulfate (GS) is a broad-spectrum antibiotic which inhibits the growth of a wide variety of microorganisms and, because of this, it has also been applied topically for treatment of local infections. The aim of this study was to develop a GS release system using NRL as matrix for Staphylococcus aureus and Escherichia coli infected skin ulcers treatment, without changing drug antibiotic properties. The matrix did not change the GS antimicrobial activity against S. aureus and E. coli strains. Moreover, the NRL-GS biomembrane did not exhibit hemolytic activity, being non-toxic to red blood cells. The eluates of NRL-GS biomembranes and GS solutions did not significantly reduce the survival of Caenorhabditis elegans worms for 24 h at any of the tested concentrations. Thus, these results emphasize that the NRL-GS biomembrane proved to be a promising biomaterial for future studies on the development of dressings for topical uses, inexpensive and practicable, keeping drug antibiotic properties against pathogens and to reduce the side effects.