Bacteriophage-cocktail hydrogel dressing to prevent multiple bacterial infections and heal diabetic ulcers in mice.

Bacteriophage (phage) has been reported to reduce the bacterial infection in delayed-healing wounds and, as a result, aiding in the healing of said wounds. In this study we investigated whether the presence of phage itself could help repair delayed-healing wounds in diabetic mice. Three strains of phage that target Salmonella enterica, Escherichia coli, and Pseudomonas aeruginosa were used. To prevent the phage liquid from running off the wound, the mixture of phage (phage-cocktail) was encapsulated in a porous hydrogel dressing made with three-dimensional printing. The phage-cocktail dressing was tested for its phage preservation and release efficacy, bacterial reduction, cytotoxicity with 3T3 fibroblast, and performance in repairing a sterile full-thickness skin wound in diabetic mice. The phage-cocktail dressing released 1.7%-5.7% of the phages embedded in 24 h, and reduced between 37%-79% of the surface bacteria compared with the blank dressing (p <.05). The phage-cocktail dressing exhibited no sign of cytotoxicity after 3 days (p <.05). In vivo studies showed that 14 days after incision, the full-thickness wound treated with a phage-cocktail dressing had a higher wound healing ratio compared with the blank dressing and control (p <.01). Histological analysis showed that the structure of the skin layers in the group treated with phage-cocktail dressing was restored in an orderly fashion. Compared with the blank dressing and control, the repaired tissue in the phage-cocktail dressing group had new capillary vessels and no sign of inflammation in its dermis, and its epidermis had a higher degree of re-epithelialization (p <.05). The slow-released phage has demonstrated positive effects in repairing diabetic skin wounds.

Preparation of nano/submicrometer Ganoderma tsugae and its mutagenic potencies and cytotoxicity.

This study explored the feasibility of preparing nano/submicrometer particles from Ganoderma tsugae to enhance the contents of bioactive compounds and to assess its mutagenic potencies and cytotoxicity. Hot-water extract, a common product, was employed as a reference. After 3 h of media milling, almost all of the particles were smaller than 1 µm with a number-mean diameter of 0.11 µm. There were about 62% particles smaller than 0.1 µm in terms of number of particles. Scanning electron microscopy (SEM) confirmed the presence of particles at nano/submicrometer scale. The content of 1→3-ß-D-glucan in nano/submicrometer G. tsugae was 3.5 times of that in hot-water extract. Both nano/submicrometer and hot-water extract G. tsugae exhibited no mutagenic potential to Salmonella Typhimurium tester strains. Cell toxicity test also confirmed the safety of both nano/submicrometer and hot-water extract G. tsugae. The effect of media milling on the structural change of hyphae was also discussed.