| Skin is the first-line protective barrier of the body that maintain environmental balance and prevent microbial invasion, but the barrier function of the skin will be disrupted by burn. Water, proteins, electrolytes and heats will be lost because of skin damage. In addition, local and general infections induced by microorganisms invasion into human body through damaged skin, which delayed the healing time, even threatened the life of wounded person. An appropriate wound dressing may avoid infections during wound healing, accelerate the reconstruction of skin tissue, shorten healing time and decrease the suffering. Therefore, it is important to develop wound dressings with the ability of wound healing and anti-infection for various of burn wounds and skin defects.Sodium alginate was oxidized by sodium periodate and the characteristic peak of aldehyde group in the oxidized sodium alginate (ADA) was confirmed by Fourier Transform infrared spectroscopy (FTIR). Additionally, the degree of oxidation and the aldehyde contents of ADA were measured by using hydroxylamine hydrochloride method, indicating that the degree of oxidation of sodium alginate increased along with the increasing amounts of sodium periodate added.Acetic acid of40%was used as solvent, and ADA was added to the gelatin solution prior to spinning. The electrospun mats were followed by further cross-linking of the as-electrospun mats in gradient ethanol (pH9). FTIR analysis indicated that the characteristic peak of C=N group was found in the electrospun membrane. SEM analysis showed that the cross-linked fibers were defect free and regular. The amount of the free amino groups in the electrospun gelatin fibers were determined by using a ninhydrin assay. The degree of cross-linking increased as the amounts of added ADA increased, while the swelling ratio decreased, but all the gelatin-ADA membranes had good swelling property, and suitable to absorb wound exudation fluid, maintaine a moist environment for wound. The degradation behavior of membranes was dependent upon the cross-linking degree, and higher degree of cross-linking produced more stable fibrous mats. The degradation time could be controlled up to28d, which overcome the shortcomings that gelatin dissolve quickly in body fluid environment. The gelatin/ADA membranes were incubated in a serum-free DMEM medium for3d, NIH3T3cells were incubated with the prepared extraction medium for1and3d. All the fibrous mats performed slight toxicity after1d of incubation, and the toxicity disappear after3d incubation, indicating that the toxicity could come from a possible release of dialdehyde from ADA.Gentamycin sulfate (Gen), ciprofloxacin (Cip) or their blends were added to gelatin/ADA fivers. SEM analysis showed that the antibiotic-loaded fibers were defect free and regular. In vitro release indicated that Gen was released faster than Cip, and a possible explanation for this finding mat be the higher water-solubility of Gen than Cip. The free amino groups of Gen should have additional cross-linking with ADA, leading to a slower release of Gen from the electrospun fibers. Bacterial growth inhibition evaluation was perfomed on Pseudomonas aeruginosa and Staphylococcus epidermidis. The antibacterial ability of the drug-loaded fibers was close to that of free drug. Drug-loaded membranes still had good antibacterial ability after they soaked in PBS for different days. Cytotoxicity evaluation on NIH3T3fibroblasts showed that the gelatin/ADA fibers had good cytocompatibility.The back of the rat area was burned with a hot circular iron billet to induce a second degree burn. P. aeruginosa was added to the wound area. The wound area was then covered with GA, GA/G, GA/C or GA/G/C mats, the wound area was covered with sterile gauze as a control group. The results showed that, compared with the gauze dressing and GA mats dressing, GA/G, GA/C and GA/G/C had good antibacterial effect, with less bacterial number in wound tissue and liver. GA, GA/G, GA/C and GA/G/C mats could promote wound healing, the wounds covered with GA/G/C mats were observed to heal more rapidly compared to all the others through photographic observations. |
