Biological dressing with human hair keratin-collagen sponge-poly 2-hydroxyethyl methacrylate composite promotes burn wound healing in SD rats / 南方医科大学学报

<p><b>OBJECTIVE</b>To develop a composite material containing human hair keratin (HHK), collagen sponge (inner layer) and poly 2-hydroxyethyl methacrylate (PHEMA) film that allows sustained release of polydatin and test its effect as a biological dressing in promoting burn wound healing in SD rats.</p><p><b>METHODS</b>Three HHK materials with fast, moderate, and low degradation rates were mixed at the ratio of 4:3:3 to prepare a reticular structure, which was processed into a composite material with bovine tendon-derived collagen sponge, and further complexed with HEMA film containing PD prepared by polymerization. Degree II burn wound was induced in SD rats by scalding and within postburn day 2-5, the wounds were cleansed and covered with the composite material or with glutaraldehyde-treated porcine skin (positive control). At week 1, 2, 4, 6 and 8 following wound dressing, 6 full-thickness skin samples were harvested from the wounds for histological observation and immunohistochemical detection of collagen and elastic fibers, and the wound healing time and healing rate were recorded.</p><p><b>RESULTS</b>The prepared collagen sponge film was transparent and porous (50-300 microm in diameter) and allowed sustained PD release into normal saline within 48 h. Compared with the porcine skin, the composite material reduced exudation and maintained ideal moisture of the wound, and significantly shortened the wound healing time (P=0.000). On day 7, 14, and 21 following dressing, the composite material and porcine skin significantly increased the wound healing rate as compared with the negative control group (P=0.000), and on day 14, the composite achieved significantly greater healing rate than the porcine skin (P<0.05).</p><p><b>CONCLUSION</b>HHK-collagen sponge-PHEMA/PD composite as a dressing material promotes burn wound healing in rats by allowing in vivo construction of tissue engineered epidermis. PHEMA is feasible for sustained drug delivery in this composite.</p>

Studies on design, synthesis and biodegradation of carrier for colon-site specific, drug delivery system / 药学学报

<p><b>AIM</b>To design and synthesize a novel vector for colon-site specific drug delivery system and investigate the relationship between the biodegradation properties and composition of materials in the simulated colon fluid.</p><p><b>METHODS</b>The azocopolymer P (HEMA-MMA-MAA) was synthesized using 2-hydroxyethylmethacrylate (HEMA), methyl methacrylate (MMA) and methacrylic acid (MAA) as comonmer, azobisisobutyronitrilel (AIBN) as initiator, cross-linked with divinylazobezene (DVAB). The chemical structure of the synthesized series of azocopolymer is examined by UV, FTIR spectroscopy and nuclear magnetic resonance data. Their swelling behavior is evaluated by the swelling equilibrium parameter Q, the biodegradation tests of the materials were carried out at physiologically relevant buffer designed to mimic the colon environment. The biodegradation properties were assessed using the differential scanning calorimeters (DSC) and gel permeation chromatography (GPC) and the morphology on the surface of materials before and after degradation was observed by scanning electron microscopy (SEM).</p><p><b>RESULTS</b>The swelling equilibrium parameter Q increased with increasing the contents of HEMA and MAA in the materials. The degradation behavior was relevant to the ratio of three components in the copolymers.</p><p><b>CONCLUSION</b>This materials may become a good carrier for the colon-site specific drug delivery system if the contents of commoners HEMA, MMA and MAA are adjusted reasonably.</p>