Development And Application Of A New Compound Patch Loaded With Nano-silver

Background and objectiveVentral hernia and abdominal wall defect are the common disease and there are 8000-10000 new cases in Beijing. Tension-free hernia repair is obtained by use of prostheses, which reduces the recurrence rate. The common prostheses are including: standard non-absorbable synthetic implants, composite synthetic implants, and bioimplants. Unfortunately, all of these implants lack the properties of ideal impants, which are sufficient mechanical strength, chemical stability, lack of carcinogenic properties, easy sterilization, less foreign body reaction, anti-infection. Polypropylene meshes are the most commonly utilized implants, which can cause strong inflammatory reaction, leading to visceral adhesion, perforation, stiffness and foreign body sensation of abdominal wall. Polyester and polytetrafluoroethylene implants have poor compatibility with surrounding tissues. Insufficient mechanical strength is the concern for the bioimplants. The most important thing is all of implants lack the ability of anti-infection, which is mandatory as contaminated abdominal wall defect is repaired or bowel surgery is performed simultaneously. So repair of contaminated or infected ventral hernia is staged, thorough debridement is needed firstly, which cause the loss of health economy and social labour.In order to solve this problem, antibacterial agent should be introduced into the prostheses for hernia repair. Nano-silver, an broad-spectum antibacterial agent derived from nano-technique with 1～100nm in diameter, has a highly efficient ability of killing microbes, because of quantum effect, little dimension effect, and tremendous specific surface area. Nano-silver has been loaded on the venous duct, wound dressing, artificial blood vessel.So if nano-silver is loaded on the compound patch for hernia repair, an ideal prosthesis may be came out. Materials and methodsPart I Development and measurement of related characteristics of new compound patch loaded with nano-silver1. Three kinds of new compound patch with different concentration of nano-silver were produced.2. An optimal compound patch with the strongest antibacterial ability and least concentration was selected through experiment of antisepsis and bacteriostasis in vitro.3. The optimal compound patch loaded with nano-silver was tested in the aspects of stretchability and scratchability, compared with common compound patch.Part II Influence of leach liquor derived from nano-silver compound patch to proliferation of human fibroblasts1. Nano-silver release pattern of new compound patch in vitro.2. Culture and identification of human fibroblasts in vitro.3. Identification of influence of different-timed leach liquor derived from nano-silver compound patch to proliferation of human fibroblasts.Part III Animal experiment of repair of clean and infected abdominal wall defect using new compound patch loaded with nano-silver1. Building of rats model with clean or infected abdominal wall defect.2. Repair of clean or infected abdominal wall defect with nano-silver compound patch, polypropylene mesh, common compound patch. The following items were identified:2.1 General conditions.2.2 Conditions of wound healing at 7d postoperatively.2.3 In the infected setting, separated bacterial count in each group operated with different material, on the Id,3d,7d,14d,21d, postoperatively.2.4 Scores of adhesive conditions of abdominal cavity on the 2Id, postoperatively.2.5 Pathologic HE staining.2.6 Examination and quantitative analysis of cell apoptosis on the wound with TUNEL method.2.7 Examination and quantitative analysis of expression of TGF-β1, IL-6, CD34 with immunohistochemistry.2.8 Examination and quantitative analysis of expression of PCNA with immunofluorescence.2.9 Examination and quantitative analysis of expression of collagen with Sirius red staining.Results1. A new compound patch loaded with nano-silver is created and compound patch with 0.5% concentration of nano-silver is definitively an ideal patch with excellent antibacterial effect.2. Nano-silver compound patch has comparable stretchability and scratchability with common compound patch.3. Released nano-silver of nano-silver compound patch is increasing with time. Accumulative released nano-silver accounts for 98.76% of loaded nano-silver at the time of postoperative 120h. At this time, proliferative inhibition of human fibroblasts is the most significant, however, the cells are still alive and proliferative.4. Abdominal wall defect repaired with nano-silver compound patch in clean or infected setting, presents less bacterial planting and wound infected, less visceral adhesion in the abdominal cavity, and less scar formation, compared with polypropylene mesh and common compound patch.ConclusionNew nano-silver compound patch has ability of anti-infection, stable physic-chemical property, and can promote the wound healing and decrease the scar formation.