| Objective:To develop a functional dermal substitute by combining silver nanoparticles with conventional tissue engineering approaches,and evaluate its effect on tissue regeneration and wound healing.Methods:Many tissue-engineered products have been used for skin defects. An ideal dermal substitute should maintain a moist environment at the wound interface, allow gaseous exchange, act as a barrier to microorganisms and remove excess exudates. Generally, skin defects with a large amount of fluid loss and bacterial infection, such as severe burns, lead to serious consequences. In addition, exudates between the wound and the dressing serve as a trigger of infection and acute inflammatory cells, which could prevent the wound from healing. Wound dressings with antibacterial agents have been used as one of the approaches for treating wound infection.Dermal scaffolds coated with NAg could be a new type of anti-infective dressing with non-toxic components. Many researchers attribute the highly efficient anti-bacterial effect of NAg to their ultrafine size and large surface area. NAg can easily destroy the membrane, pass through the microbial body, and then convert into silver ions (Ag+) in the cytoplasm to damage the intracellular structure as secondary result. NAg undergo a shape-dependent interaction with the gram-negative bacterium Escherichia.coli, so it has been speculated that NAg with the same surface area, but with different shapes, may also have different effective surface area, in terms of active facets. Sudheesh Kumar and co-workers developed novel P-chitin/nano-silver composite scaffolds for wound healing applications using a (3-chitin hydrogel containing NAg. The composite scaffolds coated with nanosilver were bactericidal and showed good blood clotting ability. Cell attachment studies showed that the cells were well attached to the scaffolds, suggesting potential as a wound dressing material. The incorporation of silver into alginate fibers was also shown to increase antimicrobial activity and to improve the binding affinity for elastase, matrix metalloprotease-2,and the pro-inflammatory cytokines.In this research we developed a novel NAg-collagen/chitosan hybrid scaffold (NAg-CCS)for wound healing applications using collagen and chitosan containing NAg resulting in good mechanical strength, flexibility, tear resistance and excellent antimicrobial properties. The in vitro experiments were carried out to investigate the physical properties, cytotoxicity and antibacterial activity of silver nanoparticles. The results demonstrated that the silver nanoparticles possessed the typical nano-scale structures, excellent antibacterial properties, but also showed a possible toxic to cells from skin depended on the concentration. Then concentration screening of silver nanoparticles was carried out to select a proper quantity. The result indicated that the nanosilver about lOppm showed little cytotoxicity. This concentration was used to constructed the scaffolds. The wound healing ability and antibacterial activity of collagen/chitosan can be further enhanced by the addition of silver nanoparticles. Thus, the NAg-CCS composite scaffolds will function as ideal wound dressings. Our results indicate that NAg-CCS is anti-inflammatory and bactericidal without discernible in vitro or in vivo cytotoxicity or negative effects on fibroblast and kerotincyte, making this substance an ideal dermal substitute for wound regeneration. Conclusions:(1)Nano-silver was cytotoxicity depended on the concentration what could be ignored at the concentration of10PPM with a obviously antibacterial effect.(2) Nano-silver could influence activation of macrophages and change the cell ratio of M1/M2to promote alternative macrophage activation, reduce abnormal activation of macrophages classic.(3)The function of the scaffolds can significantly reduce wound infection and inflammation, which can effectively accelerate wound healing. |
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