Background Most traditional wound dressings only partially meet the needs of wound healing because of their single function. Patients usually suffer from the increasing cost of treatment and pain resulting from the frequent changing of wound dressings. Herein, we have developed a mutifunctional cryogel to promote bacterial infected wound healing based on a biocompatible polysaccharide. Methods The multifunctional cryogel is made up of a compositive scaffold of chitosan (CS), gelatin (Gel) and tannic acid (TA) and in situ formed silver nanoparticles (Ag NPs). A liver bleeding rat model was used to evaluate the dynamic hemostasis performance of the various cryogels. In order to evaluate the antibacterial properties of the prepared cryogels, gram-positive bacterium Staphylococcus aureus (S. aureus) and gram-negative bacterium Escherichia coli (E. coli) were cultured with the cryogels for 12 h. Meanwhile, S. aureus was introduced to cause bacterial infection in vivo. After treatment for 2 days, the exudates from wound sites were dipped for bacterial colony culture. Subsequently, the anti-inflammatory effect of the various cryogels was evaluated by western blotting and enzyme-linked immunosorbent assay. Finally, full-thickness skin defect models on the back of SD rats were established to assess the wound healing performances of the cryogels. Results Due to its porous structure, the multifunctional cryogel showed fast liver hemostasis. The introduced Ag NPs endowed the cryogel with an antibacterial efficiency of >99.9% against both S. aureus and E. coli. Benefited from the polyphenol groups of TA, the cryogel could inhibit nuclear factor-κB nuclear translocation and down-regulate inflammatory cytokines for an anti-inflammatory effect. Meanwhile, excessive reactive oxygen species could also be scavenged effectively. Despite the presence of Ag NPs, the cryogel did not show cytotoxicity and hemolysis. Moreover, in vivo experiments demonstrated that the biocompatible cryogel displayed effective bacterial disinfection and accelerated wound healing. Conclusions The multifunctional cryogel, with fast hemostasis, antibacterial and anti-inflammation properties and the ability to promote cell proliferation could be widely applied as a wound dressing for bacterial infected wound healing.

中文翻译：

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用原位还原银纳米粒子修饰的多功能壳聚糖/明胶@单宁酸冷冻凝胶用于伤口愈合

背景大多数传统的伤口敷料由于其功能单一，只能部分满足伤口愈合的需要。患者通常会因频繁更换伤口敷料而承受不断增加的治疗费用和疼痛。在此，我们开发了一种基于生物相容性多糖的多功能冷冻凝胶，以促进细菌感染的伤口愈合。方法 多功能冷冻凝胶由壳聚糖（CS）、明胶（Gel）和单宁酸（TA）的复合支架和原位形成的银纳米颗粒（Ag NPs）组成。肝出血大鼠模型用于评估各种冷冻凝胶的动态止血性能。为了评估制备的冷冻凝胶、革兰氏阳性菌金黄色葡萄球菌（S. aureus）和革兰氏阴性菌大肠杆菌（E. 大肠杆菌）与冷冻凝胶一起培养 12 小时。同时，引入金黄色葡萄球菌引起体内细菌感染。治疗2天后，将伤口部位的渗出液浸入细菌菌落培养。随后，通过蛋白质印迹和酶联免疫吸附测定评估各种冷冻凝胶的抗炎作用。最后，建立SD大鼠背部全层皮肤缺损模型，评估冷冻凝胶的伤口愈合性能。结果由于其多孔结构，多功能冷冻凝胶表现出快速的肝脏止血作用。引入的Ag NPs赋予冷冻凝胶对金黄色葡萄球菌和大肠杆菌的抗菌效率＞99.9％。受益于 TA 的多酚基团，冷冻凝胶可以抑制核因子-κB核转位并下调炎性细胞因子以获得抗炎作用。同时，也可以有效清除过量的活性氧。尽管存在 Ag NPs，但冷冻凝胶没有表现出细胞毒性和溶血作用。此外，体内实验表明，生物相容性冷冻凝胶表现出有效的细菌消毒和加速伤口愈合。结论 多功能冷冻凝胶具有快速止血、抗菌消炎、促进细胞增殖等特性，可广泛用作细菌感染创面愈合的创面敷料。冷冻凝胶没有表现出细胞毒性和溶血作用。此外，体内实验表明，生物相容性冷冻凝胶表现出有效的细菌消毒和加速伤口愈合。结论 多功能冷冻凝胶具有快速止血、抗菌消炎、促进细胞增殖等特性，可广泛用作细菌感染创面愈合的创面敷料。冷冻凝胶没有表现出细胞毒性和溶血作用。此外，体内实验表明，生物相容性冷冻凝胶表现出有效的细菌消毒和加速伤口愈合。结论 多功能冷冻凝胶具有快速止血、抗菌消炎、促进细胞增殖等特性，可广泛用作细菌感染创面愈合的创面敷料。