皮肤创伤修复一直是再生医学领域的研究热点和难点问题。皮肤是人体表面最大的组织器官，具有抵御外来物质入侵、保护机体、维持体内环境稳定、感受外界刺激、调节体温平衡等多方面的功能。因交通事故、外科手术、烧伤、烫伤、糖尿病等各种原因引起的急性和慢性皮肤创伤，容易引发出血和细菌感染。严重的创伤和细菌感染会造成器官衰竭，甚至危及生命，给患者家庭及社会带来巨大的经济负担。目前创伤治疗常用的方法主要是止血、使用抗生素抑制感染及补充生长因子等；然而，大量使用抗生素导致菌株耐药，患者经治疗后存在伤口难以愈合或者瘢痕组织增生等问题。其主要原因是：创伤修复是一个复杂、受多因素影响、包含多个病理阶段的组织再生过程。常规治疗手段通常针对创伤愈合过程的单一影响因素或修复阶段，忽略了创伤病理微环境对最终愈合效果的影响。

最近的研究表明，与传统的纱布、止血海绵等治疗手段相比，水凝胶递送无机金属类抗菌剂、细胞因子或干细胞等能加速伤口愈合。然而，此类方法需要外部光刺激、体内不降解，并且具有潜在的细胞毒性；或受限于高成本和复杂的制造工艺，这些因素限制其临床应用。因此，研究更有效的促进伤口愈合的方法，仍然具有重要的意义。基于上述研究背景，本文以抗菌材料为出发点，开展抗菌水凝胶和多功能高分子海绵用于促进皮肤创伤修复研究，主要研究内容和结论如下：

（1）高分子抗菌水凝胶促进耐药菌感染的皮肤伤口修复研究。细菌感染是引起组织创伤难以愈合的重要因素，大量使用抗生素容易引起细菌耐药。为消除受损组织感染，我们研制了一种不需要抗生素和金属类抗菌剂的体内可完全吸收的高分子抗菌水凝胶，将季铵盐小分子（QAS）与聚乙二醇-聚己内酯三嵌段共聚物（PCEC）通过缩合反应得到PCEC-QAS聚合物，该聚合物在水溶液中自组装成纳米胶束抗菌剂。PCEC-QAS的浓度为30 wt%时，经高、低温处理形成凝胶-溶液不可逆、物理交联的多孔水凝胶。PCEC-QAS纳米抗菌剂对革兰氏阳性和革兰氏阴性菌均具有良好的抗菌活性。水凝胶内部的多孔网络结构可以促进成纤维细胞增殖和迁移以及内皮细胞成管。另外，PCEC-QAS水凝胶在体内可完全降解，具有良好的局部皮肤组织相容性。在大鼠体内构建耐甲氧西林金黄色葡萄球菌（MRSA）感染全层皮肤损伤模型，在不使用细胞因子和药物的情况下，经过抗菌水凝胶治疗重构了一层结构完整、厚度接近正常皮肤的表皮层和成熟度较高的真皮层，效果优于商品化夫西地酸乳膏和壳聚糖水凝胶。同时，显著降低了组织炎症水平。因此，该水凝胶作为一种新型伤口敷料，能够清除细菌感染、降低炎症，加快受损组织再生。此外，该水凝胶由聚合物物理聚集而成，制备简便；且易于涂抹，可完全封闭伤口，具有潜在的临床转化前景。

（2）仿生、组织微环境敏感的抗菌糖肽水凝胶促进慢性伤口愈合研究。为赋予抗菌水凝胶更优越的组织微环境仿生和促进皮肤组织再生性质，后续工作中设计了仿生细胞外基质ECM中的多糖和蛋白质组份，及其三维网状纤维结构的糖肽复合水凝胶。构建酸敏感席夫碱化学键连接的葡甘聚糖与内源性抗菌肽偶联物GM-P，基质金属蛋白酶-2敏感多肽连接的透明质酸与胶原肽结合物HA-P。将GM-P与HA-P混合形成具有三维网络和微米纤维结构的GM-P@HA-P水凝胶，为组织缺损提供适宜修复的微环境。GM-P能够通过甘露糖受体介导途径激活巨噬细胞向M2型极化，并且对MRSA和大肠杆菌均具有良好的抗菌活性；HA-P有利于细胞黏附、增殖和迁移。大鼠体内构建皮肤烫伤和糖尿病伤口感染模型，涂抹水凝胶进行治疗，显著加速伤口愈合，21天后伤口部位新生完整的表皮层，并且明显提高M2型巨噬细胞比例，加快血管新生。因此，GM-P@HA-P水凝胶在治疗慢性难愈合伤口、促进组织再生领域具有潜在的应用前景。

（3）抗菌、止血和促修复聚合物复合海绵加快伤口愈合研究。为了更好的匹配组织再生过程，以商品化聚丙烯酸钠（PAAS）、季铵化壳聚糖（QAS-CS）和胶原（COL）为原料，按照一定质量比混合，溶液冻干，制备PQC复合海绵。该海绵具有快速止血（止血时间约为50 s）、大量吸收组织液（溶胀率达到3500%）、合适的力学性能（压缩模量0.3 MPa）、良好的抗菌活性和促进细胞增殖的能力；因此，在体内应用时可以匹配创伤伤口的发生与发展过程（出血、感染、增殖与重塑）。新西兰大白兔体内构建MRSA感染皮肤伤口模型，实验证明，PQC复合海绵可以显著加速感染伤口修复，效果优于商用的壳聚糖海绵。这种复合海绵兼具制造方法简单、可大规模制造、成本低以及优异的促进创面愈合能力，在临床转化和商品化方面具有很大的前景。

总之，本研究制备了多种以抗菌水凝胶为基础的多功能创伤敷料，通过赋予敷料抗菌、止血、炎症微环境调控、促血管新生等性质，更好的匹配伤口修复过程，促进急性、慢性伤口的修复与再生。此外，这些敷料具有原料来源广泛，成本低，制备工艺简单，应用方便等特点，具备良好的市场转化潜力。本研究工作为组织再生生物材料的设计与构建提供了新策略。

The repair of skin wounds is a hotspot and difficult issue in the field of regenerative medicine. Skin is the largest organ of human body, which plays an important role in resisting the invasion of foreign substances, protecting the body, maintaining the stability of the internal environment, felling external stimuli, and regulating body temperature balance. Acute and chronic skin trauma caused by traffic accidents, surgery, burns, scalds, diabetes, etc. can easily lead to bleeding and bacterial infections. Severe trauma and bacterial infection can cause life-threatening organ failure, which impose great burden on patients and society. Current treatments mainly focus on the hemostasis, the prevention of infection and supplementation of growth factors. However, abuse use of antibiotics leads to bacterial resistance, and patients still suffer from difficult or imperfect wound healing. Wound repair is a complex multi-stage process affected by multiple factors, and possesses unique pathological stages. Current conventional treatments usually aim at the single influencing factor or process of wound healing, without paying attention to the influence of complicated pathological microenvironment on wound healing.

In recent years hydrogel dressings for wound repair have received extensive attention. Hydrogel delivering inorganic metal antibacterial agents, cytokines or stem cells can significantly accelerate the wound healing compared with traditional treatments such as gauze and hemostatic sponge. However, this approach is complicated by external light stimuli, cytotoxicity, nondegradability, and sophisticated fabrication, which limit their clinical application. Therefore, it is still of great significance to develop more effective methods that could promote wound healing. Based on the above research background, the antibacterial hydrogel and multifunctional polymer sponge are developed. The main research contents, results and conclusions are shown as follows:

(1) Polymer antibacterial hydrogel for the repair of infected skin wounds. Skin wound infection commonly leads to difficult wound healing, and the widespread abuse of antibiotics has already caused the continuous emergence of antibiotic-resistant strains of pathogenic bacteria. Herein, an inherent antibacterial, bioresorbable hydrogel was developed by the spontaneous self-aggregation of amphiphilic, oxadiazole-group-decorated quaternary ammonium salts (QAS)-conjugated poly(ε-caprolactone)-poly(ethylene glycol)-poly(ε-caprolactone) (PCEC-QAS) micellar nanoantimicrobials for methicillin-resistant Staphylococcus aureus (MRSA)-infected cutaneous wound healing. The spontaneous self-assembly of PCEC-QAS nanoparticles in water and the following noncovalent nanoparticle stacking at 30 wt% polymer concentration resulted in the formation of a gel-sol irreversible hydrogel after heating-colling treatment. PCEC-QAS nanoparticles serving as nanoantimicrobials endow the hydrogel with broad antibacterial efficiency against both Gram-positive and -negative bacteria. The highly porous network within the hydrogel enables cell proliferation and migration, thereby acting as a tissue regeneration scaffold for wound healing. The PCEC-QAS hydrogel could be fully degraded in vivo, with good skin compatibility and systemic biosafety. In vivo experiments demonstrated that the hydrogel not only showed inherent antimicrobial effect but also accelerated skin regeneration at the wound site without the presence of antibiotics, cytokines, or therapeutic cells. It is foreseeable that the PCEC-QAS hydrogel acting as a promising wound dressing material has great potential for microbe eradication and simultaneously rescuing acute skin wounds. Moreover, the hydrogel was easily fabricated by dissolving by a simple heating-cooling process. Taken together, the nanoantimicrobials were highly effective, low cost, and nontoxic, holding great promise for clinical translation.

(2) Antibacterial glycopeptide hydrogel with bioinspired and tissue microenvironmental sensitivity for chronic wound healing. Glycopeptide-complexed hydrogel was designed to mimic the glycoprotein components and 3D network fibrous architecture of cutaneous extracellular matrix (ECM). The glucomannan-antimicrobial peptide (GM-P) conjugate was established by acid-sensitive imide bond through Schiff’s base reaction. The hyaluronic acid-collagen peptide (HA-P) conjugate was constructed by matrix metalloproteinase-2 sensitive peptide through Michael addition. GM-P and HA-P were mixed to form GM-P@HA-P hydrogel with 3D network and nanofibrous structure, providing a suitable microenvironment for wound healing. It is observed that GM-P displays remarkable capability of polarizing primary macrophages to M2-type phenotype by inducing the activation of mannose receptors, which has good antibacterial activity against MRSA and E. coli. HA-P is beneficial for cell adhesion, proliferation and migration. Skin wounds induced by scald and diabetes with infection were constructed in rats, and GM-P@HA-P hydrogel significantly accelerated the wound healing. After 21 days, epidermal layer was regenerated at the wound site. The proportion of M2 macrophages was significantly increased in the wound microenvironment with promoted angiogenesis. Therefore, GM-P@HA-P hydrogel holds great promise in the treatment of chronic wounds.

(3) Clinical wound management remains a major challenge due to massive bleeding, bacterial infection, and difficult wound healing after tissue trauma. To simultaneously address these issues, composite polymer sponges for accelerating drug-resistant bacterial infected wound healing were fabricated by facilely mixing sodium polyacrylate (PAAS), double quaternary ammonium salts-conjugated chitosan (QAS-CS), and collagen (COL) in aqueous solution, followed by lyophilization. Composite sponges (PAAS/QAS-CS/COL, PQC) show highly porous microstructures (porosity ~90%, 200 μm in diameter) with moderate compress modulus (~0.3 MPa) and high swelling ratio (~3500%). Importantly, PQC sponge demonstrates superior hemostasis ability over commercially available CS sponge by inducing rapid hemagglutination, and exhibits significantly better antibacterial activity against both methicillin-resistant staphylococcus aureus (MRSA) and E. coli by destroying cell membrane and causing the leakage of bioactive components such as potassium ion and β-galactosidase from treated bacterial. Furthermore, PQC sponge can efficiently promote cell proliferation. Significantly, the sponge greatly expedited the regeneration of MRSA-infected full-thickness skin wound in rabbit by successfully eradicating bacterial infection, and reducing inflammation. PQC sponge also improved both early angiogenesis and blood vessel maturation at the wound site. Overall, this multifunctional sponge is a promising wound dressing for clinical use and holds great potential for rapid clinical translation.

In summary, a variety of multifunctional wound dressings were prepared with hemostatic, antibacterial, inflammatory microenvironment regulation, and angiogenesis, which can better match the wound healing process. In addition, these dressings have the characteristics of low cost, simple preparation process, and convenient application. These works provide new strategy for the design and construction of biomaterials for tissue regeneration.