Control of wound infections using a bilayer chitosan wound dressing with sustainable antibiotic delivery.

A novel bilayer chitosan membrane was prepared by a combined wet/dry phase inversion method and evaluated as a wound dressing. This new type of bilayer chitosan wound dressing, consisting of a dense upper layer (skin layer) and a sponge-like lower layer (sublayer), is very suitable for use as a topical delivery of silver sulfadiazine (AgSD) for the control of wound infections. Physical characterization of the bilayer wound dressing showed that it has excellent oxygen permeability, that it controls the water vapor transmission rate, and that it promotes water uptake capability. AgSD dissolved from bilayer chitosan dressings to release silver and sulfadiazine. The release of sulfadiazine from the bilayer chitosan dressing displayed a burst release on the first day and then tapered off to a much slower release. However, the release of silver from the bilayer chitosan dressing displayed a slow release profile with a sustained increase of silver concentration. The cultures of Pseudomonas aeruginosa and Staphylococcus aureus in agar plates showed effective antimicrobial activity for 1 week. In vivo antibacterial tests confirmed that this wound dressing is effective for long-term inhibition of the growth of Pseudomonas aeruginosa and Staphylococcus aureus at an infected wound site. The results in this study indicate that the AgSD-incorporated bilayer chitosan wound dressing may be a material with potential antibacterial capability for the treatment of infected wounds.     

Polyelectroylte complex composed of chitosan and sodium alginate for wound dressing application.

Drug-impregnated polyelectrolyte complex (PEC) sponge composed of chitosan and sodium alginate was prepared for wound dressing application. The morphological structure of this wound dressing was observed to be composed of a dense skin outer layer and a porous cross-section layer by scanning electron microscopy (SEM). Equilibrium water content and release of silver sulfadiazine (AgSD) could be controlled by the number of repeated in situ PEC reactions between chitosan and sodium alginate. The release of AgSD from AgSD-impregnated PEC wound dressing in PBS buffer (PH = 7.4) was dependent on the number of repeated in situ complex formations for the wound dressing. The antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. From the behavior of antimicrobial release and the suppression of bacterial proliferation, it is thought that the PEC wound dressing containing antimicrobial agents could protect the wound surfaces from bacterial invasion and effectively suppress bacterial proliferation. In the cytotoxicity test, cellular damage was reduced by the controlled released of AgSD from the sponge matrix of AgSD-medicated wound dressing. In vivo tests showed that granulation tissue formation and wound contraction for the AgSD plus dihydroepiandrosterone (DHEA) impregnated PEC wound dressing were faster than any other groups.     

A bilayer composite composed of TiO2-incorporated electrospun chitosan membrane and human extracellular matrix sheet as a wound dressing

We designed bilayer composites composed of an upper layer of titanium dioxide (TiO₂)-incorporated chitosan membrane and a sub-layer of human adipose-derived extracellular matrix (ECM) sheet as a wound dressing for full-thickness wound healing. The dense and fibrous top layer, which aims to protect the wound from bacterial infection, was prepared by electrospinning of chitosan solution followed by immersion in TiO₂ solution. The sponge-like sub-layer, which aims to promote new tissue regeneration, was prepared with acellular ECM derived from human adipose tissue. Using a modified drop plate method, there was a 33.9 and 69.6% reduction in viable Escherichia coli and Staphylococcus aureus on the bilayer composite, respectively. In an in vivo experiment using rats, the bilayer composites exhibited good biocompatibility and provided proper physicochemical and compositional cues at the wound site. Changes in wound size and histological examination of full-thickness wounds showed that the bilayer composites induced faster regeneration of granulation tissue and epidermis with less scar formation, than control wounds. Overall results suggest that the TiO₂-incorporated chitosan/ECM bilayer composite can be a suitable candidate as a wound dressing, with an excellent inhibition of bacterial penetration and wound healing acceleration effects.     

羧甲基壳聚糖膜促进大鼠微粒皮移植创面愈合的实验研究

目的：本研究旨在评估羧甲基壳聚糖膜取代异体皮作为微粒皮移植载体促进创面愈合的作用。方法28只大鼠中,每次随机抽取2只大鼠配对同时手术,在大鼠背部两侧制作直径25 mm、对称圆形全层皮肤缺损创面各1个,两侧创面分别设为实验组和对照组,均移植自体微粒皮,对照组创面覆盖相互配对大鼠的异体皮,实验组创面覆盖羧甲基壳聚糖膜。于术后7、11、14 d 观察记录各组创面愈合时间,并于术后7、14、19 d 采集创面组织行组织病理学检查。结果实验组的羧甲基壳聚糖膜覆盖下微粒皮能够成活,且能修复创面。实验组创面平均愈合时间为（15.6±2.0）d,短于对照组创面平均愈合时间为（18.8±1.9）d,两组比较,差异有统计学意义（t =8.987,P〈0.05）。组织切片结果显示：羧甲基壳聚糖膜覆盖下微粒皮修复的新生表皮层生长较异体皮覆盖下新生表皮厚。结论羧甲基壳聚糖膜作为生物敷料,能够有效地保护创面,提供微粒皮修复创面的微环境。可用于取代异体皮覆盖微粒皮移植的创面。     

Chitosan membrane as a wound-healing dressing: characterization and clinical application

Chitosan prepared from natural biopolymer chitin and cast into membranes has been tested as wound dressing at the skin-graft donor site in patients. Bactigras, a commonly used impregnated tulle gras bandage, served as a control. Chitosan membrane, prepared with a 75% degree of deacetylation and a thickness of 10 microm, was used in nonmesh or mesh form. The progress in wound healing was compared by clinical and histological examination. Itching and pain sensitivity of the wound dressed area was scored with the use of a visual analogue scale. Mesh chitosan membrane in contrast to the nonmesh membrane allowed blood to ooze into the surrounding gauze. After 10 days, the chitosan-dressed area had been healed more promptly as compared with the Bactigras dressed area. Moreover, the chitosan mesh membrane showed a positive effect on the re-epithelialization and the regeneration of the granular layer. The data confirm that chitosan mesh membrane is a potential substitute for human wound dressing.     

Development of a Wound Dressing Composed of Hyaluronic Acid Sponge Containing Arginine and Epidermal Growth Factor

Hyaluronic acid (HA) has the ability to promote wound healing. Epidermal growth factor (EGF) is able to promote the proliferation of various cell types, in addition to epidermal cells. A novel wound dressing was designed using high-molecular-weight hyaluronic acid (HMW-HA) and low-molecular-weight hyaluronic acid (LMW-HA). Spongy sheets composed of cross-linked high-molecular-weight hyaluronic acid (c-HMW-HA) were prepared by freeze-drying an aqueous solution of HMW-HA containing a crosslinking agent. Each spongy sheet was immersed into an aqueous solution of LMW-HA containing arginine (Arg) alone or both Arg and epidermal growth factor (EGF), and were then freeze-dried to prepare two types of product. One was a wound dressing composed of c-HMW-HA sponge containing LMW-HA and Arg (c-HMW-HA/LMW-HA + Arg; Group I). The other was a wound dressing composed of c-HMW-HA sponge containing LMW-HA, Arg and EGF (c-HMW-HA/LMW-HA + Arg + EGF; Group II). The efficacy of these products was evaluated in animal tests using rats. In the first experiment, each wound dressing was applied to a full-thickness skin defect with a diameter of 35 mm in the abdominal region of Sprague–Dawley (SD) rats, leaving an intact skin island measuring 15 mm in diameter in the central area of this skin defect. Commercially available polyurethane film dressing was then applied to each wound dressing as a covering material. In the control group, the wound surface was covered with polyurethane film dressing alone. Both wound dressings (Group I and Group II) potently decreased the size of the full-thickness skin defect and increased the size of the intact skin island, when compared with the control group. The wound dressing in Group II showed particularly potent activity in increasing the distance of epithelization from the intact skin island. This suggests that EGF release from the spongy sheet serves to promote epithelization. The wound dressing in Group II enhanced early-stage inflammation after 1 week, as compared with the other two groups. In the second experiment, each wound dressing was applied to a full-thickness skin defect measuring 35 mm in diameter in the abdominal region of SD rats, after removing necrotic skin caused by dermal burns. Polyurethane film dressing was applied to each wound dressing as a covering material. In the control group, the wound surface was covered with polyurethane film dressing alone. Both wound dressings (Group I and Group II) potently decreased the size of the full-thickness skin defect and increased epithelization from the wound margin, as compared with the control group. The wound dressing in Group II was found to enhance early-stage inflammation after 1 week, as compared with the other two groups. The findings in both experiments indicate that the wound dressing composed of HA-based spongy sheets containing Arg and EGF potently promotes wound healing by inducing moderate inflammation. The release of EGF in the early stages of wound healing induces moderate inflammation. This suggests that wound healing is facilitated directly by topical application of EGF, and indirectly by cytokines derived from inflammatory cells stimulated by EGF.     

含纳米银壳聚糖/聚乙烯醇抗菌敷料的制备和性能

背景：抗菌敷料是预防创面发生侵袭性感染的重要措施之一,但长期使用抗生素会使细菌产生耐药性;同时,将抗菌材料与棉织物复合制得的抗菌敷料,生物相容性差,不宜用于创面的长期覆盖。 目的：制备一种具有良好的生物相容性、抗菌消炎性的新型抗菌生物敷料,并初步检测该材料的生物学性能。 方法：通过在乙醇/水/NaOH溶液中,构建一个纳米级的吸附相反应器,制得吸附纳米银的纳米SiO₂粉末;将载银的SiO₂粉末添加到壳聚糖/聚乙烯醇反应溶液中,通过缩醛化反应制得含Ag/SiO₂纳米颗粒的壳聚糖/聚乙烯醇海绵。检测材料的各项物理性能、表面形貌、细胞毒性、抗菌性能。 结果与结论：材料呈多孔结构,吸水率、透气性和保湿性良好,具有较高的拉伸强度;材料孔隙率高、空隙致密均匀,孔径大小为0.1~1 mm;MTT法检测材料对小鼠成纤维细胞毒性显示无明显毒性,并且能促进该细胞的生长;材料对金黄色葡萄球菌、大肠杆菌、白色念珠菌、铜绿假单胞菌、伤寒沙门菌均有良好的杀菌效果。以上结果显示材料不但具有良好的物理性能、生物活性和抗菌性能,而且合成工艺简单,可作为创面敷料。     

生物材料创面敷料封闭负压引流在大面积创面植皮中的应用

背景：大面积创面植皮中封闭创面、减少渗出、避免难愈性伤口的出现是治疗中的关键,采用自主研发的新型生物材料创面敷料可以提高植皮成功率。 目的：观察基于生物材料创面敷料封闭负压引流在大面积创面植皮应用中的疗效。 方法：对于60例大面积创面植皮的患者采取志愿选择的方式,分为生物材料创面敷料组、合成敷料组及常规加压包扎组。敷料组患者清创邮票植皮后采用生物材料创面敷料、合成敷料覆盖,其外用生物半透膜封闭形成负压装置,或直接常规敷料加压包扎。常规敷料包扎组植皮后采用消毒油纱覆盖植皮创面、敷料加压包扎。植皮后1周创面的单位面积植皮覆盖率。 结果与结论：采用负压引流能明显提高单位面积植皮覆盖率,单位面积植皮覆盖率生物材料创面敷料组高于合成敷料组(P < 0.05),显著高于常规组。结果表明,新型生物材料创面敷料能有效引流,提高封闭负压引流的疗效。 关键词：创面敷料;生物材料;封闭负压引流术;植皮;植皮覆盖率 doi:10.3969/j.issn.1673-8225.2012.03.037     

Preparation of sponge-like macroporous PVA hydrogels via n-HA enhanced phase separation and their potential as wound dressing

Polyvinyl alcohol (PVA) hydrogels have been widely studied for biomedical applications due to their water solubility, non-toxicity, non-carcinogenicity, and biocompatibility. However, PVA hydrogels prepared by the physical crosslinking method usually do not exhibit a macroporous structure, which limits their application when PVA hydrogels are used alone as a wound dressing. Here, we reported a sponge-like macroporous PVA hydrogel (SPH) prepared by employing polyethylene glycol and nano-hydroxyapatite (n-HA) to enhance phase separation. After being fabricated through cyclic freezing/thawing, the resulting PVA hydrogels possessed macroporous structures. The swelling ratio could reach nearly 1500%, resulting from the excellent water absorption capacity, and the sample could rapidly restore to the original state after being pressed, suggesting a sponge-like characteristic. Furthermore, cell experiments showed that macroporous PVA hydrogels exhibited good biocompatibility and the results of wound closure and H&E analysis consistently indicated that SPHs could significantly promote the wound healing process.     

Preparation of blood-compatible hollow fibers from a polymer alloy composed of polysulfone and 2-methacryloyloxyethyl phosphorylcholine polymer

Blood-compatible hollow fibers were successfully prepared from a polymer alloy composed of polysulfone (PSf) and the 2-methacryloyloxyethyl phosphorylcholine (MPC) polymer. To improve the hydrophilicity, fouling-resistance characteristics, and blood compatibility of the PSf hollow fiber in a hemodialyzer, an MPC polymer that can be blended with PSf was synthesized in order to prepare the polymer alloy (PSf/MPC polymer). The contents of the MPC polymer blended in the PSf were 7 and 15 wt%. The PSf/MPC polymer hollow fiber could be prepared by both wet and dry-wet processing methods. The hollow fiber took an asymmetric structure, that is, the hollow-fiber membrane had a dense skin layer on the porous sponge-like structure. The mechanical strength was higher than that of conventional PSf hollow fibers for hemodialysis. The surface characterization of the PSf/MPC polymer hollow fiber by x-ray photoelectron spectroscopy revealed that the MPC units were concentrated at the surface. The permeability for solutes through the PSf/MPC polymer hollow fibers was measured for 4 h. The permeabilities of both a low-molecular-weight compound and protein were greater than those of the PSf hollow fibers. The amount of adsorbed protein was lower on the PSf/MPC polymer hollow fiber when compared to that of the PSf hollow fiber. Moreover, platelet adhesion was also effectively inhibited on the PSf/MPC polymer hollow fiber. Based on these results, the addition of the MPC polymer to the PSf is a very useful method to improve the functions and blood compatibility of the hollow fiber.     

Possibility of wound dressing using poly(L-leucine)/poly(ethylene glycol)/poly(L-leucine) triblock copolymer

ABA-type block copolymers (abbreviated as LEL) composed of poly(L-leucine) (PLL) as the A component and poly(ethylene glycol) (PEG) as the B component were synthesized by ring-opening polymerization of L-leucine N-carboxyanhydride initiated by primary amino group located at both ends of PEG chain. A silver sulfadiazine (AgSD)-impregnated wound dressing of sponge type was prepared by the lyophilization method. Morphological structure of this wound dressing by scanning electron microscopy was observed to be composed of a dense skin layer and a porous inner layer. Equilibrium water content of LEL wound dressing increased with an increase in PEG content in the block copolymer due to the hydrophilicity of PEG. AgSD release from AgSD-impregnated wound dressing in PBS buffer (pH = 7.4) was dependent on PEG content in the block copolymer. Release of AgSD was increased in proportion to the PEG content in the copolymer. Antibacterial capacity of AgSD-impregnated wound dressing was examined in agar plate against Pseudomonas aeruginosa and Staphylococcus aureus. It was found that the suppression of bacterial proliferation in the wound dressing was dependent upon the PEG content. In cytotoxicity test, cell damage did not occur by the release of AgSD from the LEL sponge matrix of AgSD-medicated wound dressing. In in vivo test, granulous tissue formation and wound contraction for the AgSD- and dehydroepiandrosterone-impregnated LEL-2 wound dressing were faster than for any other groups.     

CG创伤敷料的研制

以壳聚糖、明胶和甘油为基本原料，选用戊二醛为交联剂，探讨了交联反应的条件，避免了明胶蛋白与壳聚糖的静电沉淀反应。成膜后经再处理，制备出一种含水率高、透明的多孔网状纤维膜样的创伤敷料。该敷料的扯断强度为６．５ＭＰａ，扯断伸长率为２１０％，撕裂强度为５．３ＫＮ／ｍ，含水率为７６％。通过动物实验，证明该膜具有良好的组织相容性，对防止感染、促进伤口愈合起到良好的作用，适合作创伤敷料     

创面复合液体敷料在皮肤创伤中的治疗研究

基于羧甲基壳聚糖的高生物相容性及聚乙烯醇缩丁醛的快速成膜,构建了一种创面复合液体敷料,并对其应用效果进行评价。首先应用羧甲基壳聚糖 (CMC)、聚乙烯醇缩丁醛 (PVB)和乙醇溶液,按照一定的比例,制备创面复合液体敷料。对其防水、透气、阻菌、细胞毒性进行性能研究及安全性评价。然后选择健康成年Sprague-Dawley(SD)大鼠40只,雌雄各半,构建大鼠创面模型,并将含有不同浓度的羧甲基壳聚糖(1.0、10.0、30.0 mg/mL)应用在其创面上,通过日常观察、HE染色等,研究创面复合液体敷料在皮肤创伤中的治疗效果。结果显示创面复合液体敷料上层膜液在1.8～2.3 mm 之间具有很好的防水透气性、阻菌性及生物兼容性。运用在动物模型上可以看到,第7 d含有10.0、30.0 mg/mL CMC组的大鼠创面愈合率分别为65.42%、67.38%,明显高于对照组且存在显著性差异(P< 0.01),14 d后含有10.0、30.0 mg/mL CMC组的大鼠创面愈合率已达到100%。HE 染色的第七天含有10.0、30.0 mg/mL CMC的创面复合液体敷料组中观察到有复层扁平的表皮和真皮的胶原纤维,第12 d组织开始出现内陷结构,含有厚实、粗糙胶原纤维的正常真皮与较薄的胶原纤维水平连接,表皮的复层鳞状上皮远远大于对照组中的三到四层。而且创面连接真皮结缔组织,它的表皮构成非常接近于正常皮肤组织。构建的创面复合液体敷料(10.0 mg/mL CMC)具备良好的防水、透气、阻菌性以及生物兼容性,随着羧甲基壳聚糖浓度的升高,治疗急性创面的效果越好,创面复合液体敷料能够对创面起到早期保护和促进愈合的效果。.     

Medium (DMEM/F12)-containing chitosan hydrogel as adhesive and dressing in autologous skin grafts and accelerator in the healing process

Autologous skin grafts are considered necessary for the treatment of extensive skin defects. However, skin graft by suturing is a time-consuming medical handling and rather stressful event for recipients. To that end, tissue adhesives have been suggested in skin grafts. Chitosan hydrogel is well known as a wound dressing and tissue adhesive material showing biocompatibility, anti-infective activity, and the ability to accelerate wound healing. In this report, we evaluated the application of the chitosan hydrogel as a tissue adhesive in skin grafts. Although chitosan hydrogel shortened the operation time and resulted in a high graft absorption rate in comparison with suturing, wound epithelization was rather retarded. On the other hand, chitosan hydrogel was found more biocompatible than the commonly used tissue adhesive octyl-2-cyanoacrylate. When the chitosan hydrogel was premixed with a serum-free tissue culture medium DMEM/F12, it was found to easily degrade and promote wound epithelization. Histological examination revealed that the medium (DMEM/F12)-containing chitosan hydrogel was associated with the accumulation of polymorphonuclear leukocytes and neovascularization. In addition, immunohistochemical staining showed that the vascular endothelial growth factor (VEGF) was localized in the chitosan hydrogel degraded matrices. And infiltration of leukocytes determined the degradation activity with the D-glucose in the medium (DMEM/F12) suggested to play a central role in chitosan hydrogel degradation. Therefore, the medium (DMEM/F12)-containing chitosan hydrogel may become commonly accepted as a beneficial wound dressing and tissue adhesive in extensive wound management and skin grafts.     

Water absorbing and antibacterial properties of N-isopropyl acrylamide grafted and collagen/chitosan immobilized polypropylene nonwoven fabric and its application on wound healing enhancement

A durable sandwich wound dressing system with high liquid absorbing, biocompatibility, and antibacterial properties was designed. Various solution weight ratios of collagen to chitosan were used to immobilize on the polypropylene nonwoven fabric, which were pregrafted with acrylic acid (AA) or N-isopropyl acrylamide (NIPAAm) to construct a durable sandwich wound dressing membrane with high water absorbing, easy removal, and antibacterial activity. Swelling properties and antibacterial activity of the membranes were measured, and wound healing enhancement by skin full-thickness excision on animal model was examined. The results indicated that NIPAAm-grafted and collagen/chitosan-immobilized polypropylene nonwoven fabric (PP-NIPAAm-collagen-chitosan) showed a better healing effect than AA-grafted and collagen/chitosan-immobilized polypropylene nonwoven fabric (PP-AA-collagen-chitosan). The wound treated with PP-NIPAAm-collagen-chitosan demonstrated the excellent remodeling effect in histological examination with respect to the construction of vein, epidermis, and dermis at 21 days after skin injury. The values of water uptake and water diffusion coefficient for PP-NIPAAm-collagen-chitosan were higher than that for PP-AA-collagen-chitosan under a given solution weight ratio of collagen/chitosan. Both PP-NIPAAm-collagen-chitosan and PP-AA-collagen-chitosan demonstrated antibacterial activity.     

几种胶原型创伤敷料制作的实验研究

介绍了几各胶原型创伤敷料研制的方法。冷冻牛腱经０．０５Ｍ乙酸处理（ＰＨ３．２）４８－７２ｈ后，捣碎过滤、脱泡、加太酸软骨素（８％），制成１．５－２．５％胶原溶液。该溶液在预冷或不预冷的模具内冷冻干燥，冻干的胶的海绵在０．２５％戊二醛溶液中交联２４ｈ。并以类似的方法研制成聚氨酯膜－胶原海绵复合膜，涂聚氨酯胶原膜，和纱布胶原膜三种创伤敷料。结果表明冷冻牛腱胶原性能稳定，冻干的胶原海绵具有良好的孔洞结构     

Wound healing properties of PVA/starch/chitosan hydrogel membranes with nano Zinc oxide as antibacterial wound dressing material

In this work, hydrogel membranes were developed based on poly vinyl alcohol (PVA), starch (St), and chitosan (Cs) hydrogels with nano Zinc oxide (nZnO). PVA/St/Cs/nZnO hydrogel membranes were prepared by freezing-thawing cycles, and the aqueous PVA/St solutions were prepared by dissolving PVA in distilled water. After the dissolution of PVA, starch was mixed, and the mixture was stirred. Then, chitosan powder was added into acetic acid, and the mixture was stirred to form a chitosan solution. Subsequently, Cs, St and PVA solutions were blended together to form a homogeneous PVA/St/Cs ternary blend solution. Measurement of Equilibrium Swelling Ratio (ESR), Water Vapor Transmission Test (WVTR), mechanical properties, scanning electron microscopy (SEM), MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyl tetrazolium bromide] assay, antibacterial studies, in vivo wound healing effect and histopathology of the hydrogel membranes were then performed. The examination revealed that the hydrogel membranes were more effective as a wound dressing in the early stages of wound healing and that the gel could be used in topic applications requiring a large spectrum of antibacterial activity; namely, as a bandage for wound dressing.     

壳聚糖基聚电解质的生物医用前景

背景：利用壳聚糖阳离子聚合物特性,以不使用化学交联剂为前提在温和条件下制得的壳聚糖基聚电解质复合物,具有良好的生物相容性。 目的：综述近年来壳聚糖基聚电解质在药物载体、组织工程、伤口敷料、生物传感器、基因载体等方面的应用情况。 方法：由第一作者检索2004至2011年 ACS数据库和Elsevier Science电子期刊有关壳聚糖聚电解质在生物医用领域中的应用,尤其在药物载体、组织工程、伤口敷料、生物传感器及基因载体中的研究情况。 结果与结论：壳聚糖本身由于生物相容性好,可应用于生物体中作为良好的载体材料、支架材料、伤口敷料及生物传感器,经过与其他阴离子物质复合后可以保护壳聚糖本身良好性质,并且避免了使用化学交联剂所带来的生物毒性。壳聚糖的阳离子聚电解质本性使其能与黏液、阴离子表面和其他大分子如DNA产生强静电作用可有效应用于药物传送、基因治疗、固定生物酶等;壳聚糖聚电解质凝胶独特的性质如pH值、离子强度、电场敏感性,可使其通过对外界环境的改变作出不同响应,实现对生物组织的模拟、刺激响应药物控释,并且壳聚糖具备优异的抗菌性、止血性、亲水性和透气性,能够有效促进伤口愈合。     

Performance of an in situ formed bioactive hydrogel dressing from a PEG-based hyperbranched multifunctional copolymer

Hydrogel dressings have been widely used for wound management due to their ability to maintain a hydrated wound environment, restore the skin’s physical barrier and facilitate regular dressing replacement. However, the therapeutic functions of standard hydrogel dressings are restricted. In this study, an injectable hybrid hydrogel dressing system was prepared from a polyethylene glycol (PEG)-based thermoresponsive hyperbranched multiacrylate functional copolymer and thiol-modified hyaluronic acid in combination with adipose-derived stem cells (ADSCs). The cell viability, proliferation and metabolic activity of the encapsulated ADSCs were studied in vitro, and a rat dorsal full-thickness wound model was used to evaluate this bioactive hydrogel dressing in vivo. It was found that long-term cell viability could be achieved for both in vitro (21 days) and in vivo (14 days) studies. With ADSCs, this hydrogel system prevented wound contraction and enhanced angiogenesis, showing the potential of this system as a bioactive hydrogel dressing for wound healing.     

In vitro and in vivo evaluation of new PRP antibacterial moisturizing dressings for infectious wound repair

In this study, a solution chitosan fibroin emulsion with added Silver Nanoparticles (AgNPs) was freeze-dried to be the scaffold, and an asymmetric coating was formed on one side. PRP was loaded onto the composite scaffold using a secondary lyophilization technology to prepare the tissue engineering dressings. AgNPs were characterized using a transmission electron microscope. The morphologies of the composite dressing were examined under a scanning electron microscope. The silver content of the dressing was measured by inductively coupled plasma mass spectrometry. The asymmetric wettability of the composite dressing was demonstrated by water contact angle measurement. Relatively high porosity, favourable moisture retention capability and appropriate tensile strength were observed by measuring the physical and mechanical properties. Satisfactory antibacterial properties against various bacteria and microbial isolation performance were observed by the antibacterial effect analysis in vitro. The total protein slow-release property was measured using the BCA assay. Good biocompatibility and lower sensitization were examined both in vitro and in vivo. In addition, the healing effciency of the composite dressing on infected wound were examined in mice infected wound models. Analysis of wound healing rates, bacterial cultures of wound exudate, whole blood cell analysis and histological examination all showed satisfactory results. These results are demonstrated to provide a potential and possible pathway to promote wound tissue repair and regeneration.