Chromatographic and traditional albumin isotherms on cellulose: a model for wound protein adsorption on modified cotton

Albumin is the most abundant protein found in healing wounds. Traditional and chromatographic protein isotherms of albumin binding on modified cotton fibers are useful in understanding albumin binding to cellulose wound dressings. An important consideration in the design of cellulosic wound dressings is adsorption and accumulation of proteins like albumin at the solid-liquid interface of the biological fluid and wound dressing fiber. To better understand the effect of fiber charge and molecular modifications in cellulose-containing fibers on the binding of serum albumin as observed in protease sequestrant dressings, albumin binding to modified cotton fibers was compared with traditional and chromatographic isotherms. Modified cotton including carboxymethylated, citrate-crosslinked, dialdehyde and phosphorylated cotton, which sequester elastase and collagenase, were compared for their albumin binding isotherms. Albumin isotherms on citrate-cellulose, cross-linked cotton demonstrated a two-fold increased binding affinity over untreated cotton. A comparison of albumin binding between traditional, solution isotherms and chromatographic isotherms on modified cellulose yielded similar equilibrium constants. Application of the binding affinity of albumin obtained in the in vitro protein isotherm to the in vivo wound dressing uptake of the protein is discussed. The chromatographic approach to assessment of albumin isotherms on modified cellulose offers a more rapid approach to evaluating protein binding on modified cellulose over traditional solution approaches.     

Scanning electron microscopic examination of bacterial immobilisation in a carboxymethyl cellulose (AQUACEL) and alginate dressings

Dressings have been applied to open wounds for centuries. Traditionally they have been absorbent, permeable materials, i.e. gauze that could adhere to desiccated wound surfaces, inducing trauma on removal. With the advent of modern wound care products many dressings are now capable of absorbing large volumes of exudate whilst still continuing to provide a moist wound healing environment. Equally important is their ability to lock exudate in the dressing (i.e. bacterial retention within the dressing matrix) such that upon removal from a wound surface bacterial dispersion is minimised.In these studies detailed scanning electron microscopy techniques have demonstrated the fluid controlling properties of alginate wound dressings and a carboxymethylated cellulose wound dressing (AQUACEL) Hydrofiber) dressing (CMCH)). It was demonstrated that following hydration of the latter wound dressing, the subsequent formation of a cohesive gel was effective in encapsulating large populations of potentially pathogenic bacteria such as Psuedomonas aeruginosa and Staphylococcus aureus under the gelled surface, as well as being immobilised within the swollen fibres. In contrast, hydrated alginate wound dressings did not form a uniform, cohesive gel structure, with the result that fewer bacteria were immobilised within the gel matrix. Many bacteria were trapped on individual, non-hydrated fibres.The unique absorbent gelling properties of the CMCH dressing appears to provide an ideal environment for immobilising bacteria.     

In vitro and in vivo assays on egg white/polyvinyl alcohol/clay nanocomposite hydrogel wound dressings

Novel nanocomposite hydrogel wound dressings on the basis of egg white and polyvinyl alcohol, as matrix, and natural Na-montmorillonite clay, as reinforcing agent, were prepared and their performances on wound healing investigated in vitro and in vivo. In vitro cytotoxicity assay revealed non-cytotoxic activity and excellent biocompatibility level of prepared nanocomposite hydrogel wound dressings. The bacterial penetration assay showed the prepared nanocomposite hydrogel wound dressings are excellent barriers against microorganisms and could protect the wound from infection during the wound healing. In vivo animal study showed that the wound healing process was considerably faster in wounds covered with nanocomposite hydrogel wound dressings compared to the conventional wound dressing, i.e. sterile gauze, due to creation of a moist environment on the wound surface and faster migration rate of the epidermal cells. The mechanical properties of healed wounds with nanocomposite hydrogel wound dressings were better than those control wounds covered with sterile gauze due to their better collagen formation ability as a result of created moist healing condition as well as the presence of egg white, as a source of proteins, in their structures.     

Novel sulfonated hydrogel composite with the ability to inhibit proteases and bacterial growth

There is a growing interest in the development of wound dressings that possess functionality beyond providing physical protection and an optimal moisture environment for the wound. To this end, a novel dressing material based on a sulfonated triblock polymer has been developed. This versatile polymer possesses an ion-exchange capability that is amenable to binding and controlled release of a variety of therapeutic agents. This sulfonated polymer offers several advantages over existing commercial hydrogels used as wound dressings. These include (1) hydrophilicity that is proportional to sulfonation level, (2) easy preparation of fabric supported dressings (e.g., polyester, cotton, nylon), (3) excellent mechanical integrity of the materials when hydrated, (4) stability to a variety of chemistries, and (5) stability to a variety of sterilization methodologies. In this study, polymer was coated onto a polyester fabric and then modified by ion exchange to prepare the sodium, silver, or doxycycline salts. These sulfonated triblock polymer formulations were then evaluated for their capacity to sequester the neutrophil proteases, elastase, and collagenase-2 (MMP-8). Several of the formulations were found to sequester significant amounts of either elastase or collagenase. These formulations were demonstrated to be tested against a commercially available dressing that is currently marketed for its protease-inhibiting capability. The experimental dressing was statistically superior to the commercial dressing at inhibiting MMP-8 and elastase under the same conditions.     

Testing intelligent wound dressings.

While occlusive wound dressings help provide patients with moist wound healing to reduce pain and increase reepithelialization rate, the moisture vapor transmission rate (MVTR) of these dressings remains constant even though wound exudate levels may vary with time and from wound to wound. The clinician is therefore faced with exudate buildup in heavily exuding wounds and desiccation in lightly exuding wounds-a situation requiring frequent patient monitoring and dressing changes. Am "intelligent" wound dressing would have the ability to automatically respond to a wound's exudate level by self-adjusting its MVTR to maintain a constant moist wound environment. Such a dressing could help ensure that exudate buildup or wound desiccation is reduced or avoided. Three commercial wound dressings (hydrocolloid, thin film, and membrane laminate) were studied for their ability to alter their MVTR in response to varying moisture level. An efficient test methodology and experimental design was developed, which involved direct and indirect fluid contact with the dressings using two temperatures and two test methods. One dressing, a membrane laminate, was found to exhibit intelligent MVTR behavior. Data is presented which shows this dressing's ability to adjust its MVTR nearly eight-fold as a function of hydration level. Information regarding the mechanism of action of this intelligent dressing is also presented.     

Influence of selected wound dressings on PMN elastase in chronic wound fluid and their antioxidative potential in vitro

Exudates from non-healing wounds contain elevated levels of proteolytic enzymes, like elastase from polymorphonuclear granulocytes (PMN elastase), reactive oxygen species (ROS) and reactive nitrogen species (RNS). The overproduction of proteolytic enzymes leads to reduced concentrations of growth factors and proteinase inhibitors, resulting in an imbalance between degradation and remodelling processes. Thus, the reduction of protein-degrading enzymes and scavenging of ROS and RNS seem to be suitable ways to support the healing process of chronic stagnating wounds. The aim of this study was to test selected wound dressings from different biomaterials (collagen, oxidized regenerated cellulose (ORC) and ORC/collagen mixture), regarding their antioxidative potential in vitro and their influence on the concentration and activity of PMN elastase in chronic wound fluid. Antioxidant capacity of the investigated wound dressing was determined by a pholasin-based chemiluminescent assay. PMN elastase concentration was determined by means of ELISA. Enzyme activities could be measured by a fluorescence assay. As the presented data demonstrates, all tested materials showed antioxidant capacity. In addition, the investigated materials were able to reduce the concentration and activity of PMN elastase. Beside other aspects, such as biocompatibility, biodegradability, fluid absorption and clinical effects (e.g. angiogenesis and microcirculation), the understanding of these properties may help to support the further refinement of wound dressings for improved wound healing.     

Development of alginate gel dressing

Alginate-based wound dressing materials have been widely used to promote wound healing and to reduce blood loss from wounds. However, recently a few drawbacks of well-established commercial alginate dressings have been reported. Therefore, we tried to develop a new alginate dressing to reduce the drawbacks. First, four new dressings with different calcium content were prepared, and the cytotoxicity of these four materials, and Kaltostat and Sorbsan, was tested in vitro by culture of fibroblasts with their extracts. Second, full-thickness wounds in pigs were used for the evaluation of wound healing in vivo. Finally, a newly developed alginate dressing was used clinically for treatment of split-thickness skin graft donor sites. The extract medium from ALG3, ALG4, Kaltostat, and Sorbsan induced a significant inhibitory effect on proliferation of fibroblasts. As for wound closure rate, the ALG2-covered wounds had the smallest wound area on day 15. Histologically, foreign-body reaction was least in ALG2-treated wounds. In a clinical study, the main drawback of ALG2 was leakage of wound exudate due to dissolution of the dressing material. However, the transparency of moistened ALG2 allowed easy evaluation of the wound, and after healing it was easy to remove ALG2 from the wound without injury to the reepithelialized skin because ALG2 was relatively nonadherent to the wound.     

Hyaluronic acid nanofiber wound dressing--production, characterization, and in vivo behavior

Hyaluronic acid (HA) was electrospun. The effects of flow rate, spin length, and the applied voltage on the diameter of the HA nanofibers were analyzed. The average thickness of the webs was 0.041 cm. The air permeability of sterilized HA nanofiber wound dressing was much higher than that of gauze with Vaseline. The degree of crystallinity of HA nanofibers was characterized using powder X-ray technique and was found to be 20.6%. A preclinical study was conducted to compare healing of wounds covered by an adhesive bandage, a sterilized solid HA, gauze with Vaseline, an antibiotic dressing, and a sterilized HA nanofiber wound dressing. Results of the two methods of appraisal showed that the sterilized HA nanofiber wound dressing was the best type of dressing out of the five types of dressings compared.     

新型医用敷料的分类及特点

背景：临床应用的多种新型创面敷料可加速创面修复,减少伤口感染,提高治愈率,缩短病程,减轻患者痛苦。 目的：回顾传统医用敷料及新型医用敷料的优缺点,展望新型医用敷料的临床应用及发展。 方法：应用计算机检索2003年1月至2006年8月PubMed数据库及2000年1月至2006年8月CNKI数据库有关医用敷料种类、特点及临床应用的研究,检索词为“Medical dressing,医用敷料”。 结果与结论：医用新型敷料分为薄膜类、水凝胶类、藻酸盐类、泡沫类、水胶体类、药用类敷料。薄膜类敷料透明,便于观察伤口,能密切黏附于创面表面,有效保持创面渗出液,提供有利于创面愈合的湿润环境,促使坏死组织脱落,减轻创面疼痛会,缺点为吸水性能欠佳。水凝胶类敷料能与不平整的创面紧密粘合,减少细菌滋生,加速新生血管生成,促进上皮细胞生长。水胶体类敷料比薄膜类敷料厚许多,胶层的厚度决定其吸收能力的大小,水胶体敷料可吸收少量到中量渗液,不适用于渗出液多的创面。泡沫类敷料具有多孔性,表面张力低,富有弹性,可塑性强、轻便,对渗出液的吸收力强,对氧气及二氧化碳几乎完全通透,可作为药物载体。新型藻酸盐类敷料比较柔软,容易折叠,敷贴方便,在创面上形成柔软类似凝胶的半固体物质,为创面提供一个湿润环境,提高表皮细胞的再生能力,加快表皮细胞移动。药用类敷料有保护创面、止痛、止血、消炎、促进新生肉芽组织及上皮细胞生长,加速创面愈合等功能。     

In Vivo and Cytotoxic Assays of a Poly(vinyl alcohol)/Clay Nanocomposite Hydrogel Wound Dressing

In the present work, a nanocomposite hydrogel wound dressing was prepared on the basis of poly(vinyl alcohol) using organically-modified montmorillonite as nanoclay by the freezing–thawing cyclic method. In vivo assays were performed to evaluate its performance as an applicable wound dressing on animals. It showed an improved healing process for wounds covered by the prepared nanocomposite hydrogel compared with control wounds covered by sterile gauze. Significant improvements, such as better creation of moist surfaces on the wound with less scar formation, shorter duration of healing operation and better closing of the wound edges with enhanced tensile properties of the healed wound, i.e., tensile strength and elongation-at-break, were observed using the prepared nanocomposite hydrogel in comparison to the sterile gauze. An in vitro cytotoxic assay was also utilized to determine the biocompatibility of the prepared nanocomposite hydrogel. It showed that the prepared nanocomposite hydrogel is non-toxic and can be used as a biocompatible wound dressing in practical wound management.     

均匀设计优选智能型密闭敷料支架基质配方

背景：近年来创伤敷料的研究发展较快,但很少有中药联合高分子材料制备的复合密闭敷料,且现有的创伤敷料作用较局限,不能适用于任何创伤伤口,但怎样使高分子材料与中药完美的融合是目前一个热门的话题。 目的：优选智能型密闭敷料支架的最佳基质配方。 方法：采用均匀设计法结合SPSS 16.0软件进行多元线性回归分析,对敷料支架的吸水性、含水量、保湿性和外观评价等指标进行综合考察,优化智能型密闭敷料支架的基质设计。 结果与结论：通过实验数据分析,优选出智能型密闭敷料支架最佳基质配方比例为：壳聚糖∶明胶∶甘油∶聚乙烯醇∶聚乙二醇=8.3∶4.4∶3.1∶3.7∶1。提示智能型密闭敷料支架基质处方配比合理、制作工艺质量可控。     

脱细胞真皮基质敷料在烧伤创面治疗中的应用进展

在临床上,创面的修复依旧是烧伤治疗过程中的难题,而脱细胞真皮基质(ADM)敷料的研究与应用为创面的修复带来了新的解决方案。现通过检索国内外有关ADM敷料临床应用的文献,归纳分析了ADM敷料的生物学特性,及其在浅Ⅱ度及深度烧伤创面、削痂植皮创面、供皮区创面治疗中应用疗效,综述了ADM敷料在烧伤创面治疗中的研究进展。     

Wound care management: proper protocol differs from athletic trainers' perceptions

As research techniques in wound care management improve, treatment protocols for the care of wounds must also change to ensure safe and optimal healing. In this study, I surveyed current practices of athletic trainers regarding the care of athletic wounds and compared the findings to current literature. I contacted 501 athletic trainers, including all NATA curricular undergraduate directors. Overall response rate was 58%; 78% of the athletic trainers from the curricular schools responded. Wet-to-dry, irrigation, and soaks were the three most common methods used to debride and cleanse a wound. Povidone-iodine (Betadine) and hydrogen peroxide were the two most popular cleansing agents. Conventional gauze was the primary dressing used by 67% of the athletic trainers, while 20% of those surveyed used occlusive dressings. Although povidone-iodine and hydrogen peroxide are commonly used, both are toxic to cells involved in the wound-healing process and delay healing. Research indicates that the best method of cleansing and debriding a wound is to irrigate it with saline. Occlusive dressings have a lower infection rate, are viral barriers, and are associated with faster wound healing and less pain than gauze dressings. Athletic trainers need to assess their wound care protocols so that they give the best possible care to their athletes.     

A new high water vapor permeable polyetherurethane film dressing

This study summarizes the Ph.D.-research project concerning the development of a new high water vapor permeable wound dressing. The dressing is composed of a 15 microns thin polyetherurethane (PEU) film, which has many non-interconnected cavities to enable a high water vapor permeability up to 20.1 g.m-2.h-1.kPa-1. Since only water vapor permeates through the PEU dressing, the wound exudate underneath is condensed into a gelatinous coagulum. Epithelialization was accelerated by 25% under the clot-permissive PEU film compared with the fluid retaining OpSite film. In clinical situations on donor sites and grafted full-thickness burn wounds, the PEU film indeed prevented fluid accumulation and induced the formation of a "red" coagulum underneath. It furthermore reduces pain significantly compared to conventional paraffin gauze dressing. In conclusion, the optimum environment for epithelialization is a wound, in which the exudate is permitted to gelatinize between moist and dry.     

新型复合生物抗菌敷料的抗菌强度、吸湿能力及细胞毒性

背景：细菌感染是影响伤口愈合的主要因素之一,伤口渗出液里含有的大量炎症因子、蛋白酶和自由基都会减缓伤口的愈合速度。新型复合生物抗菌敷料的研发对治疗外科感染伤口有重要的意义,是创伤敷料发展的必然趋势。 目的：观察添加纳米银的海藻酸钙敷料的抗菌活性、吸湿能力及细胞毒性。 方法：将纳米银材料添加到海藻酸钙中制备新型复合生物抗菌敷料,并通过使用平板计数法、MTT法、电子显微镜观察法观察敷料的抗菌活性、吸湿能力及细胞毒性,再与银离子海藻酸钙敷料和海藻酸钙敷料进行对比,以期显示出新型复合生物抗菌敷料的具有强抗菌性及低细胞毒性的优势。 结果与结论：与银离子海藻酸钙敷料和海藻酸钙敷料相比,添加纳米银的新型复合生物抗菌敷料对金黄色葡萄球菌、铜绿假单胞菌均有更强的抑菌作用(P < 0.01),细胞毒性较低(P < 0.01);3种敷料的吸湿能力差异无显著性意义。证实此添加纳米银的海藻酸钙敷料的具有强抗菌性及低细胞毒性。      

甲壳素麻油蜂蜡膏促进糖尿病足创面愈合的研究进展

慢性创面（包括糖尿病足溃疡）合适敷料的应用,创造良好的伤口愈合环境,是临床工作面临的课题。甲壳素、麻油、蜂蜡能有效促进体表创面的愈合,甲壳素麻油蜂蜡膏更能有效促进创面的愈合,为临床敷料的应用提供更多的选择。     

联合应用藻酸盐和聚亚安酯敷料促进中厚皮供区创面愈合的临床观察

目的探讨联合应用藻酸盐和自粘型聚亚安酯敷料于中厚皮片供皮区,加速创面愈合的方法。方法烧伤后瘢痕整形中厚皮取皮术后,实验组19例以藻酸盐和自粘型聚亚安酯敷料顺序联合应用覆盖供皮区创面,对照组17例以传统的凡士林纱布加棉垫绷带加压包扎供皮区创面,受术者于术后第1天、第2天及第10天揭除敷料时就供皮区疼痛程度按疼痛视觉模拟评分,并对敷料对术后活动的影响、术后10d揭除敷料难易程度进行评价,记录两组供皮区创面愈合的时间。结果术后第1天、第2天及术后第10天揭除敷料时,实验组受术者的疼痛视觉模拟评分低于对照组,实验组中36.8%受术者术后活动不受限,高于对照组（P〈0.05）;术后10d,实验组揭除敷料更为容易,且实验组供皮区愈合时间平均为9.8d,短于对照组（P〈0.01）。结论藻酸盐敷料和聚亚安酯敷料联合应用于中厚皮片供皮区,具有降低术后疼痛,减轻术后活动不便,操作方便,缩短供皮区愈合时间的优点,值得临床推广应用。     

胶原/壳聚糖止血敷料在外科伤口中的应用

背景：壳聚糖与胶原联合可更有效地止血。 目的：评价胶原/壳聚糖止血敷料的材料学性能及应用于外科伤口的生物相容性。 方法：以“生物材料,止血敷料,纱布,胶原/壳聚糖,生物相容性”为中文关键词,以“biomaterial;hemostatic material;bioresorbable material;hemostasis effect;hemostatic mechanism”为英文关键词,采用计算机检索2000-01/2010-06与生物敷料、胶原/壳聚糖止血材料在伤口或创面止血过程中应用相关的文献。 结果与结论：壳聚糖独特的生物学特性,具有广谱抑菌、促进上皮细胞生长及止血,促进创面愈合的作用,在体内具有良好的生物降解性与组织相容性,可用于指端损伤和肉芽创面的治疗,如制成伤口敷料、可吸收缝线、止血材料、防粘连剂、药物缓释及组织工程支架,用于平战时伤口的处理。     

Human neutrophil elastase inhibition with a novel cotton-alginate wound dressing formulation

Occlusion and elasticity were combined in a novel cotton-based alginate dressing containing a nontoxic elastase inhibitor. Cotton gauzes were modified with a textile finishing process for incorporating alginate to yield a dressing material that retains elasticity while enhancing absorption. The algino-cellulose conjugates were formed through citric acid crosslinking of cellulose and alginate. The alginate-citrate finishes were applied to cotton gauzes in various formulations containing citric acid, sodium hypophosphite, and polyethylene glycol. The modified gauzes contain a citrate conjugate of alginate and cellulose that gels upon hydration. The alginate-citrate finishes were combined with the neutrophil elastase inhibitor, oleic acid, to demonstrate the ability of the algino-cellulose fibers to release the inhibitor and neutralize destructively high levels of neutrophil elastase found in nonhealing and burn wounds. Four types of gauzes were examined for the effect of the algino-cellulose finish on cotton gauze absorbency and elasticity. Fourier transform infrared (FTIR) spectroscopy of the film and alginate-citrate finished cotton showed formation of the alginate and citrate cellulose esters. Scanning electron microscopy analysis revealed large areas of the yarn surface covered by the alginate film with a smooth surface on the original fibers. Wetting of the gauze surface resulted in formation of a hydrated gel on the yarns with apparent swelling of the film and the fiber-coated alginate.     

Polyurethane based hybrid ciprofloxacin-releasing wound dressings designed for skin engineering purpose

PurposeEven in the 21st century, chronic wounds still pose a major challenge due to potentially inappropriate treatment options, so the latest wound dressings are hybrid systems that enable clinical management, such as a hybrid of hydrogels, antibiotics and polymers. These wound dressings are mainly used for chronic and complex wounds, which can easily be infected by bacteria.Materials and methodsSix Composite Porous Matrices (CPMs) based on polyurethane (PUR) in alliance with polylactide (PLAs) and poly(vinyl alcohol) (PVA) were prepared and analyzed using optical microscopy. Three different types of hydrogels and their Ciprofloxacin (Cipro) modified variants’ ratios were prepared and analyzed using FTIR, SEM and EDX techniques. Six Hybrid Cipro-Releasing Hydrogel Wound Dressings (H-CRWDs) were also prepared and underwent short-term degradation, Cipro release, microbiology and cell viability measurements.ResultsAverage porosity of CPMs was in the range of 69–81%. The pore size of the obtained CPMs was optimal for skin regeneration. Short-term degradation studies revealed degradability in physiological conditions regardless of sample type. A meaningful release was also observed even in short time (21.76 ?± ?0.64 ?μg/mL after 15 ?min). Microbiological tests showed visible inhibition zones. Cell viability tests proved that the obtained H-CRWDs were biocompatible (over 85% of cells).ConclusionsA promising hybrid wound dressing was labeled. Simple and cost-effective methods were used to obtain microbiologically active and biocompatible dressings. The results were of importance for the design and development of acceptable solutions in the management of chronic wounds of high potential for infection.