高吸型壳聚糖敷料的创面止血及促愈合效果

BACKGROUND: High liquid-absorbing property, high-capacity imbibition property and high antibacterial property of chitosan dressings can be promoted by chemical modification.     

Fluorinated methacrylamide chitosan hydrogel systems as adaptable oxygen carriers for wound healing

In this study a series of novel, biocompatible hydrogels able to repeatedly takeup and deliver oxygen at beneficial levels have been developed by conjugating various perfluorocarbon (PFC) chains to methacrylamide chitosan via Schiff base nucleophilic substitution, followed by photopolymerization to form hydrogels. The synthesized fluorinated methacrylamide chitosan (MACF) hydrogels were confirmed by high resolution ¹⁹F NMR. Synthesized MACF hydrogels were tested for their ability to takeup and then release oxygen for future use in dermal wound healing. Depending on the PFC substitution type maximum O₂ uptake was observed within 2–6 h, followed by complete release to the surrounding environment (5% CO₂) within 12–120 h at oxygen partial pressures of 1–25 mm Hg h^?1, providing outstanding system tuning for wound healing and regenerative medicine. MACFs with the most fluorines per substitution showed the greatest uptake and release of oxygen. Interestingly, adding PFC chains with a fluorinated aromatic group considerably enhanced oxygen uptake and extended release compared with a linear PFC chain with the same number of fluorine molecules. MACF hydrogels proved to be readily reloaded with oxygen once release was complete, and regeneration could be performed as long as the hydrogel was intact. Fibroblasts were cultured on MACFs and assays confirmed that materials containing more fluorines per substitution supported the most cells with the greatest metabolic activity. This result was true, even without oxygenation, suggesting PFC-facilitated oxygen diffusion from the culture medium. Finally, MACF gradient hydrogels were created, demonstrating that these materials can control oxygen levels on a spatial scale of millimeters and greatly enhance cellular proliferative and metabolic responses.     

Modern wound dressings: a systematic approach to wound healing.

The advent of modern wound care management constitutes one of the most innovative applications of medical device technology. The foundation for wound care recent advances has been built upon the developments achieved in polymer technology over the last three decades. New and unique materials have been engineered to provide properties with significant technical and clinical benefits. These new wound care products were made possible by the convergence of three interrelated disciplines: (1) more complete understanding of the underlying principles of dermal wound healing processes, (2) new elastomeric polymers capable of being fabricated into protective dressings, and (3) advances in breathable adhesive technology. The following discussion provides a critical review of the current status of technology and the worldwide opportunities for improved wound management products. Particular attention is focused on the clinical applications of the newer, breathable dressing products, which approximate a temporary synthetic artificial skin.     

Synthesis and properties of waterborne polyurethane hydrogels for wound healing dressings

To accomplish ideal wound healing dressing, a series of waterborne polyurethane (WBPU) hydrogels based on polyethylene glycol (PEG) were synthesized by polyaddition reaction in an emulsion system. The stable WBPU hydrogels which have remaining weight of above 85% were obtained. The effect of the soft segment (PEG) content on water absorbability of WBPU hydrogels was investigated. Water absorption % and equilibrium water content (%) of the WBPU hydrogel significantly increased in proportion to PEG content and the time of water-immersion. The maximum water absorption % and equilibrium water content (%) of WBPU hydrogels containing various PEG contents were in the range of 409-810% and 85-96%, respectively. The water vapor transmission rate of the WBPU hydrogels was found to be in the range of 1490-3118 g/m(2)/day. These results suggest that the WBPU hydrogels prepared in this study may have high potential as new wound dressing materials, which provide and maintain the adequate moist environment required to prevent scab formation and dehydration of the wound bed. By the wound healing evaluation using full-thickness rat model experiment, it was found that the wound covered with a typical WBPU hydrogel (HG-78 sample) was completely filled with new epithelium without any significant adverse reactions.     

纳米银敷料治疗烧伤创面的疗效与安全研究进展

纳米银敷料作为一种新型抗菌材料近年来被广泛用于烧伤创面的治疗,其在促进烧伤创面愈合方面有较好的效果,有着控制创面感染、缓解换药疼痛及减少换药次数等优点。本文对其促进烧伤创面愈合的原理、疗效及安全性3个方面的研究进展进行综述,并对新型纳米银敷料的研制方向进行了展望。     

Antibacterial and cell-adhesive polypeptide and poly(ethylene glycol) hydrogel as a potential scaffold for wound healing

The ideal wound-healing scaffold should provide the appropriate physical and mechanical properties to prevent secondary infection, as well as an excellent physiological environment to facilitate cell adhesion, proliferation and/or differentiation. Therefore, we developed a synthetic cell-adhesive polypeptide hydrogel with inherent antibacterial activity. A series of polypeptides, poly(Lys)_x(Ala)_y (x + y = 100), with varied hydrophobicity via metal-free ring-opening polymerization of NCA-Lys(Boc) and NCA-Ala monomers (NCA = N-carboxylic anhydride) mediated by hexamethyldisilazane (HMDS) were synthesized. These polypeptides were cross-linked with 6-arm polyethylene glycol (PEG)-amide succinimidyl glutarate (ASG) (M_w = 10 K) to form hydrogels with a gelation time of five minutes and a storage modulus (G′) of 1400-3000 Pa as characterized by rheometry. The hydrogel formed by cross-linking of poly(Lys)₆₀(Ala)₄₀ (5 wt.%) and 6-arm PEG-ASG (16 wt.%) (Gel-III) exhibited cell adhesion and cell proliferation activities superior to other polypeptide hydrogels. In addition, Gel-III displays significant antibacterial activity against Escherichia coli JM109 and Staphylococcus aureus ATCC25923. Thus, we have developed a novel, cell-adhesive hydrogel with inherent antibacterial activity as a potential scaffold for cutaneous wound healing.     

藻酸盐银联合水凝胶敷料对慢性创面愈合的作用

背景：研究发现藻酸盐及水凝胶敷料等均可促进创面愈合,而新型敷料藻酸盐银联合水凝胶敷料,对于难治慢性创面的愈合作用尚不清楚。 目的：观察藻酸盐银联合水凝胶敷料对慢性创面治疗的作用。 方法：选择江苏省人民医院烧伤整形科住院慢性创面患者34例,随机分为2组：治疗组应用藻酸盐银联合水凝胶敷料序贯换药;对照组采用1%磺胺嘧啶银冷霜抹在凡士林纱布上外敷,于治疗后7,10,14,17,21 d进行创面分泌物细菌培养、观察创面愈合情况及速度、药物不良反应、换药时创面痛感、肉芽破坏等情况。 结果与结论：治疗组创面细菌检出率明显低于对照组(P < 0.05)。治疗组创面愈合时间比对照组平均缩短约6 d,创面愈合速度较对照组明显加快(P < 0.05)。两组均无药物不良反应,治疗组创面换药时无明显疼痛感,肉芽组织无明显破坏。提示藻酸盐银联合水凝胶敷料序贯治疗慢性创面具有显著抗菌及促进创面肉芽组织和上皮再生、促进创面愈合的作用,且无不良反应。     

Dermal wound healing processes with curcumin incorporated collagen films

The wound healing process involves extensive oxidative stress to the system, which generally inhibits tissue remodeling. In the present study, an improvement in the quality of wound healing was attempted by slow delivery of antioxidants like curcumin from collagen, which also acts as a supportive matrix for the regenerative tissue. Curcumin incorporated collagen matrix (CICM) treated groups were compared with control and collagen treated rats. Biochemical parameters and histological analysis revealed that increased wound reduction, enhanced cell proliferation and efficient free radical scavenging in CICM group. The higher shrinkage temperature of CICM films suggests increased hydrothermal stability when compared to normal collagen films. Spectroscopic studies revealed that curcumin was bound to the collagen without affecting its triple helicity. Further we adopted the antioxidant assay using 2,2'-azobisisobutyronitrile to assess in vitro antioxidant activity of CICM. The antioxidant studies indicated that CICM quenches free radicals more efficiently. This study provides a rationale for the topical application of CICM as a feasible and productive approach to support dermal wound healing.     

生物与合成敷料封闭负压引流促进植皮创面愈合的对比

背景：骨科创面植皮时采用封闭负压引流可以封闭创面,减少渗出,促进软组织肉芽增生及植皮修复缺损。 目的：对比两种不同材料的创面敷料封闭负压引流在创面植皮中的临床效果。 方法：选择2010年9月至2012年3月收治的80例因创伤需植皮患者,在植皮后按自愿原则进入生物材料(基于丝瓜的植物纤维为敷料主体)及合成材料(聚乙烯乙醇化海藻盐泡沫)创面敷料封闭负压引流治疗。治疗1周后拆除封闭负压引流装置及创面敷料,记录两组的植皮覆盖率及创面愈合时间。 结果与结论：两组患者均有效达到创面植皮覆盖效果,无感染及不愈合情况出现。采用生物材料创面敷料治疗组植皮覆盖率及创面愈合时间均明显优于采用合成材料创面敷料治疗组(P < 0.05)。提示采用生物材料创面敷料封闭负压引流可以有效促进引流,改善循环,抑制细菌增生及促进修复过程。中国组织工程研究杂志出版内容重点：生物材料;骨生物材料; 口腔生物材料; 纳米材料; 缓释材料; 材料相容性;组织工程全文链接：     

Fibronectin as a component of wound exudate and its significance for wound healing

Fibronectin concentration is much lower in wound exudate from the zone of operation for postoperational ventral hernia than in blood plasma. It gradually increases, reaching the plasma level before the end of exudation and wound healing. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 125, No. 3, pp. 355–357, March, 1997     

EGF containing gelatin-based wound dressings

In case of bulk loss of tissue or non-healing wounds such as burns, trauma, diabetic, decubitus and venous stasis ulcers, a proper wound dressing is needed to cover the wound area, protect the damaged tissue, and if possible to activate the cell proliferation and stimulate the healing process. In this study, synthesis of a novel polymeric bilayer wound dressing containing epidermal growth-factor (EGF) -loaded microspheres was aimed. For this purpose, a natural, nontoxic and biocompatible material, gelatin, was chosen as the underlying layer and various porous matrices in sponge form were prepared from gelatin by freeze-drying technique. As the external layer, elastomeric polyurethane membranes were used. Two different doses of EGF was added into the prepared gelatin sponges (1 and 15 microg/cm2) to activate cell proliferation. EGF addition was carried out either in free form or within microspheres to achieve prolonged release of EGF for higher efficiency. The prepared systems were tested in in vivo experiments on full-thickness skin defects created on rabbits. At certain intervals, wound areas were measured and tissues from wound areas were biopsied and processed for histological examinations. The wound areas decreased upon low-dose EGF application but the difference between the affects of free EGF and microsphere loaded EGF was not so distinct. Upon increasing the dose of EGF by a factor of 15, it was observed that controlled release of EGF from microspheres provided a higher degree of reduction in the wound areas. Histological investigations showed that the prepared dressings were biocompatible and did not cause any mononuclear cell infiltration or foreign body reaction. The structure of the newly formed dermis was almost the same as that of the normal skin.     

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.     

A thermoreversible hydrogel as a biosynthetic bandage for corneal wound repair

Ocular trauma and disorders that lead to corneal blindness account for over 2 million new cases of monocular blindness every year. A popular ocular surface reconstruction therapy, amniotic membrane transplantation, has been shown to aid corneal wound repair. However, the success rates of the procedure are variable. Here, we proposed to bioengineer a novel synthetic material that would serve as a biomimetic corneal bandage. The PLGA-PEG-PLGA triblock copolymer was synthesised via ring-opening polymerisation. Thermoreversible gelation behaviour was investigated at different polymer concentrations (23%, 30%, 35%, 40%, 45%, w/v) at temperatures ranging between 5 and 60 degrees C. Viscoelastic properties were studied in dynamic mechanical analysis with 1 degrees C/min temperature ramp. Cryo-SEM revealed a porous hydrogel with interconnecting networks. No adverse cytotoxicity was observed with an in vitro scratch-wound assay and in in vivo biocompatibility tests. We have demonstrated that the PLGA-PEG-PLGA hydrogel possessed a suitable gelling profile and, for the first time, the biocompatibility properties for this application as a potential bandage for corneal wound repair.     

Fabrication and characterization of phlorotannins/poly (vinyl alcohol) hydrogel for wound healing application

Abstract

Phlorotannins (PH) derived from brown algae have been shown to have biological effects. However, the application of PH in biomedical materials has not been investigated. Here, we investigated the effects of PH on normal human dermal fibroblast (NHDF) proliferation and fabricated a composite hydrogel consisting PH and poly (vinyl alcohol) (PVA) (PVA/PH) by a freezing-thawing method for wound healing applications. Cell proliferation was significantly higher in the PH-treated (0.01 and 0.02%) cells than in non-treated cells. Based on the mechanical properties, the PVA/PH hydrogel had a significantly increased swelling ratio and ultimate strain compared to the PVA hydrogel, but the ultimate tensile strength and tensile modulus were decreased. Additionally, cell attachment and proliferation on the composites were evaluated using NHDFs. The results showed that after 1 and 5 days, cell attachment and proliferation were significantly increased on the PVA/PH hydrogel compared with that on the PVA hydrogel. The findings from this study suggest that the PVA/PH hydrogel may be a candidate biomedical material for wound healing applications.     

Alpha-crystallin-incorporated collagen matrices as an aid for dermal wound healing

This study evaluated the effects of noncovalently incorporated crystallin into the collagen matrix for dermal wound-healing processes in rats. Crystallin-incorporated collagen matrix (CIC) showed better healing when compared to wounds treated with collagen matrix (CS) and without collagen (CR). Biochemical parameters and histological analysis revealed that increased wound contraction enhanced cell proliferation and efficient radical scavenging in the CIC group. The higher shrinkage temperature of CIC films when compared to CS groups suggested increased hydrothermal stability for the former material. An in vitro release study of CIC has showed sustained and time-dependent release of crystallin from the collagen matrix. These results demonstrate the possibility of using crystallin as therapeutic protein in the wound-healing process.     

A concise review on drug-loaded electrospun nanofibres as promising wound dressings

The diversity of wound types has gathered momentum to develop a wide range of wound dressings to improve different aspects of the wound healing process. Wound healing is a dynamic, complex and highly regulated mechanism of tissue repair and regeneration. The wound dressing should encourage regeneration and prevent possible infection or scaring. Wound dressings are different from the bandages as they come in direct contact with the wound and are used to absorb exudates and accelerate healing. Wound dressings can have a variety of functions, depending upon the type, severity, and position of the wound. In this review, we have studied the properties of nanofibrous wound dresses and possible approaches to load biological components into them for wound healing improvement.     

Water-soluble chitin as a wound healing accelerator.

Water-soluble chitin (WSC) was prepared by controlling degree of deacetylation (DD) and molecular weight of chitin through alkaline and ultrasonic treatment. Its accelerating effect on wound healing in rats was compared with those of chitin and chitosan. Full-thickness skin incision was made on the backs of the rats and then three kinds of powders (chitin, chitosan, WSC) and an aqueous solution of WSC were embedded in the wounds. The tensile strength and the hydroxyproline content of the wounded skins were measured and histological examination was performed. The WSC was found to be more efficient than chitin or chitosan as a wound-healing accelerator. The wound treated with WSC solution was completely reepithelialized, granulation tissues in the wound were nearly replaced by fibrosis and hair follicles were almost healed at 7 days after initial wounding. Also, the WSC-solution-treated skin had the highest tensile strength and the arrangement of collagen fibers in the skin was similar to normal skins. The WSC solution is considered to be a suitable wound-healing agent due to its easy application and high effectiveness.     

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.     

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.     

Designing hydrogel adhesives for corneal wound repair

Today, corneal wounds are repaired using nylon sutures. Yet there are a number of complications associated with suturing the cornea, and thus there is interest in an adhesive to replace or supplement sutures in the repair of corneal wounds. We are designing and evaluating corneal adhesives prepared from dendrimers--single molecular weight and highly branched polymers. We have explored two strategies to form these ocular adhesives. The first involves a photocrosslinking reaction and the second uses a peptide ligation reaction to couple the individual dendrimers together to form the adhesive. These adhesives were successfully used to repair corneal perforations, close the flap produced in a LASIK procedure, and secure a corneal transplant.