Norfloxacin-loaded chitosan sponges as wound dressing material

The aim of this study was the preparation and characterization of chitosan sponges including a model antibiotic (i.e., norfloxacin). The chitosan sponges were prepared by a solvent evaporation method. The matrix was also cross-linked during the preparation. The results indicated that the chitosan sponges were in the fibrillar structure. The swelling behavior, norfloxacin loading, in vitro release characteristics, and antibacterial activity were determined. The effects of cross-linker concentration, norfloxacin/chitosan ratio, chitosan molecular weight, and base concentration were investigated. The most effective parameter was found to be the degree of neutralization. It was also observed that the equilibrium swelling ratio decreased with increasing cross-linking density. The norfloxacin release was found to be swelling controlled initially and diffusion controlled at the extended release periods. It was also found that the antibacterial activity was directly proportional to the release rate.     

Electrospun nanofibrous polyurethane membrane as wound dressing

Produced via electrospinning, polyurethane membrane, which has a unique property, has been of interest in medical fields. Electrospinning is a process by which nanofibers can be produced by an electrostatically driven jet of polymer solution. Electrospun fibers are collected in the form of membranes. The porous structured electrospun membrane is particularly important for its favorable properties: it exudates fluid from the wound, does not build up under the covering, and does not cause wound desiccation. The electrospun nanofibrous membrane shows controlled evaporative water loss, excellent oxygen permeability, and promoted fluid drainage ability, but still it can inhibit exogenous microorganism invasion because its pores are ultra-fine. Histological examination indicates that the rate of epithelialization is increased and the dermis becomes well organized if wounds are covered with electrospun nanofibrous membrane. This electrospun membrane has potential applications for wound dressing based upon its unique properties.     

Chitosan-alginate PEC membrane as a wound dressing: Assessment of incisional wound healing

Flexible, thin, transparent, novel chitosan-alginate polyelectrolyte complex (PEC) membranes, cast from aqueous suspensions of chitosan-alginate coacervates with CaCl(2), were evaluated as potential wound-dressing materials. MTT and NR assays suggested that the chitosan-alginate PEC membranes and their aqueous extracts were nontoxic towards mouse and human fibroblast cells. Cell growth was also not hindered by co-incubation with the membranes. Compared to conventional gauze dressing, the PEC membranes caused an accelerated healing of incision wounds in a rat model. Wounds closed at 14 days postoperatively, and histological observations showed mature epidermal architecture with keratinized surface of normal thickness and a subsided inflammation in the dermis. This was followed by an excellent remodeling phase with organized thicker collagen bundles and mature fibroblasts at 21 days postoperative. Control wounds continued to show signs of an active inflammatory phase under scab on Day 21. Closure rate and appearance of PEC membrane-treated wounds were comparable with Opsite(R)-treated wounds. On the basis of its biocompatibility and wound-healing efficacy, the chitosan-alginate PEC membrane can be considered for wound-dressing applications.     

Preparation and characterization of chitin beads as a wound dressing precursor

Chitin was dissolved in N, N-dimethylacetamide/5% lithium chloride (DMAc/5%LiCl) to form a 0.5% chitin solution. Chitin beads were formed by dropping the 0.5% chitin solution into a nonsolvent coagulant, ethanol. The beads were left in ethanol for 24 h to permit hardening, consolidation, and removal of residual DMAc/5%LiCl solvent in order to give spherical chitin beads uniform size distribution. The ethanol-gelled chitin beads had an average diameter of 535 microm. The chitin beads were subsequently activated in 50% (w/v) NaOH solution and reacted with 1.9 M monochloroacetic acid/2-propanol solution to introduce a carboxymethylated surface layer to the chitin beads. The bilayer character of the surface-carboxymethylated chitin (SCM-chitin) beads was verified by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and confocal microscopy. The bilayered SCM-chitin beads were found to absorb up to 95 times their dry weight of water. These SCM-chitin beads have potential as a component of wound dressings.     

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.     

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.     

Photocrosslinkable chitosan as a dressing for wound occlusion and accelerator in healing process.

Application of ultraviolet light (UV-) irradiation to a photocrosslinkable chitosan (Az-CH-LA) aqueous solution resulted in an insoluble, flexible hydrogel like soft rubber within 60 s. The chitosan hydrogel could completely stop bleeding from a cut mouse tail within 30 s of UV-irradiation and could firmly adhere two pieces of sliced skins of mouse to each other. In order to evaluate its accelerating effect on wound healing, full thickness-skin incisions were made on the back of mice and subsequently an Az-CH-LA aqueous solution was added into the wound and irradiated with UV light for 90 s. Application of the chitosan hydrogel significantly induced wound contraction and accelerated wound closure and healing. Histological examinations also have demonstrated an advanced granulation tissue formation and epithelialization in the chitosan hydrogel treated wounds. The chitosan hydrogel due to its accelerating healing ability is considered to become an excellent dressing for wound occlusion and tissue adhesive in urgent hemostasis situations.     

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.     

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.     

Systematic review of the use of honey as a wound dressing

Objective  

To investigate topical honey in superficial burns and wounds though a systematic review of randomised controlled trials.     

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。     

护创膜对兔创面愈合的影响

目的探讨护创膜对兔创面愈合的影响。方法制做兔背全层创伤模型,分成实验组和对照组,创面分别外用护创膜及无菌凡士林敷料。伤后3、5、7、10、l4、17、21d观察两组创面愈合时间和创面愈合率;并分别取创面组织进行病理组织学检查评估创面的修复质量,对实验组和对照组的创面愈合时间和创面愈合率及修复质量进行观察比较。结果护创膜与凡士林纱布相比能加速创面愈合(P<0.O5),护创膜组在皮肤愈合的组织病理等级评分上优于凡士林纱布组(P<0.05)。结论护创膜促进创面愈合并提高愈合的质量,是创面修复的一种较理想的生物敷料。     

In vivo evaluation of an ultra-thin polycaprolactone film as a wound dressing

The use of ultra-thin films as dressings for cutaneous wounds could prove advantageous in terms of better conformity to wound topography and improved vapour transmission. For this purpose, ultra-thin poly(epsilon-caprolactone) (PCL) films of 5-15 microm thickness were fabricated via a biaxial stretching technique. To evaluate their in vivo biocompatibility and feasibility as an external wound dressing, PCL films were applied over full and partial-thickness wounds in rat and pig models. Different groups of PCL films were used: untreated, NaOH-treated, untreated with fibrin, NaOH-treated with perforations, and NaOH-treated with fibrin and S-nitrosoglutathione. Wounds with no external dressings were used as controls. Wound contraction rate, histology and biomechanical analyses were carried out. Wounds re-epithelialized completely at a comparable rate. Formation of a neo-dermal layer and re-epithelialization were observed in all the wounds. A lower level of fibrosis was observed when PCL films were used, compared to the control wounds. Ultimate tensile strength of the regenerated tissue in rats reached 50-60% of that in native rat skin. Results indicated that biaxially-stretched PCL films did not induce inflammatory reactions when used in vivo as a wound dressing and supported the normal wound healing process in full and partial-thickness wounds.     

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/介孔生物活性玻璃多孔膜的制备和表征

背景：壳聚糖和介孔生物玻璃都具有良好的生物相容性和止血性能,但壳聚糖止血作用有限,介孔生物玻璃粉体方式止血,给应用带来不便。 目的：制备壳聚糖/介孔生物玻璃复合多孔膜并检测材料的性能。 方法：采用冷冻干燥法制备壳聚糖/介孔生物玻璃复合多孔膜。 结果与结论：通过冷冻干燥法可以实现壳聚糖和介孔生物玻璃的均匀复合。制备的复合多孔膜的孔隙分布较均匀;多孔膜具有很好的吸水性,吸水率的大小与壳聚糖和介孔生物玻璃质量比相关;多孔膜的孔隙率高。     

Fabrication and characterization of DTBP-crosslinked chitosan scaffolds for skin tissue engineering

Chitosan, the deacetylated derivative of chitin, is a promising scaffold material for skin tissue engineering applications. It is biocompatible and biodegradable, and the degradation products are resorbable. However, the rapid degradation of chitosan and its low mechanical strength are concerns that may limit its use. In this study, chitosan with 80%, 90% and 100% degree of deacetylation (DDA) was crosslinked with dimethyl 3-3, dithio bis' propionimidate (DTBP) and compared to uncrosslinked scaffolds. The scaffolds were characterized with respect to important tissue engineering properties. The tensile strength of scaffolds made from 100% DDA chitosan was significantly higher than for scaffolds made from 80% and 90% DDA chitosan. Crosslinking of scaffolds with DTBP increased the tensile strength. Crosslinking with DTBP had no significant effect on water vapour transmission rate (WVTR) or water absorption but had significant effect on the pore size and porosity of the samples. All samples showed a WVTR and pore size distribution suitable for skin tissue engineering; however, the water absorption and porosity were lower than the optimal values for skin tissue engineering. The biodegradation rate of scaffolds crosslinked with DTBP and glutaraldehyde (GTA) were reduced while no significant effect was observed in biodegradation of the samples made from 100% DDA chitosan whether crosslinked or uncrosslinked after 24 days of degradation.     

Chemical and physical properties of a hydrogel wound dressing

Geliperm hydrogel provides optimal physiological conditions for wound healing. The material is composed of two interlaced networks, one of polyacrylamide and one of agar, and contains about 96% firmly bound water. It is supplied in smooth, elastic, transparent sheets which are impermeable to bacteria but permeable to gases, salts, metabolites and proteins. Geliperm is nontoxic and has no irritative properties. Mechanical properties, water retention and diffusion of dyes and proteins are reported. Bacterial size should preclude penetration of the gel. The hydrogel in granular form represents a coherent material which could be used in deep fissured wounds and for the treatment of injuries with a large amount of exudation and contamination.