Antibacterial biomaterials for skin wound dressing

Bacterial infection and the ever-increasing bacterial resistance have imposed severe threat to human health. And bacterial contamination could significantly menace the wound healing process. Considering the sophisticated wound healing process, novel strategies for skin tissue engineering are focused on the integration of bioactive ingredients, antibacterial agents included, into biomaterials with different morphologies to improve cell behaviors and promote wound healing. However, a comprehensive review on anti-bacterial wound dressing to enhance wound healing has not been reported. In this review, various antibacterial biomaterials as wound dressings will be discussed. Different kinds of antibacterial agents, including antibiotics, nanoparticles (metal and metallic oxides, light-induced antibacterial agents), cationic organic agents, and others, and their recent advances are summarized. Biomaterial selection and fabrication of biomaterials with different structures and forms, including films, hydrogel, electrospun nanofibers, sponge, foam and three-dimension (3D) printed scaffold for skin regeneration, are elaborated discussed. Current challenges and the future perspectives are presented in this multidisciplinary field. We envision that this review will provide a general insight to the elegant design and further refinement of wound dressing.     

Evaluation of a flexible new liquid polymer wound dressing

Occlusive dressings are the foundation of wound care and have been shown to speed epithelialization and healing of surgical sites. Many different dressings have been introduced over the years including antibacterial ointments with gauze and adhesive, hydrocolloid bandages, and liquid adhesives. All of these have their limitations and advantages. We introduce our experience with a new organic polymer in solvent which when applied to a wound forms a flexible occlusive bandage. The material has been shown to have antimicrobial properties and be well-tolerated by patients.     

Wound healing dressings and drug delivery systems: a review

The variety of wound types has resulted in a wide range of wound dressings with new products frequently introduced to target different aspects of the wound healing process. The ideal dressing should achieve rapid healing at reasonable cost with minimal inconvenience to the patient. This article offers a review of the common wound management dressings and emerging technologies for achieving improved wound healing. It also reviews many of the dressings and novel polymers used for the delivery of drugs to acute, chronic and other types of wound. These include hydrocolloids, alginates, hydrogels, polyurethane, collagen, chitosan, pectin and hyaluronic acid. There is also a brief section on the use of biological polymers as tissue engineered scaffolds and skin grafts. Pharmacological agents such as antibiotics, vitamins, minerals, growth factors and other wound healing accelerators that take active part in the healing process are discussed. Direct delivery of these agents to the wound site is desirable, particularly when systemic delivery could cause organ damage due to toxicological concerns associated with the preferred agents. This review concerns the requirement for formulations with improved properties for effective and accurate delivery of the required therapeutic agents. General formulation approaches towards achieving optimum physical properties and controlled delivery characteristics for an active wound healing dosage form are also considered briefly.     

抗菌敷料抗菌功效体外评价研究

目的：评价抗菌敷料的体外抗菌功效。方法：本研究基于模拟临床创面微生物的实际生长状态,构建体外创面模型并建立抗菌敷料抗菌功效评价方法,用以评价抗菌敷料对金黄色葡萄球菌、铜绿假单胞菌、大肠杆菌和白色念珠菌的体外抗菌功效。结果：试验样品在12 h内抑制了金黄色葡萄球菌的增殖,在72 h内杀灭对数值未超过1.00;在24 h对铜绿假单胞菌的杀灭对数值达到4.24,随后大幅下降, 在72 h的杀灭对数值降为0.37;在12 h对大肠杆菌的杀灭对数值达到4.10,在其后至72 h内杀灭对数值均大于3.00;在12 h对白色念珠菌的杀灭对数值达到1.11,在72 h的杀灭对数值仅为0.04。结论：该抗菌敷料对金黄色葡萄球菌、铜绿假单胞菌、大肠杆菌和白色念珠菌均显示了抗菌效果,其中对铜绿假单胞菌、大肠杆菌的抗菌功效要好于金黄色葡萄球菌和白色念珠菌。     

Antimicrobial properties of silver-containing wound dressings: a microcalorimetric study

The studies reported here have been undertaken to assess the potential use of isothermal microcalorimetry in studying the antimicrobial efficacy of wound dressings that contain antimicrobial agents. The microcalorimetric technique allows non-invasive and non-destructive analysis to be performed directly on a test sample, regardless of whether it is homogeneous or heterogeneous in nature. Microcalorimetry is an established procedure that offers quantitative measurements and has the distinct advantage over traditional antimicrobial test methodologies in that calorimetric measurements are made continuously over real-time, thus the dynamic response of microorganisms to an antimicrobial agent is observed in situ. The results described in this paper are for interaction of two silver-containing wound care products AQUACEL Ag Hydrofiber (ConvaTec, Deeside, UK) and Acticoat 7 with SILCRYST (Smith and Nephew Healthcare, UK) with the wound pathogenic organisms Staphylococcus aureus and Pseudomonas aeruginosa. Both dressings are shown, microcalorimetrically, to have the capacity to kill these common wound pathogens within 1-2 h of contact. A dose-response study was conducted with the AQUACEL Ag dressing. Microcalorimetry is shown to be rapid, simple and effective in the study of the antimicrobial properties of gel forming wound dressings.     

海藻酸盐医用敷料的研究进展

海藻酸盐(alginate)是一类从褐藻中提取的天然线性多糖,具有无毒、可生物降解、生物相容性高的特点,海藻酸盐的高吸湿性和凝胶性,使其在现代伤口敷料方面得到了广泛应用。海藻酸盐敷料则具有成本低、使用方便、能促进伤口愈合的特点,有海绵形式、纤维形式和水凝胶等形式,作为医用敷料有广阔应用前景。本文对海藻酸医用辅料的主要特点和不同形式的应用进行了综述,并展望了其应用前景。     

血余炭纳米纤维膜抗菌活性的实验研究

目的:制备新型载药止血材料血余炭纳米纤维膜,并探讨其体内、体外的抗菌性能。方法:采用静电纺丝技术,将血余炭作为添加药物,以生物相容性较好的聚乳酸作为纳米纤维膜基体,制备了一种新型的载药止血材料。采用抑菌环实验法测定医用脱脂纱布、抗菌医用敷料、未载血余炭纳米纤维膜和载血余炭纳米纤维膜对金黄色葡萄球菌、大肠杆菌、铜绿假单胞菌的抑菌环直径;选用兔感染创面模型,使用材料对创面进行治疗,通过肉眼和组织病理学观察、组织内细菌计数等方法对各组材料的抗菌性能进行研究。结果:血余炭纳米纤维膜纤维直径相对较小,平均直径为400 nm,载入的血余炭与成纤维聚合物之间具有良好的相容性。血余炭纳米纤维膜在体外对金黄色葡萄球菌、大肠杆菌和铜绿假单胞菌均有一定的抑制效果;肉眼和组织学观察,血余炭纳米纤维膜治疗后的动物模型伤口炎症反应明显小于其他组;血余炭纳米纤维膜治疗后感染伤口细菌数量为(7.62±1.87)×104个.g-1组织,与空白对照组比较显著减少,差异具有统计学意义(P<0.01)。结论:血余炭纳米纤维膜具有良好的体内、体外抗菌性能。     

Application of chitosan-based nanoparticles in skin wound healing

The rising prevalence of impaired wound healing and the consequential healthcare burdens have gained increased attention over recent years. This has prompted research into the development of novel wound dressings with augmented wound healing functions. Nanoparticle (NP)-based delivery systems have become attractive candidates in constructing such wound dressings due to their various favourable attributes. The non-toxicity, biocompatibility and bioactivity of chitosan (CS)-based NPs make them ideal candidates for wound applications. This review focusses on the application of CS-based NP systems for use in wound treatment. An overview of the wound healing process was presented, followed by discussion on the properties and suitability of CS and its NPs in wound healing. The wound healing mechanisms exerted by CS-based NPs were then critically analysed and discussed in sections, namely haemostasis, infection prevention, inflammatory response, oxidative stress, angiogenesis, collagen deposition, and wound closure time. The results of the studies were thoroughly reviewed, and contradicting findings were identified and discussed. Based on the literature, the gap in research and future prospects in this research area were identified and highlighted. Current evidence shows that CS-based NPs possess superior wound healing effects either used on their own, or as drug delivery vehicles to encapsulate wound healing agents. It is concluded that great opportunities and potentials exist surrounding the use of CSNPs in wound healing.     

Surgical antibiotic irrigations.

Instillation of antibiotic solutions into surgical wound sites seems empirically attractive since relatively high concentrations of antibacterial agents can be applied directly to the probable site of infection. However, systemic effects provided by antibiotic assimilated from sites of application are responsible for much of the activity and toxicity of antibiotic irrigations. The most appropriate drugs and dosages for use as prophylactic antibiotic irrigations have not been determined. Most controlled trials conducted in recent years have utilized various cephalosporins in concentrations of 1 to 4 g/L. In some of these trials, surgical irrigation has been found as effective as prophylactic intravenous antibiotics, which are the proven and accepted standard. Reported cases of toxicity associated with antibiotic irrigations are few in number, excepting neomycin, which has caused postoperative respiratory depression/apnea, permanent deafness, and renal failure.     

A review of the in vivo and in vitro toxicity of silver and gold particulates: Particle attributes and biological mechanisms responsible for the observed toxicity

This review is concerned with evaluating the toxicity associated with human exposure to silver and gold nanoparticles (NPs), due to the relative abundance of toxicity data available for these particles, when compared to other metal particulates. This has allowed knowledge on the current understanding of the field to be gained, and has demonstrated where gaps in knowledge are. It is anticipated that evaluating the hazards associated with silver and gold particles will ultimately enable risk assessments to be completed, by combining this information with knowledge on the level of human exposure. The quantity of available hazard information for metals is greatest for silver particulates, due to its widespread inclusion within a number of diverse products (including clothes and wound dressings), which primarily arises from its antibacterial behaviour. Gold has been used on numerous occasions to assess the biodistribution and cellular uptake of NPs following exposure. Inflammatory, oxidative, genotoxic, and cytotoxic consequences are associated with silver particulate exposure, and are inherently linked. The primary site of gold and silver particulate accumulation has been consistently demonstrated to be the liver, and it is therefore relevant that a number of in vitro investigations have focused on this potential target organ. However, in general there is a lack of in vivo and in vitro toxicity information that allows correlations between the findings to be made. Instead a focus on the tissue distribution of particles following exposure is evident within the available literature, which can be useful in directing appropriate in vitro experimentation by revealing potential target sites of toxicity. The experimental design has the potential to impact on the toxicological observations, and in particular the use of excessively high particle concentrations has been observed. As witnessed for other particle types, gold and silver particle sizes are influential in dictating the observed toxicity, with smaller particles exhibiting a greater response than their larger counterparts, and this is likely to be driven by differences in particle surface area, when administered at an equal-mass dose. A major obstacle, at present, is deciphering whether the responses related to silver nanoparticulate exposure derive from their small size, or particle dissolution contributes to the observed toxicity. Alternatively, a combination of both may be responsible, as the release of ions would be expected to be greater for smaller particles.