基于壳聚糖/海藻酸钠-聚乙烯醇的双层复合水凝胶膜伤口敷料研究

目的 制备聚乙烯醇（PVA）/海藻酸钠（SA）-聚乙烯醇（PVA）/壳聚糖（CS）双层（PAPCS）水凝胶膜伤口敷料，并进行质量评价。方法 将PVA与SA以质量比2∶1混合，配制PVA/SA混合溶液；将PVA与CS分别以质量比1∶1、2∶1、3∶1、4∶1、5∶1混合，配制不同质量比的PVA/CS混合溶液；采用涂布法制备PAPCS双层水凝胶膜伤口敷料。通过水蒸气透过率、溶胀性能、保水性、力学性能、体外凝血性能和血液相容性考察对水凝胶膜的性能进行评价、筛选PVA与CS质量比；通过傅里叶变换红外光谱检测（FTIR）和扫描电子显微镜（SEM）对PAPCS水凝胶膜的结构和形貌进行表征；通过抑菌实验比较PAPCS以及PAPCS复合载碘交联环糊精金属有机骨架（I₂@COF@PAPCS）的体外抗菌性能。结果 PVA与CS质量比为2∶1时，PAPCS水凝胶膜综合性能较好。PAPCS水凝胶膜为多孔结构，具有良好的溶胀性能、保水性以及力学性能；PAPCS水凝胶膜的水蒸气透过率为（2 643.76±91.62）g·m^-2·d^-1，接近理想范围；与PVA/SA相比，PAPCS的凝血指数显著降低（P＜0.01），为（72.93±3.58）%，溶血率小于5%，具有促进血液凝固的能力且血液相容性良好；与PVA/SA相比，PAPCS对于金黄色葡萄球菌、大肠埃希菌均有明显抑制作用，抑菌圈直径分别为（11.89±0.22）、（12.28±0.25） mm；I₂@COF@PAPCS对金黄色葡萄球菌、大肠埃希菌的抑菌圈直径分别为（21.95±1.47）、（18.89±0.81）mm，抑菌效果显著优于PAPCS（P＜0.001）。结论 采用涂布法可成功制备双层PAPCS水凝胶膜敷料，其各项性能指标良好，具有明显的凝血、抑菌效果，与I₂@COF复合使用，抑菌作用进一步增强。     

Novel neomycin sulfate-loaded hydrogel dressing with enhanced physical dressing properties and wound-curing effect

To develop a novel neomycin sulfate-loaded hydrogel dressing (HD), numerous neomycin sulfate-loaded HDs were prepared with various amounts of polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) and sodium alginate (SA) using freeze-thawing technique, and their physical dressing properties, drug release, in vivo wound curing and histopathology in diabetic-induced rats were assessed. SA had a positive effect on a swelling capacity, but a negative effect on the physical dressing properties and drug release of HD. However, PVP did the opposite. In particular, the neomycin sulfate-loaded HD composed of drug, PVA, PVP and SA at the weight ratio of 1/10/0.8/0.8 had excellent swelling and bioadhesive capacity, good elasticity and fast drug release. Moreover, this HD gave more improved wound curing effect compared to the commercial product, ensured the disappearance of granulation tissue and recovered the wound tissue to normal. Therefore, this novel neomycin sulfate-loaded HD could be an effective pharmaceutical product for the treatment of wounds.     

Drug-loaded electrospun materials in wound-dressing applications and in local cancer treatment

Introduction: During the last decade, the use of electrospinning for the fabrication of nanofibrous materials loaded with antibacterial agents or anticancer drugs for biomedical applications such as dressing materials for wound treatment and for local cancer treatment has evoked considerable interest. Different drugs can be easily incorporated in electrospun materials and their release profile can be controlled through changes in the fibers morphology, porosity and composition. The large specific surface area of the electrospun materials, the possibility for gradual release and site-specific local delivery of the active compounds lead to cytotoxicity decrease and enhancement of the therapeutic effect of the drugs.

Areas covered: The most recent studies on drug-loaded electrospun mats as materials for wound dressing or local cancer treatment are briefly summarized.

Expert opinion: The possibility for local drug delivery in cancer therapy using electrospun materials allows avoiding the oral or systemic drug application, thus leading to decrease in some deleterious side effects. The recent achievements in the comprehension of the electrospinning, in control over the surface chemical composition of the electrospun materials, and in diversifying the applied approaches and techniques, propound larger prospects for creating new materials for wound dressing and local cancer treatment.     

Development of polyvinyl alcohol-sodium alginate gel-matrix-based wound dressing system containing nitrofurazone

Polyvinyl alcohol (PVA)/sodium alginate (SA) hydrogel matrix-based wound dressing systems containing nitrofurazone (NFZ), a topical anti-infective drug, were developed using freeze-thawing method. Aqueous solutions of nitrofurazone and PVA/SA mixtures in different weight ratios were mixed homogeneously, placed in petri dishes, freezed at -20 degrees C for 18h and thawed at room temperature for 6h, for three consecutive cycles, and evaluated for swelling ratio, tensile strength, elongation and thermal stability of the hydrogel. Furthermore, the drug release from this nitrofurazone-loaded hydrogel, in vitro protein adsorption test and in vivo wound healing observations in rats were performed. Increased SA concentration decreased the gelation%, maximum strength and break elongation, but it resulted into an increment in the swelling ability, elasticity and thermal stability of hydrogel film. However, SA had insignificant effect on the release of nitrofurazone. The amounts of proteins adsorbed on hydrogel were increased with increasing sodium alginate ratio, indicating the reduced blood compatibility. In vivo experiments showed that this hydrogel improved the healing rate of artificial wounds in rats. Thus, PVA/SA hydrogel matrix based wound dressing systems containing nitrofurazone could be a novel approach in wound care.     

Neomycin-loaded poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA)/polyvinyl alcohol (PVA) ion exchange nanofibers for wound dressing materials

In this study, poly(styrene sulfonic acid-co-maleic acid) (PSSA-MA) blended with polyvinyl alcohol (PVA) was electrospun and then subjected to thermal crosslinking to produce PSSA-MA/PVA ion exchange nanofiber mats. The cationic drug neomycin (0.001, 0.01, and 0.1%, w/v) was loaded onto the cationic exchange fibers. The amount of neomycin loaded and released and the cytotoxicity of the fiber mats were analyzed. In vivo wound healing tests were also performed in Wistar rats. The results indicated that the diameters of the fibers were on the nanoscale (250 ± 21 nm). The ion exchange capacity (IEC) value and the percentage of water uptake were 2.19 ± 0.1 mequiv./g-dry fibers and 268 ± 15%, respectively. The loading capacity was increased upon increasing the neomycin concentration. An initial concentration of 0.1% (w/v) neomycin (F3) showed the highest loading capacity (65.7 mg/g-dry fibers). The neomycin-loaded nanofiber mats demonstrated satisfactory antibacterial activity against both Gram-positive and Gram-negative bacteria, and an in vivo wound healing test revealed that these mats performed better than gauze and blank nanofiber mats in decreasing acute wound size during the first week after tissue damage. In conclusion, the antibacterial neomycin-loaded PSSA-MA/PVA cationic exchange nanofiber mats have the potential for use as wound dressing materials.     

盐酸莫西沙星静电纺丝膜的制备及性能研究

目的:制备具有抗菌作用的盐酸莫西沙星(MH)静电纺丝膜。方法:以聚乙烯醇(PVA)和海藻酸钠(SA)为载体,MH为模型药物,制备具有优良透气性能的抗菌静电纺丝膜。以溶液可纺性、静电纺丝的形态结构等为指标,筛选12%PVA与2%SA不同体积比(4:1、3.5:1.5、3:2、2.5:2.5、2:3、1:4)的纺丝溶液及静电纺丝膜的加药量以确定最佳处方。测定静电纺丝膜的透气性能并与口罩无纺布比较。结果:最佳处方为12%PVA与2%SA的体积比为3:2,加药量为2%;纺丝溶液可纺性好,所制静电纺丝直径小且均匀,表面光滑,串珠状纺丝少,收率为(86.73±2.92)%,透气性能优于无纺布(P<0.05)。结论:制备的MH静电纺丝膜载药均匀,具有良好的透气性能。     

Electrospun multifunctional nanofibrous mats loaded with bioactive anemoside B4 for accelerated wound healing in diabetic mice

With the worldwide prevalence of diabetes and considering the complicated microenvironment of diabetic wounds, the design and development of innovative multifunctional wound dressing materials are much wanted for the treatment of hard-to-heal wounds in diabetic patients. In the present study, anti-inflammatory ingredients loaded with nanofibrous wound dressing materials were manufactured by a promising blend-electrospinning strategy, and their capability for treating the diabetic wound was also systematically explored. A polymer blend consisting of Chitosan (CS) and polyvinyl alcohol (PVA) was electrospun into CS-PVA nanofibrous mats as control groups. In the meanwhile, a bioactive ingredient of Chinese medicine Pulsatilla, anemoside B4(ANE), with different contents were loaded into the electrospinning solution to construct CS-PVA-ANE nanofibrous mats. The developed CS-PVA-ANE wound dressing materials exhibited multifunctional properties including prominent water absorption, biomimetic elastic mechanical properties, and sustained ANE releasing behavior, as well as outstanding hemostatic properties. The in vitro studies showed that the CS-PVA-ANE nanofiber mats could significantly suppress lipopolysaccharide (LPS)-stimulated differentiation of pro-inflammatory (M1) macrophage subsets, and notably reduce the reactive oxygen species (ROS) generation, as well as obviously decrease inflammatory cytokine release. The in vivo animal studies showed that the CS-PVA-ANE nanofiber mats promoted the healing of diabetic wounds by significantly enhancing wound closure rates, accelerating excellent angiogenesis, promoting re-epithelization and collagen matrix deposition throughout all stages of wound healing. The present study demonstrated that CS-PVA-ANE nanofiber mats could effectively shorten the wound-healing time by inhibiting inflammatory activity, which makes them promising candidates for the treatment of hard-to-heal wounds caused by diabetes.     

Preparation and Characterization of Silver Sulfadiazine–Loaded Polyvinyl Alcohol Hydrogels as an Antibacterial Wound Dressing

In this study, we prepared a series of silver sulfadiazine (AgSD)–loaded polyvinyl alcohol (PVA) hydrogels via electron beam (e-beam) irradiation. Our objective was to explore the influence of e-beam irradiation on the chemical structure and crystallinity of AgSD and the antibacterial properties of AgSD/PVA hydrogels. Prior to irradiation, we mixed AgSD in PVA solution in 2 forms, either suspended in water (WS) or dissolved in ammonia solution (AS). We noted that nano silver was released from AgSD/PVA-AS hydrogels immersed in deionized water, while it would not happen in AgSD/PVA-WS hydrogels. Both kinds of AgSD/PVA hydrogels exhibited good antibacterial activities against gram-negative Escherichia coli and gram-positive Staphylococcus aureus. And their antibacterial activity was not obviously affected by different dosages of e-beam irradiation. Moreover, the antibacterial activity of the AgSD/PVA-WS hydrogels was stronger than that of AgSD/PVA-AS. Accordingly, the cell cytotoxicity of the AgSD/PVA-WS hydrogels was higher than that of AgSD/PVA-AS. Our study results reveal that e-beam irradiation of PVA solution with dispersed AgSD is a simple and efficient way to prepare AgSD/PVA hydrogels, which might be an ideal antibacterial wound dressing.     

Effect of sodium carboxymethylcellulose and fucidic acid on the gel characterization of polyvinylalcohol-based wound dressing

The purpose of this study was to investigate the effect of sodium carboxymethylcellulose (Na-CMC) and fucidic acid on the gel characterization for the development of sodium fucidate-loaded wound dressing. The cross-linked hydrogel films were prepared with polyvinyl alcohol (PVA) and sodium carboxymethylcellulose (Na-CMC) using the freeze-thawing method. Their gel properties such as gel fraction, swelling, water vapor transmission test, morphology, tensile strength and thermal property were investigated. In vitro protein adsorption test and release were performed. Na-CMC decreased the gel fraction and tensile strength of the hydrogels, but increased the swelling ability, water vapor transmission rate, elasticity and porosity of hydrogels. Thus, the wound dressing developed with PVA and Na-CMC was more swellable, flexible and elastic than that with only PVA because of its cross-linking interaction with PVA. However, the drug had a negative effect on the gel properties of hydrogels but there were no significant differences. In particular, the hydrogel composed of 2.5% PVA, 1.125% Na-CMC and 0.2% drug might give an adequate level of moisture and build up the exudates on the wound area. Thus, this sodium fucidate-loaded hydrogel could be a potential candidate for wound dressing with excellent forming.     

Accelerated wound healing and anti-inflammatory effects of physically cross linked polyvinyl alcohol–chitosan hydrogel containing honey bee venom in diabetic rats

Diabetes is one of the leading causes of impaired wound healing. The objective of this study was to develop a bee venom-loaded wound dressing with an enhanced healing and anti-inflammatory effects to be examined in diabetic rats. Different preparations of polyvinyl alcohol (PVA), chitosan (Chit) hydrogel matrix-based wound dressing containing bee venom (BV) were developed using freeze–thawing method. The mechanical properties such as gel fraction, swelling ratio, tensile strength, percentage of elongation and surface pH were determined. The pharmacological activities including wound healing and anti-inflammatory effects in addition to primary skin irritation and microbial penetration tests were evaluated. Moreover, hydroxyproline, glutathione and IL-6 levels were measured in the wound tissues of diabetic rats. The bee venom-loaded wound dressing composed of 10 % PVA, 0.6 % Chit and 4 % BV was more swellable, flexible and elastic than other formulations. Pharmacologically, the bee venom-loaded wound dressing that has the same pervious composition showed accelerated healing of wounds made in diabetic rats compared to the control. Moreover, this bee venom-loaded wound dressing exhibited anti-inflammatory effect that is comparable to that of diclofenac gel, the standard anti-inflammatory drug. Simultaneously, wound tissues covered with this preparation displayed higher hydroxyproline and glutathione levels and lower IL-6 levels compared to control. Thus, the bee venom-loaded hydrogel composed of 10 % PVA, 0.6 % Chit and 4 % BV is a promising wound dressing with excellent forming and enhanced wound healing as well as anti-inflammatory activities.     

Wound healing evaluation of sodium fucidate-loaded polyvinylalcohol/sodium carboxymethylcellulose-based wound dressing

The cross-linked hydrogel films containing sodium fucidate were previously reported to be prepared polyvinyl alcohol (PVA) and sodium carboxymethylcellulose (Na-CMC) using the freeze-thawing method and their physicochemical property was investigated. For the development of novel sodium fucidate-loaded wound dressing, here its in vivo wound healing test and histopathology were performed compared with the conventional ointment product. In wound healing test, the sodium fucidate-loaded composed of 2.5% PVA, 1.125% Na-CMC and 0.2% drug showed faster healing of the wound made in rat dorsum than the hydrogel without drug, indicating the potential healing effect of sodium fucidate. Furthermore, from the histological examination, the healing effect of sodium fucidate-loaded hydrogel was greater than that of the conventional ointment product and hydrogel without drug, since it might gave an adequate level of moisture and build up the exudates on the wound area. Thus, the sodium fucidate-loaded wound dressing composed of 5% PVA, 1.125% Na-CMC and 0.2% drug is a potential wound dressing with excellent wound healing.     

Clinical Potential of a Silk Sericin-Releasing Bioactive Wound Dressing for the Treatment of Split-Thickness Skin Graft Donor Sites

Purpose

An ethyl alcohol-precipitated silk sericin/PVA scaffold that controlled the release of silk sericin was previously developed and applied for the treatment of full-thickness wounds in rats and demonstrated efficient healing. In this study, we aimed to further evaluate the clinical potential of this scaffold, hereafter called “silk sericin-releasing wound dressing”, for the treatment of split-thickness skin graft donor sites by comparison with the clinically available wound dressing known as “Bactigras®”.

Methods

In vitro characterization and in vivo evaluation for safety of the wound dressings were performed. A clinical trial of the wound dressings was conducted according to standard protocols.

Results

The sericin released from the wound dressing was not toxic to HaCat human keratinocytes. A peel test indicated that the silk sericin-releasing wound dressing was less adhesive than Bactigras®, potentially reducing trauma and the risk of repeated injury upon removal. There was no evidence of skin irritation upon treatment with either wound dressing. When tested in patients with split-thickness skin graft donor sites, the wounds treated with the silk sericin-releasing wound dressing exhibited complete healing at 12?±?5.0 days, whereas those treated with Bactigras® were completely healed at 14?±?5.2 days (p?=?1.99?×?10^?4). In addition, treatment with the silk sericin-releasing wound dressing significantly reduced pain compared with Bactigras® particularly during the first 4 postoperative days (p?=?2.70?×?10^?5 on day 1).

Conclusion

We introduce this novel silk sericin-releasing wound dressing as an alternative treatment for split-thickness skin graft donor sites.     

PVA-PEG physically cross-linked hydrogel film as a wound dressing: experimental design and optimization

The development of hydrogel films as wound healing dressings is of a great interest owing to their biological tissue-like nature. Polyvinyl alcohol/polyethylene glycol (PVA/PEG) hydrogels loaded with asiaticoside, a standardized rich fraction of Centella asiatica, were successfully developed using the freeze–thaw method. Response surface methodology with Box–Behnken experimental design was employed to optimize the hydrogels. The hydrogels were characterized and optimized by gel fraction, swelling behavior, water vapor transmission rate and mechanical strength. The formulation with 8% PVA, 5% PEG 400 and five consecutive freeze–thaw cycles was selected as the optimized formulation and was further characterized by its drug release, rheological study, morphology, cytotoxicity and microbial studies. The optimized formulation showed more than 90% drug release at 12?hours. The rheological properties exhibited that the formulation has viscoelastic behavior and remains stable upon storage. Cell culture studies confirmed the biocompatible nature of the optimized hydrogel formulation. In the microbial limit tests, the optimized hydrogel showed no microbial growth. The developed optimized PVA/PEG hydrogel using freeze–thaw method was swellable, elastic, safe, and it can be considered as a promising new wound dressing formulation.     

Lack of prophylactic or therapeutic efficacy of 5-HT2A receptor antagonists in halothane-induced porcine malignant hyperthermia

During halothane-induced malignant hyperthermia (MH), plasma levels of serotonin (5-hydroxytryptamine, 5-HT) increase in pigs. Administration of 5-HT agonists which stimulate the 5-HT_2A subreceptor triggers MH in susceptible pigs. A possible link between MH induced by 5-HT_2A receptor agonists and halothane could be an increase of second messengers such as phosphoinositides (inositol polyphosphates), which have recently been implicated in the abnormal regulation of skeletal muscle calcium release in MH. If so, antagonists of 5-HT_2A receptors which are linked to phosphoinositide turnover should, be capable of preventing, retarding or attenuating halothane-induced MH. This possibility was investigated in the present study in MH susceptible pigs, using dantrolene for comparison. Development of MH triggered by a halothane challenge (inhalation of 3% halothane for 15 min) was completely prevented by dantrolene, 3.5 mg/i.v., whereas the 5-HT_2A receptor antagonists ritanserin (0.5–10 mg/kg i.v.) or ketanserin (0.5–10 mg/kg i.v.) exerted no prophylactic effect. In pigs in which dantrolene, ritanserin or ketanserin where given in combination with hyperventilation after development of MH, dantrolene exerted therapeutic efficacy, whereas neither ritanserin nor ketanserin were effective treatments. The data indicate that 5-HT is not critically involved in the mechanisms of halothane-induced MH, at least under the conditions of the present experimental study.Abbreviations AST aspartate aminotransferase - CK creatinkinase - 5-HT 5-hydroxytryptamine - 5-MeO-DMT 5-methoxy-N,N-dimethyltryptamine - MH malignant hyperthermia - MHA MH-atypical - MHN MH-nonsusceptible - MHS MH-susceptible Correspondence to: W. Loscher at the above address     

Novel chitosan and bacterial cellulose biocomposites tailored with polymeric nanoparticles for modern wound dressing development

Dressing biomaterials play a key role in wound management keeping a moisture medium and protecting against external factors. Natural and synthetic materials could be used as dressings where chitosan and bacterial cellulose is one of the most important solutions. These biopolymers have been used for wound dressing based on their non-toxic, biodegradable, and biocompatible features. In this study, biocomposites based on bacterial cellulose and chitosan membranes tailored with antimicrobial loaded poly(N-isopropylacrylamide)/polyvinyl alcohol nanoparticles were prepared. Core-shell polymeric nanoparticles, bacterial cellulose/chitosan membranes, and biocomposites were independently loaded with silver sulfadiazine, a well-known sulfonamide antibacterial agent used in the therapy of mild-to-moderate infections for sensitive organisms. The chemistry, structure, morphology, and size distribution were investigated by Fourier transformed infrared spectroscopy (FTIR-ATR), RAMAN spectroscopy, Scanning electron (SEM) and Transmission electron microscopy (TEM), and Dynamic light scattering (DLS). In vitro release behaviors of silver sulfadiazine from polymeric nanoparticles and biocomposites were investigated. The biological investigations revealed good biocompatibility of both the nanoparticles and the biocomposites in terms of human dermal fibroblasts viability and proliferation potential. Finally, the drug-loaded polymeric biomaterials showed promising characteristics, proving their high potential as an alternative support to develop a biocompatible and antibacterial wound dressing.     

Controlled Release of Chitosan and Sericin from the Microspheres-Embedded Wound Dressing for the Prolonged Anti-microbial and Wound Healing Efficacy

One approach in wound dressing development is to incorporate active molecules or drugs in the dressing. In order to reduce the frequency of dressing changes as well as to prolong wound healing efficacy, wound dressings that can sustain the release of the active molecules should be developed. In our previous work, we developed chitosan/sericin (CH/SS) microspheres that released sericin in a controlled rate. However, the difficulty of applying the microspheres that easily diffuse and quickly degrade onto the wound was its limitations. In this study, we aimed to develop wound dressing materials which are easier to apply and to provide extended release of sericin. Different amounts of CH/SS microspheres were embedded into various compositions of polyvinyl alcohol/gelatin (PVA/G) scaffolds and fabricated using freeze-drying and glutaraldehyde crosslinking techniques. The obtained CH/SS microspheres-embedded scaffolds with appropriate design and formulation were introduced as a wound dressing material. Sericin was released from the microspheres and the scaffolds in a sustained manner. Furthermore, an optimized formation of the microspheres-embedded scaffolds (2PVA2G+2CHSS) was shown to possess an effective antimicrobial activity against both gram-positive and gram-negative bacteria. These microspheres-embedded scaffolds were not toxic to L929 mouse fibroblast cells, and they did not irritate the tissue when applied to the wound. Finally, probably by the sustained release of sericin, these microspheres-embedded scaffolds could promote wound healing as well as or slightly better than a clinically used wound dressing (Allevyn®) in a mouse model. The antimicrobial CH/SS microspheres-embedded PVA/G scaffolds with sustained release of sericin would appear to be a promising candidate for wound dressing application.     

Delivery of Therapeutics from Layer-by-Layer Electrospun Nanofiber Matrix for Wound Healing: An Update

Increasing incidences of chronic wounds urge the development of effective therapeutic wound treatment. As the conventional wound dressings are found not to comply with all the requirements of an ideal wound dressing, the development of alternative and effective dressings is demanded. Over the past few years, electrospun nanofiber has been recognized as a better system for wound dressing and hence has been studied extensively. Most of the electrospun nanofiber dressings were fabricated as single-layer structure mats. However, this design is less favorable for the effective healing of wounds mainly due to its burst release effect. To address this problem and to simulate the organized skin layer's structure and function, a multilayer structure of wound dressing had been proposed. This design enables a sustained release of the therapeutic agent(s), and more resembles the natural skin extracellular matrix. Multilayer structure is also referred to layer-by-layer (LbL), which has been established as an innovative method of drug incorporation and delivery, combines a high surface area of electrospun nanofibers with the multilayer structure mat. This review focuses on LbL multilayer electrospun nanofiber as a superior strategy in designing an optimal wound dressing.     

Preparation and properties of a pH sensitive carrier based on three kinds of polymer blend to control the release of 5-amino salicylic acid

Abstract

Context: High concentration of 5-amino salicylic acid (5-ASA) in the distal ileum and colon is necessary for the treatment of inflammatory bowel disease (IBD). The control of small molecules, drugs, released from a polymeric matrix remains a great challenge.

Objective: To study the preparation and properties of a pH-sensitive carrier for targeting delivery of 5-ASA.

Materials and methods: The carrier was prepared by ternary blends method based on polyvinyl alcohol (PVA), sodium alginate (SA) and polylactic acid. It was characterized by infrared spectrometry and scanning electronic microscopy. The adsorption and release of 5-ASA in different pH media were investigated.

Results: We found out the best ratio of the materials for synthetic carrier. The vector exhibited good performance by the controlled release of the target drug experiment. The adsorption capacity of the carrier for 5-ASA was 70.34% in phosphate buffer saline at pH 1.00, and the release rate was 100.49% in phosphate buffer solution at pH 6.80.

Discussion and conclusion: PVA is vector backbone of the carrier, and SA plays key role in its pH performance. It is a promising material to effectively deliver 5-ASA to the specific sites of IBD.     

Novel chitosan wound dressing loaded with minocycline for the treatment of severe burn wounds

Novel wound dressings composed of chitosan (CH) film and minocycline hydrochloride (MH) were prepared using commercial polyurethane film (Tegaderm) as a backing. CHs with deacetylation degrees of 67%, 83% and 96% (mol/mol), named CH67, CH83 and CH96, respectively, were used. Wound dressing with a large piece of Tegaderm film (4 cm × 4 cm), named CH-MH-N, and wound dressing prepared by cutting CH-MH-N to the wound size, named CH-MH-A, were developed. As CH67-MH-N and CH83-MH-N showed the sustained release of minocycline in vitro, CH67 and CH83 were used as chitosan in the in vivo studies. Various formulations were applied to severe burn wounds in rats in the early stage, and the wound status and change in the wound surface area were examined. The use of 10 mg of MH and complete sealing with Tegaderm had a negative effect. MH ointment was not effective, but Geben cream was fairly effective. However, CH83-MH-A containing 2 mg of MH (CH83-MH2-A) and CH83 film showed an excellent effect. Considering the elimination of pus, CH83-MH2-A tended to be better than CH83 film. CH83-MH2-A is suggested as a useful formulation for the treatment of severe burn wounds.