Evaluation of sericin/collagen membranes as prospective wound dressing biomaterial

Sericin, a silk protein, has high potential for use in biomedical applications. In this study, wound dressing membranes of Sericin (S) and Collagen (C) were prepared by glutaraldehyde cross-linking at S/C; 2:1, 1:1, 1:2, and 0:1 weight ratios. They were stable in water for 4 weeks. However, increasing the proportion of sericin had decreasing effect on the membrane stability. Water swelling property of membranes was enhanced with sericin. The highest water swelling was obtained in 1:1 group (9.06 g/g), but increasing collagen or sericin content in the membranes had a diminishing effect. Highest water vapor transmission rate was obtained with 1:2 group (1013.80 g/m²/day). Oxygen permeability results showed that 1:2 (7.67 mg/L) and 2:1 (7.85 mg/L) S/C groups were better than the other groups. While sericin decreased the tensile strength and elongation of membranes, it increased modulus. Sericin also increased brittleness of membranes, but their UTS range (24.93–44.92 MPa) was still suitable for a wound dressing. Membranes were not penetrable to microorganisms. Cytotoxicity studies showed that fibroblasts and keratinocytes attached and gained their characteristic morphologies. They also proliferated on membranes significantly. After 1 week of subcutaneous implantation, a fibrous capsule formed around all membranes with an acute inflammation. Sericin containing membranes showed signs of degradation (at 2nd week), while collagen only membranes remained largely intact. Eventually, sericin containing membranes degraded in 3 weeks with moderate inflammatory response. Overall results suggest that sericin/collagen membranes would be favorable as wound dressing material when sericin ratio is less than or equal to the collagen component.     

创面敷料用壳聚糖基静电纺纳米纤维膜

壳聚糖具有良好的抗菌性和生物可降解性,壳聚糖纳米纤维在生物医用领域,如创面敷料领域,具有潜在的应用。以质量分数50%乙酸作为溶剂,在助纺剂聚氧化乙烯(PEO)质量分数为10%~50%的条件下,成功制备了壳聚糖基静电纺纳米纤维,其平均直径低至136 nm。采用扫描电子显微镜(SEM)和红外光谱(FT-IR)对纤维的形貌和组成进行了表征。     

医用壳聚糖敷料研究进展

介绍了壳聚糖的生物学特性以及在伤口愈合中的作用。阐述了改进壳聚糖性能的化学、物理方法以及多种形状医用壳聚糖敷料、载药类壳聚糖敷料和医用壳聚糖衍生物敷料的研究进展。     

壳聚糖非织造布的制备及壳聚糖非织造医用敷料的研究进展

阐述了壳聚糖纤维和壳聚糖非织造布的制备方法,其中用水刺法加工的壳聚糖非织造布最适合用作医用敷料。介绍了壳聚糖非织造医用敷料的优良性能及国内外的研究现状,指出壳聚糖非织造布在医用敷料方面有着广阔的市场前景。     

丝素基伤口敷料研究进展

目前丝素基伤口敷料的研究主要集中于应用静电纺技术制备含功能性物质的理想伤口敷料。添加纳米金属和抗生素等功能成分虽可增强敷料的抗菌性,却引发了细胞毒性与抗药性,威胁生物体安全。基于此,从创造微湿伤口环境、增强抗菌性能、支持细胞生长和刺激伤口愈合4个方面,综述了近年来国内外通过新型技术、复合多组分材料和功能成分制备丝素基伤口敷料的研究进展;展望了以多组分天然材料为基材,利用新技术制备添加天然抗菌药物敷料的广阔前景,以期为丝素基伤口敷料的临床应用研究提供有益参考。     

海藻酸钙医用敷料与普通棉纱布的性能比较

对海藻酸钙非织造布和机织棉纱布的性能作了分析比较,测试了2种材料在A溶液中的吸湿性、扩散性、透湿性等性能。结果显示,由于2种材料的化学结构和物理结构不同,其性能也有很大的变化,根据它们所具有的性能可被应用于不同种类的伤口。海藻酸钙非织造布的高吸湿性和可阻止液体扩散的性能使它适合用于流血、流脓较多的慢性伤口,而普通棉纱布更适合用于吸收手术过程中产生的血液。     

Physicochemical and blood compatibility characteristics of garlic incorporated polyurethane nanofibrous scaffold for wound dressing applications

Novel nanocomposite membrane based on polyurethane incorporated with garlic was fabricated using electrospinning technique for wound healing applications. Morphological analysis indicated that the incorporation of garlic into the polyurethane (PU) matrix resulted in reduction of fiber diameter and pore size compared to the pristine PU. Infrared analysis revealed the possible interaction of garlic with the PU through hydrogen bond formation. The contact angle studies and roughness measurements revealed the improved wettability and increased surface roughness of the fabricated composite compared to the pristine PU. The blood compatibility assay revealed the faster blood clotting time for the fabricated nanocomposites than the pristine PU. Furthermore, the fabricated nanocomposites showed less hemolytic index compared to the pristine PU suggesting their safety to red blood cells. Hence, with those advanced qualities PU blended with grapes may serve as a valuable candidate for wound dressing applications.     

海藻纤维针刺复合医用敷料吸湿透气性能的研究

采用海藻纤维、黏胶纤维、涤纶的纤网,通过针刺工艺制备一种新型复合医用敷料。研究不同海藻纤维含量、不同纤网结构的复合医用敷料对液体的吸收性、扩散性以及透湿性和透气性的影响。结果表明:随着海藻纤维含量的增加,复合敷料的吸液量、透湿量及透气性有所提高,防止液体扩散的性能也有所提高;杂乱排列的纤网结构相对于平行排列的纤网结构,吸湿和透气性能都明显提高。     

Evaluation of a functional food preparation based on chitosan as a meal replacement diet

The ability of chitosan to entrap large amounts of water when dispersed in an oily phase was utilized to formulate a novel meal replacement functional food. Furthermore, the proposed preparation can be fortified with nutrients. The purpose of this formulation was to produce an edible low calorie pseudo-fatty rich meal that can enhance the feeling of satiety when ingested. Different concentrations of chitosan and pectin were tested to find out a stable preparation with acceptable physical characteristics. It was found that a preparation containing 1% chitosan and 6% pectin is suitable to be consumed as a meal replacement diet. The safety of such preparation was assessed by repeated dose administration to rats. A set of other in vivo experiments was performed to assess the ability of this preparation to enhance satiety. The ingestion of chitosan preparation resulted in reduced body weight, food and water intake, and reduced faecal excretion in the emulsion administered rats (p < 0.05). Furthermore, serum lipids of tested rats were not essentially changed. Accordingly, the investigated chitosan emulsion could be introduced as a low calorie, relatively stable and a safe functional food preparation for enhancing satiety when ingested as a meal replacement diet.     

Preparation of tofu using chitosan as a coagulant for improved shelf-life

The potential of chitosan as a coagulant in commercial tofu preparation was investigated with six chitosans of different molecular weights using various treatments. The following optimum processing conditions for tofu preparation were proposed: chitosan with a molecular weight of 28 kDa; chitosan solution type, 1% chitosan/1% acetic acid; chitosan solution to soymilk ratio, 1 : 8; coagulation temperature, 80 °C; coagulation time, 15 min. However, the sensory quality of tofu was notably improved using a 1 : 1 mixture of 1% acetic acid and 1% lactic acid instead of 1% acetic acid alone as a chitosan solvent. Tofu prepared with chitosan had lower ash and higher protein content than those of commercial products tested. In storage tests, the chitosan‐tofu had a longer shelf‐life, about 3 days, than tofu made with CaCl₂. This added shelf‐life is significant in view of the magnitude (366 000 tonnes year^?1) of tofu produced from commercial tofu plants (1407 plants as of 1998) in Korea.     

Cottage cheese whey as an ingredient of cottage cheese dressing mixes

The objective of this study was to formulate and develop a good quality cottage cheese dressing using acid whey as the main ingredient. Up to 72% of cottage cheese whey was used in the dressing mixes. The percentage of fat (4.10–5.05%) and total solids (19.41–20.24%) approached the desired level and was within the legal limits for regular cottage cheese. Sensory evaluation scores for flavour, body/texture and appearance were not adversely affected by the use of acid whey. The sensory evaluation scores for all four products made with whey- or skimmed milk-based dressings were higher than the commercial control.     

Prototyping and analyzing physical properties of Weft knitted spacer fabrics as a substitute for wound dressings

In this research, the required physical properties of weft knitted spacer fabrics, as an alternative for wound dressings have been investigated. For this purpose, weft knitted spacer fabrics with five different fabric structures have been produced on the electronic flat knitting machine. Moreover, in order to compare the properties of the produced fabrics with available wound dressings in the market, two kinds of wound dressing have been prepared from the market. Then, the physical properties of the spacer fabrics and the wound dressings such as air permeability, water vapor permeability, thermal conductivity, compressibility and absorbency have been measured and compared. The results show that in weft knitted spacer fabrics with the same fabric structure of the outer layer and different inclination angle (the angle formed between the outer layer and the spacer yarn), by decreasing the inclination angle, the fabric air permeability, water vapor permeability and absorbency decrease and the thermal conductivity and compressibility increase. Moreover, the use of tuck stitches in the outer layer of the spacer fabric leads to an increase of air permeability, water vapor permeability, absorbency and thermal conductivity and decrease of compressibility. The wound dressings also exhibit less air permeability and compressibility than weft knitted spacer fabrics. On the other hand, they possess higher water vapor permeability and absorbency. According to the results, among the examined weft knitted spacer fabrics in this research, the fabric with the tuck stitches in the outer layer is specified as the most appropriate alternative for wound dressing, in case of wounds with low exudates.     

Introduction of primary antioxidant activity to chitosan for application as a multifunctional food packaging material

The objective of this study was to improve functionality of chitosan films by introducing the primary antioxidant property to chitosan molecule. Grafting of gallic acid (GA) on chitosan was most efficient when chitosan, GA, carbodiimide, and N-hydroxysuccinimide were used in the ratio 2·10⁻⁴:1:0.05:0.05. There was no significant difference in grafting efficiency when the reaction lasted 6 or 24 h. Chitosan with 80% degree of deacetylation (DDA) was efficiently grafted and increase in DDA did not improve grafting. Non-grafted, native chitosan had insignificant 2,2-diphenyl-1-picrylhydrazyl (DPPH) scavenging ability (9.4%) and no reducing power. The GA-grafted chitosan had 34.26 mg GA/g, DPPH scavenging ability of 89.5%, reducing power of A₇₀₀ = 0.51, and was soluble in aqueous acetic acid. During storage of ground peanuts under stress conditions (50 °C, 20–30% RH), both chitosan and GA-chitosan pouches provided significant reduction in oxidation reactions. Furthermore, the GA-grafted chitosan reduced level of thiobarbituric acid reactive substances (TBARS), peroxide, and conjugated trienes formation as compared to polyethylene bags. GA-grafted chitosan shows promise as a candidate for multifunctional food packaging material.     

Properties of wheat starch film-forming dispersions and films as affected by chitosan addition

In order to evaluate the impact of chitosan on the physical properties of wheat starch–glycerol films, part of the wheat starch was replaced by chitosan, and the effect of composition on the properties of both the films and the film-forming dispersions was studied. The latter became more stable and viscous as the chitosan proportion was increased in the mixture. Both polymers appeared to integrate homogeneously in the film matrix. The combined effect of the glycerol and chitosan proportions affected the mechanical and barrier properties of the films. The tensile strength and elastic modulus of the films were improved as chitosan ratio increased. The oxygen and water vapor permeability slightly increased in line with the amount of chitosan in the blend although the induced differences were very small. Chitosan ratio directly affected the antimicrobial properties of the films, which showed a significant bactericide activity when the chitosan–starch ratio in the film was 50%. Nevertheless, at a starch:chitosan ratio of 80:20, counts of coliforms did not exceed the initial value in the meat after 7 storage days.     

Wine grape pomace as antioxidant dietary fibre for enhancing nutritional value and improving storability of yogurt and salad dressing

Wine grape pomace (WGP) as a source of antioxidant dietary fibre (ADF) was fortified in yogurt (Y), Italian (I) and Thousand Island (T) salad dressings. During the 3 weeks of storage at 4 °C, viscosity and pH of WGP-Y increased and decreased, respectively, but syneresis and lactic acid percentage of WGP-Y and pH of WGP-I and WGP-T were stable. Adding WGP resulted in 35–65% reduction of peroxide values in all samples. Dried whole pomace powder (WP) fortified products had dietary fibre content of 0.94–3.6% (w/w product), mainly insoluble fractions. Total phenolic content and DPPH radical scavenging activity were 958–1340 mg GAE/kg product and 710–936 mg AAE/kg product, respectively. The highest ADF was obtained in 3% WP-Y, 1% WP-I and 2% WP-T, while 1% WP-Y, 0.5% WP-I and 1% WP-T were mostly liked by consumers based on the sensory study. Study demonstrated that WGP may be used as a functional food ingredient for promoting human health and extending shelf-life of food products.     

Antimicrobial properties of chitosan and mode of action: a state of the art review

Owing to its high biodegradability, and nontoxicity and antimicrobial properties, chitosan is widely-used as an antimicrobial agent either alone or blended with other natural polymers. To broaden chitosan's antimicrobial applicability, comprehensive knowledge of its activity is necessary. The paper reviews the current trend of investigation on antimicrobial activities of chitosan and its mode of action. Chitosan-mediated inhibition is affected by several factors can be classified into four types as intrinsic, environmental, microorganism and physical state, according to their respective roles. In this review, different physical states are comparatively discussed. Mode of antimicrobial action is discussed in parts of the active compound (chitosan) and the target (microorganisms) collectively and independently in same complex. Finally, the general antimicrobial applications of chitosan and perspectives about future studies in this field are considered.     

Isolation and identification of spoilage microorganisms using food-based media combined with rDNA sequencing: Ranch dressing as a model food

Investigating microbial spoilage of food is hampered by the lack of suitable growth media and protocols to characterize the causative agents. Microbial spoilage of salad dressing is sporadic and relatively unpredictable, thus processors struggle to develop strategies to minimize or prevent spoilage of this product. The objectives of this study were to (i) induce and characterize spoilage events in ranch-style dressing as a model food, and (ii) isolate and identify the causative microorganisms using traditional and food-based media, coupled with rDNA sequence analysis. Ranch dressing (pH 4.4) was prepared and stored at 25 °C for 14 d and microbial populations were recovered on MRS agar and ranch dressing agar (RDA), a newly formulated food-based medium. When isolates suspected as the spoilage agents were inoculated into ranch dressing and held at 25 °C for 9–10 d, three unique spoilage events were characterized. Using rDNA sequence comparisons, spoilage organisms were identified as Lactobacillus brevis, Pediococcus acidilactici, and Torulaspora delbrueckii. P. acidilactici produced flat-sour spoilage, whereas Lb. brevis resulted in product acidification and moderate gas production. The RDA medium allowed for optimum recovery of the excessive gas-producing spoilage yeast, T. delbrueckii. The isolation and identification strategy utilized in this work should assist in the characterization of spoilage organisms in other food systems.     

Shelf-life of fresh noodles as affected by chitosan and its Maillard reaction products

The effects of Maillard reaction products (MRPs) prepared from chitosan and xylose on the shelf-life of fresh noodles were studied. A model system consisting of chitosan and xylose (1:1.5, w/w) dispersed in distilled water with pH values of 5, 6, 7, 9 was used. The systems were heated to 95 °C for up to 60 h. The development of brown color was more pronounced in the model system with a higher initial pH of the water. The antibacterial activity of chitosan increased at the beginning of the Maillard reaction, and the minimum inhibition concentration (MIC) of chitosan against Bacillus subtilis CCRC 10258 decreased to 50 μg/ml of medium from 250 μg as a result of the Maillard reaction. Gram-positive bacteria were more sensitive to chitosan or its MRPs than Gram-negative bacteria. MRP of chitosan/xylose showed a bactericidal effect against Bacillus subtilis CCRC 10258, while chitosan showed a bacteriostatic effect prior to the occurrence of the Maillard reaction. Addition of 0.05 g/100 ml chitosan (in 0.5 ml/100 ml acetic acid) to fresh noodle formulation resulted in an extension of its shelf-life for 6 more days when stored at 4 °C. However, addition of MRP resulted in the longer shelf-life lasting 14 days when stored at 4 °C.     

The occurrence of a Maillard-type protein-polysaccharide reaction between β-lactoglobulin and chitosan

Reaction mixtures containing β-lactoglobulin and chitosan (1:4 weight ratio) were dry-heated at 40 °C and 79% relative humidity for 2 weeks. Absorbance measurements and SDS-PAGE analysis indicated the occurrence of the Maillard reaction and conjugate formation, respectively. Some β-lactoglobulin and chitosan properties were modified. For example, the emulsifying capacity at pH 4 and bactericidal activity against Escherichia coli of the Maillard reaction products (MRPs) increased with incubation period up to 2 days, after which these properties deteriorated. The latter was explained by MRPs degradation, which was confirmed by the increased appearance of degradation products in electrophoresis gels at longer incubation times. Data show that the Maillard reaction, under the studied conditions, can be successfully employed to generate MRPs from β-lactoglobulin and chitosan, which exhibit improved properties with respect to β–lactoglobulin alone.     

Suitability of a colorimetric method for the selective determination of chitosan in dietary supplements

A colorimetric method previously described for the determination of chitosan has been evaluated because lack of linearity had been observed at certain concentrations. Calibration curves of varied-characteristic chitosans, recovery studies and chitosan quantification in seven commercial dietary supplements have been performed. Some analysis conditions including the solvent of the samples have been studied and optimised. Different data combinations have been checked in order to select the widest range of concentrations where no serial correlation was found. With the selected conditions the method is linear, reproducible and provides reliable results in the analysis of the chitosan content in capsules. Its selectivity has been proved by the lack of interference with other compounds present in the dietary supplements. But in the case of tablet products, the presence of cellulose and magnesium stearate may produce an underestimation of the chitosan content.