TGase催化丝胶-壳寡糖交联及其复合膜材料性能探究

为了改善再生丝胶蛋白材料的成型性与功能性,文章借助TGase酶和壳寡糖进行丝胶蛋白改性,探究了酶促反应中丝胶蛋白相对分子质量和体系中氨质量浓度的变化,分析了催化接枝壳寡糖对丝胶膜力学性能、成型性、抗氧化性和抗菌性能的影响。结果表明:TGase酶能催化丝胶接枝壳寡糖,酶促反应后丝胶相对分子质量增大,体系中氨质量浓度提高;与丝胶/壳寡糖的共混膜相比,酶促丝胶接枝壳寡糖后制备的风干膜机械性能增加,水相中溶失率降低,对大肠杆菌的抗菌性较好。高温高压法脱胶与碱法脱胶相比,以前者为原料制备的丝胶膜材料具有更好的应用性能。     

干燥温度对丝胶膜结构的影响

以茧层丝胶为原料,干燥温度作为主要条件制备丝胶膜,用X射线衍射、红外光谱、DTA差热分析等测试方法研究干燥温度对丝胶膜结构的影响。实验结果表明:在30~100℃温度范围内,干燥温度对丝胶蛋白质的聚集态结构有显著影响。30℃干燥后膜内的丝胶聚集态结构基本为无定形,随着干燥温度的提高,膜内丝胶蛋白聚集态结构的紧密度增大,80℃以上增加明显。40℃左右是丝胶蛋白发生显著变性的重要温度区域。     

丝胶蛋白材料的研究与应用进展

丝胶是一种球状蛋白,对于其结构的研究近年来多侧重在部分有机物对丝胶蛋白结构构象的影响上.丝胶的提取已逐渐从传统的方法向非催化高温水解法,膜过滤和酶水解法转变.丝胶蛋白作为一种生物相容性优良的天然高分子材料,具有独特的凝胶化性能,可用作药物缓释及酶固定化载体,其保湿性及抗氧化性还可在化妆品、纤维制品及医学领域开发利用.对于丝胶新材料的进一步开发,应整合多学科领域以期后续开发研究具有广阔的应用前景.     

丝胶蛋白基水凝胶膜的合成及性能研究

以丝胶蛋白为研究主体,与另一成膜组分聚甲基丙烯酸的单体按1∶1质量分数比合成丝胶蛋白基水凝胶膜,探讨交联剂种类、用量对丝胶蛋白基水凝胶膜性能的影响。试验结果表明,聚乙二醇二缩水甘油醚（PEGO）交联剂对丝胶蛋白基水凝胶膜的交联作用明显,改善了丝胶蛋白膜的物理性能;研制出的产品具有一定的柔韧性和pH刺激响应性。     

丝胶蛋白的细胞相容性和抗菌性能研究

研究了从茧壳、茧衣中提取丝胶蛋白(S1、S2)及茧壳丝胶进行酶解制备的小分子丝胶蛋白肽(S3)的细胞相容性,以及对革兰氏阴性菌、阳性菌的抗菌作用。结果表明:三种丝胶蛋白均"对细胞无毒性",并随丝胶浓度的增大对细胞生长有促进作用。采用细菌生长抑制试验定量测试了各梯度浓度下丝胶的抑菌率,结果显示丝胶具有显著的抑菌作用,对金黄色葡萄球菌和的大肠杆菌抑制率由大到小依次为S3、S1、S2和S2、S3、S1,丝胶浓度对抑菌性有一定影响。研究结果表明丝胶是一种具有良好抑菌性能的生物相容性材料。     

丝胶结构及其改性材料研究进展

丝胶蛋白原料非常丰富且性能优异,如今其在化妆品、食品、医药和生物材料等方面已展现出优良的开发潜能。文章阐述了丝胶蛋白的组成和前人对其结构的研究,介绍了蚕丝丝胶固着原理和丝胶固着工艺目前的进展;汇总了对天然丝胶蛋白、丝胶复合材料、丝胶改性材料和再生丝胶蛋白材料的生物性能的应用研究方面的进展,并提出了当前存在的问题及今后的研究方向,以期能进一步应用丝胶,将丝胶蛋白变废为宝,获得更好的社会效益和经济效益。     

TG酶添加方式对乳清浓缩蛋白-羟丙基甲基纤维素复合膜成膜性能的影响

为了研究转谷氨酰胺酶(TG)改性乳清浓缩蛋白(WPC)-羟丙基甲基纤维素(HPMC)混合膜的最佳成膜方式,文章在制备WPC-HPMC混合膜的不同阶段添加TG酶,研究复合膜和成膜溶液的成膜性能以及结构表征。将WPC与HPMC混合后添加TG酶交联,制备WPC-HPMC-TG膜。调整TG酶的添加方式,将TG酶与WPC交联后添加HPMC,制备WPC-TG-HPMC膜。SDS-PAGE结果证实TG酶可以促进蛋白质分子间发生交联,形成大分子聚合物。FTIR分析结果表明,TG酶交联乳清蛋白能够引起蛋白质二级结构发生改变。与WPC-HPMC-TG膜相比,WPC-TG-HPMC膜具有更好的机械性能和流变性能,这说明TG酶交联WPC的能力强于TG酶交联WPC-HPMC混合物。因此,TG酶合适的添加方式对改善WPC-HPMC混合膜的成膜特性具有积极的影响。     

硼酸改性丝胶聚乙烯醇膜的性能

将硼酸加入丝胶/聚乙烯醇的共混水溶液中,通过平板膜法制备薄膜材料。研究硼酸对丝胶/聚乙烯醇膜材料的力学性能和耐溶失性能的影响,利用红外光谱分析和差示扫描量热分析研究硼酸对材料的改性机制和热稳定性。结果发现:硼酸的加入提高了材料的抗张强度和耐溶失性,硼酸对丝胶蛋白在膜材料中有明显的固定作用,明显改善了材料的热稳定性;当丝胶与聚乙烯醇物质的量比为3∶7,硼酸用量为丝胶与聚乙烯醇总质量的0.4%时,所制备膜的综合性能相对较好。     

丝胶及其溶解性能探讨

用圆二色光谱和红外光谱研究丝胶结构,探讨乙醇浓度和处理时间对丝胶膜结构和溶解性能的影响。结果表明,绢丝腺丝胶分子构象以无规卷曲为主,有β结构存在,但无α螺旋结构。茧层丝胶分子构象也是以无规卷曲为主,有β结构存在,但还有少量α螺旋。用乙醇对丝胶膜进行浸泡处理后,丝胶分子构象有β化的趋势,并使丝胶膜热水溶失率明显下降。     

利用丝胶固着技术改善蚕丝被性能研究

为解决传统蚕丝被随时间推移易板结、需经常翻拆的缺陷,从蚕丝结构出发,提出了利用丝胶交联固着的方法提高丝胶湿热稳定性的蚕丝被生产工艺。选用戊二醛(GA)为固着剂,利用正交实验,探讨不同含胶率茧丝的最优固胶工艺。结果表明:不同含胶率的茧丝可选用相同的固胶工艺,茧丝固胶最优工艺为:GA质量分数0.1%、温度40℃、反应时间2 h。采用本工艺固胶茧层丝胶溶失率均小于3%,丝胶蛋白的湿热稳定性有显著提高。选择性能相对稳定的丝胶进行丝胶固着,可有效改善丝胶蛋白的稳定性,提高丝胶在蚕丝被中的利用率。     

Enzymatic crosslinking of silk sericin through combined use of TGase and the custom peptide

Abstract

Silk sericin (SS) is derived from natural Bombyx mori silk fibers, and it has the unique biological properties like good biocompatibility and low immunogenicity. However, pure SS material exhibits poor mechanical properties and high water solubility, which greatly reduces the formability of SS material and limits its wide range of applications. In this study, a transglutaminase (TGase) was combinedly used with two custom peptides of GQGEGQG (p-Q) and KKKK (p-K), containing exogenous glutamine and lysine residues, respectively, for facilitating the enzymatic crosslinking of sericin proteins. The efficacy of enzymatic incubation was assessed by the means of SDS-PAGE, size exclusion chromatography chromatogram, and determination of the quantitative changes in amino groups. Properties of the obtained SS membranes based on different treatments were also examined. The results revealed that incubating of SS with TGase and glutamine-containing peptide led to a noticeable increase in the molecular weight compared with others. TGase-mediated treatments had detectable impact on the conformational structures of SS, the obtained formability and mechanical property for the TGase/p-Q treated SS membrane were evidently improved compared to others. The suggestive alternative, based on the combination use of TGase and p-Q has the potential applications for preparation of the sericin-based biomaterials.     

GA固胶工艺对茧丝性能的影响

为提高丝胶的稳定性,论文采用戊二醛（GA）固胶技术,探讨GA固胶工艺对茧丝性能的影响。论文从固胶茧丝回潮率、白度、茧丝蛋白稳定性、力学性能及茧丝导热系数、红外光谱的测试和分析等方面研究茧丝的性能。结果表明,GA固胶有效地减小了水溶性,提高了茧丝的蛋白稳定性;固胶茧丝的公定回潮率有所下降,下降幅度在1%～4%;断裂强力、断裂伸长率均有所增加,初始模量有所下降;导热系数变化不大,仍能保持良好的保暖性;红外光谱特征吸收峰的一些特征峰的峰形、峰位、峰高稍有改变,某些特征峰的波数发生了位移,说明固胶后茧丝分子结构发生了一定程度的变化。     

静电纺再生加工对横纹金珠丝微观结构的影响

蜘蛛丝因其优异的力学性能和良好的生物相容性引起了学者的广泛关注。为此在研究横纹金珠丝在六氟异丙醇（HFIP）中溶解性能的基础上,采用静电纺丝的方法制备再生横纹金珠丝（框丝、卵袋内层丝、卵袋外层丝）,分析比较再生横纹金蛛丝和天然横纹金蛛丝在形态结构、分子构象、结晶结构以及热稳定性方面的差异。结果发现：静电纺再生框丝呈扁平带状,带宽为(751±196)nm,卵袋内层丝和卵袋外层丝直径分别为(141±46)nm和(105±37)nm。X衍射图谱和TG-DTA测定结果表明,静电纺再生加工后,横纹金珠丝结构由silkⅡ向silkⅠ转变、结晶度下降、主要热分解温度降低。     

ANTIOXIDANT ACTIVITIES OF SILK SERICIN FROM SILKWORM BOMBYX MORI

This study was conducted to investigate the free-radical-scavenging activity and antioxidant activity of silk sericin. Silk sericin was prepared from silkworm Bombyx mori and its ability to scavenge hydroxyl, superoxide and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radicals was determined by Electron Spin Resonance (ESR) and ultraviolet spectrophotometry, respectively. The antioxidant activities of the silk sericin, including lipid peroxidation in the linoleic acid system, reducing power and ferrous-ion-chelating ability, were evaluated. The results showed that silk sericin had a strong scavenging capacity for hydroxyl, superoxide and DPPH radicals. The results also showed that silk sericin had potent antioxidative activity on the peroxidation of linoleic acid. The reducing power and ferrous-ion-chelating ability of silk sericin were significant. These results indicated that silk sericin from silkworm B. mori was a natural antioxidant with potent antioxidative activity.

PRACTICAL APPLICATIONS

Most of silk sericin must be removed during raw silk production at the reeling mill and other stages of silk processing. At present, silk sericin is mostly discarded in silk processing waste water. If silk sericin is recovered and recycled, it can represent a significant economic and social benefit. Silk sericin is a natural macromolecular protein derived from the silkworm Bombyx mori . Silk sericin is useful because of its antioxidant activity. Silk sericin can be cross linked, copolymerized and blended with other macromolecular materials, especially artificial polymers, to produce materials with improved properties. The protein is also used as an improving reagent or a coating material for natural and artificial fibers, fabrics and articles. The materials modified with silk sericin and sericin composites are useful as degradable biomaterials, biomedical materials and functional membranes.     

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.     

聚丁二酸丁二醇酯/丝胶蛋白共混纤维的制备及其性能

为提高聚丁二酸丁二醇酯(PBS)纤维的服用舒适性,将PBS与天然高分子丝胶蛋白共混,经熔融纺丝制成PBS/丝胶蛋白共混纤维,研究了丝胶蛋白质量分数对纤维形态结构、化学结构、热性能、力学性能与降解性能的影响。结果表明：共混纤维具有丝胶蛋白为分散相,PBS为连续相的形态结构;丝胶蛋白的存在改善了PBS纤维断裂伸长率过高的问题,当其质量分数达到15%时,共混纤维的断裂伸长率为8.9%;共混纤维的饱和回潮率为3.90%,接近于合成纤维中的锦纶,说明共混纤维亲肤性能优良;此外,土埋降解实验6周后共混纤维的质量损失率可达53.6%,具有快速降解的能力。     

用稀土固着丝胶真丝纤维的性能研究

探讨了稀土固着丝纤维的固着机理,对固着丝纤维的溶解性、吸湿性和力学性能、表面形态进行了分析.结果表明,稀土金属与丝纤维形成配位键,丝素纤维的间隙充满了固着的丝胶,吸湿性增加,对力学性能的影响较小.     

Study of the physical properties of whey protein: sericin protein-blended edible films

Effects of the sericin protein on the physical properties of the whey protein isolate film including the mechanical strength, water vapor permeability, light transmission, moisture content, solubility and swelling were investigated in the present work. The mechanical strength of the whey protein film could be reinforced with 0.1% sericin caused by the hydrogen bonding between the sericin and whey protein molecules. Excess addition of the sericin promoted sericin self-aggregation which made the network microstructure of the film heterogeneous and therefore reduced its mechanical strength. The water vapor permeability of the film decreased with the sericin content; in contrast, the other physical properties of the film such as the moisture content, solubility, swelling, light transmission and transparency were not be significantly affected under the present experimental conditions.     

Inhibitory effect of sericin on polyphenol oxidase and its application as edible coating

Sericin, a water‐soluble globular protein derived from silk industry wastewater, was investigated for food industrial applications. The results proved that sericin retarded polyphenol oxidase (PPO) activity. However, the degree of inhibition varied depending on the enzyme origins, the types of substrate, sericin content and sericin molecular size. Using catechol as a substrate, under the conditions studied, sericin lowered purified mushroom PPO and apple extract PPO activity by 40% and mango extract PPO by 75%. Kinetic studies on purified mushroom PPO indicated that the type of inhibition of sericin was dependent on the substrates used. Inhibitory effects of sericin increased as the sericin content increased. The reduction in sericin molecular size by enzymatic hydrolysis produced sericin hydrolysate with ability to decrease PPO activity approximately three times greater than that of sericin. Fresh‐cut Red Delicious apples coated with sericin showed significant reduction in weight loss and improvement in the colour and texture.     

丝胶蛋白的氨基酸组成、结构及功能性质

实验旨在明确从废水中回收的丝胶蛋白的氨基酸组成、二级结构及功能性质,为其进一步开发应用提供参考。实验通过圆二色谱仪及傅立叶红外光谱仪探究丝胶蛋白的结构,利用紫外分光光度计及荧光探针等方法探究丝胶蛋白的溶解性、乳化性及表面疏水性等性质。结果表明:丝胶蛋白含有16种氨基酸,其中极性氨基酸占80.41%;丝胶蛋白二级结构以无规卷曲为主,占总量的41.6%,其次是β-折叠和β-转角,分别占30.5%和23.6%,α-螺旋仅占4.3%;丝胶蛋白溶解性优于大豆分离蛋白,还具有良好的乳化和起泡性及持油性。