丝胶蛋白的结构、性能及生物医学应用

丝胶蛋白来源于天然蚕茧,具有良好的生物相容性和一系列独特的生物学性能,是一种性能卓越的天然生物材料。丝胶蛋白特有的氨基酸组成和结构性质赋予了其良好的水溶性、促细胞黏附和增殖活性、原位荧光性、抗氧化活性以及酪氨酸酶抑制活性等。在交联剂、化学活性基团和紫外光等作用下,丝胶蛋白能交联形成微纳米结构材料、二维(图案化)膜材料、水凝胶或三维多孔支架,在创伤修复、组织再生、药物传递、生物医药和材料涂层等生物医学领域显示出广阔的应用前景。本文基于丝胶蛋白近年来重要的研究成果,综述了丝胶蛋白的结构和理化性质,重点讨论了丝胶蛋白材料的设计方法及其在生物医学中的最新应用,并对丝胶蛋白的发展趋势进行了展望。     

丝胶基半互穿温敏凝胶的合成及其溶胀行为的研究

采用半互穿网络技术, 将具有生物相容性的丝胶蛋白(silk sericin)作为第二网络进入聚(N-异丙基丙烯酰胺)(PNIPAM)水凝胶网络中, 在水溶液中制备得到具有半互穿网络结构的丝胶基温敏水凝胶(SS/PNIPAM semi-IPNs). 采用称重法研究了产物的(消)溶胀、温度敏感性、最大溶胀度及脉冲响应行为; 利用扫描电镜(SEM), 差示扫描量热仪(DSC)和动态热机械分析仪(DMA)分别考察了产物的内部形态、热相转变行为和其储能模量随温度的变化. 结果表明: 具有较高亲水性的丝胶蛋白的引入增大了semi-IPNs水凝胶的内部孔径, 导致SS/PNIPAM半互穿水凝胶的溶胀度增加, 并且其储能模量随温度变化更明显. 相比于纯PNIPAM水凝胶, 半互穿水凝胶的消溶胀速率和低临界溶解温度(LCST)变化不大.     

纺丝条件及纺丝液组成对丝素-丝胶蛋白同轴干纺纤维的影响

为了模仿家蚕的纺丝工艺及天然蚕丝的组成和皮芯结构,利用同轴干法纺丝技术制备了以再生丝素蛋白（RSF）为芯层、丝胶蛋白（SS）为皮层的RSF-SS纤维。研究了卷绕速率及芯层纺丝液中RSF质量分数对纤维形貌、2级结构及力学性能的影响。结果表明：复合纤维具有明显的皮芯结构;相对于RSF的质量分数,卷绕速率对纤维结构和性能的影...     

桑蚕丝腺体和丝纤维中金属离子的含量

用不同的测试方法, 即质子诱导X射线发射(PIXE)、电感耦合等离子体质谱(ICP-MS)和原子吸收光谱(AAS)对桑蚕丝腺体和丝纤维中金属元素的含量进行了详细的表征. 结果表明, 在桑蚕丝腺体和丝纤维中含有钠、镁、钾、钙、铜、锌、铁、锰八种金属元素, 同时还可能含有微量的铷和锶. 这些金属元素在丝腺体和各种丝纤维(蚕茧丝、强拉丝和脱胶丝)中的含量都有所变化, 而这些变化可能与之在成丝过程(丝蛋白的构象转变过程)中所起的作用有关.     

快速pH响应丝胶/聚甲基丙烯酸互穿网络水凝胶的合成及表征

采用同步互穿网络方法制备丝胶蛋白(SS)/聚甲基丙烯酸(PMAA)为组分的互穿网络(IPN)水凝胶. 研究了互穿网络水凝胶对介质pH的刺激响应性能. 结果表明, IPN水凝胶具有强烈的pH刺激响应性能. 在pH=9.2的缓冲溶液中, -COOH解离成 -COO^-, 渗透压与网络之间的静电排斥作用导致IPN的溶胀度增大; 当pH减小时, 溶胀度随之减小. IPN水凝胶具有快速退溶胀速率及可逆溶胀-收缩性能.     

醋酸乙烯酯-丝胶可降解接枝共聚物的合成及性能研究

随着工业技术的发展 ,合成材料用途不断扩大 ,产量不断增加 ,相应废弃物也日益增多 ,其中多为非降解物 [1～ 3] .为了保护环境及可持续发展 ,许多国家正广泛探索合成降解材料的新技术、新方法和新工艺[3,4 ] .目前 ,共聚物降解材料的研究和应用主要是以淀粉、纤维素和木质素等天然植物及以甲壳素等动物体为基质的降解材料[5～ 7] ,而对蛋白质分子的接枝共聚物降解性研究甚少 .丝胶蛋白质(Sericin,简称 Ser)是一种天然的蛋白质资源 ,是生丝生产过程中的副产物 ,由于回收技术及成本限制 ,一些中小企业还是将丝胶蛋白质随工业废水一起被排放至…     

类牙釉状丝胶蛋白/羟基磷灰石复合材料的合成及表征

采用化学沉淀法合成了丝胶蛋白(SS)/羟基磷灰石(HAP)复合材料, 并研究了矿化时间对复合材料的影响. X射线衍射(XRD)、傅里叶变换红外光谱(FTIR)、透射电镜(TEM/HRTEM)和扫描电镜(SEM)表征结果表明: 在较短的矿化时间内, 合成的SS/HAP为直径约20 nm的复合颗粒; 随着矿化时间的延长, 这些复合颗粒能够沿轴方向组装并融合成类牙釉结构的较大晶体. 文章讨论了其可能的组装机制.     

反相高效液相色谱定量分析苄丝肼

苄丝肼(Benserazide)与左旋多巴合用治疗巴金森综合症。我所实验药厂在生产苄丝肼过程中发现该药物性质不够稳定,生 苄丝肼产品中可能含有的成分为:     

从天然动物丝到丝蛋白基材料的研究

作为具有优异综合力学性能的天然蛋白质纤维,丰产的动物丝特别是蚕丝长期伴随着人们的日常生活,近十余年来,各种具有特色的功能性丝蛋白基材料更是层出不穷.但在探索动物丝和丝蛋白基材料的过程中,动物丝纤维是经由蚕或蜘蛛等动物的纺器而纺制得到的简单事实往往被忽视;换言之,动物丝实际上是动物对丝蛋白进行体内“加工”后的产物,也是丝蛋白基材料中的一种.因此,天然动物丝中独特的各等级间构效关系与丝蛋白基材料的构效关系之间并不存在着必然的传承效应.本文着重介绍了我们在对动物丝和丝蛋白基材料探索中的经验和体会,即在强调以丝蛋白分子链结构与性能及其之间的关系为研究重点的基础上,从比较和发掘各种天然动物丝的特性入手,进而了解丝蛋白分子链在本体和溶液中的行为,并通过对动物丝蛋白分子链聚集态结构的调控,以达到设计制备一系列多形貌和多功能的动物丝蛋白基材料的目的.     

纳米银的绿色合成: 丝胶蛋白作为还原剂和分散剂

利用基于天然生物高分子的绿色环保法制备纳米贵金属材料是当今纳米技术发展的一个重要方向之一. 利用丝胶蛋白(SS)为还原剂和分散剂合成了纳米银颗粒, 利用紫外-可见(UV-Vis)光谱、X射线衍射(XRD)、透射电镜(TEM)等研究了反应温度、pH值、SS/Ag^＋物质的量比对反应速率和合成的纳米银粒子形貌的影响. 实验结果表明, 利用本方法可以合成尺寸均匀且分散性良好的球形纳米银粒子, 且随着反应温度和溶液pH值的逐渐升高, 反应速率随之加快, 合成的纳米银粒子的粒径逐渐变小, 而SS/Ag^＋物质的量比的变化主要对纳米银粒子的尺寸有影响.     

蚕丝丝素纤维中氨基酸在丝素纤维的径向分布研究

通过显微镜观察、红外光谱、氨基酸组成分析、福林试剂分析等方法研究蚕丝丝素纤维的微结构、丝素表层和内层的结构差异 ,研究氨基酸尤其是对丝素纤维的结构和性能起重要影响的主要芳香族氨基酸———酪氨酸在丝素由表及里各层中的含量和分布 ,以期最终揭示丝素结构与蚕丝织物应用中的固有缺陷 (如泛黄、易皱、色牢度等 )的关系 .结果表明蚕丝丝素存在多层次结构 ,表层无定形区的比例较高 ,里层结晶区的比例较高 ;侧基较大的氨基酸和赖氨酸、组氨酸、胱氨酸、精氨酸、天门冬氨酸、苯丙氨酸、亮氨酸、谷氨酸、酪氨酸等在丝素的表层分布相对较多 ,而乙氨酸、丙氨酸、丝氨酸等小侧基氨基酸则在中间层至里层较多     

Characterization of amino acids in silk sericin protein from Gonometa rufobrunnae by MEKC with phenyl isothiocyanate derivatization

An MEKC method was developed for the separation and characterization of phenyl-isothiocyanate (PITC)-labeled amino acids derived from Gonometa rufobrunnae silkworm after microdialysis sample cleanup. The influence of the buffer and SDS concentration on the resolution of the amino acids was investigated. A buffer system consisting of 25 mM phosphate, 10 mM borate buffer at pH 9.00, and 70 mM SDS showed the best results, with 13 PITC-amino acid derivatives being resolved out of 15 possible amino acids that were under study. Microdialysis sampling demonstrated its efficiency as a sample cleanup technique. Sericin protein from G. rufobrunnae was found to be characterized by at least 11 positively identified amino acids. These included His, Tyr, Ser, Ala, Phe, Lys, Gly, Arg, Cys, Glu, and Asp. Leu/Met and Val/Thr were coeluting pairs and hence could not be positively confirmed.     

丝胶接枝水性聚氨酯乳液对天然乳胶的改性研究

利用丝胶优良的生物相容性、抗氧化性等特点,结合水性聚氨酯优良的机械性能,合成了丝胶接枝水性聚氨酯乳液(1)。采用杂凝聚技术用1改善天然乳胶手套的机械性能和过敏性。结果表明,经1改性后的天然乳胶手套在断裂伸长率基本不变的情况下,断裂强度有了明显的提高;杂凝聚方法形成的核壳结构使丝胶包裹在手套的内表面,达到了改善过敏性的目的。     

Silk protein production by the immobilized silk gland

The posterior silk glands of the silkworm, (itBombyx mori,) were immobilized in acrylamide gel. This immobilized organ produced silk protein in the presence of amino acids and energy sources. Amino acids began to be incorporated into the immobilized silk glands 2.5 h after incubation, and the incorporation continued for more than 20 h. The apparent lifetime of the posterior silk gland was remarkably elongated by the immobilization.     

阳离子染料在真丝绸上的光褪色机理

用电化学循环伏安法研究真丝绸上染料的光褪色，发现真丝绸中的某些氨基酸和染料、氧分子３者间可以形成电荷转移复合物。这些三元电荷转移复合物的还原电位比染料本身的还原电位明显正移。用的光照射，证明是真丝绸中的氨基酸加速了阳离子染料的光褪色。     

Structural changes of silk fibroin membranes induced by immersion in methanol aqueous solutions

Structural changes of native and regenerated silk fibroin membranes were induced by immersion in water-methanol solutions and examined as a function of immersion time and methanol concentration. X-ray diffractometry and infrared spectroscopy data showed that transition from random coil to β-sheet structure occurred favorably when both native and regenerated silk fibroin membranes were immersed in water-methanol solutions, regardless of the different immersion time. Only native silk membrane, treated for 2 min with pure methanol, maintained its original amorphous structure, as demonstrated by differential scanning calorimetric (DSC) curves. The degree of displacement, measured by thermomechanical analysis (TMA), was much greater for regenerated than for native silk fibroin membranes. SDS-PAGE pattern showed that native silk fibroin has a molecular weight of 350, while the regenerated sample is formed by a large number of polypeptides in the range of 200-50 KD. The amount of acidic and basic amino acids decreased slightly in regenerated silk fibroin. Physical properties of silk membranes treated with water-methanol solutions are discussed in terms of membrane structure, treatment conditions, and chemical structure of starting material. © 1994 John Wiley & Sons, Inc.     

Amino Acid Profile and Biological Properties of Silk Cocoon as Affected by Water and Enzyme Extraction

We compared the efficacy for protein extraction of water versus enzymatic extraction. The amino-acid composition, inhibitory activity against enzymes α-amylase and α-glucosidase, and anti-glycation activities of silk protein extract (SPE) were determined. We used water extraction (100 °C, six hours) and protease-enzymatic extraction. The microstructure of silk fibers was obviously different after extraction. The results showed that enzymatic extraction gave the greater values of protein content, amino acids, total phenolic content (TPC), and total flavonoid content (TFC), as well as all biological activities parameters tested, but it also provided a more bitter taste in the extract—contributing amino acids of 51% (arginine, phenylalanine, histidine, valine, tryptophan, isoleucine, and leucine) and less sweet and umami taste contributing amino acids than did water extraction, which could be more suitable to be used as concentrated nutraceuticals.     

Changes in Amino Acid Profiles and Bioactive Compounds of Thai Silk Cocoons as Affected by Water Extraction

Silk proteins have many advantageous components including proteins and pigments. The proteins—sericin and fibroin—have been widely studied for medical applications due to their good physiochemical properties and biological activities. Various strains of cocoon display different compositions such as amino-acid profiles and levels of antioxidant activity. Therefore, the objectives of this study were to find a suitable silk protein extraction method to obtain products with chemical and biological properties suitable as functional foods in two strains of Bombyx mori silk cocoon (Nangsew strains; yellow cocoon) and Samia ricini silk cocoon (Eri strains; white cocoon) extracted by water at 100 °C for 2, 4, 6 and 8 h. The results showed that Nangsew strains extracted for 6 h contained the highest amounts of protein, amino acids, total phenolics (TPC) and total flavonoids (TFC), plus DPPH radical-scavenging activity, ABTS radical scavenging capacity, and ferric reducing antioxidant power (FRAP), anti-glycation, α-amylase and α-glucosidase inhibition. The longer extraction time produced higher concentrations of amino acids, contributing to sweet and umami tastes in both silk strains. It seemed that the bitterness decreased as the extraction time increased, resulting in improvements in the sweetness and umami of silk-protein extracts.     

Spinnenseide in der plastischen Chirurgie. Wunderwerkstoff der Natur

The experimental data show that the production of artificial nerve grafts with spider silk is a potential alternative therapy. The biologically favourable properties of the fibres from the spider Nephila clavipes should be used in human nerve reconstruction. The biological fibres promote the proliferation of cells. They are immunologically tolerated and not rejected. The muscle attraction line is kept intact which prevents muscle degeneration to a large extent. The spider fibres accelerate the migration of peripheral schwann cells into the nerve construct and promote the alignment of the nerve cells. For surgical interventions the biomechanical stability of spider silk and the composition from essential amino acids make the spider silk fibres interesting as a matrix for the cellular regeneration and in particular as a guiding structure for nerve regeneration.     

Determining secondary structure in spider dragline silk by carbon-carbon correlation solid-state NMR spectroscopy

Two-dimensional (2D) (13)C-(13)C NMR correlation spectra were collected on (13)C-enriched dragline silk fibers produced from Nephila clavipes spiders. The 2D NMR spectra were acquired under fast magic-angle spinning (MAS) and dipolar-assisted rotational resonance (DARR) recoupling to enhance magnetization transfer between (13)C spins. Spectra obtained with short (150 ms) recoupling periods were utilized to extract distinct chemical shifts for all carbon resonances of each labeled amino acid in the silk spectra, resulting in a complete resonance assignment. The NMR results presented here permit extraction of the precise chemical shift of the carbonyl environment for each (13)C-labeled amino acid in spider silk for the first time. Spectra collected with longer recoupling periods (1 s) were implemented to detect intermolecular magnetization exchange between neighboring amino acids. This information is used to ascribe NMR resonances to the specific repetitive amino acid motifs prevalent in spider silk proteins. These results indicate that glycine and alanine are both present in two distinct structural environments: a disordered 3(1)-helical conformation and an ordered beta-sheet structure. The former can be ascribed to the Gly-Gly-Ala motif while the latter is assigned to the poly(Ala) and poly(Gly-Ala) domains.