丝素蛋白作为生物医用材料的研究

丝素蛋白作为生物医用材料,具有很好的生物相容性和很多优良的物理、化学性能。我们课题组,在1994年研制成的丝素创面保护膜的基础上,“九五”期间,在国家八六三计划新材料领域的支持下,对丝素蛋白作为生物医学材料的应用作了进一步的研究和产品开发,主要工作如下:1 丝素成膜设备的研制 该设备采用载带式低温热风分层干燥方法,用以生产丝素创面保护膜,亦能用以其他医用膜的研制、开发。该设备设计合     

丝素膜表面磺酸化研究

从蚕丝中提取丝素蛋白制备成纯丝素膜及PEGO丝素膜,首次采用硫酸处理,在丝素膜材料表面引入了磺酸基团;采用电子能谱和全反射红外光谱分析材料的表面性质,表明硫酸处理丝素膜,可以使PEGO丝素膜表面带上磺酸基团,以共价键的结合方式牢固地固定在表面.这将大大提高丝素膜的抗凝血性,防止细胞在丝素膜上的粘附.X射线衍射表明,丝素膜在硫酸处理后,其结晶度增加,特别是silk Ⅰ的结晶,但是,经硫酸处理后,丝素膜的断裂伸长率与强度有所下降.     

丝素/海藻酸钠膜韧性的优化及膜释药机理分析

首先在丝素(SF)溶液中添加既定浓度的海藻酸钠(SA)溶液和一定体积的75%甘油、50%戊二醛以及模型药物罗丹明B(4g/L),将均匀混合液以浇铸方法制备丝素/海藻酸钠(SF/SA)膜模型药物缓释敷料;然后利用响应曲面法筛选最佳韧性(以断裂伸长率表示)SF/SA膜的制备参数;最后对优化膜的韧性和药物释放动力学模型进行检验与分析。实验得出,在浓度为2.5%的丝素溶液中,添加等体积0.96%浓度的海藻酸钠溶液,且甘油和戊二醛添加量分别为膜液总体积1.41%和4.47%时达到最优制备条件,此时膜的断裂伸长率为228.36%。检验结果显示相对对照组,优化组的断裂伸长率扩大了18.14倍;根据回归方程计算得出影响断裂伸长率的主效因素是甘油,且其与戊二醛具有显著协同作用。另外,根据优化组的释药结果分析表明:该体系具有药物缓释功效,释药动力学归属于Fickan模型。以上结果有利于丝素/海藻酸钠膜舒适型药物缓释敷料的制备,可为该生物材料的应用研究提供参考。     

丝素蛋白膜的研究和应用进展

主要介绍了丝素蛋白膜的制备及其结构变化特征 ,丝素膜可作为酶的固定膜、生物传感器和药物控释膜等不同材料 .它具有无毒、无污染、可降解等优良特性 ,有着广阔的应用前景 .     

丝素蛋白膜表面的等离子体磺酸化及体外抗凝血性能

从蚕丝中提取的丝素蛋白（Silk fibroin）制备成薄膜,首次采用二氧化硫等离子体处理在材料表现引入了磺酸基因;同时丝素蛋白膜用氨气等离子体处理后在表面接入氨基,利用1,3－丙磺酸内酯与氨基的反应在材料表面接枝磺酸。采用X光电子能谱和全反射红光谱分析材料的表面性质。材料的体外抗弟血性能由外凝血时间;凝血酶原时间（PT）、部分凝血活酶时间（APTT）和凝血酶时间（TT）作为评价标准。结果表明两种处理方法均能在丝素蛋白膜表面有效地接枝磺酸基因,而且材料的抗凝血性能有显著提高。     

聚乳酸-乙醇酸共聚物/丝素共混纳米纤维多孔膜的制备及性能

以六氟异丙醇（HFIP）为共溶剂,通过静电纺丝法制备了聚乳酸-乙醇酸共聚物（PLGA）/丝素（SF）共混纳米纤维多孔膜。用场发射扫描电镜（FE-SEM）、傅立叶红外光谱分析仪（FT-IR）、多功能拉伸仪、液滴形状分析仪对共混纤维多孔膜的形貌、分子结构、力学性能及亲水性进行测试。结果表明,共混多孔膜中随SF的加入纤维直径...     

聚乙二醇缩水甘油醚对丝素蛋白膜的改性

合成了不同分子量的聚乙二醇缩水甘油醚（PEGO），用1H－NMR，红外吸收光谱对其进行了表征，并将其用于改性丝素膜，用X射线衍射法，氨基酸分析仪研究了PEGO改性丝素膜的结构，并对改性丝素膜中的溶出率以及力学性能进行了测试，结果表明，PEGO可以改变丝素膜的结构，降低丝素大分子的溶出率，改性后的丝素膜具有较好的拉伸强度和较大的断裂伸长率，得到了较为柔韧的改性丝素膜。     

丝素蛋白/柠檬酸/乙二醇膜的性能研究

用丝素蛋白、柠檬酸和乙二醇制备了一种新型丝素蛋白膜(简称SFCE膜),研究了其力学性能、膜中丝素蛋白的聚集态及对水的pH值的影响．     

聚乳酸改性丝素膜的性能研究

用不同分子量的聚乳酸共混改性丝素,研究结果表明,与纯的丝素膜相比,共混合膜的力学性能明显提高,透汽性也有所提高,但透湿性略有下降;聚乳酸的分子量对共混膜的力学性能、透湿性均有一定的影响,但对共混膜的透汽性影响不大.FTIR和XRD表征结果表明聚乳酸的加入丝素分子β构像的含量明显增多;用Vigot 函数以1265和1235cm-1为中心在1200～1300cm-1之间对红外光谱进行了分峰,用I1265/1235cm-1来表征混合膜中β构像丝素分子的含量,结果表明比例为5/100的聚乳酸/丝素共混膜中,丝素分子β构像含量最多,为0.64.     

SPA用于丝素膜的生物改性研究

用生长因子RGD半抗原（GLY-ARG-GLY-ASP-SER-PRO-LYS)连接到卵清蛋白Ovalbumin(OVA)载体上诱发出了抗RGD抗体IgG，并用丝素溶液包埋SPA(Staphylo-coccal protein A，简称A蛋白或SPA)制成不溶性SPA丝素膜为材料，然后用诱发出的RGD抗体IgG结合到不溶性SPA丝素膜的表面，制成IgG-SPA丝素膜，再在其上结合粘附生长因子RGD，制成RGD-IgG-SPA丝素膜。利用这一丝素膜培养血管内皮细胞(Vas-cular Endothelial Cell，简称EC细胞)，用四甲基偶氮些盐比色方法(MTT法)检测细胞的生长增殖情况。结果表明，RGD-IgG-SPA丝素膜能有效促进EC细胞的生长。对不溶性SPA丝素膜和IgG以及IgG和RGD之间的生物结合力测定，表明其结合力远大于离解力。同时在细胞培养液中没有检测到丝素膜中SPA的渗漏。RGD-IgG-SPA丝素膜为其作具有的这些优良性质为血管支架打下了基础。     

丝素蛋白对胶原膜性能改善的研究

天然高分子由于其良好的生物相容性而受到广泛的关注。本研究用酶法自制了具有一定水溶性的猪皮胶原。尝试利用丝素和胶原蛋白各自的优点。用简单的溶液浇铸法制备了胶原-丝素共混膜。并通过FTIR、TGA、SEM等手段对其结构进行了表征。结果表明。由于共混膜中俩组份间存在的分子间作用力，加入小于50％的丝素的胶原膜经乙醇处理后与纯胶原膜相比。其力学性能及热稳定性有所的改善。通过改变丝素比例可以调整共混膜的吸水性。由于两组分良好的生物相容性，预料该共混膜可用作生物材料。     

丝素-壳聚糖共混膜的制备及其金属离子渗透行为的研究

采用壳聚糖(CS)对天然高分子丝素(SB)进行改性,制备了丝素-壳聚糖(SB-CS)共混膜.FTIR、TGA、SEM的分析表明,该共混膜中SB和CS具有良好的相容性,壳聚糖改善了丝素膜的吸水性和机械性能.通过渗透实验发现不同的金属离子在共混膜中的渗透速率有很大的差异,一些常见的金属离子渗透速率的大小顺序为:K+>Ca2+>Cd2+>Pb2+>Cu2+>Ni2+.     

Preparation and characterization of regenerated fiber from the aqueous solution of Bombyx mori cocoon silk fibroin

The regenerated silk fibers with high strength and high biodegradability were prepared from the aqueous solution of Bombyx mori silk fibroin from cocoons with wet spinning method. Although the tensile strength of the regenerated silk fibroin fiber, 210 MPa is still half of the strength of native silk fiber, the diameter of the fiber is about 100 μm which is suitable for monofilament of suture together with high biodegradability. The high concentration (30%, w/v) of the aqueous solution of the silk fibroin which corresponds to the high concentration in the middle silkgland of silkworm was obtained. This was performed by adjusting the pH of the aqueous solution to 10.4 which corresponds to pK_a value of the OH group of Tyr residues in the silk fibroin. The mixed solvent, methanol/acetic acid (7:3 in volume ratio) was used as coagulant solvent for preparing the regenerated fiber. The structural change of silk fibroin fiber by stretching was monitored with both ¹³C solid state NMR and X-ray diffraction methods, indicating that the high strength of the fiber is related with the long-range orientation of the silk fibroin chain with β-sheet structure.     

The preparation of insoluble fibroin films induced by degummed fibroin or fibroin microspheres

Blending degummed fibroin (DF) or insoluble fibroin microspheres with concentrated fibroin solution, the insoluble films were obtained through drying the solution at 40–45 ^∘C. The conformation of silk fibroin films was analyzed by infrared spectrum and X-ray diffractometry. The results demonstrated that β-sheet conformation increased rapidly when the degummed silk or insoluble microspheres blended with fibroin, while the pure SF membrane was mainly composed of α/random coil conformation when the other conditions kept same. This suggested that fibroin microspheres and degummed fibroin could induce the formation of β-sheet crystal and the insoluble films, without methanol after-treatment, could be obtained at approximately room temperature. Although the fibroin films blending with DF had many protuberances, the films containing fibroin microspheres had the smooth surface and could be used effectively in biotechnological materials and biomedical application.     

Fabrication of a composite vascular scaffold using electrospinning technology

Intermolecular forces and morphology demonstrated that there was an excellent compatibility between silk fibroin and gelatin. The silk fibroin/gelatin composite vascular scaffold (inner diameter 4.5 mm) was prepared successfully by electrospinning. The scaffold was treated with ethanol to enhance the water-resistant ability and biomechanical properties. After ethanol treatment, the scaffold could hardly dissolve in the water, and FTIR showed that the conformation of the treated silk fibroin/gelatin composite vascular scaffold was mainly β-sheets. The electrospun silk fibroin/gelatin vascular scaffold possessed outstanding biomechanical properties. In vitro cell culture and in vivo subcutaneous implantation demonstrated that the electrospun silk fibroin/gelatin vascular scaffold had an appropriate biocompatibility. The results indicated that the electrospun silk fibroin/gelatin composite vascular scaffold could be considered as an ideal candidate for tissue-engineered blood vessel.     

丝素共混膜的结构、性能及应用研究进展

丝素膜是一种性能优良、用途广泛的天然高分子生物材料、但纯丝素膜存在着在干燥情况下力学性能很差等缺点，这些缺点可以通过与其他高分子化合物共混得到改善，从而拓宽丝素膜的应用范围，综述了丝素与其它天然或合成高分子形成的共混膜的种类，结构、性能及应用发展状况。     

Tissue response and biodegradation of composite scaffolds prepared from Thai silk fibroin,gelatin and hydroxyapatite

This work aimed to investigate tissue responses and biodegradation, both in vitro and in vivo, of four types of Bombyx mori Thai silk fibroin based-scaffolds. Thai silk fibroin (SF), conjugated gelatin/Thai silk fibroin (CGSF), hydroxyapatite/Thai silk fibroin (SF4), and hydroxyapatite/conjugated gelatin/Thai silk fibroin (CGSF4) scaffolds were fabricated using salt-porogen leaching, dehydrothermal/chemical crosslinking and an alternate soaking technique for mineralization. In vitro biodegradation in collagenase showed that CGSF scaffolds had the slowest biodegradability, due to the double crosslinking by dehydrothermal and chemical treatments. The hydroxyapatite deposited from alternate soaking separated from the surface of the protein scaffolds when immersed in collagenase. From in vivo biodegradation studies, all scaffolds could still be observed after 12 weeks of implantation in subcutaneous tissue of Wistar rats and also following ISO10993-6: Biological evaluation of medical devices. At 2 and 4 weeks of implantation the four types of Thai silk fibroin based-scaffolds were classified as “non-irritant” to “slight-irritant”, compared to Gelfoam^® (control samples). These natural Thai silk fibroin-based scaffolds may provide suitable biomaterials for clinical applications.     

A novel electrospun silk fibroin/hydroxyapatite hybrid nanofibers

A novel electrospinning of silk fibroin/hydroxyapatite hybrid nanofibers with different composition ratios was performed with methanoic acid as a spinning solvent. The silk fibroin/hydroxyapatite hybrids containing up to 30% hydroxyapatite nanoparticles could be electrospun into the continuous fibrous structure. The electrospun silk fibroin/hydroxyapatite hybrid nanofibers showed bigger diameter and wider diameter distribution than pure silk fibroin nanofibers, and the average diameter gradually increased from 95 to 582 nm. At the same time, the secondary structure of silk fibroin/hydroxyapatite nanofibers was characterized by X-ray diffraction, Fourier transform infrared analysis, and DSC measurement. Comparing with the pure silk fibroin nanofibers, the crystal structure of silk fibroin was mainly amorphous structure in the hybrid nanofibers. X-ray diffraction results demonstrated the hydroxyapatite crystalline nature remained as evidenced from the diffraction planes (002), (211), (300), and (202) of the hydroxyapatite crystallites, which was also confirmed by Fourier transform infrared analysis. The thermal behavior of hybrid nanofibers exhibited the endothermic peak of moisture evaporation ranging from 86 to 113 °C, and the degradation peak at 286 °C appeared. The SF/HAp nanofibers mats containing 30% HAp nanoparticles showed higher breaking tenacity and extension at break for 1.1688 ± 0.0398 MPa and 6.55 ± 1.95%, respectively. Therefore, the electrospun silk fibroin/hydroxyapatite hybrid nanofibers should be provided potentially useful options for the fabrication of biomaterial scaffolds for bone tissue engineering.     

Characterization and deposition behavior of silk hydrogels soaked in simulated body fluid

This paper reports the mineralization ability of semi-interpenetrating networks composed of regenerated silk fibroin and polyacrylamide hydrogels soaked in simulated body fluid (SBF1x). Hydrogels were prepared by polymerization of acrylamide and N,N′-methylenebisacrylamide in silk fibroin solution with a redox pair as initiator. The incorporation of the fibroin within the polyacrylamide matrix was proved by FTIR–ATR spectroscopy. Swelling measurements in saline solution were performed to evaluate the behavior of these hydrogels having various compositions. Mineralization assays in SBF1x solution revealed the presence of apatite-like crystals onto the surface of the silk fibroin/polyacrylamide hydrogels. Cytotoxicity test by extract method revealed that these hydrogels with various contents in silk fibroin have not developed cytotoxic effects on human fibroblast cultures which increases the possibility of their use in biomedical applications. Mechanical compressive tests revealed good strengths for silk fibroin/polyacrylamide hydrogels. In this way, organic–inorganic hybrids analogous to bone structure can be produced under biomimetic conditions and could be further used in biomedical applications.