丝素改性胶原膜的低温等离子体改性及体外抗凝血性研究

选用SO2、NH3、CO2三种工作气体，采用低温等离子体技术对丝素改性胶原膜进行了表面改性。运用X光电子能谱分析了材料的表面性质。材料的体外抗凝血性能由体外凝血时间——凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)作为评价标准。结果表明，SO2、CO2等离子体处理可分别在材料表面引入磺酸和酸酸基团，材料的体外抗凝血性得到很大的改善。NH3等离子体处理可以增加材料表面的氨基的数目，它对材料的抗凝血性没有贡献。     

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.     

丝素蛋白膜上vWf抗体的固定化及其体外抗凝血性能

用凝血因子的抗体对生物材料进行表面改性以提高其抗凝血性能。以丝素蛋白膜为基质，利用等离子体处理辅助的共价交联方法对vWf因子（von Wilebrand factor)抗体进行了固定化。用酶联免疫法和抗体过剩法对固定化效果进行了评价，固定化抗体的活性采用体外凝血时间（APPT，TT和PT）测定进行检测。结果显示，通过这种方法可以有效地将vWf抗体固定化，丝素蛋白膜固定化vWf抗体后，其抗凝血性能有了一定的改善。本研究结果拓宽了抗体固定化技术的应用范围，同时为抗凝血材料的设计提供了一种新的思路。     

等离子体引发接枝聚合改善聚丙烯表面的亲水性

将等离子体引发接枝技术用于聚丙烯（PP）膜表面接枝丙烯酸。FT—IR证明处理后的膜表面存在有羧基,染色法定量测定了羧基的含量。另外,对修饰后的聚丙烯膜表面进行接触角的测定。结果表明,等离子体引发接枝聚合可明显改善聚丙烯膜表面亲水性,能控制PP膜表面的接枝率大小,可得到不同水接触角的PP膜,进而能人为调节PP膜的表面亲水性。     

XPS研究氨等离子体处理的聚丙烯膜表面结构

用氨等离子体技术处理聚丙烯膜表面，并用Ｘ射线光电子能谐（ＸＰＳ）测定了膜表面的元素组成，相对含量和表面功能团的类型。结果表明：氨等离子体处理后，聚丙烯膜表面除原有的Ｃ－Ｈ、Ｃ＝Ｃ键外，新形成Ｃ－Ｏ，Ｏ－Ｃ＝Ｎ，Ｃ－Ｎ，Ｏ－Ｃ＝Ｏ等键。图谱解析得改性表面具有含氮活性基团（如氨基等）。这些表面带氨基的聚丙烯材料为固定化酶技术提供了新型载体     

丝素改性胶原膜的肝素化及其体外抗凝血性能评价

以1-(3-二甲氨基丙基)-3-乙基碳二亚胺(简称EDCI)为缩合剂对丝素改性胶原膜进行了肝素固定化,测定并研究了固定化肝素的稳定性,应用X光电子能谱分析了材料的表面性质。以凝血酶原时间(PT)、部分凝血活酶时间(APTT)、凝血酶时间(TT)等3个体外凝血时间为评价标准,考察了材料的抗凝血性能。结果表明,肝素化后的丝素改性胶原膜具有良好的抗凝血性。     

低温等离子体表面处理PEGDA/HEMA水凝胶的时效性及亲水性

采用低温等离子体工艺对聚乙二醇双丙烯酸酯(PEGDA)/甲基丙烯酸-2-羟基乙酯(HEMA)共聚物凝胶膜进行表面改性,研究了等离子处理的时效性,通过紫外接枝法在等离子处理材料表面接枝丙烯酰胺(AAm),并探讨了时效性对丙烯酰胺接枝率的影响和表面改性后材料的亲水性。研究结果表明,氩等离子处理凝胶材料具有一定的时效性,随着放置时间的延长,AAm的接枝率降低,接枝后PEGDA/HEMA材料的亲水性得到改善,材料的亲水性随着AAm的浓度的增大而增大。     

羧化左旋聚乳酸膜的表面性能

用低温等离子体接枝聚合丙烯酸获得表面羧基化的PLLA膜并对其表面性能进行表征.结果表明,等离子体处理条件对膜表面羧基接枝密度有较大影响;与空白PLLA膜相比,羧基化后膜的亲水性得到显著提高,表面接触角由75°减少到24°并长时间保持稳定;L929成纤维细胞在羧化膜上的生长状态良好,呈现出细胞的聚集态,其细胞密度大于空白组.材料表面的羧基化能改善其亲水性并使其带上负电荷,从而有效的促进细胞的黏附和生长.     

远程氩气等离子体引发接枝丙烯酸改性聚丙烯微孔膜的研究

采用远程氩气等离子体对聚丙烯(PP)微孔膜进行表面亲水处理,并引发接枝丙烯酸单体实现永久亲水改性.研究了放电参数及样品位置对于亲水性及接枝率的影响,并运用扫描电镜(SEM)、红外光谱(FTIR)和光电子能谱(XPS)对等离子体处理后的微孔膜进行了表面分析.实验结果显示等离子体功率对处理后的微孔膜的表面亲水性和接枝率有较大影响:在低功率时,放电中心位置的微孔膜经等离子体处理后亲水性最好,同时该位置的接枝率也相应最大;而在高功率时,则是距放电中心20cm位置的微孔膜的亲水性和接枝率优于其他位置.＃红外光谱显示在低功率时膜表面有羧基生成,而在高功率时则仅生成醛基酮基羰基.对于高功率等离子体处理后的PP微孔膜,SEM结果显示在放电中心位置的膜表面有丝状胶合现象发生,XPS结果显示在距放电中心20cm位置处的膜表面含氧量增加最多.     

聚砜膜的低温等离子体改性及其在膜式氧合器的应用

采用低温等离子体技术对用于膜式氧合器的聚砜(PSf)膜进行表面改性,通过接枝聚乙二醇(PEG)和肝素以改善其血液相容性.系统研究了接枝的PEG分子量及不同等离子体处理条件对改性效果的影响.研究结果表明,当PEG分子量为6 000,等离子预处理功率为150W,预处理时间为2min,处理气体为氩气(Ar)时,改性效果最佳,接触角明显降低,蛋白吸附显著减少.膜的汽液双侧传输性质测试结果表明,改性后的PSf膜保留了初始膜的气体传输性能,基本达到了医用人工肺材料的标准.     

Surface sulfonation of silk fibroin film by plasma treatment and in vitro antithrombogenicity study

To improve the blood compatibility of Bombyx mori silk fibroin (SF) film, the film was modified by SO₂ gas plasma treatment, or by a two-step process including NH₃ gas plasma treatment and reaction with 1,3-propane sultone. XPS and ATR-FTIR were used to analyze the surface chemical elements. In vitro antithrombogenicity was determined by the method of the activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) tests. Percents of sulfur element on the surfaces of both modified SF films were 4.03% and 3.30%, respectively, while that of the control film was only 0.32%. Moreover, the antithrombogencity of treated films was increased remarkably due to surface sulfonation. The results implied a potential use of sulfonated SF for blood-contacting biomaterials.     

A versatile click-grafting approach to surface modification of silk fibroin films

Silk fibroin is a biocompatible, mechanically robust protein polymer that can be made optically transparent, and is widely used and studied as biomaterial for different applications. Its chemical modification is a fascinating way for tuning the properties and widening its application field. Herein, PEG grafting on the surface of regenerated silk fibroin films is obtained by direct linking based on a click reaction between the azido activated silk surface and an alkyne terminated PEG. The so obtained PEGylated films exhibit modified surface properties in comparison with the unmodified films. Through the same click approach, we also show that arrays of ordered fluorescent spots are steadily printed onto the film surface. This expands the versatility of our silk modification to different molecules and polymers, hence allowing for the realization of new functional hybrid materials.     

Bovine pericardium coated with biopolymeric films as an alternative to prevent calcification: In vitro calcification and cytotoxicity results

Bovine pericardium, for cardiac valve fabrication, was coated with either chitosan or silk fibroin film. In vitro calcification tests of coated and non coated bovine pericardium were performed in simulated body fluid solution in order to investigate potential alternatives to minimize calcification on implanted heart valves. Complementary, morphology was assessed by scanning electron microscopy — SEM; X-ray diffraction (XRD) and infrared spectroscopy (FTIR-ATR) were performed for structural characterization of coatings and biocompatibility of chitosan. Silk fibroin films were assayed by in vitro cytotoxicity and endothelial cell growth tests. Bovine pericardium coated with silk fibroin or chitosan did not present calcification during in vitro calcification tests, indicating that these biopolymeric coatings do not induce bovine pericardium calcification. Chitosan and silk fibroin films were characterized as non cytotoxic and silk fibroin films presented high affinity to endothelial cells. The results indicate that bovine pericardium coated with silk fibroin is a potential candidate for cardiac valve fabrication, since the affinity of silk fibroin to endothelial cells can be explored to induce the tissue endothelization and therefore, increase valve durability by increasing their mechanical resistance and protecting them against calcification.     

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。     

Mulberry non-engineered silk gland protein vis-à-vis silk cocoon protein engineered by silkworms as biomaterial matrices

Silk fibroin from silk gland of Bombyx mori 5th instar larvae was utilized to fabricate films, which may find possible applications as two-dimensional matrices for tissue engineering. Bombyx mori cocoon fibroin is well characterized as potential biomaterial by virtue of its good mechanical strength, water stability, thermal properties, surface roughness and biocompatibility. The present study aims to characterize the biophysical, thermal, mechanical, rheological, swelling properties along with spectroscopic analysis, surface morphology and biocompatibility of the silk gland fibroin films compared with cocoon fibroin. Fibroin solutions showed increased turbidity and shear thinning at higher concentration. The films after methanol treatment swelled moderately and were less hydrophilic compared to the untreated. The spectroscopic analysis of the films illustrated the presence of various amide peaks and conformational transition from random coil to beta sheet on methanol treatment. X-ray diffraction studies also confirmed the secondary structure. Thermogravimetric analysis showed distinct weight loss of the films. The films were mechanically stronger and AFM studies showed surfaces were rougher on methanol treatment. The matrices were biocompatible and supported L929 mouse fibroblast cell growth and proliferation. The results substantiate the silk gland fibroin films as potential biomaterial matrices.     

Flexible bio-composites based on silks and celluloses

Biomaterials have attracted worldwide attention due to the concerns regarding health and the environment. Silk, a natural protein produced by several species of insects, has been examined as a potential material for applications in many biotechnological and biomedical fields. However, regenerated silk fibroin has poor ductility and mechanical properties. Therefore, in this study, silk fibroin-cellulose composite films were prepared in an aqueous system to increase the ductility of regenerated silk fibroin. The morphology of the silk fibroin-cellulose composite film was observed by field emission scanning electron microscopy. The structure of the silk fibroin-cellulose composite films was examined by Fourier transform-infrared spectroscopy. The flexibility was analyzed using a bending test.     

Stem cell response to multiwalled carbon nanotube-incorporated regenerated silk fibroin films

Multiwalled carbon nanotubes (MWCNTs) are considered to be the ideal reinforcements for biorelated applications on account of their remarkable structural, mechanical and thermal properties. However, before MWCNTs can be incorporated into new and existing biomedical devices, their toxicity and biocompatibility need to be investigated thoroughly. In this study, regenerated silk fibroin/MWCNT nanocomposite films were prepared using a solvent system with pre-dispersed MWCNTs. Their biocompatibility was examined in vitro using human bone marrow stem cells. Scanning electron microscopy and a WST-1 assay demonstrated that the silk fibroin/MWCN film supported BMSC attachment and growth over 7 days in culture similar to the silk fibroin only film.     

Processing methods to control silk fibroin film biomaterial features

Control of silk structural and morphological features is reported for fibroin protein films via all aqueous processing, with and without polyethylene oxide (PEO). Silk films with thicknesses from 500 nm to 50 μm were generated with controllable surface morphologies by employing soft-lithography surface patterning or by adjusting PEO concentrations. FTIR analysis indicated that water-annealing, used to cure or set the films, resulted in increased β-sheet and α-helix content within the films. Steam sterilization provided an additional control point by increasing β-sheet content, while reducing random coil and turn structures, yet retaining film transparency and material integrity. Increased PEO concentration used during processing resulted in decreased sizes of surface globule structures, while simultaneously increasing uniformity of these features. The above results indicate that both surface and bulk morphologies and structures can be controlled by adjusting PEO concentration. The combined tool set for controlling silk film geometry and structure provides a foundation for further study of novel silk film biomaterial systems. These silk film biomaterials have potential applicability for a variety of optical and regenerative medicine applications due to their optical clarity, impressive mechanical properties, slow degradability, and biocompatibility.     

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.