接枝RGD多肽磷灰石-硅灰石材料的矿化和生物学特性

应用等离子辅助化学接枝方法在磷灰石-硅灰石(AW)生物活性玻璃的表面接枝精氨酸-甘氨酸-天冬氨酸(RGD)多肽。采用模拟体液(SBF)浸泡方法研究了AW表面接枝RGD基团对材料体外矿化特性的影响。SEM和EDS检测结果表明,RGD多肽的引入有利于羟基磷灰石(HA)的沉积,能够增强RGD-AW复合材料的体外矿化能力,HA形貌为蠕虫状。材料MG-63细胞共培养实验以及材料新西兰成年大白兔体内植入实验的结果表明,表面化学接枝RGD多肽的RGD-AW复合材料能够显著地促进类成骨细胞的黏附和铺展,并且在2周、4周和8周时均能够加速新骨的生成及骨组织结构和功能的重建。     

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。     

海藻酸钠水凝胶中粘附位点及空间构建促进MG-63细胞铺展及成骨分化

细胞粘附与铺展是三维水凝胶基质中贴壁依赖型细胞存活所必须的两个条件,将细胞粘附位点的引入和凝胶中细胞铺展空间的构建相结合,提出了同时含有RGD多肽和明胶微球的粘附型大孔水凝胶模型,以促进细胞在其中的铺展与分化。该模型采用光交联海藻酸钠水凝胶为基础,同时引入RGD多肽和明胶微球,通过RGD多肽的共价接枝为细胞粘附提供前提,利用明胶微球在37℃下的快速降解性,为细胞的进一步增殖和铺展以及分化提供所需空间。结果显示,明胶微球的加入提高了凝胶的力学性能,同时降低了凝胶的溶胀率。RGD和明胶微球的引入能够很好地支持MG-63细胞在其中的增殖、粘附与铺展,并显著提高其碱性磷酸酶活性,上调成骨相关基因(BMP-2,COL-I和OCN)的表达。而在不含微球的RGD-ALG和ALG凝胶中,细胞铺展及成骨分化均受到很大抑制。     

基于贻贝仿生化学改善聚己内酯纤维多孔支架的 细胞相容性

在组织工程领域,支架的表面化学性能对调控细胞的生长行为起着关键的作用。为进一步改善聚己内酯(PCL)纤维支架的细胞相容性,开发了一种基于贻贝仿生化学在PCL纤维支架表面接枝生物相容性大分子的方法。该方法主要包含多巴胺在PCL纤维的表面涂覆和自聚合,以及生物活性大分子精氨酸-甘氨酸-天冬氨酸(RGD)和肝素的引入。傅里叶变换红外光谱测试结果表明RGD和PDA被成功地引入到PCL纤维支架表面。扫描电镜形貌检测和水接触角测试结果表明该改性手段不仅增大了纤维支架的表面粗糙度并且改善了支架的表面润湿性能。血管内皮细胞在改性的支架表面表现出了良好的细胞黏附性和细胞存活性。这种不涉及任何有毒溶剂的改性方法在组织工程支架领域具有广阔的应用前景。     

静电自组装表面修饰HA/PA6膜:表征及其细胞相容性研究

通过表面改性引入活性生物分子可以用来增强材料表面的生物相容性。采用静电自组装技术将明胶和聚乙烯亚胺引入羟基磷灰石/聚酰胺6(HA/PA6)材料表面,最终获得大分子修饰的复合材料。利用水接触角测量(WCA)、X射线光电子能谱(XPS)和原子力显微镜(AFM)测试手段对表面改性前后HA/PA6膜的表面化学、亲水性和表面形貌进行表征。并研究了其对细胞活性的影响。结果表明,改性后膜表面的亲水性增强,粗糙度增大。体外细胞实验表明,明胶涂层后的HA/PA6表面细胞更利粘附、铺展和生长。该固定方法模拟细胞外基质组成制备出的生物活性膜能进一步满足生物医学工程需求。     

壳聚糖涂层聚乳酸细胞微载体的制备和性能

采用氨解技术在聚乳酸微球表面引入自由氨基,再利用戊二醛将氨基转化为醛基,最后采用接枝涂层技术将壳聚糖固定到聚乳酸微球表面,制备了壳聚糖表面改性的聚乳酸细胞微载体.分别采用茚三酮法和乙酰丙酮-对二甲氨基苯甲醛法测定了聚乳酸微球表面的氨基和壳聚糖含量.发现氨基的量初始随氨解时间的延长而增大,达到最大(2.94×10-7mol/mg)后保持不变.与空白聚乳酸微球相比,软骨细胞在壳聚糖改性聚乳酸微球表面能够更有效地粘附和生长,分布更为均匀.     

氨化碳纳米管接枝生物分子(蛋白质和DNA)

报告-种氨基功能化处理的多壁碳纳米管(f-MWCNTs)用于生物分子[如牛血浆蛋白素(BSA)蛋白质及脱氧核醣核酸(DNA)]的接枝处理高效方法.以苯-二茂铁喷入氩氛炉于～850 ℃裂解制得MWCNTs,,而后向纳米管表面导入羧基化合物,再以氨基基团对MWCNTs,进行功能化处理.该过程包括:乙二胺与羧基基团直接结合,经酰胺化引入胺基基团.对制得的MWCNTs、 f-MWCNTs以及由BSA蛋白质和DNA接枝的氨化f-MWCNTs等样品,采用SEM、TEM、FTIR进行表征.结果表明:生物分子(BSA蛋白质和DNA)接枝于氨化的f-MWCNTs.     

聚酰胺66膜表面明胶固定化研究

生物材料可通过表面改性引入活性基团来增强其生物相容性.采用紫外辐照方法,以亚铁离子辅助引发接枝聚合,将羧基引入聚酰胺66(PA66)膜表面,再用水溶性碳化二亚胺(WSC)作为缩合剂,进一步将明胶固定在聚酰胺膜表面,最终获得大分子修饰的聚酰胺材料.利用衰减全反射-傅里叶红外光谱(ATR-FTIR)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和水接触角测量(WCA)等测试手段对PA66膜和表面改性PA66膜进行了表征.结果表明,在40℃条件下,光氧化的最佳时间为60min.接枝聚合后,膜的亲水性增强,水接触角由纯聚酰胺的67.5°变为固定明胶分子后的60°,并且膜表面的粗糙度增加.表面改性PA66膜可促进细胞活性,适用于组织工程中.     

基于共价固定高密度透明质酸构建具有抗菌抗凝血双功能的表面

表面血栓生成和细菌感染是导致体外血液循环装置及留置器械等血液接触类器材失效的重要原因,表面接枝生物活性分子是赋予材料表面抗血栓及抗菌性能的重要手段。然而,现有的抗菌抗凝血双功能改性方法通常基于复杂的改性策略并难以良好地整合抗菌抗凝血的效能,如普遍使用的含银抗菌策略对血液抗凝并不友好。因此,利用简单接枝生物分子同时提高血液接触材料的抗菌抗凝血性能具有很大的挑战和意义。本研究将透明质酸(HA)分子高密度地接枝在氨基化表面,利用透明质酸的高度水合能力和除污特性,赋予了材料表面有效的抗菌与抗凝血功能。本策略首先将聚烯丙胺(PAa)在碱性条件下以席夫碱反应和迈克尔加成方式接枝在聚多巴胺(PDA)涂层表面,从而构建出富氨基涂层(PADA)。进一步通过酰胺化反应将HA共价固定在PADA表面,得到功能化涂层(HA-PADA)。衰减全反射傅里叶变换红外光谱(ATR-FTIR)和X射线光电子能谱(XPS)结果证实成功制备了HA-PADA涂层。体外纤维蛋白原和血小板的粘附激活实验以及抗菌实验的结果验证了HA-PADA涂层可以显著抑制凝血和细菌粘附。因此,该方法构建的具有高HA密度且稳定的HA-PADA双功能涂层对于提高血液接触类器材表面的血液相容性和抗菌性能具有很好的参考意义。     

图案化与生物功能化聚3,4-乙烯二氧噻吩生物界面

本工作制备了具有可调控蛋白/细胞作用且低阻抗的功能化聚3,4-乙烯二氧噻吩(PEDOT)的图案化生物界面,并在空间上引导细胞的粘附行为.功能化PEDOT共聚物由具有抗非特异性粘附的磷酸胆碱功能化的EDOT(EDOT-PC)和可进行生物耦合反应的羧基功能化的EDOT(EDOT-COOH)两种单体共聚而成.本工作研究了不同组分共聚物的电化学阻抗性能及其对蛋白、细胞的抗粘附性能,同时通过精氨酸-甘氨酸-天冬氨酸(RGD)多肽的引入实现了在抗非特异性粘附背景下对细胞的特异性粘附.在此基础上,通过光刻及电化学沉积技术制备了由细胞特异性粘附区与抗细胞粘附区组成的图案化PEDOT生物界面,可有效地在空间上控制细胞粘附行为.该工作为研究细胞在材料表面的其他行为提供了可能性,在组织修复、再生工程中有着潜在的应用价值.     

Dextran‐based coating system for the immobilization of cell adhesion promoting molecules on titanium surfaces

Immobilization of adhesive peptides interacting with cellular integrin receptors onto metallic implant surfaces represents a promising approach to improve osseointegration of implants into the surrounding tissue. In the present study, a functional dextran‐based coating system consisting of an amino titanate adhesion promoter with dendritic structure and a carboxymethyl dextran was established to bind an RGD‐containing adhesive peptide via a selective coupling methodology onto titanium surfaces. The three‐step reaction procedure was characterized by X‐ray photoelectron spectroscopy. In cell adhesion experiments it could be demonstrated that dextran coatings containing immobilized RGD promote attachment and spreading of fibroblast and pre‐osteoblastic cells compared to native as well as CMD‐coated titanium surfaces without RGD. The direct attachment of the RGD sequence to the metal surface via the amino titanate adhesion promoter did not increase pre‐osteoblastic cell spreading, whereas coupling of RGD to the polymeric carboxy­methyl dextran layer slightly enhanced spreading of the cells.     

Initial Attatchment of rMSC and MG‐63 Cells on Patterned Bioglass® Substrates

A soft lithography technique was used to introduce surface patterns on the surface of sintered bioactive glass substrates. Osteoblast‐like MG‐63 cells and rat mesenchymal stem cells (rMSC) seeded on micropatterned bioactive glass surfaces showed different behavior with rMSC exhibiting a better initial attachment than MG‐63 cells. Both cytoskeleton formation and cell spreading of rMSC were supported by the bioactive surfaces. In addition, the structured surfaces seemed to guide MG‐63 cells to a larger extent than rMSC. The in vitro results are important considering the continuous development of bone tissue scaffolds based on silicate bioactive glasses.     

Immobilization of RGD peptide on HA coating through a chemical bonding approach

In this work, Arg-Gly-Asp (RGD) sequence containing peptide was immobilized on hydroxyapatite (HA) coatings through a chemical bonding approach in two steps, surface modification with 3-aminopropyltriethoxysilane (APTES) and RGD immobilization. The results indicate that RGD has been successfully immobilized on HA coatings. Comparing with physical adsorption coatings, the chemically bonded RGD on the coatings shows much better anti-wash-out ability. Since RGD is able to recognize cell-membrane integrins on biointerfaces, the present method will be an effective way to favor interaction of cells with HA coatings.     

骨形成蛋白-2转染MG-63细胞增加其对壳聚糖膜的粘附

为了观察壳聚糖膜对转染载有骨形成蛋白基因（bone morphogenetic protein,BMPDNA）的成骨样细胞（MG 63）粘附及增殖的影响,本研究构建重组BMP-2质粒并转染入MG 63,分别经酶切、PCR、Western、免疫组化鉴定;制备壳聚糖膜（chitosan,CS）,然后将转染细胞与该材料分别培...     

Enhanced In Vivo Tumor Detection by Active Tumor Cell Targeting Using Multiple Tumor Receptor‐Binding Peptides Presented on Genetically Engineered Human Ferritin Nanoparticles

Human ferritin heavy‐chain nanoparticle (hFTH) is genetically engineered to present tumor receptor‐binding peptides (affibody and/or RGD‐derived cyclic peptides, named 4CRGD here) on its surface. The affibody and 4CRGD specifically and strongly binds to human epidermal growth factor receptor I (EGFR) and human integrin αvβ3, respectively, which are overexpressed on various tumor cells. Through in vitro culture of EGFR‐overexpressing adenocarcinoma (MDA‐MB‐468) and integrin‐overexpressing glioblastoma cells (U87MG), it is clarified that specific interactions between receptors on tumor cells and receptor‐binding peptides on engineered hFTH is critical in active tumor cell targeting. After labeling with the near‐infrared fluorescence dye (Cy5.5) and intravenouse injection into MDA‐MB‐468 or U87MG tumor‐bearing mice, the recombinant hFTHs presenting either peptide or both of affibody and 4CRGD are successfully delivered to and retained in the tumor for a prolonged period of time. In particular, the recombinant hFTH presenting both affibody and 4CRGD notably enhances in vivo detection of U87MG tumors that express heterogeneous receptors, integrin and EGFR, compared to the other recombinant hFTHs presenting either affibody or 4CRGD only. Like affibody and 4CRGD used in this study, other multiple tumor receptor‐binding peptides can be also genetically introduced to the hFTH surface for actively targeting of in vivo tumors with heterogenous receptors.     

Surface modification of apatite-wollastonite glass ceramic by synthetic coupling agent

In this study, lysine was introduced into the surface of apatite-wollastonite glass ceramic （AW-GC） to improve its cytocompatibility by two steps reaction procedure. Firstly, lysine connected to N-β-（aminoethyl）-y-aminopropyl trimethoxy silane （A-1120） by covalent binding of amide group. Secondly, the lysine-functionalized A-1120 was deposited on the surface of AW-GC through a silanization reaction involving a covalent attachment. FTIR spectra indicated that lysine had been immobilized onto the surface of AW-GC successfully. Bioactivity of the surface modified AW-GC was investigated by simulated body fluid （SBF）, and the in vitro cytocompatibility was evaluated by coculturing with human osteosarcoma cell MG63. The results showed that the process of hydroxyapatite layer formed on the modified material was similar to AW-GC while the mode of hydroxyapatite deposition was changed. The growth of MG63 cells showed that modifying the AW-GC surface with lysine enhances the cell adhesion and proliferation.     

Molecular dynamics simulation of RGD peptide adsorption on titanium oxide surfaces

Peptide Arg-Gly-Asp (RGD) sequence is a ubiquitous adhesive motif found in various bone extracellular matrix proteins and is crucial in the biomaterial surface/interface reaction. This study analyzed the adsorption of RGD on different titanium oxide surfaces with molecular dynamics simulation. The simulation results indicate that the RGD peptide binds strongly with anatase (001) and rutile (010). RGD conformation changes due to the variation of the backbone torsion angle in the middle of the RGD chain. Pair correlation function analysis indicates that the interaction of the RGD peptide and the titanium oxide results from hydrogen bonding and the groups in RGD play different roles during the adsorption process. This study provides useful information on how to design titanium surfaces in order to modulate peptide or protein adsorption.     

Preparation and properties of gold nanoparticle-electrodeposited titanium substrates with Arg-Gly-Asp-Cys peptides

Titanium metal has good biocompatibility, superior mechanical properties and excellent corrosion resistance. Like most metals, however, it exhibits poor bioactive properties and fails to bond to bone tissue. To improve its bioactivity, bioactive molecules, such as peptides, can be grafted onto titanium surfaces. In order to do this, the first step may be to establish a stable and compatible linking layer on the titanium surface. In this study, we used electrochemical methods to deposit gold (Au) nanoparticles onto titanium substrates, to which we then grafted arginine-glycine-asparagine-cysteine (RGDC) peptides by thiolate covalent coupling. Properties of electrodeposited Au nanoparticles were evaluated using a variety of techniques, including microstructural, chemical and electrochemical measurements. The biological responses of the RGDC-grafted Ti substrates were evaluated using MG3 human osteoblast-like cells. The results of thin-film X-ray diffraction (TFXRD) and scanning electron microscopy (SEM) indicated the polycrystalline orientation of Au nanoparticles deposited on the titanium surfaces with high density and controllable particle size. The RGDC peptide could be covalently bonded to Au-deposited Ti substrates via Au-thiolate species, as expected. Cell morphology showed that, on RGDC-immobilized titanium with Au particles, MG63 cells attached and spread more rapidly than on Ti substrates either without peptide or with direct loading of the peptide. Immunostaining for focal adhesion kinase (FAK) demonstrated that RGDC enhanced cell attachment. The present method for the formation of Au nanoparticles may serve as an alternative route for bioactive molecule immobilization on Ti implants.     

Roughened titanium surfaces with silane and further RGD peptide modification in vitro

The strategy to achieve osteoregeneration of dental implants during early-stage regeneration is strongly related to surface conditions for achieving highly successful effects after implantation. Surface modifications, namely, mechanical ground, silanization, bonded and sandblasted with pentasequence Gly-Arg-Gly-Asp-Ser (GRGDS) peptide, and acid-etched with Arg-Gly-Asp (RGD) peptide, were compared for their ability to support cell attachment, proliferation, and differentiation on titanium surfaces. The characteristics and comparative in vitro bio-interactions toward osteoprogenitor cells were tested in the four groups with various surface modifications. Compared with the other groups, the sandblasted and acid-etched, and silane with subsequent RGD peptide modified surfaces had the smallest wetting angle, absence of a significant cell viability difference, and largest quantity of alkaline phosphatase production during the expressions of early-stage cell differentiation. The method of synthesizing GRGDS peptides on roughened titanium surfaces has the potential to provide a combination of early bone regeneration and implant of long-term anchored capabilities.