Behavior of MC3T3-E1 Osteoblast Cultured on Chitosan Modified with Polyvinylpyrrolidone

The physical and chemical properties of four kinds of modified chitosan materials made by blending chitosan with polyvinylpyrrolidone （PVP） were investigated. All four of these modified chitosan materials were hydrophilic with water contact angles ranging from 59°to 69°. Fourier transform-infrared spectra of the modified materials showed a new band at 1288 cm^-1, implying formation of a surface physical interpenetrating network structure. Enzyme linked immunosorbent assay results indicated that much less fibronectin was adsorbed on the modified materials than on only chitosan. The viability of MC3T3-E1 osteoblasts cultured on the materials was assessed by 3-（4,5-dimethyl-2-thiazolyl）-2,5-diphenyl- 2H-tetrazolium bromide assay. The results show that adding PVP10000 into the chitosan promotes adhesion of MC3T3-E1 osteoblasts on the modified materials, but has no effect on cell growth and proliferation; while adding PVP40000 reduces cell adhesion, growth, and proliferation. The results suggest that the increased hydrophilicity of the material surface does not always improve its biocompatibility, which will influence the selection and design of biomaterials.     

壳聚糖多孔支架的制备与生物学性质

用一种蛋白改性壳聚糖,通过冷冻干燥方法制备三维多孔支架,对支架材料的细胞毒性、贴壁率和细胞增殖等生物学特性进行评价.结果显示,采用-20,-70,-196 ℃不同温度预冻后冻干,可以制成孔结构不同的支架材料.通过冻干法制备的蛋白改性壳聚糖多孔支架对细胞没有毒性,L929细胞和人成纤维细胞可以在支架表面和内部正常生长和增殖,角质细胞在材料表面可以正常老化、角质化.     

Protein adsorption on the poly（L-lactic acid） surface modified by chitosan and its derivatives

Surface modification of biomaterials has been adopted over the years to improve their biocompatibility. In this study, aiming to promote hydrophilicity and to introduce natural recognition sites onto poly（L-lactic acid） （PLLA） films, chitosan and its derivatives, carboxymethyl chitosan（CMC） and N-methylene phosphonic chitosan （NPC）, were used to modify the surface of PLLA films by an entrapment method. Radiolabeled （^125I） proteins were used to measure the amount of protein adsorbed to PLLA surfaces. Fibronectin （Fn） was used to study the protein adsorption on the modified PLLA surfaces, including isotherm adsorption and adsorption kinetics of single protein, competitive adsorption of binary proteins system and serum multi-proteins and the desorption behavior in serum solution. The results showed that in the isotherm adsorption, Fn had a larger adsorption capacity on the CS-modified surface at lower concentrations, but had a high adsorption capacity at CMC-modified surface at higher concentrations. In the study of absorption kinetics, Fn had a fastest adsorption equilibrium and a highest equilibrium adsorption capacity at the CS-modified surface, while it was opposite at the PCS-modified surface. When BSA and serum were added, it had the greatest effect on the adsorption of Fn on the PCS-modified surface. After 6 hours soaking in the desorpUon study, Fn had reached desorption equilibrium on all the modified surfaces, which had different effects on the desorption rate and the remaining percentage of Fn.     

牛血清白蛋白改性壳聚糖纤维及其细胞亲和性研究

采用牛血清白蛋白对壳聚糖纤维进行化学改性，通过扫描电镜和含水量测定对改性的牛血清白蛋白-壳聚糖纤维进行表征．并对改性材料进行细胞相容性和细胞亲和性测定与评价．结果表明：牛血清白蛋白-壳聚糖纤维表面有明显附着物，纤维略微变粗；含水量增加到93．49％(质量分数)；细胞在改性克聚糖纤维上的形态无异常，粘附、生长、增殖情况良好；细胞毒性试验结果呈阴性．该改性壳聚糖纤维具有良好的生物学特性，能够应用于器官组织工程及生物医药领域．     

Hepatic Bel-7402 Cell Proliferation on Different Phospholipid Surfaces

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聚氨酯/ 羧甲基壳聚糖/壳聚糖) n 复合涂层血液相容性

在心血管支架表面构建仿生细胞外基质结构的涂层是提高支架生物相容性的有效方法.结合静电纺丝及静电自组装技术,在316L医用不锈钢基底上制备出网状聚氨酯/(羧甲基壳聚糖/壳聚糖)n复合涂层.血小板黏附实验表明,对于网状聚氨酯涂层,血小板较易黏附在直径小于1μm的纤维上,在直径大于1μm的纤维上几乎无血小板黏附;而聚氨酯/(羧甲基壳聚糖/壳聚糖)n复合涂层的血小板黏附数量明显下降,血液相容性得到改善.     

Ti基六钛酸钾涂层复合材料生物相容性的实验研究

应用小鼠成骨细胞系OCT-1细胞对两种植入性材料(纯钛及钛基六钛酸钾涂层复合材料)进行体外细胞培养,比较二者的生物相容性.结果显示钛基六钛酸钾涂层复合材料的生物相容性和纯钛材料相当;连续培养可提高材料的生物相容性,材料表面的平整程度对其表面细胞生长状况起着重要的作用.     

甲壳胺对水稻根生长的促进作用1

用三种不同粘度的甲壳胺 (其中 1、 3号为虾壳制品、 2号为蟹壳制品 )处理水稻种子 ,其中 3号对水稻种子有明显促进生长作用 ,特别是对根的生长促进作用更强     

基于有限元法的活细胞粘附问题的力学建模及分析

活细胞粘附在诸如细胞生长、分化、移动和死亡等行为中扮演着重要的角色.同时,基底的力学特性也显著影响着活细胞粘附.为了找出并解释基底力学参数对细胞粘附行为的影响,本文尝试提出了一种弹簧绑定的力学模型.在该模型中,粘附力由处于粘附区域并连接细胞表面和基底表面的弹簧所表示,细胞和基底则分别由弹性壳体和固体所描述.通过改变细胞...     

Cadherin-based biomaterials: Inducing stem cell fate towards tissue construction and therapeutics

The precise regulation of cell fate by biomaterials is one of the core focuses in tissue engineering and regenerative therapeutics. Cell fate is controlled by the niche signaling cues, including growth factors/morphogens, direct cell-cell contact, and extracellular matrix components. Here, we discuss how to bio-mimic cell-cell interaction by tailoring the interface of biomaterials to design effective scaffolds. Cadherins, as a key cell membrane protein family mediating the intercellular adherens junction, have attracted extensive attention in the functional modification of biomaterials. Therefore, cadherin-based biomaterials, their ability to modulate stem cell fate, and their applications in regenerative medicine are reviewed. Furthermore, we provide an outlook for exploiting the bio-mimic biomaterials in advanced cell therapeutics.     

壳聚糖包衣剂对黄瓜和辣椒种子发芽及幼苗素质的影响

以黄瓜和辣椒为供试材料，采用壳聚糖对于种子进行包衣处理，对黄瓜和辣椒的室内发芽、田间出苗及幼苗素质进行测定。结果表明：壳聚糖种子包衣剂对种子发芽无不良影响，可促进苗期幼苗的生长，增加最大叶的长度和宽度，叶绿素含量提高，根系活力增强，可溶性蛋白与过氧化物酶都明显提高，说明壳聚糖包衣对提高蔬菜内在品质具有较好的促进作用。     

Cellular transformation and the 'morphologic phenotype' of transformed cells.

Expression of the product of the transforming gene (src) of RNA tumour viruses promotes growth and usually alters the adhesion, appearance and surface properties of cultured fibroblasts. The latter group of properties termed the 'morphologic phenotype' of transformed cells is largely due to diminished cell-to-substratum adhesion. The role of cyclic AMP, cell surface protein (CSP), and other factors in producing the 'morphologic phenotype' are discussed. The effects of src expression bear a striking resemblance to the action of peptide hormones such as insulin on appropriate target cells.     

A study on poly (N-vinyl-2-pyrrolidone) covalently bonded NiTi surface for inhibiting protein adsorption

Near equiatomic NiTi alloys have been extensively applied as biomaterials owing to its unique shape memory effect, superelasticity and biocompatibility. It has been demonstrated that surfaces capable of preventing plasma protein adsorption could reduce the reactivity of biomaterials with human blood. This motivated a lot of researches on the surface modification of NiTi alloy. In the present work, following heat and alkaline treatment and silanization by trichlorovinylsilane (TCVS), coating of poly (N-vinyl-2-pyrrolidone) (PVP) was produced on the NiTi alloy by gamma ray induced chemical bonding. The structures and properties of modified NiTi were characterized and in vitro biocompatibility of plasma protein adsorption was investigated. The results indicated that heat treatment at 823 K for 1 h could result in the formation of a protective TiO2 layer with “Ni-free” zone on NiTi surface. It was found that PVP was covalently bonded on NiTi surface to create a hydrophilic layer for inhibiting protein adsorption on the surface. The present work offers a green approach to introduce a bioorganic surface on metal and other polymeric or inorganic substrates by gamma irradiation.     

Evolutionary mechanism of b-oriented TS-1 film on porous α-Al2O3 supported chitosan surface in hydrothermal reactions

The acid-base titration, atomic force microscopy (AFM), contact angle technique, energy dispersive X-ray (EDX) and electron probe microanalysis (EPMA) were performed to check the existence of the gel-layer on the chitosan surface after it was dipped in aqueous TPAOH solution as well as in TS-1 synthesis solution. The evolution of TS-1 monolayer and multi-layered film on the chitosan surface was studied using SEM imaging at different stages during hydrothermal reactions. Experimental evidence for the formation mechanism of supported zeolite films and membranes revealed that a gel-layer enriched with TPA cations and TS-1 precursors was first formed on the chitosan surface, followed by the nucleation within the gel-layer especially on the chitosan surface. The nuclei formed on the chitosan surface were further transformed into crystalline particles and TS-1 crystal grains. The nuclei beyond the chitosan surface subsequently grew up, leading to the formation of multi-layered TS-1 film with preferential b-orientation. The result is significant for engineering the microstructure of supported zeolite films and membranes in hydrothermal reactions.     

离心—冷冻法制备梯度孔结构的真皮支架

胶原基真皮支架的结构和性能受多方面因素影响,比如除胶原外的其他主要材料、支架的孔径和孔隙率以及交联度等.采用离心—冷冻法结合冷冻干燥法制备梯度孔结构的真皮支架,表征支架的孔径和孔隙率,并以细胞培养检验其生物相容性,其中采用扫描电镜对上中下3部分支架结构及孔径进行表征,并通过细胞培养生长实验检测该支架材料的细胞粘附性能,以达到表征离心力的影响.结果显示,离心力对支架的微观结构产生了影响,支架的致密程度从下到上有明显的不同,具体表现在孔径上:上层孔径52±27.8μm,中层孔径57±8.7μm,下层孔径49±40.4μm.同时,细胞粘附实验表明,致密的下层更适合细胞的粘附生长.     

封闭Her—2蛋白拮抗碱性成纤维细胞生长因子对人肝癌细胞的粘连效应

目的：探索碱性成纤维细胞生长因子(basic fibroblast growth,bFGF）影响癌细胞粘连的信号传递途径,提供抗癌治疗的线索。方法：以人肝癌细胞系（HepG2）为靶子,明确靶细胞存在Her-2蛋白表达的同时,利用Her-2蛋白抗体封闭靶细胞Her-2蛋白来研究bFGF作为配体与否的细胞粘连效应性。结果：靶细胞HepG2确实具有Her-2蛋白表达;利用抗体封闭靶细胞Her-2蛋白时,靶细胞明显地呈现拮抗bFGF作为配体的细胞粘连加强效应。结论：bFGF对人肝癌细胞粘连性的影响与Her-2基因蛋白介导的信号传递作用有关。     

Regulation of focal adhesion-associated protein tyrosine kinase by both cellular adhesion and oncogenic transformation.

Increasing evidence indicates that the integrin family of cell adhesion receptors can transduce biochemical signals from the extracellular matrix to the cell interior to modulate cell growth and differentiation. We have shown that integrin/ligand interactions can trigger tyrosine phosphorylation of a protein of M(r) 120,000 (pp120), so it is possible that signal transduction by integrins might involve activation of intracellular protein tyrosine kinases as an early event in cell binding to the extracellular matrix. Here we report that pp120 is identical to the focal adhesion-associated protein tyrosine kinase pp125FAK (refs 3, 4). We show that tyrosine phosphorylation of this protein is modulated both by cell adhesion and transformation by pp60v-src, and that these changes in phosphorylation are correlated with increased pp125FAK tyrosine kinase activity. A model is proposed to relate these findings to the molecular basis of anchorage-independent growth of transformed cells.     

壳聚糖对活性染料的脱色效果

比较了3种壳聚糖对活性红BF-DB染料的脱色效果.探讨了壳聚糖用量、pH值、吸附温度、搅拌速度与搅拌时间对染料脱色效果的影响.结果表明,3种壳聚糖对活性红BF-DB染料溶液的最佳脱色工艺为:壳聚糖1、2、3的质量浓度分别为200、200、150 mg/L时,在20℃,pH值为6.0左右的条件下,以350 r/min搅拌10 min,再以150 r/min搅拌15 min,静置2 h,脱色率可达95%以上.分子量和脱乙酰度较大的壳聚糖对活性染料的脱色效果最好.     

壳聚糖对活性染料的脱色效果

比较了3种壳聚糖对活性红BF-DB染料的脱色效果.探讨了壳聚糖用量、pH值、吸附温度、搅拌速度与搅拌时间对染料脱色效果的影响.结果表明,3种壳聚糖对活性红BF-DB染料溶液的最佳脱色工艺为：壳聚糖1、2、3的质量浓度分别为200、200、150 mg/L时,在20℃,pH值为6.0左右的条件下,以350 r/min搅拌10 min,再以150 r/min搅拌15 min,静置2 h,脱色率可达95%以上.分子量和脱乙酰度较大的壳聚糖对活性染料的脱色效果最好.     

纳米仿生骨组织材料的生理响应及生物矿化

利用溶胶－凝胶法合成了两种具有纳米结构的新型高生物活性骨修复及骨组织工程支架材料，并利用体外实验方法（In Vitro)以及X－射线衍射（XRD），扫描电子显微镜（SEM），红外光谱（FTIR），氮气吸附－解吸（BET）和等离子发射光谱（ICP）等技术对材料的显微结构及其在模拟生理溶液（SBF）中的降解过程，表面反应产物及生物矿化机理进行了研究，研究表明：两种溶胶－凝胶材料均具有较高的生物活性；由于化学组成不同，它们在SBF溶液中的离子扩散规律及生物矿化行为有所不同。