具有梯度孔结构特征的聚己内酯多孔支架的3D打印制备及表征

软骨组织工程生物支架材料的内部结构(如孔结构)对于细胞行为有着重要影响。3D打印技术可以实现对支架结构的精确控制。聚己内酯(poly(ε-caprolactone),PCL)是广泛应用的组织工程支架材料,具有良好的生物相容性,支持多种细胞的黏附、增殖和基质分泌。3D打印制备的PCL多孔支架包含相邻三部分,每部分由六层纤维堆积,相邻两层的纤维夹角分别为30、45和60°,而同层中纤维间距为分别为450、400和300μm;力学性能测试梯度支架的杨氏模量在47 MPa左右,与天然软骨组织20 MPa相匹配;微断层扫描和扫描电镜观察支架表面和内部形貌的结构特征,Image J软件对支架特征参数进行量化分析。支架表面和内部形貌规整,呈现孔结构梯度分布,具有良好的孔连通性和57%左右的孔隙率,孔径梯度大小为342~747μm。经细胞接种培养后,应用扫描电镜、CCK8检测和死活染色方法分析支架材料对细胞生长及活性的影响。梯度支架能够很好地支持细胞生长和活性。研究通过对支架材料的设计和制备为软骨组织工程研究奠定了基础。     

组织工程支架材料研究进展

组织工程支架材料在组织工程研究中起中心作用，不仅为特定的细胞提供结构支撑作用，而且还起到模板作用，引导组织再生和控制组织结构。寻找一种既有良好生物相容性和生物降解性又具有特定形状和连通三维多孔结构的支架材料是组织工程的重要方面。本文概述了几种常用的组织工程支架材料，并对组织工程支架材料目前存在的问题作了分析、对其发展趋势进行了展望。     

组织工程支架材料的研究进展

组织工程支架材料在组织工程研究中起中心作用，它不仅为特定的细胞提供结构支撑怍用，而且还起到模板作用，引导组织再生和控制组织结构。因此，寻找一种既有良好生物相容性和生物降解性又具有特定形状和连通三维多孔结构的支架材料是组织工程的一个重要方面。本文主要对组织工程中常用支架材料的研究进展进行了综述．并对组织工程支架材料目前存在的问题作了分析以及对其发展趋势进行了展望。     

脱细胞真皮基质微结构的碱法调控及其细胞相容性

作为组织工程支架材料,脱细胞真皮基质（ADM）孔径小、孔隙率不高、孔隙连通情况不理想,不符合细胞生长对支架材料微结构的理想要求。针对这一问题,选用猪皮为原料,以优化微结构为目的,综合碱处理、酶处理、去污剂处理和盐处理手段制备了一种ADM。扫描电子显微镜分析了碱处理中碱液浓度对ADM微结构的调控作用,MTT法检测了小鼠胚胎成纤维细胞（3T3）在ADM上的生长增殖,共聚焦激光扫描电镜观察了细胞的分布。结果显示：ADM不含细胞,维持了胶原纤维的天然结构,具有连通的三维孔道,孔径约100 μm;随着碱液浓度的增加,孔径与孔隙率增大,孔隙的连通性改善,骨架的形貌由膜状向纤维状转变;细胞在ADM上增殖良好、分布均匀。调节碱处理中碱液浓度可调控ADM微结构,获得微结构和细胞相容性良好的ADM。     

PGA细胞支架在大鼠胰岛体外实验中的应用

应用聚乙醇酸（Polyglycolic acid,PGA）细胞支架与大鼠胰岛细胞共培养,构建胰岛细胞间三维立体的网络结构,观察胰岛细胞在PGA细胞支架三维培养环境中的生存状态。实验结果表明,支架上的胰岛细胞形态良好,细胞数量减少不显著,死亡细胞较少;DTZ胰岛特异性染色胰岛着色显著;AO—PI荧光双染法证实了胰岛细胞活性较强（P〈0．05）;葡萄糖刺激胰岛素释放功能的检测显示,胰岛细胞的胰岛素分泌功能较强,胰岛素分泌指数明显高于对照组,两组间胰岛素释放指数有显著差异（P〈0．05）;扫描电镜下胰岛细胞紧密黏附并包绕在PGA细胞支架上,胰岛细胞呈三维立体生长。研究结果表明,大鼠胰岛在PGA细胞支架上能黏附生长,并具有活性及分泌胰岛素的功能,并可延长胰岛在体外的生存时间。     

微观结构与组织工程丝素支架研究进展

丝素蛋白因其具有良好的生物相容性、生物可降解性以及卓越的力学性能而被广泛应用于组织工程。为了促进丝素支架更利于细胞的黏附和增殖、促进新的细胞外基质生成、组织向内生长以及利于营养物质及代谢产物的运输等,丝素支架微观结构的构建仍是组织工程的一个重大挑战。本文着重围绕丝素支架的微观结构展开,介绍了多孔结构、纤维结构、多孔-纤维结构和水凝胶结构近年来在组织工程中的应用,从不同支架结构制备方法及功能方面并结合作者实验相关工作对比分析了不同支架结构的优势和存在的问题以及对细胞的影响,指出应从分子水平及原子水平上研究天然组织的结构来精准、有效地体外模拟构建组织工程丝素支架。     

纳米纤维实用研究介绍

<正>未来,纳米纤维可以在生物医学的细胞组织材料、药物的释放、过滤材料领域的水处理、离子吸附等方面得到应用。1生物医药(再生医疗)组织再生工程是将细胞/分子生态学和材料化学工程相结合,研究损伤组织的修复或置换。其研究的焦点之一是模仿天然细胞外基质的结构及生物学功能的三维纳米纤维细胞支架材料。有关的静电     

SF/COL/PLCL静电纺丝三维纳米纤维支架与人脐带血间充质干细胞的细胞相容性研究

目的研究SF/COL/PLCL静电纺丝三维纳米纤维支架与人脐带血(human umbilical cord blood,hUCB)间充质干细胞(mesenchymal stem cells,MSCs)的细胞相容性。方法分离、培养hUCBMSCs,并进行传代,取第3代hUCBMSCs,茜素红染色和Von Kossa染色检测其体外诱导成骨分化的能力;流式细胞术检测其表面相关抗原的表达。制备SF/COL/PLCL静电纺丝三维纳米纤维支架,扫描电镜观察其形貌表征,并检测其力学性能。将hUCBMSCs接种于静电纺丝三维纳米纤维支架上,观察细胞在支架上的生长及增殖情况。结果 hUCBMSCs具有成骨诱导分化能力,其表达CD44、CD29、CD90和CD105,不表达CD45和CD34。SF/COL/PLCL复合纳米纤维的纤维形貌良好,随着PLCL含量的增加,纤维的直径和力学性能均逐渐增加。hUCBMSCs能够在三维纳米纤维支架上很好地黏附,并相互连接向周围扩展,三维纳米纤维支架能很好地促进细胞黏附和增殖,与常规培养的细胞相比,差异有统计学意义(P0.05或P0.01),当SF/COL与PLCL的质量比为30∶70时,最有利于细胞的生长。结论 hUCBMSCs能够在SF/COL/PLCL静电纺丝纳米纤维支架上生长、增殖,这种支架材料具有良好的力学性能及细胞相容性,有望成为一种新型组织工程支架材料。     

肝组织工程材料的研究进展

肝组织工程支架材料是肝组织工程学的重要研究内容，是解决肝脏器官严重短缺的关键。目前用于肝组织工程支架材料的主要有天然生物材料和人工合成生物材料。天然类主要包括生物相容性较好的壳聚糖、海藻酸钠等，但其力学性能和可加工性较差；人工合成材料主要包括优良机械性能和可加工性的聚乙酰内脂、聚乳酸-羟基乙酸共聚物等，但其组织相容性较差。如果能利用修饰或者改性的方法，使天然生物材料和人工高分子聚合物扬长避短，则有可能制造出一类兼有良好的力学性能和细胞相容性的生物材料。     

各向异性水凝胶的制备和应用

水凝胶具有类似于生物组织的富水结构,长期以来被认为是人工组织和器官的良好支架。在结构各向异性方面,大多数合成水凝胶与生物体系有本质上的不同。合成水凝胶通常由随机定向的三维聚合物网络组成,而生物系统是由有序分层单元组成的各向异性结构。这种各向异性结构在生物系统中发挥着重要的作用。在此背景下,各向异性水凝胶为探索水凝胶的仿生应用提供了一个切入点。综述了几种重要的各向异性水凝胶,包括具有定向纳米填料的各向异性水凝胶、具有定向聚合物链网络结构的水凝胶、具有定向空腔通道的水凝胶和具有各向异性微组装结构的水凝胶,介绍了各向异性水凝胶的用途和前景,特别是它们的制备、结构和应用。     

Bioinspired design of hybrid composite materials

ABSTRACT

Mimicking the natural design motifs of structural biological materials is a promising approach to achieve a unique combination of strength and toughness for engineering materials. In this study, we proposed a 2D computational model, which is a two-hierarchy hybrid composite inspired by the ultrastructural features of bone. The model is composed of alternating parallel array of two subunits (A & B) mimicking ‘mineralized collagen fibril’ and ‘extrafibrillar matrix’ of bone at ultrastructural level. The subunit-A is formed by short stiff platelets embedded within a soft matrix. The subunit-B consists of randomly distributed stiff grains bonded by a thin layer of tough adhesive phase. To assess the performance of the bioinspired design, a conventional unidirectional long-fiber composite made with the same amount of hard and soft phases was studied. The finite element simulation results indicated that the toughness, strength and elastic modulus of the bioinspired composite was 312%, 83%, and 55% of that of the conventional composite, respectively. The toughness improvement was attributed to the prevalent energy-dissipating damage of adhesive phase in subunit-B and crack-bridging by subunit-A, the two major toughening mechanisms in the model. This study exemplifies some insights into natural design of materials to gain better material performance.     

Effects of Tenascin C on the Integrity of Extracellular Matrix and Skin Aging

Tenascin C (TNC) is an element of the extracellular matrix (ECM) of various tissues, including the skin, and is involved in modulating ECM integrity and cell physiology. Although skin aging is apparently associated with changes in the ECM, little is known about the role of TNC in skin aging. In this study, we found that the Tnc mRNA level was significantly reduced in the skin tissues of aged mice compared with young mice, consistent with reduced TNC protein expression in aged human skin. TNC-large (TNC-L; 330-kDa) and -small (TNC-S; 240-kDa) polypeptides were observed in conditional media from primary dermal fibroblasts. Both recombinant TNC polypeptides, corresponding to TNC-L and TNC-S, increased the expression of type I collagen and reduced the expression of matrix metalloproteinase-1 in fibroblasts. Treatment of fibroblasts with a recombinant TNC polypeptide, corresponding to TNC-L, induced phosphorylation of SMAD2 and SMAD3. TNC increased the level of transforming growth factor-β1 (TGF-β1) mRNA and upregulated the expression of type I collagen by activating the TGF-β signaling pathway. In addition, TNC also promoted the expression of type I collagen in fibroblasts embedded in a three-dimensional collagen matrix. Our findings suggest that TNC contributes to the integrity of ECM in young skin and to prevention of skin aging.     

Influence of ultrasound on diffusion through skin/leather matrix

Leather is a unique porous material, which is composed of a three-dimensional weave of tanned collagen fibre bundles. Collagen is a fibrous protein well organized in the formation of skin as building block. This paper studies the use of ultrasound in improving the diffusion process through porous skin/leather matrix. A diffusion model for leather processing has been proposed taking into account of pore characteristics in leather. Dye diffusion experiments have been carried out with leather and powdered leather to show the influence of ultrasound under two different diffusion conditions. Apparent diffusion coefficient (D) of dye through leather matrix has been calculated from the experimental dye uptake data. The results indicate that the use of ultrasound could achieve, 16.2 and 8.56 times improvement in D value for leather at 50 °C and 30 °C, respectively as compared to 2.99 and 1.55 times for powdered leather. Scanning electron microscopy (SEM) analysis of leather has also been performed which shows that fibre structure and morphology are not affected by the use of ultrasound. This study throws some light on enhanced transport through porous materials of complex nature such as skin/leather using ultrasound.     

Highly elastomeric poly(3-hydroxyoctanoate) based natural polymer composite for enhanced keratinocyte regeneration

A novel nanocomposite material combining the biocompatible, elastomeric, natural, biodegradable homopolymer poly(3-hydroxyoctanoate) (P(3HO)) with hemostatic and antibacterial bioactive glass nanoparticles (n-BG) was developed as a matrix for skin related applications. P(3HO) is a unique member of the family of natural polyhydroxyalkanoate biopolymers. The P(3HO)/n-BG composite films were fabricated using the solvent casting method. Microstructural studies revealed n-BG particles both embedded in the matrix and deposited on the surface, which introduced nanotopography and increased its hydrophilicity. The composite exhibited an increase in the Young’s modulus when compared to the control, yet maintained flexible elastomeric properties. These changes in the surface topography and chemistry of the composite system led to an increase of protein adsorption and cytocompatibility for the seeded human keratinocyte cell line. The results from this study demonstrated that the fabricated P(3HO)/n-BG composite system is a promising novel matrix material with potential applications in skin tissue engineering and wound healing.     

Ceramization and oxidation behaviors of silicone rubber ablative composite under oxyacetylene flame

Silicone rubber ablative composite filled with silica and carbon fibers was prepared and tested using an oxyacetylene torch. After the material was fired, the structure, composition and thermal-oxidative properties of the composite were analyzed. The results showed that a pyrolysis layer, a ceramic layer and a silica layer were formed in turn by decomposition, ceramization and oxidation reactions of the virgin ablative composite. Aromatic carbon was formed in the porous pyrolysis and ceramic layers by the degradation of the silicone rubber matrix, which transformed into inorganic carbon in the zone close to the silica layer. Crystallite growth of silicon carbide, the content of which is 10.2 wt% of the ablative products, is revealed in the ceramic layer. Oxidation of the compounds in the ceramic layer yields a silica layer, which is composed primarily of by silica. The thermo-oxidative stabilities of the ablative layers were better than that of the virgin material as a result of the formation of an inorganic ceramic structure.     

TMC/TMPIP纳滤超薄复合膜的制备

基于哌嗪(PIP)与均苯三甲酰氯(TMC)界面聚合制备纳滤膜的原理,设计并合成了具有支化结构的三亚胺功能基团水相单体--均苯三甲酰哌嗪(TMPIP)盐酸盐,并与TMC界面聚合制得分子结构与TMC/PIP相同的TMC/TMPIP超薄纳滤复合膜。采用傅里叶红外光谱(FTIR)和扫描电镜(SEM)表征了复合膜皮层的化学结构和表面形貌,结果表明在聚砜底膜表面形成了膜厚为100 nm左右的TMC/TMPIP超薄皮层。通过与TMC/PIP复合膜对PEG 200水溶液的分离性能相比较发现,TMC/TMPIP复合膜因其高度的网络化结构和超薄皮层,因而具有更高的截留率和水通量。考察了TMC/TMPIP复合膜对水中不同盐的截留性能,其截留率顺序与TMC/PIP复合膜相同,而通量和截留率均优于后者。     

Preparation and cell compatibility evaluation of chitosan/collagen composite scaffolds using amino acids as crosslinking bridges

In this study, a novel freeze‐gelation method instead of the conventional freeze‐drying method was used to fabricate porous chitosan/collagen‐based composite scaffolds for skin‐related tissue engineering applications. To improve the performance of chitosan/collagen composite scaffolds, we added 1‐ethyl‐3‐(3‐dimethylaminopropyl)‐carbodiimide (EDC) and amino acids (including alanine, glycine, and glutamic acid) in the fabrication procedure of the composite scaffolds, in which amino acid molecules act as crosslinking bridges to enhance the EDC‐mediated crosslinking. This novel combination enhanced the tensile strength of the scaffolds from 0.70 N/g for uncrosslinked scaffolds to 2.2 N/g for crosslinked ones; the crosslinked scaffolds also exhibited slower degradation rates. The hydrophilicity of the scaffolds was also significantly enhanced by the addition of amino acids to the scaffolds. Cell compatibility was demonstrated by the in vitro culture of human skin fibroblasts on the scaffolds. The fibroblasts attached and proliferated well on the chitosan/collagen composite scaffolds, especially the one with glutamic acid molecules as crosslinking bridges, whereas cells did not grow on the chitosan scaffolds. Our results suggest that the collagen‐modified chitosan scaffolds with glutamic acid molecules as crosslinking bridges are very promising biomaterials for skin‐related tissue engineering applications because of their enhanced tensile strength and improved cell compatibility with skin fibroblasts. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007     

Extracellular Matrix Remodeling by Fibroblast-MMP14 Regulates Melanoma Growth

Maintaining a balanced state in remodeling the extracellular matrix is crucial for tissue homeostasis, and this process is altered during skin cancer progression. In melanoma, several proteolytic enzymes are expressed in a time and compartmentalized manner to support tumor progression by generating a permissive environment. One of these proteases is the matrix metalloproteinase 14 (MMP14). We could previously show that deletion of MMP14 in dermal fibroblasts results in the generation of a fibrotic-like skin in which melanoma growth is impaired. That was primarily due to collagen I accumulation due to lack of the collagenolytic activity of MMP14. However, as well as collagen I processing, MMP14 can also process several extracellular matrices. We investigated extracellular matrix alterations occurring in the MMP14-deleted fibroblasts that can contribute to the modulation of melanoma growth. The matrix deposited by cultured MMP14-deleted fibroblast displayed an antiproliferative and anti-migratory effect on melanoma cells in vitro. Analysis of the secreted and deposited-decellularized fibroblast’s matrix identified a few altered proteins, among which the most significantly changed was collagen XIV. This collagen was increased because of post-translational events, while de novo synthesis was unchanged. Collagen XIV as a substrate was not pro-proliferative, pro-migratory, or adhesive, suggesting a negative regulatory role on melanoma cells. Consistent with that, increasing collagen XIV concentration in wild-type fibroblast-matrix led to reduced melanoma proliferation, migration, and adhesion. In support of its anti-tumor activity, enhanced accumulation of collagen XIV was detected in peritumoral areas of melanoma grown in mice with the fibroblast’s deletion of MMP14. In advanced human melanoma samples, we detected reduced expression of collagen XIV compared to benign nevi, which showed a robust expression of this molecule around melanocytic nests. This study shows that loss of fibroblast-MMP14 affects melanoma growth through altering the peritumoral extracellular matrix (ECM) composition, with collagen XIV being a modulator of melanoma progression and a new proteolytic substrate to MMP14.     

Variation of pore structure of organosilicone‐modified skin collagen matrix

The pore structure of skin collagen matrix modified by organosilicone alone, combination of organosilicone and chromium respectively, was investigated mainly through nitrogen adsorption, scanning electron microscopy and fractal analysis. The results indicated that increasing the dosage of organosilicone endowed more numbers of uniform smaller pores, increased porosity in modified collagen matrix and improved thermal stability verified by differential scanning calorimeter analysis. A similar trend was observed after incorporating less amount of chromium to organosilicone modification in the process. It can be presumed that a rigid and stable three‐dimensional silica network structure formed in the interior of the collagen fiber plays a role in fixing the collagen molecular chain, conferring improved hydrothermal stability to the skin matrix. The findings are of great significance to explore chrome‐less and further chrome‐free silicone tanning technology, and are helpful to promote sustainable development of the leather industry. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44831.     

含缺陷复合材料加筋壁板承载能力的数值预测

碳纤维复合材料加筋壁板是飞机结构的典型部件,成型过程中的制造缺陷对其极限承载能力和失效行为具有显著影响,是结构完整性评估的重要内容。通过数值手段开展了3点弯曲载荷作用下含缺陷复合材料加筋壁板的数值分析,重点考虑了缺陷尺寸和位置对结构承载能力的影响。首先基于Abaqus/Standard建立了加筋壁板的三维有限元模型,引入双线性内聚力模型用于描述复合材料加筋壁板的层间失效行为,然后结合文献相关实验数据验证了该模型的有效性,最后基于该有限元模型研究了缺陷尺寸和位置对结构承载能力的影响。结果表明:建立的有限元模型计算结果与文献实验结果吻合;结构的承载能力随着缺陷尺寸的增大而降低,且对蒙皮/桁条界面中部缺陷较为敏感;缺陷的存在导致结构的破坏模式发生转变,但起始裂纹始终发生在界面附近的基体区域。