分级多孔壳聚糖/聚乳酸复合支架的制备及骨修复性能

为了仿生莲藕内部的贯穿大孔结构,以生物相容性好的壳聚糖(CS)作为基质材料,利用冰粒致孔、石蜡模具和冰模具成型3种成型方法制备了分级多孔CS支架材料,然后与力学强度较高的聚乳酸(PLLA)复合,制备网络互穿CS/PLLA复合支架。通过SEM、压缩强度测试和兔股骨髁骨缺损模型对CS/PLLA复合材料的形貌、力学强度和骨修复性能进行了表征。结果表明:利用冰模具制备的CS/PLLA复合支架能可控、批量制备,具有微米-毫米分级多孔结构,大孔孔径约为2mm,内部均匀分布着孔径约为60μm的贯穿微孔,并在微孔内形成密集的PLLA絮状网络结构。干态复合材料的压缩强度和模量分别比纯CS支架的提高了6倍和15倍。体内植入实验结果表明,CS/PLLA复合材料能够促进骨缺损的愈合,并随着新骨的形成,复合材料逐渐被降解吸收。     

半乳糖修饰大孔壳聚糖支架的制备及表征

生物人工肝反应器中肝细胞的数量和功能是能否有效替代已衰竭肝脏功能的关键,与此紧密相关的是细胞支架材料结构和性能的优化.采用冷冻干燥法,制备了大孔壳聚糖支架,孔隙率在90%以上,平均孔径在100～200μm之间.以肝细胞表面去唾液酸糖蛋白受体(asialoglycoprotein receptor,ASGPR)的特异性配体-半乳糖,对材料表面进行糖基化修饰,制备了半乳糖基修饰的大孔壳聚糖支架,肝细胞在其上生长状况良好,细胞培养密度高,为高密度培养肝细胞提供了一种性能优良的支架材料.     

碳纤维/聚乳酸/壳聚糖三元多孔复合支架材料的制备及评价

利用溶液共混法以及冷冻干燥法制备了多孔碳纤维/聚乳酸/壳聚糖(CF/PLA/CS)三元复合生物材料,通过扫描电子显微镜(SEM)观察了其表面形貌特征,并对其细胞相容性进行了评价.实验结果表明,利用上述复合方法制备的三维多孔材料的孔径为20～500μm,孔分布均匀,孔与孔之间相互连通;碳纤维的分散、冷冻干燥温度对材料结构影响较大,随冷冻温度的降低,支架的孔隙变小、变规则,内部结构趋向均一,孔隙率有所降低;该材料与细胞具有较好的相容性,符合组织支架材料的基本要求.     

造孔剂和发泡剂结合法制备氟化羟基磷灰石多孔支架研究

本研究采用添加造孔剂和发泡剂相结合法制备多孔氟化羟基磷灰石, 合成具有大孔与小孔套连、3D方向上分布的多孔支架。通过化学沉淀法制备了氟化羟基磷灰石(FHA)粉体, 以碳酸氢铵为发泡剂、PMMA为造孔剂, 通过烘干和烧结工艺制备孔洞均匀且相互贯通、坯体致密的多孔支架。经X射线衍射分析, 支架的相组成是FHA和β-TCP。SEM观察结果显示支架孔洞形貌规整、大孔尺寸100~400 µm, 小孔尺寸10~50 µm。以HA和β-TCP为原料对造孔方法的普适性进行验证, 并对支架孔的形成及其影响因素进行了分析。     

双交联明胶-壳聚糖复合人工真皮支架的制备及其性能研究

采用1-乙基-(3-二甲基氨基丙基)碳化二亚胺盐酸盐(EDC.HCl)和三聚磷酸钠(STPP)作为共价-离子双交联剂交联制备了明胶-壳聚糖(gel-CS)复合人工真皮支架。通过FT-IR和SEM对复合多孔支架结构及形貌进行表征,同时对复合多孔支架的孔隙率、平均孔径、溶胀性能和降解性能进行了研究。研究结果表明,明胶和壳聚糖两相间成功地发生了交联反应,形成了具有贯通孔结构和良好孔隙率的复合多孔支架。该支架平均孔径在136.1～182.9μm之间,且随着壳聚糖含量的增加,孔径及孔隙率随之降低;溶胀性能研究发现,相较于单一共价交联方法,采用双交联法制备的支架溶胀率有所降低,再次印证双交联法制备的支架其交联度较单一共价交联的高;酶降解实验表明,固定STPP含量,随着EDC含量增加,复合支架的降解性能越好,而EDC含量一定,则STPP含量为0.5%时,复合支架具有最好的降解性能。     

海藻酸钙水凝胶/聚乳酸复合材料的制备与性能

通过化学发泡-冷冻干燥-粒子滤出复合法制备聚乳酸(PLLA)大孔支架, 然后在大孔内以海藻酸钠(SA)、碳酸钙、葡萄糖酸内酯(GDL)为原料, 通过原位相转变制备海藻酸钙水凝胶/聚乳酸复合材料(CA/PLLA); 分别利用SEM、压缩强度测试和细胞培养对CA/PLLA支架的形貌、力学性能及生物相容性进行了研究。结果表明: PLLA具有直径小于2 mm、孔道相互连通的孔洞, 且在大孔中能够形成均匀的CA。CA/PLLA复合材料的压缩强度(2.74 MPa)远大于单一的海藻酸钙水凝胶的压缩强度(0.10 MPa)。在CA/PLLA复合支架中, 软骨细胞呈簇状圆形生长状态, 与其在天然软骨陷窝里生长状态一致。这种软硬结合、天然与合成高分子杂化的CA/PLLA复合材料的力学强度和生物相容性同时得到提高, 可进一步作为骨和软骨修复材料研究。     

纳米非计量磷灰石/聚合物复合支架的制备和性能研究

采用快速成形法制备了孔径和孔隙率可控、大孔互相贯通的纳米缺钙羟基磷灰石(cd-HA)与聚己内酯(PCL)复合材料多孔支架,并对复合支架的微结构进行了表征.通过细胞培养和体内动物实验研究了该支架的生物学性能.结果表明:复合材料的亲水性和细胞粘附率随磷灰石含量增加而提高;成骨细胞在复合支架上的增殖明显高于纯PCL;μ-CT和组织学分析结果显示,新骨在支架的表面形成并长入其中.相互贯通的多孔支架促进了细胞的增殖和新骨长入支架内部.cd-HA/PCL复合材料支架具有很好的生物相容性,在组织工程领域中有潜在的应用前景.     

用海绵浸渍法制备多孔β-TCP生物材料

利用海绵浸渍方法制备出具有优良生物降解特性的β-Ca3(PO4)2(β-TCP)多孔陶瓷材料，采用图象分析和扫描电镜分析了样品内部孔结构特点，实验结果表明，这种材料不仅孔径大、气孔率高，而且孔洞之间相互连通，构成网状结构，从而非常有利于材料植入体内后生物降解并诱导新骨组织长入。     

超临界CO_2诱导相分离法工艺条件对左旋聚乳酸多孔支架孔形貌和结构的优化调控

采用超临界CO_2诱导相分离法制备了左旋聚乳酸多孔支架材料,研究了原料的分子量、超临界CO_2的压力和温度对制备多孔材料的孔结构如孔隙率、大孔孔径及内连通孔径的影响和优化调控。与传统方法所制得的材料相比较,制备的多孔材料杂质少,分布均匀,孔洞表面粗糙,而且在大孔之间布满了直径为5~20μm的微孔。同时通过SEM、FT-IR以及DSC对优化条件制备的产品表面及截面结构、形貌及理化性质进行了系统分析研究。结果表明,制备的支架材料的孔结构和形貌可以通过对左旋聚乳酸原料的分子量、处理样品的压力和温度等工艺参数优化选择来对产品结构进行优化调控而适合不同生物及医学应用需要。     

β-磷酸三钙/壳聚糖复合支架的制备及其对成骨细胞生长的影响

采用冷冻萃取和冷冻凝胶法制备了β-磷酸三钙/壳聚糖(-βTCP/CS)复合支架,并采用SEM、XRD、FTIR和万能材料试验机对其性能进行表征。研究结果表明,复合支架的孔隙率85%,且随-βTCP含量的增加而减小。力学性能的测试结果显示,当壳聚糖含量为30%时,复合支架的抗压强度最大(1.73MPa)。同时SEM结果表明壳聚糖与-βTCP的比值为30∶70时,复合支架的孔径在200～500μm之间。将成骨细胞MC-3T3-E1接种于-βTCP/CS复合支架上,培养7d后,发现细胞在-βTCP/CS复合支架上能够很好地粘附、生长和分化,即所制备的复合支架具有良好的细胞相容性。     

Effects of designed tubular porosity on compressive strengths of honeycomb ceramics

Three-dimensional honeycomb porous ceramics were fabricated using the fused deposition process. The structures were designed to have a controlled interconnected porosity. Elastic interactions between pores of honeycomb ceramic materials were then evaluated for different pore parameters using the finite element modeling (FEM) approach. The FEM results were compared experimentally with the compressive failure strengths of the honeycomb ceramics. The effect of relevant pore parameters on the compressive strength was studied. An analytical fracture mechanics based approach is presented for comparison with the FEM to reflect on the relative importance of pore parameters for different volume fractions of porosity. A detailed insight is also provided into the interrelation between various porosity parameters, mechanical behavior and design of these structures.     

Highly porous hydroxyapatite scaffolds with elongated pores using stretched polymeric sponges as novel template

This study reports a simple way of improving the compressive strength of highly porous hydroxyapatite (HA) scaffolds by adopting elongated polymeric sponges as a novel template. In this method, as-received polymeric sponges with isotropic pores were stretched uniaxially to 50% elongation at 200 °C for 2 h, and then coated with a HA slurry. The HA-coated sponges were heat-treated at 800 °C for 3 h to remove the polymeric sponges and at 1250 °C for 3 h to sinter the HA walls. The fabricated samples showed a highly anisotropic pore structure with elongated pores parallel to the direction of the elongation of the polymeric sponge. This simple method allowed a highly porous scaffold to have a high compressive strength of 3.8 ± 0.1 MPa at a porosity of 76% when tested parallel to the direction of pore elongation.     

Coating of collagen on a poly(l-lactic acid) sponge surface for tissue engineering

Porous scaffolds play important roles in tissue engineering. Biodegradable synthetic polymers, such as poly(l-lactic acid) (PLLA), frequently are used in the preparation of porous scaffolds. Pretreating the surface of a PLLA porous scaffold is required to increase its wettability for smooth cell seeding due to the hydrophobic property of the scaffold's surface. In this study, a simple coating method was used to modify the surface of the PLLA sponges. The coating method included three steps: filling the PLLA sponge pores with collagen aqueous solution, centrifuging to remove excess collagen, and, finally, freeze-drying. Compared with the uncoated PLLA sponge, the collagen-coated PLLA sponge demonstrated both improved wettability and high water absorption. Cells were smoothly seeded in the collagen-coated PLLA sponges by dropping a cell suspension solution onto the sponges. Cells adhered to the collagen-coated sponge and were distributed homogeneously throughout the collagen-coated PLLA sponge.     

有机硅交联剂对硅树脂/聚苯乙烯多孔复合材料性能的影响

以苯乙烯(St)为单体,含甲基丙烯酰氧基丙基的有机硅树脂(MTQ)为交联剂,采用高内相比乳液模板(HIPE)法制备了蜂窝状、低密度及高孔隙率的MTQ/聚苯乙烯(PS)多孔复合材料,研究了MTQ对聚合物多孔复合材料微观结构、压缩性能及热稳定性的影响。结果表明:MTQ/PS多孔复合材料的泡孔呈立体球形且泡孔壁上有丰富的互连孔,相互贯通性良好,泡孔直径为2~9μm,互连孔的孔径大小介于0.35~1.85μm;所得多孔材料孔隙率可控,总孔隙率最高可达92%;该多孔复合材料的压缩强度为0.28~0.74 MPa,压缩模量为4.86~13.54MPa。当MTQ与St的质量比为30:100时,可获得泡孔直径较小、互连孔道较窄、压缩性能和热稳定性较好的MTQ/PS多孔复合材料。      

Intact collagen and atelocollagen sponges: Characterization and ESEM observation

In this study we have investigated the chemical–physical and morphological properties of intact and atelocollagen sponges used for tissue engineering. The porous sponges were prepared by lyophilization and their physico-chemical characteristics (water binding capacity, denaturing temperature, amino group content) were investigated. Considering the importance of the “in vivo” interactions between these sponges and the tissue, our attention was addressed (a) to clarify the relationships between the morphology and the amount of water absorbed and (b) to evaluate the influence of pepsin-alkaline treatment on the reorganization of the atelocollagen fibres. Conventional scanning electron microscopy (SEM) and environmental scanning electron microscopy (ESEM) were employed to study the morphology and wetting behaviour of the intact and atelocollagen sponges. The observations by SEM indicated remarkable differences both in the structure and dimension of the pores between intact and atelocollagen sponges. At the data are related to a different water binding capacity. However, the ESEM observations, achieved by changing the relative humidity in the operative chamber, demonstrated that the water adsorbed can be removed with major difficulty from atelocollagen sponges than from intact ones.     

Improving the cellular invasion into PHEMA sponges by incorporation of the RGD peptide ligand: The use of copolymerization as a means to functionalize PHEMA sponges

A monomer that contained the RGD ligand motif was synthesized and copolymerized with 2-hydroxyethyl methacrylate using polymerization-induced phase separation methods to form poly(2-hydroxyethyl methacrylate)-based hydrogel sponges. The sponges had morphologies of aggregated polymer droplets and interconnected pores, the pores having dimensions in the order of 10 μm typical of PHEMA sponges. RGD-containing moieties appeared to be evenly distributed through the polymer droplets. Compared to PHEMA sponges that were not functionalized with RGD, the new sponges containing RGD allowed greater invasion by human corneal epithelial cells, by advancing the attachment of cells to the surface of the polymer droplets.     

Hydrophilic sponges based on 2-hydroxyethyl methacrylate Part VII: Modulation of sponge characteristics by changes in reactivity and hydrophilicity of crosslinking agents

Despite previous unsuccessful attempts to use hydrated poly(2-hydroxyethyl methacrylate) sponges as implantable biomaterials, recently these materials became important as peripheral components in an artificial cornea of the core-and-skirt design. The low mechanical strength of sponges prompted this study on possible improvement of tensile properties by the use of a variety of crosslinking agents. Three vinylic (dimethacrylates) and two allylic compounds were used at different concentrations (0.1 to 2% (mol)) as crosslinking agents in the production of sponges. Their influence on the mechanical properties, porous morphology and swelling behavior of resulting sponges was evaluated. The onset of phase separation during polymerization was also measured by visible spectrophotometry. The results suggested an inherent heterogeneity of sponges, i.e. pores of non-uniform size and structural inhomogeneities. While the effects of changes in the nature and concentration of crosslinking agents on the equilibrium water content of sponges were ambiguous, some of the mechanical properties, such as toughness and elasticity, were improved by crosslinking with allylic agents. Scanning electron microscopic examination suggested that the mechanical effect is related to the variation of size of the polymer particles constituting the sponge structure, which was proved to be dependent upon the onset of phase separation during polymerization. ©2000 Kluwer Academic Publishers     

Production of porous poly(ε-caprolactone)/silica hybrid membranes with patterned surface pores

This paper reports a novel way of synthesizing porous poly(ε-caprolactone) (PCL)/silica hybrid membranes with a patterned surface pores by casting a mixture containing a PCL solution and sol-gel derived silica sol at room temperature. When the initial TEOS content in relation to the PCL content in the mixture was ≥ 20 vol.%, a highly porous structure containing patterned surface pores, ~ 40-70 μm in size, was formed successfully. The silica phase was hybridized uniformly with the PCL polymer without any noticeable phase separation, as confirmed by energy dispersive X-ray spectroscopy (EDS). The porosity increased from 4.5 to 39.2 vol.% with increasing initial TEOS content from 0 to 40 vol.%. However, the hybrid membranes prepared at an initial TEOS content of ≥ 20 vol.% showed a reasonably high tensile strength and elastic modulus, ranging from 7.6 to 5.0 MPa and 79 to 51 MPa, respectively.     

Facilitated and site-specific assembly of functional polystyrene microspheres on patterned porous films

Functional patterned materials have received considerable attention because of their potential applications in biochips, sensors, and optical or electronic materials. Here, we report a versatile approach to functional patterned films based on facilitated and site-specific assembly of microspheres. This method includes the hierarchical formation of honeycomb-patterned porous films from amphiphilic block copolymers and the assembly of functional polystyrene microspheres driven by the gravity and the electrostatic interaction. Polystyrene microspheres containing carboxyl groups with a narrow size distribution were synthesized by dispersion polymerization. Honeycomb-patterned porous films were prepared from polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) (PS-b-PDMAEMA) by the breath figure method and then quaternized. We found that direct deposition of the microspheres on the patterned films reaches high filling ratio only when using ethanol dispersions that can wet the film pores. Plasma treatment of the films improves the hydrophilicity and introduces charged species to the external surface as well as the pore surface, leading to nonspecific assembly of microspheres. Negatively charged microspheres dispersed in buffer solution show a facilitated and site-specific assembly on the quaternized film. The electrostatic interaction as well as the gravity facilitates the assembly and the suborder arrangement of the hydrophilic PDMAEMA block around the pores is responsible for the site-specific assembly. In addition, we demonstrate the applicability of this method in preparing photoluminescent patterns by the assembly of porphyrinated microspheres, which is useful in various fields such as intelligent sensing.     

由蜂窝状结构TBT/PMMA杂化膜制备有序孔结构的TiO_2膜

采用BreathFigures法制备了蜂窝状结构的TBT/PMMA前驱体膜,气相水热处理(VPH)、热裂解前驱体膜,制备了TiO2有序孔结构膜,探讨了气相水热处理、经热裂解去除前驱体膜中聚合物成分过程中结构的变化,结果表明VPH过程中TBT水解成氢化氧化钛水合物,形成完善的-Ti-O-网络结构,抵御了高温热裂解去除聚合物过程中"液态化"聚合物的影响,最终得到有序孔结构的TiO2膜.同未经水热处理而直接热裂解得到的TiO2膜相比,有序孔结构的TiO膜紫外光电化学响应显著提高,其光电流密度约为前者的3倍.