Self-supporting nanoporous alumina membranes as substrates for hepatic cell cultures

Membranes made from nanoporous alumina exhibit interesting properties for their use in biomedical research. They show high porosity and the pore diameters can be easily adjusted in a reproducible manner. Nanoporous alumina membranes are thus ideal substrates for the cultivation of polar cells (e.g., hepatocytes) or the establishment of indirect co-cultures. The porous nature of the material allows supply of nutrients to both sides of adherent cells and the exchange of molecules across the membrane. However, it is well-known that surface features in the nanometer range affect cellular behavior. In this study, the response of HepG2 cells to nanoporous alumina membranes with three different pore diameters, ranging from 50 to 250 nm, has been evaluated. The cellular interactions with the nanoporous materials were assessed by investigating cell adhesion, morphology, and proliferation. Cell functionality was measured by means of albumin production. The membranes supported good cell adhesion and spreading. Compared to tissue culture plastic, the cells on the porous substrates developed distinct focal adhesion sites and actin stress fibers. Additionally, electron microscopical investigations revealed the penetration of cellular extensions into pores with diameters bigger than 200 nm. Furthermore, cell proliferation significantly increased with an increase in pore diameter, whereas the albumin production followed a reverse trend. Thus, it seems to be possible to direct cellular behavior of HepG2 cells growing on nanoporous alumina by changing the pore diameter of the material. Hence, nanoporous alumina membranes can be useful culture substrates to develop new approaches in the field of liver tissue engineering.     

血透氧化铝透析膜的生成及膜的特性实验研究

研究氧化铝膜生成的不同反应条件与膜孔特性之间的关系,以探讨符合透析膜结构特性的氧化铝膜最佳生成条件。分别以3%硫酸、5%硫酸和2.7%草酸为电解液,反应温度恒定在0℃、反应时间为48h,在不同的电压条件下,将高纯度铝箔氧化生成氧化铝膜。用扫描电镜观察、测定膜的孔径,有效多孔和多孔性。测定氧化铝膜对水的传导力,评估膜的选择通透性。实验结果显示:在我们的实验条件下,能稳定地生成膜孔孔径均匀、排列整齐规则的氧化铝膜。在相同的电解液中,随着电压的增加,生成氧化铝膜的孔径和多孔性显著增大(P<0.05),有效多孔性显著减小(P<0.05)。在3%和5%硫酸电解液中氧化生成的氧化铝膜的孔径比在2.7%草酸中生成的膜孔径小。本实验条件下生成的氧化铝膜对水的传导力比目前临床上使用的一些透析器膜的水传导力大。研究结果表明,生成符合透析膜结构特性的氧化铝膜的最佳反应条件是以3%硫酸或5%硫酸为电解液、反应温度0℃、反应时间48h、反应电压12.5~17.5V。     

Characterization of hemophan hemodialysis membranes by thermoporometry.

A new wet-state membrane characterization method, thermoporometry, was used to study the effect on membrane structure of commonly used sterilization methods for artificial kidney membranes. The porosity and pore size distribution of differently sterilized hollow fiber Hemophan hemodialysis membranes were determined. Also the effect of a glycerol treatment (before sterilization) on porosity and pore size distribution after sterilization was studied. Hemophan was found to have a pore size distribution of pores with radii between 1.5 and 12 nm. Most of the samples had a maximum pore volume at a pore radius of 2.5 nm, only the steam sterilized and non glycerol treated sample had a maximum pore volume at 1.5 nm. The porosity was found to vary between 14 and 31% and was dependent on the applied treatment.     

Membranes for biohybrid liver support: the behaviour of C3A hepatoblastoma cells is dependent on the composition of acrylonitrile copolymers

Co-polymers based on acrylonitrile, N-vinylpyrrolidone, aminoethylmethacrylate and sodium methallylsulfonate were used to prepare flat membranes by phase inversion. The surface properties of membranes were characterised by water contact angle measurements, atomic force microscopy and X-ray photoelectron spectroscopy (XPS). Membrane permeability was estimated by porosity measurements with water as test liquid. Human C3A hepatoblastoma cells were plated on these materials. Cell-material interaction was characterised by overall cell morphology, formation of focal adhesion contacts and intercellular junctions. Furthermore, cell proliferation was measured and compared with the functional activity of cells as indicated by 7-ethoxycoumarin-O-deethylation. More hydrophilic materials reduced spreading of cells, formation of focal adhesion and subsequent proliferation while homotypic cell adhesion was facilitated in correlation with stronger expressions of intercellular junctions and improved functional activity. In contrast, membranes with stronger adhesivity enhanced cell proliferation but reduced the functional activity of cells. It was concluded that the co-polymerisation of acrylonitrile with hydrophilic co-monomers, such as N-vinylpyrrolidone, could be used to tailor membrane materials for the application in biohybrid liver support systems.     

Fabrication and evaluation of porous 2,3-dialdehydecellulose membrane as a potential biodegradable tissue-engineering scaffold

A simple, novel method to produce porous 2,3-dialdehydecellulose (DAC) membranes as a potential tissue-engineering scaffold has been developed from methylolcellulose by the simultaneous water-induced phase separation and sodium chloride salt leaching techniques, followed by oxidation with sodium periodate in water. Membrane pores increased in size with increasing weight or particle size of the sodium chloride salt. The porosity of the membrane was not affected by the salt particle size, but it increased with an increase in the salt weight to 60%. At higher salt weight percentages, no significant change in the membrane porosity was observed. The oxidation step had no effect on the membrane porosity or pore size. All membranes with a porosity value ranging between 87 and 93% showed interconnected porous structures. The use of these membranes as a potential tissue-engineering scaffold was evaluated with the use of human neonatal skin fibroblast cells. Confocal microscopy showed cell attachment and spreading on these membranes. Immunohistochemical tests revealed the presence of collagen type III and fibronectin, indicating that the cells were viable and formed the extracellular matrix. In conclusion, the DAC membrane supports cell adhesion and proliferation and hence shows potential to be used as a tissue-engineering scaffold.     

Increased osteoblast adhesion on physically optimized KRSR modified calcium aluminate

Calcium aluminate (CA) is a porous biocompatible material easily cast at room temperature. Through this casting process, the average surface pore size of CA was varied from an average of 100 to 290 microns. The optimal surface pore size of the hydrated CA for cell viability was determined to be 100 microns. Further, a three step-solution deposition technique was developed to covalently immobilize cell adhesion peptides, RGD, and KRSR to the CA surface. Cell adhesion for 1-, 4-, and 7-day time periods was tested with primary osteoblasts and NIH 3T3 fibroblasts. Both peptides were found to increase fibroblast adhesion to the CA surface. However, only KRSR increased osteoblast adhesion to the surface of the CA, which may aid in bone formation after implantation.     

A method for evaluating the influence of porosity on the early reactions of blood with materials.

A method is presented for evaluating the influence of porosity on the early reactions of blood with polymer membranes of cellulose acetate and polyethersulfone with two different pore sizes, 0.1-0.2 microm and 0.8 microm. A system of two phases consisting of capillary blood and Dulbecco's phosphate buffered saline was constructed. Platelet adhesion and exposure of thrombospondin was examined by immunofluorescence. Platelet adhesion was higher on the membrane with 0.8 microm pore size. Leukocyte adhesion and viability was measured by fluorescein diacetate/propidium iodide staining, and the respiratory burst response to PMA and opsonized zymosan was measured by chemiluminescence. Leukocyte viability was higher on the membranes with 0.8 microm pore size and higher on the cellulose membrane for exposures upto 2 h. After 3 h the leukocyte viability was highest on the polyethersulfone membrane with a pore size of 0.8 microm. The respiratory burst response of membrane-adhering leukocytes could not be triggered by opsonized zymosan on any of the tested membranes. A response was seen after stimulation with PMA of cells adhering to the cellulose membrane with a pore size of 0.8 microm.     

Nano- and sub-micron porous polyelectrolyte multilayer assemblies: Biomimetic surfaces for human corneal epithelial cells

In vivo, corneal epithelial cells adhere on basement membranes that exhibit porosity on the nanoscale with the diameters of pores and fibers ranging from 20 to 200 nm. Polyelectrolyte multilayers with porosity ranging from the nano to the microscale were assembled to mimic the pore sizes of corneal membranes in vivo. The average pore diameter was found to be 100 nm and 600 nm for the nanoporous and sub-micron porous films respectively. In this study, a purely physical feature, specifically, porosity, provided cues to human corneal epithelial cells. Porous surfaces that exhibited either 100 nm or 600 nm pore diameters supported corneal cell adhesion, however, nanoscale porosity significantly enhanced corneal epithelial cellular response. Corneal epithelial cell proliferation and migration speeds were significantly higher on nanoporous topographies. The actin cytoskeletal organization was well defined and vinculin focal adhesions were found in cells presented with a nanoscale environment. These trends prevailed for fibronectin-coated surfaces as well suggesting that for human corneal epithelial cells, the physical environment plays a defining role in guiding cell behavior.     

In vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate

This study was aimed at investigating the in vitro biocompatibility of a novel membrane of the composite poly(vinylidene-trifluoroethylene)/barium titanate (P(VDF-TrFE)/BT). Osteoblastic cells were obtained from human alveolar bone fragments and cultured under standard osteogenic condition until subconfluence. First passaged cells were cultured on P(VDF-TrFE)/BT and expanded polytetrafluoroethylene (e-PTFE--control) membranes in 24-well plates. Cell adhesion and spreading were evaluated at 30 min, and 4 and 24 h. For proliferation assay, cells were cultured for 1, 7, and 10 days. Cell viability was detected by trypan blue at 7 and 10 days. Total protein content and alkaline phosphatase (ALP) activity were measured at 7, 14, and 21 days. Cultures were stained with Alizarin red at 21 days, for detection of mineralized matrix. Data were compared by ANOVA and Student t test. Cell attachment (p = 0.001), cell number (p = 0.001), and ALP activity (p = 0.0001) were greater on P(VDF-TrFE)/BT. Additionally, doubling time was greater on P(VDF-TrFE)/BT (p = 0.03), indicating a decreased proliferation rate. Bone-like nodule formation took place only on P(VDF-TrFE)/BT. The present results showed that both membranes are biocompatible. However, P(VDF-TrFE)/BT presented a better in vitro biocompatibility and allowed bone-like nodule formation. Therefore, P(VDF-TrFE)/BT could be an alternative membrane to be used in guided tissue regeneration.     

Clinical investigation of the role of membrane structure on blood contact and solute transport characteristics of a cellulose membrane

Regenerated cellulose membranes contain cellulose chains with crystalline and amorphous regions in the direction of extrusion. A study was undertaken to investigate if reduced contact surface arising from alteration of pore size alters biocompatibility (complement activation (C3a and C5a) and neutropenia) and solute transport. The average pore size for the membrane studied (RC HP400A) was 7.23 compared to 2.76 nm for the standard membrane (Cuprophan). C3a levels rose to 6861+/-1595 compared to 2723+/-1228 ng/ml for Cuprophan at 15 min after initial blood contact (P < 0.0001). C5a levels also rose to 30.1+/-11.9 compared to 21.3+/-6.6 ng/ml for Cuprophan (P = 0.18). Both fractions gradually returned to baseline levels thereafter. Circulating white cell count fell rapidly over the same time period to 39+/-17% of the baseline value by 15 min and was similar to Cuprophan (27.5+/-11.2%) (P = 0.25). A small (< 10%) change in platelet numbers was noted for both membranes. Removal of urea (60 Da) was independent of pore size; however, the RC HP400A removed r2 microglobulin (11818 Da). These findings indicate that pore distribution fails to influence material-induced complement activation but influences large solute transport.     

In vitro chondrocyte behavior on porous biodegradable poly (e-caprolactone)/polyglycolic acid scaffolds for articular chondrocyte adhesion and proliferation

In this study, poly(e-caprolactone)/polyglycolic acid (PCL/PGA) scaffolds for repairing articular cartilage were fabricated via solid-state cryomilling along with compression molding and porogen leaching. Four distinct scaffolds were fabricated using this approach by four independent cryomilling times. These scaffolds were assessed for their suitability to promote articular cartilage regeneration with in vitro chondrocyte cell culture studies. The scaffolds were characterized for pore size, porosity, swelling ratio, compressive, and thermal properties. Cryomilling time proved to significantly affect the physical, mechanical, and morphological properties of the scaffolds. In vitro bovine chondrocyte culture was performed dynamically for 1, 7, 14, 28, and 35 days. Chondrocyte viability and adhesion were tested using MTT assay and scanning electron microscopy micrographs. Glycosaminoglycan (GAG) and DNA assays were performed to investigate the extracellular matrix (ECM) formation and cell proliferation, respectively. PCL/PGA scaffolds demonstrated high porosity for all scaffold types. Morphological analysis and poly(ethylene oxide) continuity demonstrated the existence of a co-continuous network of interconnected pores with pore sizes appropriate for tissue engineering and chondrocyte ingrowth. While mean pore size decreased, water uptake and compressive properties increased with increasing cryomilling times. Compressive modulus of 12, 30, and 60 min scaffolds matched the compressive modulus of human articular cartilage. Viable cells increased besides increase in cell proliferation and ECM formation with progress in culture period. Chondrocytes exhibited spherical morphology on all scaffold types. The pore size of the scaffold affected chondrocyte adhesion, proliferation, and GAG secretion. The results indicated that the 12 min scaffolds delivered promising results for applications in articular cartilage repair.     

The effect of surface roughness of microporous membranes on the kinetics of oxygen consumption and ammonia elimination by adherent hepatocytes.

In membrane hybrid liver support devices (HLSDs) using isolated hepatocytes where oxygen is transported only by diffusion to the cells, about 15-40% of the cell mass is likely to be in direct contact with the semipermeable membranes used as immunoselective barriers: quantitative effects of membrane surface properties on the kinetics of hepatocyte metabolic reactions may also affect HLSD performance. In this paper, we report our investigation of the effects of surface morphology of two microporous commercial membranes on the kinetics of oxygen consumption and ammonia elimination by primary hepatocytes in adhesion culture. Isolated rat hepatocytes were cultured on polypropylene microporous membranes with different surface roughness and pore size in a continuous-flow bioreactor whose fluid dynamics was optimized for the kinetic characterization of liver cell metabolic reactions. Collagen-coated membranes were used as the reference substratum. Hepatocyte adhesion was not significantly affected by membrane surface morphology. The rates of the investigated reactions increased with ammonia concentration according to saturation kinetics: the values of kinetic parameters Vmax and K(M) increased as cells were cultured on the membrane with the greatest membrane surface roughness and pore size. For the reaction of oxygen consumption, Vmax increased from 0.066 to 0.1 pmol h(-1) per cell as surface roughness increased from 70 to 370 nm. For the kinetics of ammonia elimination. K(M) increased from 0.23 to 0.32 mM and Vmax increased from 1.49 to 1.79 pmol h(-1) per cell with membrane surface roughness increasing from 70 to 370 nm. Cells cultured on collagen-coated membranes consistently yielded the highest reaction rates. The Vmax values of 0.18 and 2.84 pmol h(-1) per cell for oxygen consumption and ammonia elimination, respectively, suggest that cell functions are also affected by the chemical nature of the substratum.     

Novel apatite fiber scaffolds can promote three-dimensional proliferation of osteoblasts in rodent bone regeneration models

We have successfully synthesized hydroxyapatite fibers via a homogenous precipitation method. Using these hydroxyapatite fibers, we have produced the apatite fiber scaffolds (AFS) with well-controlled pore sizes (porosity above 95%). The AFS is relatively simple to synthesize, and its porosity and pore size are controllable. The usefulness of AFS as a scaffold for bone regeneration was evaluated by (1) seeding and culturing cells in the AFS in vitro, (2) implanting the AFS seeded with cells inside the subcutaneous tissue of mice. The AFS had biocompatibility to support cell adhesion, proliferation, and differentiation. Ectopic bone formation could be formed in the AFS at 12 weeks after implantation into the subcutaneous tissue. Because of its high interpore connection, pore diameters, and porosity, it was believed that AFS was an effective scaffold that provided a three-dimensional cell culture environment. In both in vitro and in vivo environments, the more porous AFS was more advantageous in cell proliferation, cell adhesion, proliferating capacity, robust cell differentiation, ultimately inducing bone ingrowth inside the scaffolds.     

Vascular cell viability on polyvinyl alcohol hydrogels modified with water-soluble and -insoluble chitosan

Polyvinyl alcohol (PVA) hydrogels blended with chitosan or other biological macromolecules have shown promise for cell culture and tissue engineering. This study investigates the attachment and growth of bovine aortic endothelial (BAEC) and smooth muscle cells (BASMC) on the PVA hydrogels modified with water soluble and water insoluble chitosan. Cell adhesion on the surface of the membranes was examined by phase contrast microscopy while cell morphologies were studied using immunocytochemistry staining with EC and SMC specific biomarkers (F-actin and alpha actin respectively). Cells cultured on 6% PVA, 0.4% chitosan (water soluble and insoluble) hydrogel membranes displayed excellent adhesion and spreading characteristics, in addition to negligible cell structural morphological changes in comparison to a polystyrene control. Similar vascular cell adhesion features were apparent on PVA membranes blended with water-soluble and -insoluble chitosan. Fluorescent activated cell sorter (FACS) analysis was used to determine BAEC and BASMC proliferation and cell viability. Apoptotic levels in BAEC after 7 days were 12.8% +/- 2.5% on the PVA- chitosan WS-1 membrane and 10.1% +/- 1.5% on the control well (n = 3) while comparable results were also noted for BASMC. Equivalent proliferative activity was apparent for BAEC on the control and PVA-chitosan membrane after 7 days, while BASMC showed increased proliferative activity on the membranes. These results indicate that the PVA-chitosan blended hydrogel membranes show promise for cell culture and tissue engineering applications.     

Characterization of the insertion of Pseudomonas exotoxin A into membranes.

Pseudomonas aeruginosa exotoxin A (PTx) is an extremely potent inhibitor of protein synthesis, similar to diphtheria toxin in its mode of action. It is synthesized in precursor form and secreted as an Mr 66,583 protein lacking a 25-amino acid leader sequence. While the primary sequence and the nature of the enzyme activity that leads to inactivation of elongation factor 2 are known, the mechanism of PTx internalization remains obscure. To elucidate the entry pathway, we examined PTx-membrane interactions using vesicle targets of defined lipid composition. Insertion was monitored with an intramembranous photoreactive probe; pore formation was determined from liposomal swelling rates. Our results show that the efficiency of PTx binding to vesicles increases dramatically with decreasing pH. In general, the insertion efficiency correlated with the binding efficiency. At pH 4, we noted a slight decrease in binding below the melting point (23 degrees C) of the target vesicles. Not only was PTx able to insert into frozen bilayers, but the efficiency of penetration at 0 degrees C was actually somewhat higher than expected based on binding efficiency. Liposome swelling assays analyzed by the Renkin equations indicated that PTx-liposomes made at pH 4 were permeable to solutes up to 2.8 nm in diameter. Pores of a similar size were found when the liposomes were made at pH 7, but the efficiency of pore formation at this pH was very low. Chymotrypsin fragmentation profiles of PTx depended on incubation conditions, e.g., pH, presence of NAD, reducing agents, and membranes. Liposomes containing PTx cleaved at pH 4 displayed up to 40-fold more pore activity than liposomes containing uncleaved PTx or PTx cleaved at pH 7. Pore activity at pH 7 was negligible. Addition of reducing agents caused a 50 to 60% increase in pore activity. Cleaved toxin was active in target membrane insertion even at 0 degrees C, and all of the major fragments were photolabeled.     

In vitro and in vivo characteristics of PCL scaffolds with pore size gradient fabricated by a centrifugation method

Polycaprolactone (PCL) cylindrical scaffolds with gradually increasing pore size along the longitudinal direction were fabricated by a novel centrifugation method to investigate pore size effect on cell and tissue interactions. The scaffold was fabricated by the centrifugation of a cylindrical mold containing fibril-like PCL and the following fibril bonding by heat treatment. The scaffold showed gradually increasing pore size (from approximately 88 to approximately 405 microm) and porosity (from approximately 80% to approximately 94%) along the cylindrical axis by applying the centrifugal speed, 3000 rpm. The scaffold sections were examined for their in vitro cell interactions using different kinds of cells (chondrocytes, osteoblasts, and fibroblasts) and in vivo tissue interactions using a rabbit model (skull bone defects) in terms of scaffold pore sizes. It was observed that different kinds of cells and bone tissue were shown to have different pore size ranges in the scaffold for effective cell growth and tissue regeneration. The scaffold section with 380-405 microm pore size showed better cell growth for chondrocytes and osteoblasts, while the scaffold section with 186-200 microm pore size was better for fibroblasts growth. Also the scaffold section with 290-310 microm pore size showed faster new bone formation than those of other pore sizes. The pore size gradient scaffolds fabricated by the centrifugation method can be a good tool for the systematic studies of the interactions between cells or tissues and scaffolds with different pore size.     

Periodontal ligament cellular structures engineered with electrospun poly(DL-lactide-co-glycolide) nanofibrous membrane scaffolds

Periodontal tissue engineering is expected to overcome the limitations associated with the existing regenerative techniques for the treatment of periodontal defects involving alveolar bone, cementum, and periodontal ligament. Cell-based tissue engineering approaches involve the utilization of in vitro expanded cells with regenerative capacity and their delivery to the appropriate sites via biomaterial scaffolds. The aim of this study was to establish living periodontal ligament cell-containing structures on electrospun poly(DL-lactic-co-glycolic acid) (PLGA) nanofiber membrane scaffolds, assess their viability and characteristics, and engineer multilayered structures amenable to easy handling. Human periodontal ligament (hPDL) cells were expanded in explant culture and then characterized morphologically and immunohistochemically. PLGA nanofiber membranes were prepared by the electrospinning process; mechanical tensile properties were determined, surface topography, nanofiber size, and porosity status were investigated with SEM. Cells were seeded on the membranes at approximately 50,000 cell/cm(2) and cultured for 21 days either in expansion or in osteogenic induction medium. Cell adhesion and viability were demonstrated using SEM and MTT, respectively, and osteogenic differentiation was determined with IHC and immunohistomorphometric evaluation of osteopontin, osteocalcin, and bone sialoprotein marker expression. At days 3, 6, 9, and 12 additional cell/membrane layers were deposited on the existing ones and multilayered hybrid structures were established. Results indicate the feasibility of periodontal ligament cell-containing tissue-like structures engineering with PDL cells and electrospun nanofiber PLGA scaffolds supporting cell adhesion, viability and osteogenic differentiation properties of cells in hybrid structures amenable to macroscopic handling.     

Highly porous 3D nanofiber scaffold using an electrospinning technique

A successful 3D tissue-engineering scaffold must have a highly porous structure and good mechanical stability. High porosity and optimally designed pore size provide structural space for cell accommodation and migration and enable the exchange of nutrients between the scaffold and environment. Poly(epsilon-carprolactone) fibers were electrospun using an auxiliary electrode and chemical blowing agent (BA), and characterized according to porosity, pore size, and their mechanical properties. We also investigated the effect of the BA on the electrospinning processability. The growth characteristic of human dermal fibroblasts cells cultured in the webs showed the good adhesion with the blown web relative to a normal electrospun mat. The blown nanofiber web had good tensile properties and high porosity compared to a typical electrospun nanofiber scaffold.     

Effect of varying physical properties of porous, surface modified bioactive glass 45S5 on osteoblast proliferation and maturation

The objective of this study was to determine the effect of porous bioactive glass (45S5) substrate characteristics on the expression and maintenance of the osteoblastic phenotype. We cultured ROS 17/2. 8 cells on substrates with different pore size and porosity for periods up to 14 days and analyzed the characteristics of the cells and extracellular matrix. Results of the study show that the glass substrates supported the proliferation and growth of osteoblast-like cells. Although the morphologies of the cells differed on the various substrates, their shape and the extent of membrane ruffling suggested that they maintained high levels of metabolic activity. Cells on all substrates expressed high levels of alkaline phosphatase activity and produced extracellular matrices that mineralized to form nonstoichiometric, carbonated, calcium-deficient apatites. An important finding was that at a given porosity of 44%, the pore size neither directed nor modulated the in vitro expression of the osteoblastic phenotype. In contrast, porosity did affect cellular function. We noted that at an average pore size of 92 microm, as the porosity increased from 35 to 59%, osteoblast activity was reduced. As designed in this experiment, an increase in the porosity led to a corresponding increase in total surface area of the specimens. With increasing porosity and surface area, glass reactions in the media may persist for longer durations at higher intensities, thereby affecting local media composition. As such, we suggest that extensive conditioning treatments before cell seeding can reduce this effect. Our results also revealed that the expression of the osteoblastic phenotype is enhanced by the ongoing glass dissolution. The reaction pathway at the origin of this effect still needs to be elucidated. Taken together, the findings support the overall hypothesis that in vitro cell activity can be controlled by a careful selection of substrate properties.     

多孔铌基生物材料的制备及其性能研究

目的 制备多孔铌并评价其相关性能。 方法 采用新型的泡沫浸渍法,以聚氨酯泡沫为载体制备出具有较高强度和良好生物相容性的多孔铌基材料。并借助分析天平、XRD、CS600碳硫测试仪和SEM对多孔铌的孔隙率、性能和微观结构进行了测试及观察,运用细胞生物学技术评价多孔铌的细胞生物相容性。 结果　多孔铌具有三维、连通孔隙结构且无任何杂质相,孔隙率为71.4%,孔径500 μm,平均密度为2.45 g/cm3,具有与人体松质骨相匹配的弹性模量和抗压强度;多孔铌不影响成骨细胞的增殖、黏附和表型表达。 结论　多孔铌具有高孔隙率结构,良好的力学性能及细胞生物相容性。