Effect Of Pore Architecture Research Articles

Preparation and Properties of Self‐Setting Calcium Phosphate Scaffolds: Effect of Pore Architecture

Self‐setting calcium phosphate cement (CPC) scaffold with interconnected macropores is hard to prepare without compromising its hydration reaction. Herein, an indirect 3D printing method is using to prepare CPC scaffolds. Detailedly, polycaprolactone (PCL)‐sacrificed models with different strut sizes are first printed by 3D plotting technique, and then the CPC pastes are perfused into the PCL models and then self‐setting. After the removal of the PCL models, the CPC scaffolds with different pore sizes are obtained. It is showed in the results that the prepared CPC scaffolds had uniform shape and 3D interconnected macropore structure. Meanwhile, the compressive strength of CPC scaffolds all meets the requirements of repairing cancellous bone. More interestingly, the CPC scaffold with about 300 μm in macropore size is more conducive to the ingrowth and osteogenesis differentiation of mouse bone marrow mesenchymal stem cells. As a whole, the indirect 3D printing method is a promising strategy for preparing CPC scaffolds, which are hard to form directly by 3D printing technique.

Synthesis and Investigation into Apatite-forming Ability of Hydroxyapatite/Chitosan-based Scaffold

Synthesis and Investigation into Apatite-forming Ability of Hydroxyapatite/Chitosan-based Scaffold

Effect of pore architecture on the mesenchymal stem cell responses to graphene/polycaprolactone scaffolds prepared by solvent casting and robocasting

In the study graphene-containing porous, three dimensional polycaprolactone (PCL) scaffolds were prepared by solvent casting-salt leaching and robocasting methods for tissue engineering applications. Graphene nanopowders in the form of nanoflakes were incorporated into the polymer matrix at different concentrations namely 1, 3, 5 and 10 wt%. The dichloromethane was used as the solvent and sodium chloride crystals were utilized as the water-soluble porogen for the formation of an interconnected porous network (with non-oriented pores) inside the composite scaffolds in solvent casting-salt leaching method. On the other hand, acetone was utilized as solvent and PCL solutions were prepared at 20 wt% in robocasting method to construct scaffolds (with oriented pores) having a grid-like structure. The biological response of bone marrow mesenchymal stem cells seeded on these composite constructs having different architecture were tested using MTT method, live-dead cell viability assay and Alcian blue stanining. Cytotoxicity experiments revealed that mesenchymal stem cells did not show toxic response to composite robocast scaffolds. Cells proliferate and differentiate well on the surface of the robocast scaffolds compared to solvent-cast scaffolds under the same conditions. Results showed that scaffolds prepared in the study have potential to be used in cartilage tissue engineering in the presence of electric stimulation.

Ordered Mesoporous TiO2 Gyroids: Effects of Pore Architecture and Nb‐Doping on Photocatalytic Hydrogen Evolution under UV and Visible Irradiation

AbstractPure and Nb‐doped TiO2 photocatalysts with highly ordered alternating gyroid architecture and well‐controllable mesopore size of 15 nm via co‐assembly of a poly(isoprene)‐block‐poly(styrene)‐block‐poly(ethylene oxide) block copolymer are synthesized. A combined effort by electron microscopy, X‐ray scattering, photoluminescence, X‐ray photoelectron spectroscopy, Raman spectroscopy, and density functional theory simulations reveals that the addition of small amounts of Nb results in the substitution of Ti4+ with isolated Nb5+ species that introduces inter‐bandgap states, while at high concentrations, Nb prefers to cluster forming shallow trap states within the conduction band minimum of TiO2. The gyroidal photocatalysts are remarkably active toward hydrogen evolution under UV and visible light due to the open 3D network, where large mesopores ensure efficient pore diffusion and high photon harvesting. The gyroids yield unprecedented high evolution rates beyond 1000 µmol h−1 (per 10 mg catalyst), outperforming even the benchmark P25‐TiO2 more than fivefold. Under UV light, the Nb‐doping reduces the activity due to the introduction of charge recombination centers, while the activity in the visible triple upon incorporation is owed to a more efficient absorption due to inter‐bandgap states. This unique pore architecture may further offer hitherto undiscovered optical benefits to photocatalysis, related to chiral and metamaterial‐like behavior, which will stimulate further studies focusing on novel light–matter interactions.

Effect of Pore Architecture of Titanium Implants on Stress-Strain State upon Compression

The problem of stress-strain state upon compression of implant of titanium alloy with cellular architecture was formulated by means of ABAQUS software and finite element analysis. The volume of the material was segmented on the unit cells characterized by specific configuration. The boundary conditions and physical equations were stated to describe the correlation between stresses and strains. The calculations of stress values, area reduction and mean stress were performed. The increased strain rates were revealed in horizontal pore cell walls. Joint simulating of several individual unit cells was provided. Zone seeing tensile stresses were observed in the segment of radius of the unit cell. The estimation of threatening sections location of the construction was conducted.

Effect of pore architecture and stacking direction on mechanical properties of solid freeform fabrication‐based scaffold for bone tissue engineering

Fabrication of a three-dimensional (3D) scaffold with increased mechanical strength may be an essential requirement for more advanced bone tissue engineering scaffolds. Various material- and chemical-based approaches have been explored to enhance the mechanical properties of engineered bone tissue scaffolds. In this study, the effects of pore architecture and stacking direction on the mechanical and cell proliferation properties of a scaffold were investigated. The 3D scaffold was prepared using solid freeform fabrication technology with a multihead deposition system. Various types of scaffolds with different pore architectures (lattice, stagger, and triangle types) and stacking directions (horizontal and vertical directions) were fabricated with a blend of polycaprolactone and poly lactic-co-glycolic acid. In compression tests, the triangle-type scaffold was the strongest among the experimental groups. Stacking direction affected the mechanical properties of scaffolds. An in vitro cell counting kit-8 assay showed no significant differences in optical density depending on the different pore architectures and stacking directions. In conclusion, mechanical properties of scaffolds can be enhanced by controlling pore architecture and stacking direction.

Gold nanoparticles supported on periodic mesoporous organosilicas for epoxidation of olefins: Effects of pore architecture and surface modification method of the supports

Periodic mesoporous organosilicas (PMOs), namely MCM-41, MSU, and SBA-15 ordered mesoporous silicas (OMSs) incorporated with bridging disulfide-ionic liquid moieties prepared either by the one-pot or the post-synthesis procedure, were used as supports for the gold nanoparticle (GNP) catalysts. The catalytic properties of various supported GNP/PMO catalysts were evaluated by epoxidation reaction of various olefins. It was found that the pore architectures of the PMO materials as well as the method by which organic moieties were incorporated onto the mesoporous silica materials play crucial roles in the particle size and dispersion of the GNPs which, in turn, dictate the catalytic performances of the supported GNP/PMO catalysts. In comparison with those synthesized by the one-pot procedure, PMO materials prepared by the post-synthesis method are more favorable in terms of dispersion of GNPs. Moreover, PMOs originated from OMSs with one-dimensional (1-D) pore structures also exhibit better GNP dispersions and catalytic activities than those with three-dimensional (3-D) pore architectures. This has been ascribed due to the restricted Ostwald ripening and/or migration-coalescence of the GNPs between adjacent pores of the PMOs with 1-D pore structures.

The effects of pore architecture in silk fibroin scaffolds on the growth and differentiation of mesenchymal stem cells expressing BMP7

The pore architecture of scaffolds is known to play a critical role in tissue engineering as it provides the vital framework for seeded cells to organize into a functioning tissue. In this report we have investigated the effects of different concentrations of silk fibroin protein on three-dimensional (3D) scaffold pore microstructure. Four pore size ranges of silk fibroin scaffolds were made by the freeze drying technique, with the pore sizes ranging from 50 to 300 microm. The pore sizes of the scaffolds decreased as the concentration of fibroin protein increased. Human bone marrow mesenchymal stromal cells (BMSC) transfected with the BMP7 gene were cultured in these scaffolds. A cell viability colorimetric assay, alkaline phosphatase assay and reverse transcription-polymerase chain reaction were performed to analyze the effect of pore size on cell growth, the secretion of extracellular matrix (ECM) and osteogenic differentiation. Cell migration in 3D scaffolds was confirmed by confocal microscopy. Calvarial defects in SCID mice were used to determine the bone forming ability of the silk fibroin scaffolds incorporating BMSC expressing BMP7. The results showed that BMSC expressing BMP7 preferred a pore size between 100 and 300 microm in silk fibroin protein fabricated scaffolds, with better cell proliferation and ECM production. Furthermore, in vivo transplantation of the silk fibroin scaffolds combined with BMSC expressing BMP7 induced new bone formation. This study has shown that an optimized pore architecture of silk fibroin scaffolds can modulate the bioactivity of BMP7-transfected BMSC in bone formation.

Comparison of the effect of pore architecture and bead size on the extent of plasmachemical amine functionalisation of poly(styrene-co-divinylbenzene) permanently porous resins

Comparison of the effect of pore architecture and bead size on the extent of plasmachemical amine functionalisation of poly(styrene-co-divinylbenzene) permanently porous resins