Papers by Keyword: Porous Scaffold

Abstract: In this paper, bionic designs and 3D modeling of external and internal porous scaffold with different pore sizes and porosities were precisely fabricated using CAD software. The mechanical performance and stress distribution pattern of two porous scaffolds were studied using finite element analysis. The results indicated that the static mechanical performance of external porous scaffold deteriorated with increasing pore size, and large peak stress and total deformation were observed. However, the calculated peak stress of internal porous scaffold was reduced by almost 58.3% to 69.4%, and the elastic modulus remains almost unchanged. The mechanical properties of porous scaffold can be optimized and greatly improved by adding a solid layer with a suitable thickness. The novel optimized design of porous scaffold is conducive to bone tissue repair and reconstruction.

Abstract: Three-dimensional (3D) porous carbonated hydroxyapatite (CHA) scaffolds were successfully prepared using polyurethane (PU) replication technique. Two sets of porous scaffolds were prepared using as-synthesized and as-calcined CHA powder as the main component of the slurry. The effect of the condition of starting material was investigated in terms of structure, phase purity, crystallinity and morphology of the fabricated porous scaffolds. Regardless of the condition of starting material used, the porous scaffolds fabricated was single phase B-type CHA and free of secondary phases. Interestingly, scaffolds made of as-calcined CHA powder (SC scaffolds) showed a smoother surface and more solidified struts when compared to as-synthesized CHA powder (SA scaffolds). This is attributed to the state of semi-crystalline phase of the as-calcined powder being amorphous phase. SC scaffold was found to be better scaffold with respect to handling, compaction strength and microstructure with better strut properties.

Abstract: Three-dimensional (3D) carbonated hydroxyapatite (CHA) porous scaffolds were successfully fabricated via polyurethane (PU) replication technique. Two sets of porous CHA scaffolds were prepared using: 1) as-synthesized CHA slurry (SCHA) and (2) as-synthesized CHA slurry with the addition of sintering aid, magnesium hydroxide (SCHA+Mg (OH)₂). The aim of this study was to investigate the influences of the addition of sintering aid in the fabrication of porous CHA scaffolds in terms of phase purity, crystallinity, architecture, and mechanical properties. Result suggested that both of the fabricated porous scaffolds remained as single phase B-type CHA and free of secondary phases. Interestingly, the use of Mg (OH)₂ as sintering aid led to better internal architecture resulted in smoother surface and less micro-cracks/pores formation on the struts since the struts was found to be more densified as compared to SCHA scaffolds. In terms of mechanical properties, SCHA+ Mg (OH)₂ scaffolds showed higher compressive strength, indicating that the use of Mg (OH)₂ had successfully reduced the sintering temperature and improve the densification of porous scaffolds. Thus, SCHA+ Mg (OH)₂ scaffolds was found to be a better choice of scaffold with respect to its handling, compaction strength and architecture with improve strut properties.

Abstract: Porous Hyaluronan/β-tricalcium phosphate composite scaffolds were synthesized through lyophilizing and subsequent heterogeneous crosslinking method. The morphology of the composite scaffolds were investigated by scanning electron microscopy (SEM). The swelling behavior, mechanical property, degradation behavior and cell adhesion ability of samples were also studied. The results revealed that hyaluronan mainly contributed to the polymer matrix and water adsorption, whereas β-TCP acted as a reinforcement to strengthen the porous structure, while too much β-TCP would make the structure collapse. The pose size of obtained scaffolds ranges from100μm to 200μm and the porosity decreased with the increase of β-TCP content. The degradation behavior and cell adhesion test indicated that increasing hyaluronan concentration can effectively improve the degradability of scaffolds and the incorporation of β-TCP improved the cell adhesion performance. Thus a simple way to prepare hyaluronan-based composite scaffolds was provided, which could be potentially used as an tissue engineering material.

Abstract: Autografting is a bone replacement technique used in orthopedic surgery. Bone tissue engineering is a new technique that offers promise, and could help alleviate this risk. Bioceramics, biopolymers or composite can be fabricated for artificial bone scaffold and used for bone regeneration. This study used three types of biomaterials – hydroxyapatite (HA), fibroin, and chitosan – to form porous scaffold. HA and fibroin were prepared from natural materials. HA was synthesized from mollusk shell by wet chemical precipitation method, while silk fibroin was extracted from silk worm’s cocoons. The HA and fibroin were mixed in a variety of ratios along with a fixed amount of chitosan before fabricating composite porous scaffolds by freeze-drying. The resulting scaffolds were evaluated for biodegradability, biocompatibility, porosity pore morphology and mechanical property. The fabricated scaffolds had an interconnected porous structure with a pore size of 200-400 μm and porosity in a range of 93-95%. The average degradation rate of the scaffold in lysozyme was between 7-17% at 7 days. A biocompatibility test showed that the scaffold was non-cytotoxic, making it a good candidate for future bone tissue engineering applications.

Abstract: The 1, 4-dioxane/ethanol mixed solvent was used as solvent system, and the gel extraction phase separation method was adopted to prepare porous PLLA nanofibrous scaffolds. At that, we studied the effect of using different gel temperature to influence nanofibrous PLLA scaffolds’ structure and performance. The results showed that the morphology of nanofibers and the diameter of fibers could be regulated by gel temperature; a lower gel temperature resulted in higher crystallinity of PLLA scaffold. In addition, the PLLA scaffolds have excellent interconnected network when the gel temperature was in the range of-20 to-10°C. The PLLA scaffolds will become a material to repair the bone tissue, hopefully.

Abstract: Models with main-branch channel, crossing channel and net type channel are established and nutrient liquid with a velocity of 0.01m/s is adopted in the study to investigate the fluid field in the channel by using FEA software FLUENT. The velocity and pressure distribution have been obtained in the investigation. By comparing the results in the three models, pressure and velocity distribution in the second and the third models are relatively uniform and are appropriate for the bionics principles. Studies in this paper will be of benefits for the development of tissue engineering.

Abstract: Introduction: Many polymer supports for cell seeding formulations based on chitosan are usually prepared by chemical cross-linking with glutaraldehyde, urea formaldehyde, epichlorohydrine, even if the chemical cross-linking agents possibly induce toxicity and other undesirable effects. Experimental: Derivatized poly (vinyl alcohol) was blended and foamed with chitosan to produce porous scaffolds with improved elastic and mechanical properties and also acceptable water solubility. Derivatized PVA (in example phosphorylated PVA) (P-PVA) also exhibited improved hydrophilicity, anionic properties and molecular electrostatic repulsion, and retained the bulk morphological features, compatible property, and solution stability. Results: Porous scaffolds formed by derivatized PVA crosslinked with chitosan proved a good cytocompatibility for human fibroblasts. Viability and apoptosis assays were performed indicating that this porous scaffold allow cell multiplication and scarce apoptotic induction. Conclusion: Tested porous scaffolds may represent an interesting support for three dimensional cell cultures destined to simulate tumor or normal tissue microenvironment.

Abstract: Autograft is a general method used in orthopedic surgery for a bone replacement. However, the disadvantage of this method is the amount of risk factor to the donor sites. Currently, bone tissue engineering is another technique that could be implemented to solve this problem. Artificial bone scaffold generated by bone tissue engineering can be employed in order to accelerate damaged bone regeneration. In fact, this scaffold can be fabricated from synthetic contents such as bioceramics, biopolymers or composite. Three types of biomaterials: Chitosan, Hydroxyapatite (HA) and Fibroin were used to form porous scaffold. This research investigated the preparation of Hydroxyapatite and Fibroin from natural materials. Hydroxyapatite was synthesized from mollusk shell by wet chemical precipitation method. While, Fibroin was extracted from silk worms cocoons. Freeze drying method was employed to fabricate this composite porous scaffold. A mixing ratio of 1:2:1 among Fibroin: Chitosan: HA was studied to evaluate biodegradability, biocompatibility, porosity and pore structure of the output scaffolds. Results show that the output scaffolds have an interconnected porous structure with a pore size around 150-200μm and an average porosity of 94.26%. While the average degradation rate of the scaffold in lysozyme was 10.46% at 7 days. In addition, the biocompatibility test based on XTT assay test, shown that the scaffolds were non-cytotoxicity, which could be good for bone filling application in the future.

Abstract: The multistage aperture nanofibrous composite scaffolds were fabricated by frozen extraction combined with particle leaching from a PLLA/PCL/HA/dioxane/ ethanol ternary system. and then the morphology and biological activity of composite scaffolds were analyzed. Results show that adding the porogen is advantageous to the formation of multistage aperture nanofiber composite scaffolds. And HA adds more conducive to the deposit of CHA on composite scaffolds, raises the biologic activity of the composite scaffold.