Papers by Keyword: Porous Scaffold

Abstract: Porous calcium sulfate/hydroxyapatite whiskers composites scaffold is possible to be used in bone tissue engineering, for its biocompatibility, controllable degradation, and good mechanical properties. In this study, porous calcium sulfate/hydroxyapatite whisker composite scaffolds were fabricated by adding pore-forming agent and were characterized. The characteristics of the porous scaffolds were assessed by means of scanning electron microscopy (SEM), X-ray diffraction (XRD) and immersing testing techniques. It is shown that the scaffolds prepared in this article have the porous structure with the content of CaSO₄ and HA. The scaffolds prepared in this article have been confirmed to be ideally used as biodegradable implants.

Abstract: As the tissue engineering scaffolds, the pore structure and condensed structure of silk fibroin scaffolds should be adjusted and controlled. In this study, Antheraea pernyi/Bombyx mori (A. p/B. m) silk fibroin blend scaffolds were prepared by freeze-drying. The influence of blend ratios on the pore structure and condensed structure of the scaffolds was investigated. The results showed that the average pore diameter of the blend scaffolds changed from 56 to 326 μm. Due to the difference of properties and the macromolecules aggregation status of two silk fibroin solutions, the pore diameter, content of α-helix and crystallinity of the scaffolds decreased with the increasing of the proportion of B. m silk fibroin. By adjusting the blend ratios, the pore structure and condensed structure of A. p/B. m silk fibroin blend scaffolds could be controlled.

Abstract: Poly (lactic acid) (PLA) scaffolds with different sizes are often fabricated for various requirements. A cellular automaton simulation was used to investigate the effect of the size on the degradation behaviors of porous PLA scaffolds. Four porous PLA scaffolds with 90% initial porosity and different sizes were established by a novel repeat unit method. Mass loss and the change in molecular weight during the degradation were simulated. The results indicate that mass loss is related to the size of the porous scaffold while molecular weight change is independent on the size. With the size of the porous scaffold increasing, the mass loss increases while the difference in mass loss between the scaffolds with different sizes decreases. All these changes can be attributed to the difference in the autocatalytic effect and corresponding oligomer diffusion ability of the porous scaffolds with different sizes.

Abstract: Based on our experimental data of neovascularization of porous silk fibroin films (PSFF)，in this study we characterized the formation of new blood vessel system at different periods. Firstly, we regarded a wound as two sections, namely, an interface layer and a material layer. Angiogenesis of the interface layer underwent three periods that were rehabilitation period of primary vascular plexus (postoperative 1st day-3rd day), rapid growth period (postoperative 3rd day - 7th day) and remodeling period (after the 7th day). In addition, angiogenesis of the material layer underwent initiation period (postoperative 5th day - 7th day), rapid growth period (postoperative 7th day - 13th day) and remodeling period (after the 13th day). According to the analysis results for angiogenesis, we realized that the efficacy of PSFF on repairing wound was reflected in coordination between infiltration of cells in the pores and angiogenesis, and in timeliness of the newly formed blood vessels’ extention from the interface layer to the material layer.

Abstract: In this study, strontium doped hydroxyapatite (SrHA) nanopowder was synthesized through a sol-gel method. Strontium concentration was varied from 0 to 15 mol%. The obtained gel was then dried and subsequently subjected to 900 °C calcination. SrHA porous bodies were fabricated by using polymeric sponge method with different chemical compositions (0, 2 and 10 mol% SrHA). To prepare the porous samples, the synthesized SrHA powders was mixed with distilled water and appropriate amount of dispersing agent followed by drying in the ambient air for 72 hours. The dried impregnated sponges were then sintered at 1300°C for 3 hours. The XRD patterns showed high crystallinity of HA phase only for all porous samples. Morphological evaluation by FESEM measurement revealed that the SrHA scaffolds were characterized by a uniform distribution of interconnected pores (200-800 µm). Compression test on the porous scaffolds revealed that doping 10 mol% of strontium in HA has increased the compressive strength compared to the undoped HA.

Abstract: The polylactic acids (PLA) scaffolds materials have been used to be the scaffolds materials of bone, cartilage gristle, blood vessel, nerve and skin due to its bioactivity, biocompatibility and biodegradable, today, the porous polylactic acid scaffolds had widely applied to tissue engineering. In the paper, the advance in study of microstructure and biocompatibility for this material were summarized. The lack in study of microstructure and compatibility has been pointed out and some viewpoints for further investigations are also made in this paper.

Abstract: The interconnected porous scaffolds are crucial to support the attachment, differentiation, proliferation of cells so to construct 3-dimensional (3-D) tissues. Up to now, there are several approaches to prepare porous scaffolds. In our experiments, we designed a novel porous bioceramic scaffold, called the hydroxyapatite (HA) spherule scaffold, by accumulating HA spherules in an HA porous tube to establish an interconnected porous structure which can be reconstructed exactly. The porous HA tube was manufactured by polymer sponge template while HA spherules were prepared by sol-gel process. In the animal experiment, the HA spherule scaffolds were implanted at 2 different non-osseous sites such as muscle and abdominal cavity in dogs. The new bone growth was investigated after six months. The preliminary results demonstrated that the proliferation of osteocytes on the scaffolds in muscle was obviously better than in abdominal cavity, and about ten times more blood vessels (BVs) were appeared in the former site than those in the latter site. This study presents an alternative way to reveal the relationship between the porous structure of scaffolds and ectopia bone growth because the interconnection and porosity can be controlled easily by the size and porosity of HA spherules.

Abstract: The aim of this study was to investigate the feasibility of utilizing selective laser sintering (SLS) to build 3D porous tissue engineering scaffolds from small quantities of poly(L-lactide) (PLLA). PLLA microspheres with suitable particle sizes for the SLS process were produced by the oil-in-water emulsion solvent evaporation technique. A miniature build platform was designed, fabricated and incorporated in an existing Sinterstation® 2000 system to enable small quantities of polymer powder to be used for the production of 3D porous scaffolds. Trial runs were first performed using the DuraForm™ polyamide powder and interfacing problems between the miniature build platform and the existing machine were solved. Then 3D porous scaffolds were successfully built from the PLLA microspheres using the modified SLS machine. This study paved the way for further comprehensive studies on selective laser sintering of tissue engineering scaffolds using expensive biopolymers and their composites.

Abstract: This paper reports a preliminary study on the development and characterization of a porous calcium phosphate glass-ceramic for tissue engineering application. To obtain porous glass scaffolds, a mixture of 3CaO.P2O5-SiO2-MgO glass (grain size below 20 'm) and NaCl with 200- 300 'm of particle size was taken in the volume proportion 1:1. The mixture was shaped into cylindrical samples (10 mm diameter x 10 mm thick) by using unidirectional pressing. The sintering thermal cycle was selected by means of thermal analyses (DTA/TG and dilatometry) in order to attain a high enough cohesion among the glass particles. After thermal consolidation, the salt was dissolved in water, resulting in highly porous materials. The effect of the sintering thermal cycle on the structure and microstructure characteristics of the scaffolds was investigated in this paper.

Abstract: A novel foaming method of design and synthesis of porous Carbonate-apatite/gelatine composite scaffolds is proposed for biomedical applications. Two different suspensions, one constituted by a biomimetic inorganic phase (B-CHA) and the second by a protein (gelatine), are mixed, foamed, lyophilized and, in some cases, cross-linked to stabilize the organic phase. Chemical, morphological and mechanical features of the scaffolds are evaluated. The samples have chemical composition, compressive and flexural strengths and Young modulus values in the range of trabecular bone ones. A high interconnected porosity (about 90%) showing a micro- to macrosize distribution, that is needed for osteoconduction and vascolarization processes in vivo, is also detected.