Preparation And Properties Of Porous Scaffold Calcium Sulfate Groups

As all important research field of bone tissue engineering, Bone scaffolds are widely used in the clinic. They have many kinds and different characters, although they are useful some extent, disadvantages such as less bioactivity, unsuitable degradation compared with tissue growth can’t be overcame by themselves. Therefore, it is always a hot topic to search a bone scaffold with good degradation and bioactivity. The calcium sulfate (CS) has been used for many years to produce materials for bone defects. The previous studies show that CS has good biocompatibility, osteoconductivity, completely degradation, no stimulation for body and also has the potential osteoinductivity. However, CS has some drawbacks, which significantly limit its clinical applications. CS cannot form a chemical bond with bone tissue at the early stage of therapy because of its poor bioactivity, and the in vivo degradation rate of the CS is too fast, which may negatively affect bone regeneration. So we use calcium sulfate which has a complete performance as the basic material to fabricate CS composite scaffold with Na2SiO3and Na2SiO3solutions, including spherical particles CS scaffold for alveolar bone regeneration and porous composite scaffold based on CS for bone regeneration and study the preparation process and characteristics of the scaffolds. The main research contents of the experiment include the following three aspects:1. α-Calcium sulfate hemihydrate powders were prepared by autoclave method and were used to prepare spherical particles calcium sulfate with stir pelletizing method. The influences of powder addition, pelletizing time and concentration of water-glass on properties of the spherical particles were studied under laboratory conditions. The results indicate that when the adhesive is deionized water and pelletizing time is4min, with increasing the powder addition, the particle size of the spherical particles is increased, the granulous sphere yield and the compression strength have no significant change; when the adhesive is deionized water and the powder addition is2.0g, with increasing the pelletizing time, the compression strength of the spherical particles is increased until4min, the granulous sphere yield and the particle size have no significant change; when powder addition is2.0g and pelletizing time is4min, with increasing the concentration of water-glass in preparation process, the shape of the spherical particles becomes non-circular, the granulous sphere yield is decreased and the compression strength is improved, the particle size have no significant change.2. In order to improve the degradation and bioactivity properties of spherical particles of calcium sulfate, Na2SiO3solutions was introduced in the materials. a-Calcium sulfate hemihydrate was used as the raw materials to prepare spherical particles of calcium sulfate with stirring method. Microstructures, degradation, and bioactivity of the materials were characterized by XRD, FT-IR and SEM. The effects of Na2SiO3solutions on the structure and properties of the materials were analyzed. The results indicate that the spherical particles of calcium sulfate which was made with Na2SiO3solutions have a higher bioactivity and carbonization function than pure calcium sulfate spherical particles in the SBF solution. Calcium silicate hydrates gel which has a lower dissolution rate than that of calcium sulfate dihydrate, the Si-O membrane which wraps calcium sulfate grains and the mineralization result in a decrease in dissolution, and the weight loss ratio of the composites can be controlled by the adjustment of the concentration of solutions of Na2Si03.3. Porous composite scaffold based on CS for bone regeneration was fabricated with a-calcium sulfate hemihydrate and Na2SiO3by particle leaching method to improve the degradation and bioactivity properties. The influences of content of pore formers and Na2SiO3on properties of the porous composite scaffold were studied. The results indicate that with increasing content of pore formers, the porosity of the pure porous scaffold is increased and compression strength is significantly decreased. The content of pore formers can also influence the crystal morphology and size. Some Na2SiO3is combined with a-calcium sulfate hemihydrate to form CaSiO3and Na2SO4. Others become into a silica gel. With increasing the content of Na2SiO3, the compression strength is improved, but the he compression strength is decreased after content reach20%. CaSiO3with lower dissolution rate than calcium sulfate dihydrate, Si-O membrane which wraps calcium sulfate grains and the close-packed large crystals result in a decrease in dissolution, and the weight loss ratio of the composites can be controlled by the adjustment of the content of Na2SiO3.