Preparation And Characterization Of Oxygen Release Porous Composite Scaffolds

Scaffold Materials in tissue engineering are not only used to support cells and tissues and offer physical adherence between them,but also applied for adjustation of cells' various activities.The study on tissue engineering and biological materials have focused on preparation of ideal scaffold materials.However,Cells,bearing low oxygen concentration suddenly,would die easily because of hypoxia after the cell-scaffols composition being implanted into the tissue injury.Otherwise,when artificial bone was used to repair long bone defect,its effects would fail due to huge difficulty of connection and crawling of blood vessel between two sides of bone defects.These could cause the lack of oxygen and nutrients supporting survival and growth of bone cells and failure of bone implantation.So,oxygen release scaffolds are potential to put the axe in the helve.In this paper,Poly(l-lactic acid)(PDLLA) was adopted as the matrix materials in order to obtain the scaffold materials with sustainable oxygen release,well-controlled pore size,high porosity,good biocompatibility,biodegradability,bioactivity and hydrophilicity which can be applied in the area of biomedical engineering and bone tissue engineering.Moreover,some referrences could also be provided for design of novel scaffold materials.The oxygen release scaffold were prepared by compounding inorganic peroxide into PLLA using thermal induced phase separation(TIPS) and TIPS/solvent casting and particulate leaching(TIPS/SCPL) method.Porosity was tested by gravimetric method.The morphology,pore size and the pore connectivity were investigated by scanning electrical microscopy(SEM) and three-dimensional video microscopy (3-DVM).And the influencing factors of porosity,pore size and pore morphology and comparison of advantages and disadvantages between these two preparation method were studied in paper.The results showed that the porous organic-inorganic composite scaffolds with three-dimensional network,good pore connectivity and no residual porogen were prepared by TIPS.However,the pore-size of them was less than 50μm and the porosity was also low(about 70%).Nevertheless,samples prepared by TIPS/SCPL had regular pore distribution,high porosity(＞90%),and good pore connectivity which obtained by big pores mixed with tiny pores.Pores were uniformed,shaped and round basically.And porous scaffolds with different size of pore were obtained by choosing different sizes of paraffin microspheres particles.The preparation process using paraffin microspheres as porogen was simple and convenient and could avoid contacting the water during the manufacturing procedure which ensured the stability of the peroxides.Otherwise,the results also showed that the scaffold materials composite with peroxides realized sustained release of oxygen at least 21days.The oxygen-releasing amount and rate was controlled by the kind and contents of peroxides.When the total content of peroxides was 4%-5%,the rate of oxygen release could reach 0.1 mg/L per day,at the same time,pH kept at 7.2-7.4 which was good for growth of cells.And the mechanical properties and biocompatibility could improve largely as apatite formed after declaim phosphate anhydrous was added into the system and reacted with hydrolyzate products of peroxides.