Papers by Author: Y.S. Dong

Abstract: The poly (L-lactic acid) (PLLA) porous scaffolds were prepared by porogen leaching combined freeze drying with the porogen particulates of ice in this paper. The ice particulates are made of distilled water sprayed into liquid nitrogen through a nozzle under a certain pressure. The pore morphology, porosity and residual porogen of the scaffolds was studied. There is no residual porogen when the ice particulate is used and the leaching mechanism of porogen is discussed. The scaffolds are composed of macro and micro pores and with a porosity of 80-90%. The macro pores are formed by ice particulate and the micro pores by thermal induced phase separation of solvent. The pore size can be changed easily by altering the size of ice particulate. The MTT assay was used to estimate cellular activity by L-929 cells culture in vitro. The results demonstrate that the scaffolds have no cytotoxicity. It could confidently be stated that the combined process seems to be a promising technique for the fabrication of porous polymer scaffold.

Abstract: Submicron hydroxyapatite powder with particle size in the range of 80-250 nm was fabricated by sol-gel process in our laboratory. To make ceramic slurry with good flowability, the powder was mixed with binder and distilled water. The binder was consisted of acid magnesium and aluminum phosphates. The polyurethane foam was impregnated in the slurry, squeezed out the excess slurry and the composite porous body gained. Green body was dried in room temperature naturally and then moved to electric furnace and sintered at high temperature. The sintered scaffolds possess interconnected open pore structure and with a porosity of 70-85% and compressive strength 10-20 MPa, and was consisted of doped HA and other phosphates. The scaffolds were co-cultured with osteoblasts in vitro. SEM analyses revealed that the cells adhere to the ceramic surface, proliferate and growth properly. Experimental results showed that the scaffold possesses good biocompatibility and could be used in bone tissue engineering.