| In this work, The poly(L-latic acid)-based hybrid scaffolds were fabricated, to overcome the limitations of exsiting fabrications for cell scaffolds and the brittle fracture behaviors of PLLA, especially under impact loading conditions. The resulting scaffolds were then modificated by using electrochemical mineralization (EM) and their biocompatibility were evaluated. The main contents are as follows:Part I:3-D porous PLLA/PCL hybrid scaffolds were fabricated by using a phase separation/phase reversal method, and the effects of the PLLA/PCL ratios on the porous topography of the scaffolds were investigated. In the hybrid system, PCL plays the role of porogen and intensifier. The SEM observations suggested that the hybrid scaffolds exhibited the porous structure with pore size of10-100μm, while the pore wall showed nanofibrous structure and the nanofiber diameter of scaffolds with different PCL content has not significant difference and the average diameter of nanofibers was250nm. The size and morphology of pores varied with different PCL content. FTIR results indicated that the hybrid scaffolds had similar chemical bonding because of the presence of identical functional groups of PLLA and PCL. It also suggested that PCL components not only played a role of porosity promoter but also severd as the composition of the scaffolds, which can improve the mechanical property of PLLA hybrid scaffolds. Morever, the porosity, swelling ratio, in vitro degradation properties and thermal property of the hybrid scaffolds varied with changes in the ratios of PLLA to PCL. SEM results revealed the Porcine iliac artery endothelial cells (PIECs) grew well on both pure PLLA and PLLA/PCL hybrid scaffolds with a well-extended morphology. The adhesion and proliferation of PIECs on the scaffolds were assayed by MTT, and the results suggested that PIECs had good adhesion and proliferation behaviors on these hybrid scaffolds, especially on the scaffold with the PLLA/PCL ratio of60/40.The combined results of the physicochemical and biological studies suggested that the PLLA/PCL hybrid scaffolds exhibited good potential and biocompatibility for further tissue engineering applications.Part II:Cathodic electrochemical deposition was applied for the fabrication of composite hydroxyapatite-BSA coatings on three-dimensional nanofibrous scaffolds by a constant voltage method. The SEM observations suggested that the morphology of the mineral crystals deposited at a constant voltage (3V) and temperature (37℃) almost attached to the edge of the pore wall and dispersed well with more delicate crystals. The obstained crystals was needle-like structure and similar to the topography of hydroxyapatite (HA) in nature bone tissue. However, the mophogical of the crystals was changed from needle-like to leaf-like when bovine serum albumin (BSA) and HA were co-deposited on the surface of scaffold. The results of FTIR studies showed the existence of HA and BSA in mineralized PLLA/PCL hybrid scaffolds. The XRD results suggested that the main component of coatings deposited at a constant voltage (3V) and temperature (37℃) were HA with small amount of DCPD. The biological response of mouse pre-osteoblasts MC3T3-E1on the mineralized PLLA/PCL hybrid scaffolds with HA and BSA was superior to unmineralized counterparts in terms of higher proliferation, well-spread morphology, higher ALP activity and maximal OCN expression. The activity of ALP was the highest and reached to3.25pg/cell, which was triple compared to blank cover slips on the day7. The contant of OCN was improved with the time of cell culture extended. When the cell cultured at14day, the OCN expression was significant improved, which was double than blank cover slips. The results suggested that EM is a promising alternative for the biomineralization of3-D polymer scaffolds, and the mineralized hybrid porous scaffolds with calcium phosphate and BSA coatings exhibited good potential for bone tissue engineering applications. |
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