Polymer monolith is a matrix with three-dimensionally continuous pores and has large surface areas. Since poly(L-lactic acid) (PLLA) is excellent in biocompatibility, monoliths of PLLA is expected as a scaffold material for biomedical application. In this study, for the aim to apply it as a scaffold material for bone regeneration, we investigated the production of PLLA monolith with pores suitable for invasion of osteoblast cells. PLLA was synthesized by ring-opening polymerization of L-lactide (LLA) using Sn(Oct)2 as a catalyst, and its molecular weight was measured by GPC. The molecular weight of PLLA was controllable by the amount of catalyst, reaction temperature, and reaction time. PLLA was soluble in chloroform, dichloromethane (DCM), and insoluble in methanol and hexane. As a preparation of PLLA monolith, non-solvent induced phase separation (NIPS) method was adopted. PLLA was dissolved in DCM at 30 degrees. After dissolution, a given amount of hexane was gradually added while stirring. After standing the solution for 48 h at r.t., solvent substitution with methanol was carried out for 30 h. After drying for 24 h at r.t., PLLA monoliths were obtained. The size of macropore of the monolith fabricated with 16 wt.% PLLA (Mn = 224,000 g mol-1) solution was about 50 μm when mixed solvent of hexane and DCM (1.5 : 1.0, v/v) was used. To investigate the influence of PLLA monolith on the differentiation inducing effect, we cultured MC3T3-E1 cells in a differentiation induction medium, and evaluated the cellular alkaline phosphatase (ALP) activity and calcification. Cells were seeded in PLLA monolith and cultured for 4 days until control became subconfluent with α-MEM, then switched to differentiation induction medium and further cultured. On day 4th and 14th day, we dyed PLLA monolith with ALP which is the initial marker of osteoblasts, and alizarin red which is a mineralization marker. As a result of culture using differentiation induction medium, purple coloration was observed by ALP, and mineralization was not observed on the 14th day.

Preparation of porous materials using biodegradable polymers and application to scaffold materials: Differentiation-induction of poly(L-lactic acid) monolith

2019 Fall National Meeting

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