Development and characterization of reinforced poly(l-lactide) scaffolds for bone tissue engineering

Novel reinforced poly( l -lactic acid) (PLLA) scaffolds such as solid shell, porous shell, one beam and two beam reinforced scaffolds were developed to improve the mechanical properties of a standard PLLA scaffold. Experimental results clearly indicated that the compressive mechanical properties such as the strength and the modulus are effectively improved by introducing the reinforcement structures. A linear elastic model consisting of three phases, that is, the reinforcement, the porous matrix and the boundary layer was also introduced in order to predict the compressive moduli of the reinforced scaffolds. The comparative study clearly showed that the simple theoretical model can reasonably predict the moduli of the scaffolds with three phase structures. The failure mechanism of the solid shell and the porous shell reinforced scaffolds under compression were found to be buckling of the solid shell and localized buckling of the struts constructing the pores in the porous shell, respectively. For the beam reinforced scaffolds, on the contrary, the primary failure mechanism was understood to be micro-cracking within the beams and the subsequent formation of the main-crack due to the coalescence of the micro-racks. The biological study was exhibited that osteoblast-like cells, MC3T3-E1, were well adhered and proliferated on the surfaces of the scaffolds after 12 days culturing.