Study On Preparation And Properties Of PLLA And BCP Porous Composite Scaffold

The scaffold materials play an important role in the repair of bone tissue engineering.For successful tissue regeneration, these ideal bone scaffold materials need to have certainaperture size and required porosity for cell adhesion and proliferation. Further, they haveenough mechanical strength to provide structural support during the bone growth andremolding. Then they must still have bone induction and conduction function. Poly(L-lactic acid)(PLLA) is a kind of biocompatible and degradable material. Its degradationproducts are non-toxic and can be soluble in water or participate in the metabolismprocess. However, this kind of material is of insufficient mechanical strength, hydrophilicperformance, and lack of bioactivity and the ability to combine with bone tissue. Biphasiccalcium phosphate(BCP) ceramics have excellent mechanical properties and goodosteogenisis effect, but its brittleness and poor toughness limit its applications. Polyvinylalcohol(PVA) is a kind of cheap biomaterial with excellent hydrophilic property andtoughness, and it has a good biocompatibility and degradability. Therefore, in this paper,the ideal composite bone scaffold was prepared with appropriate method combinesd withthe advantages and disadvantages of organic and inorganic materials.A well-developed porous PLLA/BCP scaffold with good porosity and moderatecompressive strength as well as good biocompatibility was fabricated by gas foamingtechnology. The pore size of the scaffold could be controlled to appropriate size(＜250μm，250-500μm，＞500μm) byadjusting the size of foaming agent NH4HCO3(AB), andthe porosity (54.5%±2.3%-81.2%±0.9%), compressive strength(0.52MPa-1.23MPa),hydrophilicity and biological properties could be controlled by different content of PLLAand BCP. The pore size of scaffold increased with the particles size of foaming agent. Andthe scaffold showed an increase of the porosity and a decrease of the compressive strengthwith the increase of AB’s content. BCP particles could improve the compressive strength and hydrophilicity properties of the scaffold remained the unchange of the porosity. Inaddition, the PLLA/BCP porous scaffold has good cytocompatibility, showing no negativeeffects on cells growth and proliferation. And the cells proliferation increased with thecontent of BCP particles.PLLA/PVA composite film used for the coating of the BCP porous scaffold wasprepared by casting method. PVA with excellent hydrophilicity was used to modifiy thehydrophilic property of PLLA and adjust its degradation property. This study showed thatthe hydrophilicity and degradation properties of the PLLA/PVA composite film could beconcrolled in a certain range by adjusting the relative proportion of each component in thesystem.