Structure and Characteristics of Novel Hydroxyapatite/Polylactide Bi-Layered Porous Scaffold for Bone Regeneration

Abstract

The goal of this study was to develop novel hydroxyapatite (HAp)/ polylactide (PLA) bi-layered porous scaffold for tissue-engineered bone regeneration. To mimic normal bone structures, the Outside cortical-like shells fabricated consisted of porous HAp and ail inner trabecular-like core was made of porous PLA. Cortical-like porous HAp scaffolds with hollow in its inside was fabricated using a polymer sponge template. Trabecular-like porous PLA scaffold was directly formed by a particle leaching/gas foaming technique with sodium percarbonate as a novel porogen in inner diameter of HA scaffolds. The oxygen plasma treatment was performed to modify, the PLA surface of bi-layered porous scaffold. The plasma-treated bi-layered scaffold was subsequently dipped in ail alcoholic solution containing calcium and phosphate ions to deposit precursors oil the surface. The surface modified bi-layered scaffold was immersed in simulated body fluid (SBF) at 5 times ionic concentration for 24 hr to obtain the final bone-like apatite coated HAp/PLA bi-layered porous scaffold. It was observed that the HAp and PLA parts of fabricated bi-layered scaffolds contain open and interconnected pore structures, with no structural delaminations oil the external Surfaces. Using helium pyenometry, the maximum porosity was observed to be greater than 96% for bi-layered scaffold. Additionally, the distribution of pore size for the PLA scaffolds was from 100 to 700 pm. Also, the dense and uniform bone-like apatite layer was successfully formed on surface of HAp/PLA bi-layered scaffold after immersion for 1 day in SBF solution. Total protein and alkaline phosphatase (ALP) content of bi-layered scaffold were higher than the control HAp scaffold during 4 weeks in vitro Culture study using human embryonic palatal mesenchymal (HEPM) cells. It is indicated that bi-layered porous scaffold has stronger ability to induce HEPM cell attachment, proliferation, differentiation, and mineralization than that of the control HAp porous scaffold. The resulting apatite coated HAp/PLA bi-layered porous scaffold is more bioactive that might be applicable as a promising scaffold for osteogenesis.