Evaluation of Hydroxyapatite distribution in a Poly-L-Lactic Acid (PLLA) scaffolds via Micro Computed Tomography (µCT)

Abstract

Bone Tissue Engineering offers promising clinical alternative substitutes for bone defects, focusing on the use of polymer/ceramic composites. Hydroxyapatite (HA), a bioactive ceramic, has been implemented in bone substitution and regeneration due to its biocompatibility, osteoconductivity and close resemblance to the mineralized phase of human bone. Several techniques have been adopted to characterize composite scaffolds in terms of morphology, pore size and interconnection, filler content and distribution, but most of them are destructives. In this work, composite Poly-L-Lactic Acid (PLLA)-HA scaffolds (17.6 mm diameter and35.7 mm height) were prepared via Thermally Induced Phase Separation (TIPS) by using a ternary PLLA- dioxane-water solution (polymer-solvent-nonsolvent). Two different concentrations (10% and 20% wt/wt filler/polymer ratio) of HA particles were chosen. The samples were characterized via Scanning Electron Microscopy (SEM) and Microcomputed Tomography (µCT), a non-invasive technique capable to analyze the internal structure of the sample. After the µCT reconstruction, an investigation of the distribution and average sizes of the filler was carried out through a 3D analysis software (CTAn). The obtained results demonstrated the possibility to analyze the internal distribution of the particles via a non-invasive technique; furthermore a homogeneous HA content and a uniform size distribution in the whole sample was observed, which allows one to assess that the scaffold production technique does not create neither a filler gradient nor a particle sedimentation.