Produção de matrizes tridimensionais porosas de policaprolactona-nanohidroxiapatita.

Abstract

Polycaprolactone (PCL) have been largely used as a biodegradable matrix. This polymer in a combination with bioactive calcium deficient nanohydroxyapatite (CD-nHA) represent promising materials to be applied for bone tissue engineering. Nevertheless, processing routes to optimize the interaction between these materials should be investigated. Thus, the aim of this work was to develop PCL/nHA spherebased scaffolds structured by sinterization at low temperatures. For this, nHA were produced by wet chemical precipitation method, using the precursors Ca(NO3)2.4H2O and (NH4)2HPO4, conducted at 80 °C (pH>10). The powder was characterized by Xray diffraction (XRD), fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). nHA surface was modified with stearic acid (SA), verified with FTIR and TEM analysis and stability control in dichloromethane (DCM). PCL and PCL/nHA spheres were produced by oil-in-water and solid-in-oil-in-water emulsion solvent evaporation method. This production occurred in 02 steps, to obtain diameters ranging 10-150 µm and higher than 800 µm. The follow parameters were investigated: PCL concentration, nHA content with and without AE, polyvinyl alcohol concentration (stabilizing agent) and emulsification stirring. The material was characterized by DRX, FTIR, scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and thermogravimetric analysis (ATG), and the percent yield was calculated. PCL and PCL/nHA porous scaffolds were produced and characterized by SEM, optical microscopy (MO), and in vitro bioactivity and cell adhesion assays. Calcium deficient nHA, shaped as rods (~47 nm x ~8 nm), with a specific surface of 90,1 m2/g was obtained. PCL and PCL/nHA spheres were produced with diameters ranging 2-3000 µm, dense or porous, containing nHA effectively distributed internally and at the surface. Scaffolds were successfully obtained by sintering the spheres at low temperatures. It was observed connections shaped as necks in adjacent spheres, and a hierarchical porous architecture with pores measuring up to 1500 µm. It was demonstrated satisfactory bioactivities capacity, cellular adhesion, and cellular development. Our results suggested the advantageous applicability of these scaffolds to bone tissue regeneration.