Development of P(3HB-co-3HHx) nanohydroxyapatite (nHA) composites for scaffolds manufacturing by means of fused deposition modeling

Abstract

This work reports on the development of nanocomposites based on poly(3- hydroxybutyrate-co-3-hydroxyhexanoate) [P(3HB-co-3HHx)] and nanohydroxyapatite (nHA) for the development of scaffolds by means of a two-stage extrusion process followed by a 3D printing process. Tensile test samples were produced for the characterization of the materials. Each processing thermal cycle promoted a slight thermal degradation, identified by means of differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). Also, a viscosity reduction was observed in the rheological measurements. The 3D-printed tensile test samples exhibited increasing stiffness at increasing nHA content (with elastic modulus values close to 1000 MPa), while tensile strength and strain at break were reduced. Nonetheless, the deposition direction oriented with the tensile direction (raster angle of 0°C) exhibited the highest tensile strength (18 MPa) but lower elongation at break than the 45°/−45°C deposition, which resulted in the highest strain (up to 17%). Regarding the scaffolds, they were degraded in phosphate-buffered saline at 37°C for 8 weeks. This degradation was identified by a reduction of their weight (between 1.5% and 3.0%) and reduced mechanical behavior measured by means of a compression test. Scaffolds showed a decrease of the compression strength (from values close to13 MPa to 9 MPa)

This work is supported by the grant PID2020-116496RB-C22 funded by MCIN/AEI/10.13039/501100011033 and the grant TED2021-131762A-I00 funded by MCIN/ AEI/10.13039/501100011033 and by the European Union. Authors also thank Generalitat Valenciana-GVA for funding this research through the grant numbers AICO/2021/025 and CIGE/2021/094. This study is also funded by Aid for First Research Projects (PAID-06-22), Vice-rectorate for Research of the Universitat Politècnica de València (UPV)