Periodic Reporting for period 1 - FLEXOBONEGRAFT (FLEXOELECTRIC SCAFFOLDS FOR BONE TISSUE ENGINEERING)
Período documentado: 2017-09-15 hasta 2019-09-14
Second, we have measured the flexoelectricity of biodegradable and/or biocompatible polymers and bioglass materials that have proven efficacy in bone repair strategies. The polymers chosen were:
- poly(L-lactic acid) (PLLA)
- polycaprolactone (PCL)
- a copolymer of PLLA and PCL: 85PLLA/15PCL
These polymers as stand-alone devices lack in mechanical, osteoconductive and osteogenic properties. In the view of improving their performance as devices for bone repair, nanoparticles of hydroxyapatite were incorporated (from 0 to 50 wt %) and the flexoelectric character of these composites were also determined. It is also remarkable that bioglass is flexoelectric. This, to our knowledge, is the first evidence that a glass (a non-cristalline material) can be flexoelectric. An article compiling the catalogue of flexoelectric and mechanical properties is being drafted.
The results obtained in this action provide a bridge from the fundamental science to the applications. At the fundamental side, the measurement of the effect of fracture-generated flexoelectricity on bone cells provides a motivation for adding flexoelectricity to osteogenic therapies. At the materials side, our quantification of the flexoelectric properties of biocompatible polymers and composites (PLLA, PCL, their copolymers and composites based on PLLA, PCL and nanoparticles of hydroxyapatite, bioglass) are likely to be a very useful tool for biomedical engineers aiming to introduce flexoelectricity as a design parameter. This action has identified a few compositions of the above mentioned polymers and composites that have the ability to generate flexoelectric field theoretically large enough to stimulate cells.
One of the most interesting aspect of flexoelectricity is the possibility to design non-piezoelectric materials to exhibit piezoelectric-like properties by clever texture-engineering at the microscale. Our results show that this can be achieved using the right compositions in devices with in-built strain gradients, e.g. polymeric scaffolds with porosity gradients where the texturization generates large strain gradients. While the project has fallen short of producing an actual flexoelectric bone prosthesis, it has laid the foundations (fundamentals, materials, design parameters) for this to be achieved.