Nanoparticles distribution and agglomeration analysis in electrospun fiber based composites for desired mechanical performance of poly(3-hydroxybuty-rate-co-3-hydroxyvalerate (PHBV) scaffolds with hydroxyapatite (HA) and titanium dioxide (TiO2) towards medical applications

Abstract

Scaffolds designed for tissue engineering must meet multiple criteria, including mechanical performance matching particular tissue properties. One of the strategies to improve electrospun scaffolds strength is the incorporation of ceramic nanoparticles. In this work, the effect of the addition of hydroxyapatite (HA) and titanium dioxide ($TiO_{2}$) nanoparticles on tensile strength, elongation and toughness of poly (3-hydroxybuty-rate-co-3-hydroxyvalerate (PHBV) based fibers was tested. Samples morphology along with chemical composition and particles distribution were characterized by scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and Fourier transform infrared spectroscopy (FTIR). Mechanical properties of PHBV-based electrospun scaffolds were correlated with the nanoparticles' distributions examined via microscopy analysis to understand the failure mechanism of composite fibers. We observed a significant improvement of mechanical properties of composites containing HA nanoparticles compared with solely PHBV fibers. Notably, 3 times higher tensile strength and strain at failure, followed by 16 times improved toughness, was correlated with homogenous distribution of HA nanoparticles with an average area of aggregates reaching 0.11 μm2. At the same time, two times larger $TiO_{2}$ aggregates were irregularly formed along PHBV fibers and caused deterioration of their mechanical properties. We showed the relevant strategy of particle distribution in fibers that are able to tailor mechanical properties by controlling the size and distribution of ceramic fillers in hybrid scaffolds.