Capability of core-sheath polyvinyl alcohol-polycaprolactone emulsion electrospun nanofibrous scaffolds in releasing strontium ranelate for bone regeneration

Core-sheath nanofibrous scaffolds from polyvinyl alcohol (PVA)-strontium ranelate (SrR)-Polycaprolactone (PCL) were prepared by water in oil electrospinning method. Thus, PCL (the oil phase) was used as the shell part and a mixture of PVA and SrR (the water phase) was inserted in the core. The amounts of SrR was varied from 0 to 15 wt.% Mussel-inspired dopamine-gelatin coating was done on the nanofibrous to improve their hydrophilicity and cellular attachment. The effect of the SrR content on morphology, mechanical, physicochemical, in vitro release behaviors, and biological properties as well as in vivo bone regeneration was investigated. Morphological observations revealed that continuous nanofibers with a core/shell structure were successfully obtained and the fibers diameter increased as the SrR content rose. X-ray diffraction (XRD) analysis revealed that SrR was molecularly distributed in the nanofibers and increasing the amount of the SrR decreased the crystallinity of the nanofibers. Moreover, the SrR release was regulated through the mechanism of Fickian diffusion and it was assumed as fast as possible in the samples with higher SrR content. The mesenchymal stem cell culturing showed improved cell proliferation by adding SrR and accelerating the expression of ALP, Runx2, Col I, and OCN genes. Besides, the SrR-loaded nanofibers improved bone formation of calvarial defects in a rat model as revealed by in vivo investigations.