Surface-Potential-Controlled Cell Proliferation and Collagen Mineralization on Electrospun Polyvinylidene Fluoride (PVDF) Fiber Scaffolds for Bone Regeneration

This study represents the unique analysis of the electrospun scaffolds with the controlled and stable surface potential without any additional biochemical modifications for bone tissue regeneration. We controlled surface potential of polyvinylidene fluoride (PVDF) fibers with applied positive and negative voltage polarities during electrospinning, to obtain two types of scaffolds PVDF(+) and, PVDF(-). The cells' attachments to PVDF scaffolds were imaged in great details with advanced scanning electron microscopy (SEM) and 3D tomography based on focus ion beam (FIB-SEM). We presented the distinct variations in cells shapes and in filopodia and lamellipodia formation according to the surface potential of PVDF fibers that was verified with Kelvin probe force microscopy (KPFM). Notable, cells usually reach their maximum spread area through increased proliferation, suggesting the stronger adhesion, which was indeed double for PVDF(-) scaffolds having surface potential of -95 mV. Moreover, by tuning the surface potential of PVDF fibers, we were able to enhance collagen mineralization for possible use in bone regeneration. The scaffolds built of PVDF(-) fibers demonstrated the greater potential for bone regeneration than PVDF(+), showing after 7 days in osteoblasts culture produce well-mineralized osteoid required for bone nodules. The collagen mineralization was confirmed with energy dispersive X-ray spectroscopy (EDX) and Sirius Red staining, additionally the cells proliferation with fluorescence microscopy and Alamar Blue assays. The scaffolds made of PVDF fibers with the similar surface potential to the cell membranes promoting bone growth for next-generation tissue scaffolds, which are on a high demand in bone regenerative medicine.