Ultrasound stimulated piezoelectric barium titanate and boron nitride nanotubes in nonconductive poly-ϵ-caprolactone nanofibrous scaffold for bone tissue engineering

Nanomaterials can provide unique solutions for the problems experienced in tissue engineering by improving a scaffold’s physico-bio-chemical properties. With its piezoelectric property, bone is an active tissue with easy adaptation and remodeling through complicated mechanisms of electromechanical operations. Although poly(ϵ-caprolactone) (PCL) is an excellent polymer for bone tissue engineering, it is lack of conductivity. In this study, piezoelectric barium titanates (BaTiO₃) and boron nitride nanotubes (BNNTs) are used as ultrasound (US) stimulated piezoelectric components in PCL to mimic piezoelectric nature of bone tissue. Electric-responsive Human Osteoblast cells on the scaffolds were stimulated by applying low-frequency US during cell growth. Biocompatibility, cell adhesion, alkaline phosphatase activities and mineralization of osteoblast cells on piezo-composite scaffolds were investigated. BaTiO₃ or BNNTs as reinforcement agents improved physical and mechanical properties of PCL scaffolds. In vitro studies show that the use of BaTiO₃ or BNNTs as additives in non-conductive scaffolds significantly induces and increases the osteogenic activities even without US stimulation. Although BaTiO₃ is one of the best piezoelectric materials, the improvement is more dramatic in the case of BNNTs with the increased mineralization, and excellent chemical and mechanical properties.