Built‐In Electric Fields Dramatically Induce Enhancement of Osseointegration

Abstract

Rapid and effective osseointegration is a great challenge in clinical practice. Endogenous electronegative potentials spontaneously appear on bone defect sites and mediate healing. Thus, bone healing can potentially be stimulated using physiologically relevant electrical signals in implants. However, it is difficult to directly introduce physiologically relevant electric fields in bone tissue. In this study, built-in electric fields are established between electropositive ferroelectric BiFeO 3 (BFO) nanofilms and electronegative bone defect walls to trigger implant osseointegration and biological healing. Epitaxial growth technique is used to organize the crystal panel at an atomic scale, and ferroelectric polarization of BFO nanofilms matching the amplitude and direction of endogenous electric potentials on bone defect walls is achieved. In the presence of built-in electric fields, implants with BFO nanofilms with downward polarization (BFO+) show rapid and superior osseointegration in the rat femur. The mechanism of this phenotypic osteogenic behavior is further studied by protein adsorption and stem cell behavior in different time points. BFO+ promotes protein adsorption and mesenchymal stem cell (MSC) attachment, spreading, and osteogenic differentiation. Custom-designed PCR array examination shows sequentially initiated Ca 2+ signaling, cell adhesion and spreading, and PI3K-AKT signaling in MSCs. The results of this study provide a novel strategy for the development of implant surface modification technology.

Piezoelectric Nano‐Biomaterials for Biomedicine and Tissue Regeneration

“…Finally, the stimulation strategy triggered cortical‐like bone deposition as well as osseointegration of implanted BFO+/STO in rat femoral defects. 6a In response to mechanical stress arising from body movements, piezoelectric materials undergo polarization. This has considerable effects on bioactive protein adsorption and apatite deposition from Ca 2+ and PO 4 3− ions.…”

“…Nevertheless, the complexity and inconvenience to patients associated with electrotherapy have triggered the development of piezoelectric biomaterials possessing a built‐in capacity for electric signaling 6. Such piezoelectric biomaterials offer numerous advantages over conventional biomaterials as they can easily transduce electricity to living systems in response to processes such as cell migration, body movements or external stimulation (e.g., ultrasound (US), vibration, etc.)…”

Water printing of ferroelectric polarization

“…Over the past century, exploration and artificial control of molecular/ion absorption, charge transfer and associated structures across the solid–liquid interface 1 , 2 is of particular interest for diverse communities including life science 3 , chemical catalyzing 4 , efficient energy transition and storage 1 , 5 – 7 . Benefiting from the non-volatile/reversible electric polarization and high charge density at surfaces 8 , ferroelectrics could be a distinguished model system to artificially construct and switch the solid–liquid interfacial states in liquid environment 9 – 12 , which has been proposed to play critical roles on facilitating the energy storage 13 , cells proliferation 14 , and chemical reactions 15 – 17 etc. However, it is usually challenging to in-situ control such ferroelectric–liquid interfacial structures, which severely inhibit the energy transformation with high efficiencies 15 .…”

Charge injection based electrical stimulation on polypyrrole planar electrodes to regulate cellular osteogenic differentiation

“…[1][2][3] Inspired by the natural electrical properties of bone, an electric eld stimulation generated by exogenous electric devices demonstrates a great potential to regulate osteogenic functions of stem and osteoblast-like cells and promote bone growth. [4][5][6][7][8][9][10] To generate an effective electrical stimulation, the electric devices/ electrodes and material selections are crucial. Compared with traditional parallel electrodes, planar interdigitated electrodes (IDE) integrate the pairing electrodes onto the same plane and generate stimulation under low voltage and in a direct, effective, highly reproducible and controlled manner.…”