ZnO Nanosheet-Coated TiZrPdSiNb Alloy as a Piezoelectric Hybrid Material for Self-Stimulating Orthopedic Implants

Abstract

A Ti-based alloy (Ti45Zr15Pd30Si5Nb5) with already proven excellent mechanical and biocompatibility features has been coated with piezoelectric zinc oxide (ZnO) to induce the electrical self-stimulation of cells. ZnO was grown onto the pristine alloy in two different morphologies: a flat dense film and an array of nanosheets. The effect of the combined material on osteoblasts (electrically stimulable cells) was analyzed in terms of proliferation, cell adhesion, expression of differentiation markers and induction of calcium transients. Although both ZnO structures were biocompatible and did not induce inflammatory response, only the array of ZnO nanosheets was able to induce calcium transients, which improved the proliferation of Saos-2 cells and enhanced the expression of some early differentiation expression genes. The usual motion of the cells imposes strain to the ZnO nanosheets, which, in turn, create local electric fields owing to their piezoelectric character. These electric fields cause the opening of calcium voltage gates and boost cell proliferation and early differentiation. Thus, the modification of the Ti45Zr15Pd30Si5Nb5 surface with an array of ZnO nanosheets endows the alloy with smart characteristics, making it capable of electric self-stimulation.

Physicochemical, Antibacterial Properties, and Compatibility of ZnO-NP/Chitosan/β-Glycerophosphate Composite Hydrogels

“…Careta et al . found that a ZnO-NP coating on the surface of Ti alloy is non-cytotoxic and could promote the expression of early differentiation genes of osteoblasts without external stimulation [ 32 ]. Therefore, we should verify the cytotoxicity of synthesized hydrogels in further investigations and select a compound hydrogel with better antibacterial performance and no cytotoxicity.…”

Functionalized ZnO-Based Nanocomposites for Diverse Biological Applications: Current Trends and Future Perspectives

“…Electrical stimulation of cells has shown great potential in wound healing and tissue repair [ 188 ] through activation of different mechanisms and pathways, resulting in enhanced cell proliferation, migration, and differentiation. Attempts were made in order to take advantage of these effects in a targeted manner; hence the piezoelectric properties of ZnO-based nanomaterials have been employed, creating a self-activating source, inside the tissue, producing electric fields through non-invasive and selective means [ 189 , 190 ].…”

Research progress of stimuli-responsive ZnO-based nanomaterials in biomedical applications

“…105,106 Among them, ZnO is a typical piezoelectric inorganic material, usually with extremely high piezoelectric coefficient and good mechanical properties, showing excellent application potential in the field of electroactive tissue repair. 107 Based on this, related researchers have prepared a series of therapeutic platforms endowed with mechanical response functions based on ZnO NPs, comprising tissue engineering scaffolds, 108,109 composite material coatings, 110 piezoelectric dermal patches, 111 etc. Their effects on angiogenesis, wound healing and bone tissue formation were also explored.…”

“…On this basis, researchers modified a ZnO nanosheet coating on the surface of a Ti-based alloy (Ti 45 Zr 15 Pd 30 Si 5 Nb 5 ) to induce electrical self-stimulation of osteoblasts, while avoiding the use of silicon. 110 Besides, in terms of nerve repair, Zheng et al 113 loaded ZnO into polycaprolactone (PCL), a commonly used material for nerve conduit manufacturing, and fabricated ZnO/PCL piezoelectric nanogenerator scaffolds by means of 3D injectable multilayer biofabrication technology. Subsequently, the effect of the ZnO/ PCL scaffold on the viability of Schwann cells was investigated, which suggested that the ZnO/PCL scaffold had low toxicity similar to the PCL scaffold (Fig.…”