Incorporation of Ca, P, and Si on bioactive coatings produced by plasma electrolytic oxidation: The role of electrolyte concentration and treatment duration

Abstract

The objectives of the present study were to produce bioactive coatings in solutions containing Ca, P, and Si by plasma electrolytic oxidation (PEO) on commercially pure titanium, to investigate the influence of different electrolytes concentration and treatment duration on the produced anodic films and to evaluate biocompatibility properties. The anodic films were characterized using scanning electron microscopy, energy-dispersive spectroscopy, atomic force microscopy, and x-ray diffraction and x-ray photoelectron spectroscopies. The surface energy and roughness were also evaluated. PEO process parameters influenced the crystalline structure formation and surface topography of the anodic films. Higher Ca content produced larger porous (volcanolike appearance) and thicker oxide layers when compared to the lower content. Treatment duration did not produce any topography difference. The treatment modified the surface chemistry, producing an enriched oxide layer with bioactive elements in the form of phosphate compounds, which may be responsible for mimicking bone surface. In addition, a rough surface with increased surface energy was generated. Optimal spreading and proliferation of human mesenchymal stem cells was achieved by PEO treatment, demonstrating excellent biocompatibility of the surface. The main finding is that the biofunctionalization with higher Ca/P on Ti-surface can improve surface features, potentially considered as a candidate for dental implants.

Comparison between Plasma Electrolytic Oxidation Coating and Sandblasted Acid-Etched Surface Treatment: Histometric, Tomographic, and Expression Levels of Osteoclastogenic Factors in Osteoporotic Rats

“…Thus, the PEO surface coating was shown to be extremely promising and offered excellent performance in terms of bone repair, as demonstrated in the present study. This surface coating also has superior mechanical [2,17,18] and antimicrobial parameters [21,22,45]. Given the investigations into the favorable structural properties of the PEO surfaces of implants, which were corroborated in the present study by the biological responses of the bone-implant interface, we believe that the next steps include industrial production for human clinical studies.…”

“…Previous studies of PEO surface characterization have shown that on surfaces coated by this method, an oxide layer is produced, which provides increased wear and corrosion resistance, thermal protection, and the possibility of good adhesion by ions that are important to surface osseointegration, such as Ca and P. This incorporation of Ca and P showed a more homogeneous crystalline structure, as well as large, volcano-like pores, as proven by Scanning electron microscopy. It has also promoted antibacterial properties in microbiological tests [1,2,7,21]. In the study by He et al, the evaluation of commercially pure PEO-treated titanium implants by means of microtomographic and histometric analyses demonstrated that implants with modified surfaces exhibited better bioactivity when compared with pure titanium surfaces [41].…”

“…PEO surface was prepared according to previous in vitro studies [21,22]. Briefly, the electrical circuit consisted of the following components: a pulse direct power supply with variable output voltage, a transformer, a rectifying circuit, a circuit breaker, an ammeter, and a voltmeter.…”

“…This electrochemical process gives titanium or its alloys mechanical and thermal superiority in addition to corrosive and tribocorrosive properties [2,[17][18][19]. Thus, electrolytic oxidation is a promising technique that involves simple steps and well-controlled chemical methods for producing bioactive micropores on implant surfaces [20][21][22]. In addition, Ca/P-incorporated PEO has exhibited antibacterial properties in microbiological tests and improved mesenchymal stem cell proliferation in cell culture tests [21,22].…”

Functionalization of PEO layer formed on Ti‐15Mo for biomedical application

“…The possibility of faster adsorption of the selected ions from the solution (or body fluid) on the anodized surface supports the formation of an apatite layer (Heng et al, ). Calcium also facilitates protein adhesion on the surface of the biomaterial (Marques et al, ). The presence of silicates advances the growth of the bone tissue, cell proliferation, and gene expression (Krząkała et al, ).…”