Preparation of highly wettable coatings on Ti\u20136Al\u20134V ELI alloy for traumatological implants using micro-arc oxidation in an alkaline electrolyte

Roman Gabor,Klara Drobikova,Martina Doubkova,Katerina Mamulova Kutlakova,Marta Vandrovcova,Simona Gorosova,Ladislav Cvrcek,Lucie Bacakova,Karel Malanik

doi:10.1038/s41598-020-76448-w

Abstract

Pulsed micro-arc oxidation (MAO) in a strongly alkaline electrolyte (pH > 13), consisting of Na2SiO3⋅9H2O and NaOH, was used to form a thin porous oxide coating consisting of two layers differing in chemical and phase composition. The unique procedure, combining MAO and removal of the outer layer by blasting, enables to prepare a coating suitable for application in temporary traumatological implants. A bilayer formed in an alkaline electrolyte environment during the application of MAO enables the formation of a wear-resistant layer with silicon incorporated in the oxide phase. Following the removal of the outer rutile-containing porous layer, the required coating properties for traumatological applications were determined. The prepared surfaces were characterized by scanning electron microscopy, X-ray diffraction patterns, X-ray photoelectron spectroscopy, atomic force microscopy and contact angle measurements. Cytocompatibility was evaluated using human osteoblast-like Saos-2 cells. The newly-developed surface modifications of Ti–6Al–4V ELI alloy performed satisfactorily in all cellular tests in comparison with MAO-untreated alloy and standard tissue culture plastic. High cell viability was supported, but the modifications allowed only relatively slow cell proliferation, and showed only moderate osseointegration potential without significant support for matrix mineralization. Materials with these properties are promising for utilization in temporary traumatological implants.

Highlights

Pulsed micro-arc oxidation (MAO) in a strongly alkaline electrolyte, consisting of Na2SiO3⋅9H2O and NaOH, was used to form a thin porous oxide coating consisting of two layers differing in chemical and phase composition
The results showed that two layers with a different phase composition were prepared during the MAO process
Samples of Ti–6Al–4V alloy, i.e. a material currently used in orthopedic surgery, were modified by the pulsed micro-arc oxidation (MAO) technique in order to improve the tribological properties of the alloy and to modulate its interaction with osteoblasts

Summary

Introduction

Pulsed micro-arc oxidation (MAO) in a strongly alkaline electrolyte (pH > 13), consisting of Na2SiO3⋅9H2O and NaOH, was used to form a thin porous oxide coating consisting of two layers differing in chemical and phase composition. The unique procedure, combining MAO and removal of the outer layer by blasting, enables to prepare a coating suitable for application in temporary traumatological implants. High cell viability was supported, but the modifications allowed only relatively slow cell proliferation, and showed only moderate osseointegration potential without significant support for matrix mineralization Materials with these properties are promising for utilization in temporary traumatological implants. Surface that allows for desired biological interactions between a medical implant and the tissue, depending on its intended application For these purposes, various mechanical methods (fine working, grinding, tumbling, blasting), chemical methods (pickling, CVD, anodic oxidation, sol–gel) and physical methods (PVD, thermal spraying, ion implantation) have been investigated and are in use in practical a pplications[5]. Degreasing and pickling are used as chemical pre-treatments to remove contaminants and the thin naturally occurring oxide layer (< 10 nm)[7]

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