Fabrication of a Novel Ta(Zn)O Thin Film on Titanium by Magnetron Sputtering and Plasma Electrolytic Oxidation for Cell Biocompatibilities and Antibacterial Applications

Heng-Li Huang,Yin-Yu Chang,Ming-Tzu Tsai,Jui-Ting Hsu,Yi-Jyun Lin

doi:10.3390/met10050649

Abstract

Pure titanium (Ti) and titanium alloys are widely used as artificial implant materials for biomedical applications. The excellent biocompatibility of Ti has been attributed to the presence of a natural or artificial surface layer of titanium dioxide. Zinc oxide and tantalum oxide thin films are recognized due to their outstanding antibacterial properties. In this study, high power impulse magnetron sputtering (HiPIMS) was used for the deposition of tantalum oxide and zinc-doped Ta(Zn)O thin films on Ti with rough and porous surface, which was pretreated by plasma electrolytic oxidation (PEO). Surface morphology, antibacterial property as well as cell biocompatibility were analyzed. The antibacterial effect was studied individually for the Gram-positive and Gram-negative bacteria Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemcomitans (A. actinomycetemcomitans). The deposited Ta (Zn)O coating was composed of amorphous tantalum oxide and crystalline ZnO. The antibacterial results on the tantalum oxide and Ta(Zn)O coated Ti indicated a significant inhibition of both S. aureus and A. actinomycetemcomitans bacteria when compared with the uncoated Ti samples. The deposited Ta(Zn)O showed the best antibacterial performance. The Ta(Zn)O coated Ti showed lower level of the cell viability in MG-63 cells compared to other groups, indicating that Zn-doped Ta(Zn)O coatings may restrict the cell viability of hard tissue-derived MG-63 cells. However, the biocompatibility tests demonstrated that the tantalum oxide and Ta(Zn)O coatings improved cell attachment and cell growth in human skin fibroblasts. The cytotoxicity was found similar between the Ta2O5 and Ta(Zn)O coated Ti. By adopting a first PEO surface modification and a subsequent HiPIMS coating deposition, we synthetized amorphous tantalum oxide and Ta(Zn)O coatings that improved titanium surface properties and morphologies, making them a good surface treatment for titanium-based implants.

Highlights

With the growing demand for metal implants in the medical industry, surface treatment, which includes various types of bio-coating and different surface modification techniques used for fabricationMetals 2020, 10, 649; doi:10.3390/met10050649 www.mdpi.com/journal/metalsMetals 2020, 10, 649 of biomaterials, is widely applied in implants for enhancing the biocompatibility and antibacterial properties between metals and tissues
The antibacterial results on the tantalum oxide and Ta(Zn)O coated Ti indicated a significant inhibition of both S. aureus and A. actinomycetemcomitans bacteria when compared with the uncoated Ti samples
Microbial infection is one of the main causes of implant failure. Most of these infections are caused by common bacteria, such as Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemocomitans (A. actinomycetemocomitans) which show enhanced activity on metallic and biocompatible surfaces used for implants [4,5]

Summary

Introduction

Metals 2020, 10, 649 of biomaterials, is widely applied in implants for enhancing the biocompatibility and antibacterial properties between metals and tissues. Microbial infection is one of the main causes of implant failure Most of these infections are caused by common bacteria, such as Staphylococcus aureus (S. aureus) and Actinobacillus actinomycetemocomitans (A. actinomycetemocomitans) which show enhanced activity on metallic and biocompatible surfaces used for implants [4,5]. It is worth using surface treatments with two main categories: surface modification (physical, chemical or combined) and coatings (physical, chemical or combined)

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