Preparation of tantalum-containing coatings on NiTi shape memory alloys with enhanced in vitro cytocompatibility and antibacterial effectiveness

Abstract

In this work, the magnetron sputtering method is used to deposit tantalum-containing coatings on NiTi shape memory alloys under various sputtering atmospheres including (i) 100% argon, (ii) 16.6% oxygen and 83.4% argon, and (iii) 16.6% nitrogen and 83.4% argon. This research examines how the sputtering atmosphere can impact surface morphology, roughness, wettability, biocompatibility, in vitro cytocompatibility, and antibacterial performance of tantalum-containing coatings. The calculation of nickel ions release by coupled inductively coupled plasma-optical emission spectrometry displayed that none of the coated samples showed any traces of nickel, unlike the bare NiTi substrate. This has led to an improvement in biocompatibility. Topographical measurements demonstrated the formation of a smooth surface under the argon-oxygen atmosphere, whereas the deposited layer in the argon-nitrogen atmosphere exhibited irregular ups and downs. The coatings deposited under the argon-nitrogen atmosphere result in a hydrophobic surface with many hills and valleys which can considerably enhance protein and cellular absorption. Besides, the samples coated under an argon-oxygen atmosphere with a smooth surface exhibited excellent antibacterial efficiency only as early as 6 h of incubation. This is probably due to the formation of amorphous tantalum pentoxide.

Keywords

• NiTi shape memory alloy
• Tantalum-containing coatings
• Antibacterial behavior
• Human umbilical vein endothelial cells
• Cytotoxicity