Reactive ion etching for fabrication of biofunctional titanium nanostructures

Mahya Ganjian,Khashayar Modaresifar,Amir A Zadpoor,Hongzhi Zhang,Lidy E Fratila-Apachitei,Peter-Leon Hagedoorn

doi:10.1038/s41598-019-55093-y

Mahya Ganjian, Khashayar Modaresifar + Show 4 more

Open Access

https://doi.org/10.1038/s41598-019-55093-y

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Journal: Scientific Reports	Publication Date: Dec 1, 2019
Citations: 35	License type: open-access

Affiliation: Delft University of Technology

Abstract

One of the major problems with the bone implant surfaces after surgery is the competition of host and bacterial cells to adhere to the implant surfaces. To keep the implants safe against implant-associated infections, the implant surface may be decorated with bactericidal nanostructures. Therefore, fabrication of nanostructures on biomaterials is of growing interest. Here, we systematically studied the effects of different processing parameters of inductively coupled plasma reactive ion etching (ICP RIE) on the Ti nanostructures. The resultant Ti surfaces were characterized by using scanning electron microscopy and contact angle measurements. The specimens etched using different chamber pressures were chosen for measurement of the mechanical properties using nanoindentation. The etched surfaces revealed various morphologies, from flat porous structures to relatively rough surfaces consisting of nanopillars with diameters between 26.4 ± 7.0 nm and 76.0 ± 24.4 nm and lengths between 0.5 ± 0.1 μm and 5.2 ± 0.3 μm. The wettability of the surfaces widely varied in the entire range of hydrophilicity. The structures obtained at higher chamber pressure showed enhanced mechanical properties. The bactericidal behavior of selected surfaces was assessed against Staphylococcus aureus and Escherichia coli bacteria while their cytocompatibility was evaluated with murine preosteoblasts. The findings indicated the potential of such ICP RIE Ti structures to incorporate both bactericidal and osteogenic activity, and pointed out that optimization of the process conditions is essential to maximize these biofunctionalities.

Highlights

Fadeeva et al have reported the bacterial response to superhydrophobic, self-organized titanium microstructures created by femtosecond laser ablation, but the killing efficiency has not been reported[33], and there are some limitations in reducing the size of the structures to nanometers
Hasan et al have reported that black Ti surfaces produced by inductively coupled plasma reactive ion etching (ICP RIE) can be bactericidal[40]
The killing efficiency of bactericidal nanostructures produced by ICP RIE method is reported to be much higher than the values found when using other processes (95 ± 5% for E. coli and 98 ± 2% for P. aeruginosa after 4 hr, and 76 ± 4% for S. aureus after 20 hr)

Summary

Introduction

RIE can rapidly generate biomimetic, high aspect ratio nanostructures (e.g., inspired by the dragonfly wing[4,30,31], damselfly wing[32], and gecko skin13) on large areas without any need for masks This process has been applied to create bSi topographies with antibacterial properties[4,5,9,28]. In another work, which used the hydrothermal technique to create TiO2 nanowires on the titanium substrate[20], the bactericidal effects of the created nanostructures against S. aureus were insignificant. The killing efficiency of bactericidal nanostructures produced by ICP RIE method is reported to be much higher than the values found when using other processes (95 ± 5% for E. coli and 98 ± 2% for P. aeruginosa after 4 hr, and 76 ± 4% for S. aureus after 20 hr). The effects of ICP RIE parameters on those characteristics are unknown

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