Titania Nanotube Architectures Synthesized on 3D-Printed Ti-6Al-4V Implant and Assessing Vancomycin Release Protocols

Abstract

The aim of this study is to synthesize Titania nanotubes (TNTs) on the 3D-printed Ti-6Al-4V surface and investigate the loading of antibacterial vancomycin drug dose of 200 ppm for local drug treatment application for 24 h. The antibacterial drug release from synthesized nanotubes evaluated via the chemical surface measurement and the linear fitting of Korsmeyer-Peppas model was also assessed. The TNTs were synthesized on the Ti-6Al-4V surface through the anodization process at different anodization time. The TNTs morphology was characterized using field emission scanning electron microscope (FESEM). The wettability and the chemical composition of the Ti-6Al-4V surface and the TNTs were assessed using the contact angle meter, Fourier transform infrared spectrophotometer (FTIR) and the X-ray photoelectron spectroscopy (XPS). The vancomycin of 200 ppm release behavior under controlled atmosphere was measured by the high-performance liquid chromatography (HPLC) and hence, the position for retention time at 2.5 min was ascertained. The FESEM analysis confirmed the formation of nanostructured TNTs with vertically oriented, closely packed, smooth and unperforated walls. The maximum cumulative vancomycin release of 34.7% (69.5 ppm) was recorded at 24 h. The wetting angle of both Ti-6Al-4V implant and the TNTs were found below 90 degrees. This confirmed their excellent wettability.

Keywords: 3D printing; Ti-6Al-4V; electrostatic interaction; titania nanotubes; vancomycin.

Figure 1

A schematic diagram depicting a stage-by-stage the vancomycin release protocol from the fabricated titania nanotubes surface on the 3D-printed Ti-6Al-4V implant material. The as-printed specimen was ground and chemically etched to a suitable roughness surface. The titanium oxide nanotubes (TNTs) were synthesized at different at anodization duration.

Figure 2

Atomic force micrograph showing the 3D surface topography of the 3D-printed Ti-6Al-4V specimen prior to the TNTs fabrication through the anodization process. Various measured roughness values were presented.

Figure 3

The FESEM micrographs showing the top and side morphological views of the titanium oxide nanotubes fabricated at 1 h (a,e), 2 h (b,f), 3 h (c,g) and 4 h (d,h). The morphology images depict the TNTs orientation and the size of the pores. The pores diameter of the nanotube increased with increase in the anodization time while the length decreased.

Figure 4

Water contact angle of (a) as-printed Ti-6Al-4V, (b) TNTs_1h, (c) TNTs_2h, (d) TNTs_3h and (e) TNTs_4h. The wetting angle of “0” degrees were found in all nanotube surfaces, suggesting the high hydrophilicity of the fabricated TNTs surface.

Figure 5

The ATR-FTIR spectra of the 3D-printed Ti-6Al-4V and the synthesized TNTs_1h, TNTs_2h, TNTs_3h and TNTs_4h at a different anodization time and scanning range of 4000–600 cm⁻¹, containing various functional groups, which signifies the chemical properties of each specimen.

Figure 6

The XPS spectrums presenting the chemical composition of the oxide species of pre-post anodization process on the printed Ti-6Al-4V surface and the nanotubes of (a) C1s, (b) Ti2p, (c) O1s, (d) Al2p and (e) V2p, and the survey scan spectra for V2p.

Figure 7

Drug release profiles of (a) the percentage of cumulative drug release and (b) the concentration of drug release at different anodization time of the titanium oxide nanotubes.

Figure 8

The model of vancomycin release is proposed. The hydroxyl group (OH) and other functional hydrophilic group from the ATR-FTIR characterization donated by negatively charge ions is attributed to the nanotube surface after anodization.

Figure 9

The measured values of vancomycin release was fitted to Korsmeyer-Peppas model which describes the behavior in two main stages. The tabulated fitting the kinetic values of K and n from Korsmeyer-Peppas model, which described the kinetics of drug release in two stages. The 1st stage is the anomalous diffusion or Non-Fickian diffusion in the burst stage in which the n values are in the range of 0.54–0.56 while the 2nd stage shows the n values in the range of 0.05–0.12 suggesting Quasi-Fickian diffusion behavior.