Enhanced Hydrophilicity and Protein Adsorption of Titanium Surface by Sodium Bicarbonate Solution

Abstract

The aim of this study was to investigate a novel and convenient method of chemical treatment to modify the hydrophilicity of titanium surfaces. Sand-blasted and acid-etched (SLA) titanium surfaces and machined titanium surfaces were treated with sodium bicarbonate (NaHCO3) solution. The wetting behavior of both kinds of surfaces was measured by water contact angle (WCA) test. The surface microstructure was assessed with scanning electron microscopy (SEM) and three-dimensional (3D) optical microscopy. The elemental compositions of the surfaces were analyzed by X-ray photoelectron spectroscopy (XPS). The protein adsorption analysis was performed with fibronectin. Results showed that, after 1 M NaHCO3treatment, the hydrophilicity of both SLA and machined surfaces was enhanced. No significant microstructural change presented on titanium surfaces after NaHCO3treatment. The deprotonation and ion exchange activities might cause the enhanced hydrophilicity of titanium surfaces. The increased protein adsorption of NaHCO3-treated SLA surfaces might indicate their improved tissue-integration in clinical use.

Titanium and Protein Adsorption: An Overview of Mechanisms and Effects of Surface Features

“…Treatments in NaOH result in a formation of Ti-O-Na layer that changes the surface electrical charge further increasing adsorption of negatively charged proteins such as albumin. AA treatments are more effective in promoting protein adsorption when compared to other surface treatments, such as alkali-heat (AH) [ 114 ] or anodic oxidation treatments (AO) [ 115 ] and also SLA modification [ 116 ]. Better BSA adsorption capability of AA-Ti than AH-Ti, where samples are heated at 600 °C for 1 h after alkali treatment, relied on the higher number of OH groups and on the positive surface charge of AA-Ti [ 114 ].…”

“…In this case, AA-Ti can increase FN effect thanks to the disruption of α-helices and the formation of β-sheets [ 115 ]. AA-treatments were also found to increase protein adsorption of SLA modified surfaces by turning the surface from hydrophobic to super-hydrophilic [ 116 ]. On hydrophobic samples, air bubbles may be trapped in micropores in a Cassie-Baxter regime, hindering solution-surface interactions thus reducing protein adsorption.…”

Synergistic Effect of Cold Plasma Treatment and RGD Peptide Coating on Cell Proliferation over Titanium Surfaces

“…Despite various studies reporting no remarkable improvement of cellular attachment to surfaces with contact angle values less than 60°, there are also reports stating improved cellular attachment in consequence of decreasing contact angle below 60°. Increased contact angle of metallic implants was correlated to enhanced cell adhesion, proliferation differentiation and mineralization particularly on titanium implants [22,54]. Positive influence of the superhydrophilicity on enhanced cellular attachment was attributed to increased interaction of blood components with implant surface which is needed for protein adhesion on implant-a crucial process for cellular attachment [55][56][57].…”

Surface Modification of Direct-Current and Radio-Frequency Oxygen Plasma Treatments Enhance Cell Biocompatibility

“…Recek et al indicated that a large number of proteins can be absorbed on hydrophilic surfaces, leading to better cell proliferation and adhesion compared to hydrophobic surfaces [ 34 ]. The titanium rough surface with superhydrophilicity can cover with protein solution rapidly, and the rough property also increases protein contact areas [ 11 ]. Rupp et al indicated that the higher free energy which correlated to superhydrophilicity can induce protein adsorption [ 35 ].…”

“…Although SLA treatment for bone fixation does not alter the surface composition of titanium, SLA-treated surfaces belong to hydrophobic properties. The hydrophobicity of SLA surfaces is unfavorable for protein adsorption and cell affinity [ 11 ]. Zhao et al used nitrogen protection to diminish hydrocarbon contamination and enhance hydrophilic property of SLA-treated titanium [ 12 ].…”