A Ru/RuO2-Doped TiO2 Nanotubes as pH Sensors for Biomedical Applications: The Effect of the Amount and Oxidation of Deposited Ru on the Electrochemical Response

Abstract

In the field of orthopedic or dental implants, titanium and its alloys are most commonly used because of their excellent mechanical and corrosion properties and good biocompatibility. After implantation into the patient’s body, there is a high risk of developing bacterial inflammation, which negatively affects the surrounding tissues and the implant itself. Early detection of inflammation could be done with a pH sensor. In this work, pH-sensitive systems based on TiO2-Ru and TiO2-RuO2 combinations were fabricated and investigated. As a base material, Ti-6Al-4V alloy nanostructured by anodic oxidation was used. Ruthenium was successfully deposited on nanotubular TiO2 using cyclic polarization, galvanostatic and potentiostatic mode. Potentiostatic mode proved to be the most suitable. The selected samples were oxidized by cyclic polarization to form a TiO2-RuO2 system. The success of the oxidation was confirmed by XPS analysis. The electrochemical response of the systems to pH change was measured in saline solution using different techniques. The measurement of open circuit potential showed that unoxidized samples (TiO2-Ru) exhibited sub-Nernstian behavior (39.2 and 35.8 mV/pH). The oxidized sample (TiO2-RuO2) containing the highest amount of Ru exhibited super-Nernstian behavior (67.3 mV/pH). The Mott–Schottky analysis proved to be the best method. The use of the electrochemical impedance method can also be considered, provided that greater stability of the samples is achieved.

Review of the Design of Ruthenium-Based Nanomaterials and Their Sensing Applications in Electrochemistry

“…For instance, RuO 2 is a stable oxide and a focus of research interests in the development of pH sensors. 12 process takes place over the phenolic −OH group in benzene ring. Using the DPV method, quantifying EE2 and AMX with a WLR (0.055−1.20 μM), LOD (0.00204 μM; 0.00163 μM), and sensitivity ∼2.27 μA μM −1 , respectively.…”

“…10,11 Different configurations of Ru particles in various phases will alter the electrical, geometric structures, and superior electrocatalytic activities are predicted. 12 Combining a porous solid matrix or semiconductors with Ru nanostructures could further confirm that the active portions of the composites were totally showing and avoiding Ru from clumping during the EC sensing process. 13 The introduction of Ru NPs into suitable solid supports 14−16 not only served as supports, it also shows a significant impact on their surface chemistry, electronic structure, and significant improvement made in changing metal−support interfaces and efficient in growth catalysis.…”

“…When the quantity of DA was excessive in biological fluids, it can cause a range of disorders, including Parkinsonism, schizophrenia, Alzheimer's, epilepsy, euphoria, pleasurable feelings, etc. 79 Panov et al 80 fabricated Ru-based microstructures synthesized by the laser-induced metal deposition technique using triruthenium dodecacarbonyl (Ru 3 (CO) 12 ) and DMF solvent. The developed Ru microelectrode (Ru ME) had a large surface area with 10 μm pores and 10 nm zigzag cracks.…”

pH Sensing for Early Detection of Septic Inflammation Based on Intrinsic Titanium β-Alloy Nanotubular Oxides

“…Titanium dioxide is an n-type semiconductor with a high chemical stability. At the same time, TiO 2 can be modified by anodization to obtain a nanotubular structure, which is characterized by a several times larger real area compared to the geometrical one, leading to a larger number of hydroxyl groups, which are involved in pH sensing [12,19,20]. In the work of Zhao R. et al [19], TiO 2 nanotubes were created by anodic oxidation, and these tubes exhibited a near Nernstian response of 54 mV/pH and achieved a response of 59 mV/pH in the pH range of 2-12 after surface treatment with UV radiation.…”

Preparation, Characterization and Electrochemical Response of Nanostructured TiAlV with Potentiostatically Deposited IrOx as a pH Sensor for Rapid Detection of Inflammation

“…Moreover, TiO 2 exhibits unique ionic and electrical properties, distinguishing it from other oxides and amplifying its utility in sensor technologies. Multiple fabrication techniques exist for producing TiO 2 nanostructures, among which sol-gel and electrochemical methods are prominent [22,23,25].…”