Electrochemical Characterisation of Bovine Serum Albumin Adsorption on Phenolic- Coated Nickel-Titanium

Abstract

Understanding molecular interactions at the solid-liquid interface is essential to the development of biomaterials intended to function in the physiologic environment. Superelastic nickel-titanium, widely used for biomaterials applications, is here coated with two different phenolic compounds: pyrogallol and tannic acid. The adsorption of bovine serum albumin protein on these phenolic-coated surfaces is assessed by electrochemical impedance spectroscopy and cyclic voltammetry to understand the behavioural kinetics of proteins in a physiological environment. Using an electrical equivalent model, we show that pyrogallol coated surfaces adsorb more proteins than the native and the tannic acid-treated surfaces. We also show that in all cases, the amount of nickel ions leaching from the biomterial falls well withing the acceptable range for biocompatibility.

In vitro corrosion behaviour of phenolic coated nickel–titanium surfaces

“…Commercially available superelastic nitinol (55.67% nickel by weight, ASTM 2063) in the form of 1 mm thick mirror surface cold rolled sheets, (HLMET Co. Ltd in China) was stamped into Ø6.2 mm coins on a CNC turret punch press (Amada Arcade, Japan). Prior to surface treatment, to remove any machining contaminant and to reveal the native surface oxide layer, coins were successively washed in five steps [21]: 100 mM bicine buffered at pH 7.8 with 100 mM sodium chloride at 1 mg ml −1 [19,20]. After agitating samples in the solutions for 24 h on a rocking machine at 30 oscillations min −1 at room temperature, coins were thoroughly rinsed with deionised water and dried by blowing nitrogen to prevent further oxidation before storage in a dry polyethylene well plate.…”

“…Commercially available superelastic nitinol (55.67% nickel by weight, ASTM 2063) in the form of 1 mm thick mirror surface cold rolled sheets, (HLMET Co. Ltd in China) was stamped into Ø6.2 mm coins on a CNC turret punch press (Amada Arcade, Japan). Prior to surface treatment, to remove any machining contaminant and to reveal the native surface oxide layer, coins were successively washed in five steps [21]: first, in 70% vol. ethanol; second, for 5 min at 40°C in an ultrasonic bath with deionised water Milli‐Q Direct (Millipore, Billerica, MA) with a resistivity of 18.2 MΩ cm at 25°C; third, in 40% NaOH and water bath for 5 min; fourth, sonicated in deionised water for 5 min with a subsequent rinse with deionised water for 5 min; fifth, immersed for 10 min in 50% vol.…”