Impedimetric Detection of Albumin-Bound Fatty Acids Using Graphene Oxide Electrode


UYGUN Z. O. , DUMAN S. , ORAN İ.

CHEMOSENSORS, vol.9, no.9, 2021 (Journal Indexed in SCI) identifier identifier

  • Publication Type: Article / Article
  • Volume: 9 Issue: 9
  • Publication Date: 2021
  • Doi Number: 10.3390/chemosensors9090240
  • Title of Journal : CHEMOSENSORS
  • Keywords: graphene, fatty acid, albumin, chronoimpedance, impedance spectroscopy, ACUTE MYOCARDIAL-INFARCTION, ACTIVATED CARBON, PLASMA, MONOLAYERS, REMOVAL, BINDING, DEATH, RISK

Abstract

The fatty acid/albumin (FA/Alb) molar ratio is <= 1 in healthy subjects; this ratio can reach 3-4 in patients with acute myocardial ischemia. We describe the spontaneous desorption-adsorption kinetics of FAs from albumin to a graphene electrode at neutral pH. Albumin-depleted human serum was prepared via ultrafiltration and then mixed with defatted human albumin and sodium oleate at different FA/Alb molar ratios, at a final albumin concentration of 0.6 mM. A commercially available screen-printed graphene oxide (GO)-modified carbon electrode was used for the electrochemical experiments. Frequency-ranged Faradaic electrochemical impedance spectroscopy (EIS) and a single-frequency non-Faradaic impedance measure (chronoimpedance) were used to derive the desorption-adsorption kinetics. The surface of the GO electrode was finally evaluated with the aid of X-ray photoelectron spectroscopy (XPS). With the chronoimpedance experiment, the measured impedance increased accordingly to the FA/Alb ratios. The frequency-ranged EIS showed good linearity between the impedance and the FA/Alb ratio, with a limit of quantification value of 1.06. XPS surface analysis revealed that the FA was adsorbed onto the electrode, with the amount of the adsorbed FA proportional to the FA/Alb ratio. The electrochemical method applied on this peculiar desorption-adsorption kinetics of FAs has the ability to differentiate serum having excess FAs.