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

• Published in: Chemosensors Vol. 9; no. 9; p. 240
• Main Authors: Uygun, Zihni Onur, Duman, Soner, Oran, Ismail
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.09.2021
• Subjects: Adsorption; Albumin; Albumins; Angina pectoris; Carbon; Cardiovascular disease; chronoimpedance; Desorption; Electrochemical impedance spectroscopy; Electrodes; Experiments; fatty acid; Fatty acids; Graphene; Heart attacks; impedance spectroscopy; Ischemia; Kinetics; Myocardial ischemia; Pain; Photoelectron spectroscopy; Photoelectrons; Sodium oleate; Spectrum analysis; Surface analysis (chemical); Surface chemistry; Ultrafiltration; X ray photoelectron spectroscopy; United States > US; Spain
• ISSN: 2227-9040; 2227-9040
• DOI: 10.3390/chemosensors9090240

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.