Ultrasensitive microfluidic electrochemical immunosensor based on electrodeposited nanoporous gold for SOX-2 determination

• Published in: Analytica chimica acta Vol. 1127; pp. 122 - 130
• Main Authors: Regiart, Matías, Gimenez, Alba Marina, Lopes, Alexandre T., Carreño, Marcelo N.P., Bertotti, Mauro
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier B.V 29-08-2020
• Subjects: Antibodies, Immobilized; Biosensing Techniques; Electrochemical; Electrochemical Techniques; Gold; Gold nanoporous; Hydrogen Peroxide; Immunoassay; Immunosensor; Limit of Detection; Metal Nanoparticles; Microfluidic; Microfluidics; Nanopores; SOX-2; Gold nanoporous; Immunosensor; Microfluidic; SOX-2; Electrochemical
• ISSN: 0003-2670; 1873-4324
• DOI: 10.1016/j.aca.2020.06.037

An ultrasensitive and portable microfluidic electrochemical immunosensor for SOX-2 cancer biomarker determination was developed. The selectivity and sensitivity of the sensor were improved by modifying the microfluidic channel. This was accomplished through a physical-chemical treatment to produce a hydrophilic surface, with an increased surface to volume/ratio, where the anti-SOX-2 antibodies can be covalently immobilized. A sputtered gold electrode was used as detector and its surface was activated by using a dynamic hydrogen bubble template method. As a result, a gold nanoporous structure (NPAu) with outstanding properties, like high specific surface area, large pore volume, uniform nanostructure, good conductivity, and excellent electrochemical activity was obtained.
SOX-2 present in the sample was bound to the anti-SOX-2 immobilized in the microfluidic channel, and then was labeled with a second antibody marked with horseradish peroxidase (HRP-anti-SOX-2) like a sandwich immunoassay. Finally, an H2O2 + catechol solution was added, and the enzymatic product (quinone) was reduced on the NPAu electrode at +0.1 V (vs. Ag). The current obtained was directly proportional to the SOX-2 concentration in the sample. The detection limit achieved was 30 pg mL−1, and the coefficient of variation was less than 4.75%. Therefore, the microfluidic electrochemical immunosensor is a suitable clinical device for in situ SOX-2 determination in real samples.
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•An ultrasensitive and portable microfluidic electrochemical immunosensor for SOX-2 cancer biomarker detection was developed.•Selectivity and sensitivity were improved by a physical-chemical channel treatment in order to obtain a hydrophilicity functional platform.•The gold electrode was modified by using a dynamic hydrogen bubble template method, resulting in a gold nanoporous electrode.•SOX-2 present in the sample was detected by a type sandwich immunoassay.