Magnetic force assisted electrochemical sensor for the detection of thrombin with aptamer-antibody sandwich formation

• Published in: Biosensors & bioelectronics Vol. 117; pp. 480 - 486
• Main Authors: Chung, Saeromi, Moon, Jong-Min, Choi, Jaekyu, Hwang, Hyundoo, Shim, Yoon-Bo
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 15-10-2018
• Subjects: Aptamer; Aptamers, Nucleotide - metabolism; Biosensing Techniques - instrumentation; Biosensing Techniques - methods; Blood Chemical Analysis; Electrochemistry; Electrodes; Magnetic force; Magnetics; Reproducibility of Results; Sandwich assay; Thrombin; Thrombin - analysis; Electrochemistry; Thrombin; Magnetic force; Aptamer; Sandwich assay
• ISSN: 0956-5663; 1873-4235
• DOI: 10.1016/j.bios.2018.06.068

A magnetic force assisted electrochemical aptamer-antibody sandwich assay (MESA) was developed for the detection of thrombin as a model protein in serum samples. The MESA using the formation of sandwich complexes on the electrochemical sensor probe for reaction and the removal of unbound bioconjugates from the sensor surface without washing are controlled by a magnetic field. Thrombin was determined by the cathodic currents of a toluidine blue O (TBO) attached with thrombin antibody modified magnetic nanoparticle (MNP) at the sensor surface. To detect thrombin in a serum sample, we applied a thrombin-specific aptamer as the capture molecule bound to the functionalized conducting polymer layer (poly-(2,2´:5´,5″-terthiophene-3´-p-benzoic acid) (pTBA)), and streptavidin and starch coated-MNP was conjugated with biotinylated thrombin antibodies (Ab) and TBO as the bioconjugate (MNP@Ab-TBO). The characterization of MNP@Ab-TBO and sensor probe was performed using voltammetry, impedance spectroscopy, XPS, and UV–VIS spectroscopy. The experimental conditions were optimized in terms of pH, binding time, removal time of unbound bioconjugates, and applied potential. The dynamic ranges of thrombin were from 1.0 to 500 nM with detection limit of 0.49 ( ± 0.06) nM. The recovery test demonstrates the reliability of the proposed sensing system for a handheld device.
•A magnetic force assisted electrochemical sandwich assay was developed.•Aptamer-conducting polymer, magnetic NP with antibodies and TBO were used.•The device reduced sensing time without washing controlled by magnetic field.•The sensor was applied for the detection of thrombin in human serum samples.