An Amine-Reactive Phenazine Ethosulfate (arPES)-A Novel Redox Probe for Electrochemical Aptamer-Based Sensor

Electrochemical aptamer-based biosensors (E-ABs) are attractive candidates for use in biomarker detection systems due to their sensitivity, rapid response, and design flexibility. There are only several redox probes that were employed previously for this application, and a combination of redox probes affords some advantages in target detection. Thus, it would be advantageous to study new redox probes in an E-AB system. In this study, we report the use of amine-reactive phenazine ethosulfate (arPES) for E-AB through its conjugation to the terminus of thrombin-binding aptamer. The constructed E-AB can detect thrombin by square-wave voltammetry (SWV), showing peak current at -0.15 V vs. Ag/AgCl at pH 7, which differs from redox probes used previously for E-ABs. We also compared the characteristics of PES as a redox probe for E-AB to methylene blue (MB), which is widely used. arPES showed stable signal at physiological pH. Moreover, the pH profile of arPES modified thrombin-binding aptamer revealed the potential application of arPES for a simultaneous multianalyte detection system. This could be achieved using different aptamers with several redox probes in tandem that harbor various electrochemical peak potentials. Our findings present a great opportunity to improve the current standard of biological fluid monitoring using E-AB.