Redox probes tagged electrochemical aptasensing device for simultaneous detection of multiple cytokines in real time

Simultaneous detection of multiple cytokines is facing challenges due to cytokine complex network, dynamic and transient process of secretion. Herein we designed a molecular beacon aptamer-functionalized electrochemical sensing platform for simultaneous and real-time monitoring of three significant cytokines (VEGF, IFN-γ and TNF-α). Three biotinylated molecular beacon aptamers respectively tagged by redox probes anthraquinone (AQ) for VEGF, methyl blue (MB) for IFN-γ, and ferrocene (Fc) for TNF-α to achieve multiplex detection, were randomly immobilized on the gold electrode modified with graphene oxide/streptavidin (GO/SA) composite via strong non-covalent interaction between biotin and SA. The presence of VEGF, IFN-γ and TNF-α could induce the conformational transformation of aptamers while leaving the terminal redox probes far from the electrode resulting in changes of the electrochemical signal which corresponds the concentration of cytokines. The designed sensing interface successfully achieved simultaneous quantification of VEGF, IFN-γ and TNF-α with the sensitivity of 5 pg mL−1 in Tris buffer for each cytokine. Desirable discoveries were observed for simultaneous detection of three cytokines in human serum and artificial sweat. It promises a reliable electrochemical sensing platform in sweat wearables and implants for simultaneous monitoring of multiple analyes in real time.