Dual-functional electrochemical bio-sensor built from Cu2O for sensitively detecting the thiols and Hg2+

Highlights: • Dual-functional electrochemical sensor was successfully fabricated. • The work establishes a novel approach for distinguishing biothiols with S^2-. • The limit of detections of Cys and S^2- could achieve to 6.2 nM and 11.3 nM. • Cu₂O-S system can sensitively detect Hg²⁺ with low limit of detection at 0.3 nM. • The sensor performs a great potential in the application of biothiols detection. Electrochemical bioanalysis has been drawing more attention in recent years, due to the advantages of fast and effective detection capabilities. Intracellular thiols including biothiols (glutathione (GSH), cysteine (Cys) and homocysteine (Hcy)) and endogenous H₂S play important biological roles in physiological processes. Therefore, the development of a method for detecting biothiols and distinguishing from endogenous H₂S has become a challenge to be addressed. In this work, Cu₂O nanostructure was successfully synthesized by electrodeposition process and employed as core part of electrochemical sensing platform for sensitive detecting thiols. The sensor exhibits excellent sensing performance, which is due to the interaction of -SH with Cu (I) via the formation of Cu-S bond. Significantly, the sensor establishes a novel approach for distinguishing biothiols and S^2- via different peak current responses for the first time. The limit of detections of the sensor for Cys and S^2- have achieved to 6.2 nM and 11.3 nM, respectively. The practical applicability of the sensor was assessed in human urine samples. It is noteworthy that Cu₂O-S and Cu₂O-Cys systems have been found significant response toward Hg²⁺, which can be used for detecting Hg²⁺. The detection limit of Cu₂O-S system for Hg²⁺ was realized at 0.3 nM.