A new ultrasensitive platform based on f-GCNFs@nano-CeO2 core-shell nanocomposite for electrochemical sensing of oxidative stress biomarker 3-nitrotyrosine in presence of uric acid and tyrosine

Electrode materials with high sensitivity and selectivity play a central role in the fabrication of electrochemical sensing platforms. In this work, functionalized graphitized carbon nanofibers (f-GCNFs)core and nano-sized CeO2 (nano-CeO2)shell was synthesized. The XRD, SEM, HRTEM and the EDX results confirmed the formation of the f-GCNFs@nano-CeO2 core-shell nanocomposite. To construct the sensor, the graphite rod electrode (GRE) has been modified with f-GCNFs@nano-CeO2. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) results revealed that the charge transfer on the f-GCNFs@nano-CeO2/GRE was dramatically enhanced compared to the other electrodes. The prepared platform (f-GCNFs@nano-CeO2) exhibited high electro-catalytic activity and the strong synergistic activity between f-GCNFs and nano-CeO2 increased the electroactive surface area. The fabricated f-GCNFs@nano-CeO2/GRE sensor has been utilized for the detection of the oxidative stress biomarker nitrotyrosine (NTyr) using SW-AdASV. The LOD and the LOQ are found to be 0.86 and 2.9 nM, respectively, with the dynamic range 2.0-1720 nM and sensitivity of 145 mu A mu M-1 cm-2. The developed sensor is highly selective for NTyr detection in the presence of uric acid (UA) and tyrosine (Tyr). Moreover, the fabricated sensor also shows good selectivity, favorable reproducibility, and long-term stability. The applicability of the fabricated sensor demonstrated excellent recovery of NTyr in spiked human serum, urine, and saliva samples. In the end, f-GCNFs@nano-CeO2/GRE was applied to the determination of UA, NTyr, and Tyr simultaneously.

Automated summary

In this work, a composite material consisting of functionalized graphitized carbon nanofibers (f-GCNFs) core and nano-sized CeO2 shell was synthesized and used for sensor construction. The prepared platform showed high electro-catalytic activity and selectivity, and exhibited excellent sensitivity and dynamic range for the detection of nitrotyrosine (NTyr) as an oxidative stress biomarker. The fabricated sensor also demonstrated good selectivity, reproducibility, and long-term stability, and showed excellent recovery of NTyr in spiked human serum, urine, and saliva samples.