Molybdenum carbide nanotubes: a novel multifunctional material for label-free electrochemical immunosensing

Abstract

Herein, a multifunctional nanoarchitecture has been developed by integrating well-crystalline molybdenum carbide (Mo₂C) nanotubes and an electrochemical indicator – thionin (TH). The Mo₂C nanotubes were synthesized through the self-degradable template method and high-temperature calcination, and their structure and morphology were characterized through scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). Due to the high electrocatalytic properties, excellent conductivity and highly active surface area of Mo₂C nanotubes, the Mo₂C-based material was used as a nanocarrier to load TH molecules for the development of a label-free electrochemical immunosensor for α-fetoprotein (AFP) detection. The decorated TH probe on the Mo₂C nanotubes not only acted as a bridging molecule to effectively capture and immobilize primary anti-AFP on the Mo₂C nanotubes, but also acted as a signal indicator for the detection of AFP. The proposed immunosensor exhibited excellent selectivity (with a detection limit of 3 pg mL⁻¹), high stability and good reproducibility by combining the unique structure and features of the Mo₂C nanotubes. Furthermore, this sensing platform was finally used for the detection of AFP in human serum with satisfactory results. Therefore, the Mo₂C nanotubes can be considered as a candidate carbon material for fabrication of simple, label-free and ultrasensitive electrochemical sensors, broadening the application of this material.