A V2CTx Mxene-Based Immune Tag for the Electrochemical Detection of Interleukin 6 (IL-6) from Breast Cancer Cells
Authors: Zhou Zhiru , Cui Feiyun , Vessella Theadora , Zhang Hui , Zhou Hong Susan 
Published: September 2023

Interleukin 6 (IL-6) is a cytokine that can act in an anti-inflammatory or pro-inflammatory role1 and over-expression of IL-6 in the tumor microenvironment (TME) has been linked to numerous tumors including breast cancer 2. The quantitative detection of IL-6 is critical for the diagnosis of tumors and biological research. Although there are several methods for the detection of IL-6, an enzyme-linked immunosorbent assay (ELISA) is the most standard and conventional approach 3. Conventional methods have the disadvantages of complex operation, time-consuming, usage of expensive or bulky instruments and need for trained personnel, which make them unadaptable for point-of-care (POC) tests. Therefore, the development of a reliable, rapid and on-site detection platform for the quantitative analysis of IL-6 is needed.
Electrochemical (EC) biosensors are an alternative technique for detection of IL-6 owing to their advantages of a quick readout, low cost, ultra-sensitivity, high selectivity, and simplicity. Furthermore, electrochemical biosensors are easier to be miniaturized and mass fabricated, which makes them more desirable for POC applications 4. MXenes possessing high hydrophilicity, metallic conductivity and excellent plasmon resonance in the visible range are a novel family of 2D materials and are a suitable nanomaterial for enhancing EC signal 5.
Herein, a sensitive EC platform was proposed and developed based on a 2D vanadium carbide (V2CTx) MXene-based immune tag. V2CTx@ Fe₄[Fe(CN)6]₃ (Prussian Blue) @Au NPs was prepared by an in-situ generation method. Then, the anti-IL-6 antibody was fixed on the V2CTx@ PB @Au NPs. The prepared V2CTx MXene-based immune tag and EC platform was characterized by electrochemical impedance spectroscopy (EIS), cyclic voltammetry (CV), differential pulse voltammetry (DPV), scanning electron microscope (SEM), x-ray diffraction (XRD) method, x-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier transform infrared spectroscopy (FTIR). The in-situ generated V2CTx@PB@Au NPs showed stronger signal than electrostatic attracted Au NPs on V2CTx@PB. The linearity range were obtained as 0.005-0.5 ng/mL. The V2CTx@PB@Au maintained an EC signal of ~80% after 10 days and also performed well in real breast cancer cell samples. Our study thus suggests that the EC with V2CTx MXene-based immune tag is an effective platform for detecting cytokines secreted by breast cancer cells cultured in confined chips.

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Figure 1