Development of an Efficient Immunosensing Platform by Exploring Single-Walled Carbon Nanohorns (SWCNHs) and Nitrogen Doped Graphene Quantum Dot (N-GQD) Nanocomposite for Early Detection of Cancer Biomarker

In this work, a novel electrochemical immunosensor based on nitrogen doped graphene quantum dot (N-GQD) and single-walled carbon nanohorns (SWCNHs) was developed for the detection of alpha-fetoprotein (AFP), a cancer biomarker. Thus, to fabricate the platform of the immunosensor, nanocomposite architecture was developed by decorating N-GQD on the surface of the SWCNHs. The resulting hybrid architecture (N- GQD@ SWCNHs) functioned as an exceptional base for the immobilization of antibody (Anti-AFP) through carbodiimide reaction with good stability and bioactivity. The immunosensor was prepared by evenly distributing the bioconjugates (N-GQD@SWCNHs/Anti-AFP) dispersion on the surface of the glassy carbon electrode, and subsequently blocking the remaining active sites by bovine serum albumin to prevent the nonspecific adsorption. Cyclic voltammetry and electrochemical impedance spectroscopy technique was employed to investigate the assembly process of the immunosensor. Under optimal conditions, the immunosensor exhibited a broad dynamic range in between 0.001 ng/mL to 200 ng/mL and a low detection limit of 0.25 pg/mL. Furthermore, the sensor showed high selectivity, desirable stability, and reproducibility. Measurements of AFP in human serum gave outstanding recovery within 99.2% and 102.1%. Thus, this investigation and the amplification strategy exhibited a potential role of the developed nanocomposite based sensor for early clinical screening of cancer biomarkers.

Automated summary

A novel electrochemical immunosensor based on N-GQD and SWCNHs was developed for detecting the cancer biomarker AFP. The nanocomposite architecture N-GQD@SWCNHs served as an excellent base for antibody immobilization, showing broad dynamic range and low detection limit with high selectivity, stability, and reproducibility. AFP measurements in human serum demonstrated outstanding recovery, highlighting the potential role of the sensor for early clinical screening of cancer biomarkers.