Electrochemical Biosensor Based on Lectin-functionalized Nitrogen, Sulfur-doped Graphene Quantum Dot Decorated Gold Nanoparticles for Breast Cancer Diagnosis: From Academic Research to Clinical Translation

In this research, considering benefits of the nitrogen, sulfur-doped graphene quantum dot (NSGQDs) and 3-dimensional gold nanoparticle (AuNP), we used these materials for the construction of a novel electrochemical biosensor to apply the synergy contributions on the enhancement of the potential in clinical and cancer diagnostic applications. The synthesis of a novel nanocomposite through the integration of NSGQDs with AuNP yields a hybrid material (NSGQDs/AuNP) that combines the advantages of both its organic and inorganic properties, potentially revealing unique characteristics to enhance the electrochemical behaviors, which establishes a robust foundation for constructing a label-free electrochemical biosensor. This pioneering biosensor was then conjugated with PhaL (NSGQDs/AuNP/PhaL) through the amide bond between the COOH group of NSGQDs and the NH2 group of PhaL, which has the potential for the ultra-sensitive detection of cancer markers, featuring heightened electrochemical and sensing capabilities that make substantial contributions to the field of cancer detection. The detection principle of breast cancer is based on the change in impedance of NSGQDs/AuNP/PhaL after the addition of breast cancer cell, which can inhibit the electron transfer after the formation of breast cancer cell bioconjugate with NSGQDs/AuNP/PhaL. NSGQDs/AuNP/PhaL are used as the bi-functional probe to amplify the electrochemical activity as well as to link cancer cell. The developed novel NSGQDs/AuNP/PhaL biosensor show high sensitivity and good stability for quantitative determination of breast cancer cell in a linear range of 5 - 2500 cell mL-1 with limit of detection (LOD) of 6 cancer cell mL-1, which exhibits a great potential in clinical and cancer diagnostic applications. The superior sensitivity of the developed impedimetric immunosensor is mainly attributed to the remarkable electro-conductivity of NSGQDs/AuNP, which can accelerate the electron transfer process between NSGQDs/AuN