Flower-Shaped Graphitic Carbon Nitride Decorated with Boron–Nitrogen-Doped Carbon Quantum Dots for Electrochemical Oral Cancer Determination

Early-stage cancer diagnosis significantly diminishes mortality rates; hence, it is imperative to prioritize the development of effective techniques for noninvasive, fast, and economical cancer-related biomarker detection. In this regard, we have synthesized an innovative flower-shaped graphitic carbon nitride (gC₃N₄)-decorated boron-nitrogen-doped carbon quantum dot (BN-CQD) nanohybrid (BN-CQD_gC₃N₄)-based immunosensing platform for sensitive and noninvasive determination of CYFRA21-1 in artificial saliva. The BN-CQD_gC₃N₄ nanohybrid was synthesized and has been characterized using a range of characterization techniques, such as Fourier transform infrared analysis, field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy, X-ray diffraction, high-resolution transmission electron microscopy, ultraviolet-visible spectroscopy, photoluminescence analysis, and X-ray photoelectron spectroscopy, to investigate the structural, morphological, optical, and elemental properties of the samples. Electrochemical properties of fabricated sensing platforms were analyzed using cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy techniques. Utilization of the screen-printed carbon electrode (SPCE), modified with a nanohybrid material, resulted in a notable improvement in the electrochemical performance compared to an unmodified SPCE, owing to mutually reinforcing effects of BN-CQD_gC₃N₄. Consequently, the developed electrochemical sensor illustrates a broad dynamic range spanning from 0.1 to 30 ng/mL, with a low limit of detection value of 0.014 ng/mL and a limit of quantification of 0.681 ng/mL. Additionally, it demonstrates a sensitivity of 95.609 μA cm⁻² (log (ng/mL))⁻¹ along with outstanding reproducibility and selectivity for the CYFRA21-1 biomarker determination. Thus, this study opens an exciting path for investigating the electrochemical nature of the BN-CQD_gC N₄ nanohybrid and its potential for developing other point-of-care devices for rapid cancer diagnosis.