Borophene is an allotropic form of boron that exists in different dimensional forms from zero-dimensional (0D) to three-dimensional (3D) and has excellent properties including high tensile strength, thermal and electrical conductivity, high capacitance, metallic nature, etc.

We report results of the studies relating to the development of an efficient biosensor for non-invasive detection of CYFRA-21-1 cancer biomarker. We used a low dielectric constant material (nanostructured yttrium oxide, nY₂O₃) for the fabrication of the biosensing platform. The nY₂O₃ was synthesized via solvothermal process and functionalized using 3-aminopropyl triethoxy silane (APTES). Electrophoretic deposition (EPD) of the functionalized nanomaterial (APTES/nY₂O₃) onto an indium tin oxide (ITO)-coated glass electrode was conducted at a DC potential of 50 V for 60 s. The EDC-NHS chemistry was used for covalent immobilization of −COOH bearing monoclonal anti-CYFRA-21-1 onto −NH₂ groups of APTES/nY₂O₃/ITO electrode. To avoid the non-specific interaction on the anti-CYFRA-21-1/APTES/nY₂O₃/ITO immunoelectrode, bovine serum albumin (BSA) was used. X-ray diffraction (XRD), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FESEM) were utilized for structural and morphological studies, whereas Fourier-transform infrared spectroscopy (FTIR) was used for the bonding analysis. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques were used for electrochemical characterization and response studies of fabricated electrodes. The fabricated immunosensor (BSA/anti-CYFRA-21-1/APTES/nY₂O₃/ITO) exhibited linearity in the range of 0.01–50 ng·mL⁻¹, sensitivity of 226.0 Ω·mL·ng⁻¹, and lower detection limit of 0.01·ng·mL⁻¹. A reasonable correlation was observed between the results obtained using this biosensor and concentration of CYFRA-21-1 measured through ELISA (enzyme-linked immunosorbent assay) technique in salivary samples of oral cancer patients.

Schematic representation of the fabrication steps of the BSA/anti-AFB1/APTES/nZrO₂@RGO/ITO immunoelectrode.