2D transparent few-layered hydrogen substituted graphdiyne nano-interface for unprecedented ultralow ANXA2 cancer...

Herein, we report synthesis of 2D few-layered transparent hydrogen substituted graphdiyne (HsGDY) nanosheets and explored its electrochemical characteristics for the first time to develop a nano-interface for cancer biomarker detection [liver cancer (LC) biomarker; ANXA2]. The semiconducting HsGDY (band gap; 1.98 eV) contains considerable number of sp and sp² hybridised π-electrons with abundant hierarchical pores, thus reveals a negative peripheral charge and high surface area respectively, making it competent to immobilize mass anti-ANXA2 antibodies. The nano-interface platform is fabricated through electrophoretic deposition of HsGDY onto indium tin oxide (ITO) coated glass substrate (50V, 60s) with subsequent immobilization of anti-ANXA2 biomolecules and bovine serum albumin (BSA) to minimize non-specific binding. The pristine HsGDY and fabricated electrodes were characterized using spectroscopic, microscopic, zetasizer, surface area and pore size analyzer as well as electrochemical techniques. The electrochemical response of fabricated HsGDY nano-interface based biosensing platform (BSA/anti-ANXA2/HsGDY/ITO) is investigated via cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques, which covers a wider linear detection range in between 0.01 fg mL^-1 to 1000 ng mL^-1 along with an exceptional sensitivity of 13.8 μA [log (ng mL^-1)]^-1 cm^-2 and 2.8 μA [log (ng mL^-1)]^-1 cm^-2 via CV and DPV techniques, respectively. This developed biosensor has the ability for unprecedented ultralow level i.e., upto 3 molecules of ANXA2 cancer biomarker detection. Moreover, the obtained electrochemical results show excellent correlation with the concentration of ANXA2 cancer biomarker present in LC patients obtained through enzyme linked immunosorbent assay (ELISA) technique.