Electrochemiluminescence immunosensor for the sensitive detection of the pancreatic neuroendocrine tumor biomarker chromogranin B based on graphdiyne quantum dots†

Neuroendocrine tumor (NET) is a rare and heterogeneous tumor with an increasing incidence, which is often misdiagnosed and frequently presents with distant metastases at the time of diagnosis. Chromogranin B (CgB) is not influenced by other diseases or drug factors, such as proton pump inhibitors (PPIs), and is therefore expected to serve as a complementary biomarker to improve the early diagnosis of NET. However, the detection sensitivity of CgB urgently requires improvement. In this study, a highly sensitive ECL immunosensor was designed for the detection of CgB. Graphdiyne quantum dots (GDY QDs), synthesized via the hydrothermal treatment of graphdiyne (GDY) nanosheets, exhibited good biocompatibility and a high electrochemiluminescence (ECL) quantum yield (Φ_ECL = 218.5%) when using K₂S₂O₈ as a co-reactant. With remarkable conductivity and a large surface area, Au NPs effectively loaded a high amount of GDY QDs, thereby enhancing the ECL response. Therefore, the developed ECL immunosensor showed exceptional analytical performance for CgB detection, demonstrating excellent linearity over a range of 10 fg mL⁻¹ to 100 ng mL⁻¹, with a limit of detection as low as 1.84 fg mL⁻¹ (S/N = 3). Moreover, this immunosensor could detect CgB levels in clinical serum and functioned synergistically with enzyme-linked immunosorbent assay (ELISA). This work expands the application of GDY QDs in ECL biosensors while also providing a highly sensitive detection method for CgB.