Highly sensitive electrochemiluminescence biosensor for VEGF₁₆₅ detection based on a g-C₃N₄/PDDA/CdSe nanocomposite

In this work, an electrochemiluminescence (ECL) biosensor was fabricated for the selective detection of vascular endothelial growth factor (VEGF₁₆₅). g-C₃N₄/PDDA/CdSe nanocomposites were used as the ECL substrate. Then, DNA labeled at the 5' end with amino groups (DNA₁) was immobilized on the surface of g-C₃N₄/PDDA/CdSe nanocomposite-modified glassy carbon electrode (GCE) by amido linkage. AuNP-labeled target DNA (Au-DNA₂) could hybridize with DNA₁ to form a double strand. The ECL of the g-C₃N₄/PDDA/CdSe nanocomposite was efficiently quenched due to the resonance energy transfer between CdSe QDs and Au NPs. After VEGF₁₆₅ was recognized and bound by Au-DNA₂, the double helix was disrupted, and the energy transfer was broken. In this case, Au-DNA₂ was released from the electrode surface, and the ECL intensity recovered to a higher level. Under optimal conditions, this ECL biosensor possesses excellent selectivity, accuracy, and stability for VEGF₁₆₅ detection in a linear range of 2 pg mL^-1 to 2 ng mL^-1 with a detection limit of 0.68 pg mL^-1. In addition, this assay has been successfully applied to the determination of VEGF₁₆₅ in serum samples. Graphical abstract Schematic representation of the electrochemiluminescence sensor based on a g-C3N4/PDDA/CdSe nanocomposite, which can be determined in the concentration of vascular endothelial growth factor in serum.