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 (VEGF(165)). g-C3N4/PDDA/CdSe nanocomposites were used as the ECL substrate. Then, DNA labeled at the 5 ' end with amino groups (DNA(1)) was immobilized on the surface of g-C3N4/PDDA/CdSe nanocomposite-modified glassy carbon electrode (GCE) by amido linkage. AuNP-labeled target DNA (Au-DNA(2)) could hybridize with DNA(1) 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 VEGF(165) was recognized and bound by Au-DNA(2), the double helix was disrupted, and the energy transfer was broken. In this case, Au-DNA(2) 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 VEGF(165) 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 VEGF(165) in serum samples.