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-C 3 N 4 /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-C 3 N 4 /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-C 3 N 4 /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. 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.