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.

中文翻译：

---

基于g-C3N4 / PDDA / CdSe纳米复合材料的高灵敏度电化学发光生物传感器，用于VEGF165检测。

在这项工作中，电化学发光（ECL）生物传感器被制造用于选择性检测血管内皮生长因子（VEGF165）。g-C3N4 / PDDA / CdSe纳米复合材料用作ECL底物。然后，通过酰胺键将在5'端标记有氨基的DNA（DNA1）固定在g-C3N4 / PDDA / CdSe纳米复合修饰玻碳电极（GCE）的表面上。AuNP标记的目标DNA（Au-DNA2）可以与DNA1杂交形成双链。g-C3N4 / PDDA / CdSe纳米复合材料的ECL由于CdSe QD和Au NP之间的共振能量转移而被有效淬灭。VEGF165被Au-DNA2识别并结合后，双螺旋被破坏，能量转移被破坏。在这种情况下，Au-DNA2从电极表面释放出来，并且ECL强度恢复到更高的水平。在最佳条件下，此ECL生物传感器在2 pg mL-1至2 ng mL-1的线性范围内具有极好的选择性，准确性和VEGF165检测稳定性，检测极限为0.68 pg mL-1。另外，该测定法已经成功地应用于血清样品中VEGF165的测定。基于g-C3N4 / PDDA / CdSe纳米复合材料的电化学发光传感器的图形化抽象示意图，可以确定血清中血管内皮生长因子的浓度。