Electrochemiluminescent Sensor Based On Solid-phase CdTe Quantum Dots

In this paper, we use3-aminopropyl trimethoxy silane (APTMS) and glutaraldehyde (GD) as crosslinkers to immobilize CdTe quantum dots (QDs) on the surface of indium tin oxide coated glass. By optimized series of modifier concentration ECL parameters, the solid-phase CdTe Quantum Dots ECL sensor with excellent combination property is realized. When graphene oxide (GO) was mixed into APTMS film, the modified electrode ECL signal is further enhanced. The properties of the ITO/APTMS/GD/CdTe and ITO/APTMS/GO/GD/CdTe modified electrodes are characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM), atomic force microscopy (AFM) and electrochemical impedance spectroscopy (EIS). The modified electrodes were apply to luminol electrochemiluminescence, the experimental results demonstrated that the modified electrodes not only efficiently intensified the ECL of luminol, but also extends its practicable pH window and reduces the required exciting potential to avoid some possible interference. The stability and repeatability of the modified electrodes are also investigated. After keeping at room temperature for18days, it shows that the ECL intensity of luminol on two electrodes decreased only4.3%or2.0%. The RSD for nine repetitive detections with single electrode and seven detections on different electrodes are4.2%/5.6%for ITO/APTMS/GD/CdTe and3.7%/7.9%for ITO/APTMS/GO/GD/CdTe, respectively. These results evidenced the good stability and repeatability of the modified electrodes. At the same time, the modified electrodes are very sensitive to luminol and hydrogen peroxide. For ITO/APTMS/GD/CdTe, the the detection limit of luminol and hydrogen peroxide are9.97×10-10M and1.13×10-11M respectively; For ITO/APTMS/GO/GD/CdTe, the the detection limit of luminol and hydrogen peroxide are9.03×10-10M and2.45×10-10M respectively. Meanwhile the mechanism of enhanced ECL of luminol on QDs solid-phase ECL substrate is discussed.At last, we attempt to modify both CdTe QDs and luminol on the surface of indium tin oxide coated glass to obtain solid-phase ECL sensor. The research laid the foundation for the preparation of well performance of CdTe QDs and luminol modified electrode electrochemiluminescence sensor.