Low-Potential Electrochemiluminescent Sensing Based on Surface Unpassivation of CdTe Quantum Dots and Competition of Analyte Cation to Stabilizer

Abstract

A novel electrochemiluminescent (ECL) sensing system was constructed for low-potential detection of metal ion by immobilizing surface-unpassivated CdTe quantum dots (QDs) on a glassy carbon electrode. The surface-unpassivated CdTe QDs were prepared using meso-2,3-dimercaptosuccinic acid (DMSA) as a stabilizer to cap CdTe QDs and characterized with scanning electron micrograph and X-ray photoelectron spectroscopy. The immobilized QDs showed a strong cathodic ECL emission peak at -0.87 V with an onset potential at -0.64 V (vs Ag/AgCl/saturated KCl) in air-saturated, pH 9.0 HCl-Tris buffer. On the basis of the competition of metal ion to the stabilizer, the quenching effect of metal ion on ECL emission was observed, which led to a sensitive chemical sensing application. Using cupric cation as a model analyte, the sensor showed a linear range from 5.0 nM to 7.0 muM with a detection limit of 3.0 nM and had been successfully applied in the detection of copper in human hair. It could be extended to detect other metal ions with stronger metal-S interaction than with the Cd-S bond. As an example, the sensor could be used to detect Hg(2+) down to 1.4 nM. The bidentate chelate QD-based sensor exhibited a promising platform for rapid detection of cations with strong metal-S interaction and could be further applied for development of other low-potential electrochemical sensing systems.

One‐Pot Synthesis of Dual‐Stabilizer‐Capped CdTe Nanocrystals with Efficient Near‐Infrared Photoluminescence and Electrochemiluminescence

“…The effects of the MPA stabilizer on the PL of the CdTe NCs are shown in Figure 2. Although a higher molar ratio of MPA to Cd 2+ at the initial stage tends to slow down the growth rate of CdTe NCs, PL spectra with an FWHM range from 40 to 84 nm ( Figure 2B) are obviously narrower than those of NIR InAs/ZnSe NCs (about 77-85 nm), [25] Cu-In-Se NCs (about 100 nm), [26] and NAC-capped CdTe/ CdS (about 62-97 nm) [13] within similar emission ranges. A relatively higher PLQY beyond 10 % in the NIR region was obtained with a varied molar ratio of MPA/Cd 2+ , and the highest PLQY of up to 47 % was achieved at 560 nm with a molar ratio of MPA/Cd 2+ of 3:1.…”

A visible light induced photoelectrochemical aptsensor constructed by aligned ZnO@CdTe core shell nanocable arrays/carboxylated g-C3N4 for the detection of Proprotein convertase subtilisin/kexin type 6 gene

“…To increase the light-harvesting efficiency, various semiconductor nanocrystals have been adopted to sensitize ZnO, including CdS (Fan et al 2014;Maity et al 2015;Robel et al 2006;, CdSe Jiang and Ju 2007;Jie et al 2011;Josell et al 2014;Robel et al 2006;Zou and Ju 2004), CdTe (Cheng et al 2010;Eley et al 2014;Fan et al 2014;Li et al 2005;, PbS (Eita et al 2015;Karki et al 2014;Zheng et al 2014), PbSe (Chen et al 1998;Oh et al 2014;Schornbaum et al 2014;Zhu et al 2000), InP (Kim et al 2015;Zaban et al 1998) and InAs (Ni et al 2011;Wang et al 2013;Wang et al 2014). Among the most widely used inorganic semiconductor sensitizers, CdTe has a high optical absorption coefficient (10 -4 cm -1 ) and narrow band gap of about 1.5 eV at room temperature and match the preferred range of the radiation spectrum (Cao et al 2007;Shokhovets et al 2007).…”

Reprint of "Cathode photoelectrochemical immunoassay based on analyte- induced formation of exciton trapping for carcinoembryonic antigen detection"

“…The Cd3d and S2p XPS of QDs ( Fig. 2A and B) showed a Cd:S molar ratio of about 1:8, after Cu 2 + was added to the QDs solution, this ratio became 1:13, indicating that more S 2 − ions were exposed and cupric ions were captured on the surface of dimercaptosuccinic acid -CdS QDs [30]. Moreover, after interaction of Cu 2+ with QDs, the binding energy of Cu2p3/2 split into two parts with peak values of 931.4 and 932.7 eV, respectively (Fig.…”