The design of novel Cu 2+ quantitative sensors with highly sensitivity and selectivity is a hot topic of modern chemistry . Herein, a novel ratiometric fluorescence (PL) sensor based on the red-emitting CdTeS quantum dots (QDs) and blue-emitting polyethyleneimine-functionalized carbon dots (PEI-CDs) was firstly designed for sensing Cu 2+ . In the presence of Cu 2+ , a good linear relationship between the ratios (F 520 /F 690 ) of the two peak intensities and the concentrations of Cu 2+ was observed in the range of 0.01–250 µM with the correlation coefficient (R 2 ) of 0.993 and the detection limit as low as 8.07 nM. The ratiometric nanosensor was also used to successfully determine Cu 2+ in plasma samples with satisfactory results obtained. Therefore, we hold the opinion that the developed ratiometric fluorescent sensor based on CdTeS QDs/PEI-CDs will provide technical support for the point-of-caretesting of Cu 2+ .
In this study, a core-shell structural nano-composite material, namely CdTeS@SiO 2 , is synthesized by a simple silanization of Te-doped CdS quantum dots (CdTeS QDs). Through SiO 2 capping, CdTeS QDs not only improve the fluorescence performance effectively, but also greatly enhance the anti-interference ability in the environment. Based on its excellent optical properties , a novel fluorescence sensor is constructed for the ultramicro detection of Ag + . The fluorescence of CdTeS@SiO 2 is strongly quenched in the presence of Ag + and shows good linearity in the range of 0.005–5.0 μmol L −1 with a detection limit as low as 1.6 nmol L −1 . This is mainly due to its unique quenching mechanism: Ag + destroys the spherical structure of SiO 2 and promotes the formation of non-radiative electron-hole pairs through electron transfer , leading to fluorescence quenching . At the same time, it competes with Cd for Te, S and MPA on the CdTeS surface, forming Ag–Te, Ag–S and Ag–MPA complexes attached to the CdTeS surface leading to wavelength red-shift. The feasibility of the proposed sensor is demonstrated through spiking experiments, which confirmed the potential value of the constructed fluorescence probe for real-world applications in detecting Ag + in environmental water.
Min Yang,Yujia Yan,Huanxian Shi,Cunjin Wang,Enzhou Liu,Xiaoyun Hu,Jun Fan
In the design of new fluorescence sensors, exploration of new sensors with excellent performances and smart designs for the detection of ions and biomolecules is of continuing interest. Therefore, we designed an inner filter effect (IFE) based sensor by effectively combining between CdTeS quantum dots (QDs) and Ag nanoparticles (NPs). Ternary alloyed CdTeS QDs were synthesized by two steps and using 3-mercaptopropionic acid (MPA) as stabilizer , polyvinylpyrrolidone (PVP) stabilized Ag NPs were prepared by crystal-seed. The emission peak of CdTeS QDs and the absorption peak of Ag NPs could availably overlap by changing the Te/S molar ratios and l -ascorbic acid (AA) concentrations. The CdTeS QDs/Ag NPs (QNs) with an obviously emission at 580 nm were used as IFE-based sensors for l -cysteine (L-Cys). The QNs fluorescence was increasing with addition of l -Cysteine (L-Cys), the fluorescence (PL) intensity (F/F 0 ) was linearly proportional to the L-Cys concentrations ranging from 20 μM to 400 μM with the correlation coefficient (R 2 ) of 0.9942 and the detection limit was calculated to be 0.025 μM (S/N = 3), where F and F 0 were the PL intensity in the presence and absence of L-Cys at 580 nm, respectively. Moreover, there was no interference to some potential interfering substances, which showed high sensitivity and selectivity for L-Cys.
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