Ligand displacement-induced fluorescence switch of quantum dots for ultrasensitive detection of cadmium ions.
This paper reports the construction of a simple CdTe quantum dots (QDs)-based sensor with 1,10-phenanthroline (Phen) as ligand, and the demonstration of a novel ligand displacement-induced fluorescence switch strategy for sensitive and selective detection of Cd(2+) in aqueous phase. The complexation of Phen at the surface quenches the green photoluminescence (PL) of QDs dominated by a photoinduced hole transfer (PHT) mechanism. In the presence of Cd(2+), the Phen ligands are readily detached from the surface of CdTe QDs, forming [Cd(Phen)2(H2O)2](2+) in solution, and as a consequence the PL of CdTe QDs switches on. The detection limit for Cd(2+) is defined as ∼0.01 nM, which is far below the maximum Cd(2+) residue limit of drinking water allowed by the U.S. Environmental Protection Agency (EPA). Two consecutive linear ranges allow a wide determination of Cd(2+) from 0.02 nM to 0.6 μM. Importantly, this CdTe QDs-based sensor features to distinctly discriminate between Cd(2+) and Zn(2+), and succeeds in real water samples. This extremely simple strategy reported here represents an attempt for the development of fluorescent sensors for ultrasensitive chemo/biodetection.
State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China; Qiannan Medical College for Nationalities, Duyun 558000, China.
Xianyun
X
Hu
State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
Kao
K
Zhu
State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
Qingsheng
Q
Guo
State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
Yuqian
Y
Liu
State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China.
Mingfu
M
Ye
State Key Laboratory of Bioelectronics, School of Biological Science & Medical Engineering, Southeast University, Nanjing 210096, China. Electronic address: sunqj@seu.edu.cn.
Qingjiang
Q
Sun
D002104:Cadmium / Q000032:analysis*; D005453:Fluorescence; D008024:Ligands; D057230:Limit of Detection; D045663:Quantum Dots; D013056:Spectrophotometry, Ultraviolet; D013818:Thermogravimetry
D008024:Ligands; D002104:Cadmium
1,10-Phenanthroline; Cadmium ions; Ligand displacement; Photoluminescence; Quantum dot; Sensor