Ligand replacement-induced fluorescence switch of quantum dots for ultrasensitive detection of organophosphorothioate pesticides.
The development of a simple and on-site assay for the detection of organophosphorus pesticed residues is very important for food safety and exosystem protection. This paper reports the surface coordination-originated fluorescence resonance energy transfer (FRET) of CdTe quantum dots (QDs) and a simple ligand-replacement turn-on mechanism for the highly sensitive and selective detection of organophosphorothioate pesticides. It has been demonstrated that coordination of dithizone at the surface of CdTe QDs in basic media can strongly quench the green emission of CdTe QDs by a FRET mechanism. Upon the addition of organophosphorothioate pesticides, the dithizone ligands at the CdTe QD surface are replaced by the hydrolyzate of the organophosphorothioate, and hence the fluorescence is turned on. The fluorescence turn on is immediate, and the limit of detection for chlorpyrifos is as low as ∼0.1 nM. Two consecutive linear ranges allow a wide determination of chlorpyrifos concentrations from 0.1 nM to 10 μM. Importantly, the fluorescence turn-on chemosensor can directly detect chlorpyrifos residues in apples at a limit of 5.5 ppb, which is under the maximum residue limit allowed by the U.S. Environmental Protection Agency. The very simple strategy reported here should facilitate the development of fluorescence turn-on chemosensors for chemo/biodetection.
Zhang
Kui
K
Institute of Intelligent Machines, Chinese Academy of Sciences, Hefei, Anhui 230031, China.
Mei
Qingsong
Q
Guan
Guijian
G
Liu
Bianhua
B
Wang
Suhua
S
Zhang
Zhongping
Z
D001628:Beverages / Q000032:analysis; D031541:Fluorescence Resonance Energy Transfer / Q000379:methods*; D008024:Ligands; D057230:Limit of Detection; D027845:Malus / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000032:analysis* / Q000737:chemistry*; D010573:Pesticide Residues / Q000032:analysis* / Q000737:chemistry*; D045663:Quantum Dots
D008024:Ligands; D009943:Organophosphorus Compounds; D010573:Pesticide Residues