CdTe Quantum Dots Modified with Cysteamine: A New Efficient Nanosensor for the Determination of Folic Acid

In this paper, we report the synthesis, characterization, and application of a new fluorescent nanosensor based on water-soluble CdTe quantum dots (QDs) coated with cysteamine (CA) for the determination of folic acid (FA). CdTe/CA QDs were characterized by high-resolution transmission electron micro...

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Bibliographic Details
Published in:Sensors (Basel, Switzerland) Switzerland), 2019-10, Vol.19 (20), p.4548
Main Authors: Ramírez-Herrera, Doris E., Reyes-Cruzaley, Ana Patricia, Dominguez, Giselle, Paraguay-Delgado, Francisco, Tirado-Guízar, Antonio, Pina-Luis, Georgina
Format: Article
Language:English
Subjects:
Acids
Beverages
Cadmium tellurides
Chromatography
Cysteamine
electron transfer
Fluorescence
fluorescence quenching
Folic acid
folic acid nanosensor
High resolution electron microscopy
Infrared spectroscopy
Nanomaterials
Nanoparticles
Nanosensors
Photoluminescence
Physiology
positive quantum dots
Quantum dots
Quenching
Selectivity
Sensors
Spectrum analysis
Transmission electron microscopy
Zeta potential
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Summary:In this paper, we report the synthesis, characterization, and application of a new fluorescent nanosensor based on water-soluble CdTe quantum dots (QDs) coated with cysteamine (CA) for the determination of folic acid (FA). CdTe/CA QDs were characterized by high-resolution transmission electron microscopy, the zeta potential, and Fourier-transform infrared (FT-IR), UV-visible, and fluorescence spectroscopy. CdTe QDs coated with mercaptopropionic acid (MPA) and glutathione (GSH) were prepared for comparison purposes. The effect of FA on the photoluminescence intensity of the three thiol-capped QDs at pH 8 was studied. Only CdTe/CA QDs showed a notable fluorescence quenching in the presence of FA. Then, a nanosensor based on the fluorescence quenching of the CdTe QDs at pH 8 was explored. Under optimum conditions, the calibration curve showed a linear fluorescence quenching response in a concentration range of FA from 0.16 to 16.4 μM (R2 = 0.9944), with a detection limit of 0.048 μM. A probable mechanism of fluorescence quenching was proposed. The nanosensor showed good selectivity over other possible interferences. This method has been applied for FA quantification in orange beverage samples with excellent results (recoveries from 98.3 to 103.9%). The good selectivity, sensitivity, low cost, and rapidity make CdTe /CA QDs a suitable nanosensor for FA determination.
ISSN:1424-8220
1424-8220
DOI:10.3390/s19204548