科研之友
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摘要
We describe a novel near-infrared (NIR) "turn-on" fluorescent nanosensor for highly sensitive and selective detection of Zn(II) ion. It is based on the use of the fluorescent probe 8-aminoquinoline conjugate to CuInS2 quantum dots. Water-soluble CuInS2 QDs capped by mercaptopropionic acid (MPA) were synthesized in aqueous solution via a hydrothermal method, and the carboxy groups on the surface of the capped QDs were then covalently linked to the amino groups of the probe 8-aminoquinoline to form the conjugate acting as a nanosensor. The fluorescence of the modified QDs is almost completely quenched via a hole-transfer mechanism. If, however, Zn(II) is added, the lone pair electrons of the nitrogen atom of 8-aminoquinoline become involved into the mechanism of binding Zn(II), and hole-transfer quenching is suppressed which results in turn-on fluorescence. The nanoprobe enables Zn(II) to be determined by measurement of the increase in fluorescence intensity. Under optimized experimental conditions, the nanosensor displays a wide and fairly linear response in the 0.005 to 1 mM concentration range, with a 4.5 mu M detection limit. The nanosensor reported here was successfully employed to the detection of Zn(II) in spiked tap water samples.
