Carbon
Nanoparticle-based Ratiometric Fluorescent Sensor for Detecting Mercury
Ions in Aqueous Media and Living Cells
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Abstract
A novel nanohybrid ratiometric fluorescence
sensor is developed for selective detection of mercuric ions (Hg<sup>2+</sup>), and the application has been successfully demonstrated
in HEPES buffer solution, lake water, and living cells. The sensor
comprises water-soluble fluorescent carbon nanoparticles (CNPs) and
Rhodamine B (RhB) and exhibits their corresponding dual emissions
peaked at 437 and 575 nm, respectively, under a single excitation
wavelength (350 nm). The photoluminescence of the CNPs in the nanohybrid
system can be completely quenched by Hg<sup>2+</sup> through effective
electron or energy transfer process due to synergetic strong electrostatic
interaction and metal–ligand coordination between the surface
functional group of CNPs and Hg<sup>2+</sup>, while that of the RhB
remains constant. This results in an obviously distinguishable fluorescence
color variation (from violet to orange) of the nanohybrid solution.
This novel sensor can effectively identify Hg<sup>2+</sup> from other
metal ions with relatively low background interference even in a complex
system such as lake water. The detection limit of this method is as
low as 42 nM. Furthermore, the sensing technique is applicable to
detect Hg<sup>2+</sup> in living cells