Carbon-Dot-Based Ratiometric Fluorescent Probe for
Imaging and Biosensing of Superoxide Anion in Live Cells
- Publication date
- Publisher
Abstract
In
this article, a ratiometric fluorescent biosensor for O<sub>2</sub><sup>•–</sup> was developed, by employing carbon dots
(C-Dots) as the reference fluorophore and hydroethidine (HE), a specific
organic molecule toward O<sub>2</sub><sup>•–</sup>,
playing the role as both specific recognition element and response
signal. The hybrid fluorescent probe CD-HE only emitted at 525 nm
is ascribed to C-Dots, while HE was almost nonfluorescent, upon excitation
at 488 nm. However, after reaction with O<sub>2</sub><sup>•–</sup>, a new emission peak ascribed to the reaction products of HE and
O<sub>2</sub><sup>•–</sup> was clearly observed at 610
nm. Meanwhile, this peak gradually increased with the increasing concentration
of O<sub>2</sub><sup>•–</sup> but the emission peak
at 525 nm stayed constant, leading to a ratiometric detection of O<sub>2</sub><sup>•–</sup>. The inorganic–organic
fluorescent sensor exhibited high sensitivity, a broad dynamic linear
range of ∼5 × 10<sup>–7</sup>–1.4 ×
10<sup>–4</sup> M, and low detection limit down to 100 nM.
The present probe also showed high accuracy and excellent selectivity
for O<sub>2</sub><sup>•–</sup> over other reactive oxygen
species (ROS), metal ions, and so on. Moreover, the C-Dot-based inorganic–organic
probe demonstrated long-term stability against pH changes and continuous
light illumination, good cell-permeability, and low cytotoxicity.
Accordingly, the developed fluorescent biosensor was eventually applied
for intracellular bioimaging and biosensing of O<sub>2</sub><sup>•–</sup> changes upon oxidative stress