Fluorescence Modulation by Absorbent on Solid Surface:
An Improved Approach for Designing Fluorescent Sensor
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Abstract
Inner
filter effect (IFE), a well-known phenomenon of fluorescence
quenching resulting from absorption of the excitation or emission
light of luminescent species by absorbent, has been used as a smart
approach to design fluorescent sensors, which are characterized by
the simplicity and flexibility with high sensitivity. However, further
application of IFE-based sensors in complex environment is hampered
by the insufficient IFE efficiency and low sensitivity resulting from
interference of the external environment. In this paper, we report
that IFE occurring on a solid substrate surface would solve this problem.
As a proof of concept, a fluorescent sensor for intracellular biothiols
has been developed on the basis of the absorption of a newly designed
thiols-specific chromogenic probe (<b>CP</b>) coupled with the
use of a thiols-independent fluorophore, rhodamine 6G (R6G), operative
on the IFE on graphene oxide (GO). To construct an efficient IFE system,
R6G was covalently attached to GO, and the <b>CP</b> molecules
were adsorbed on the surface of <b>R6G-GO</b> via π–π
stacking interaction. The reaction of thiols with <b>CP</b> on <b>R6G-GO</b> decreases the absorption of <b>CP</b>, resulting
in the increase of the intensity of R6G fluorescence. The results
showed that the IFE efficiency, sensitivity, and dynamic response
time of <b>R6G-GO/CP</b> for biothiols could be significantly
improved compared with <b>R6G/CP</b>, and furthermore, <b>R6G-GO/CP</b> functioned under complex system and could be used
for assaying biothiols in living cells and in human serum samples.
This new strategy would be general to explore the development of more
effective IFE-based sensors for other analytes of interest