1 research outputs found
Micelle-Induced Versatile Sensing Behavior of Bispyrene-Based Fluorescent Molecular Sensor for Picric Acid and PYX Explosives
The
effect of surfactant micelles on the photophysical properties
of a cationic bispyrene fluorophore, Py-diIM-Py, was systemically
examined. The results from series of measurements including UV–vis
absorption, steady-state fluorescence emission, quantum yield, fluorescence
lifetime, and time-resolved emission spectra reveal that the cationic
fluorophore is only encapsulated by the anionic sodium dodecyl sulfate
(SDS) surfactant micelles and not incorporated in the cationic dodecyltrimethylammonium
bromide (DTAB) and neutral Triton X-100 (TX100) surfactant micelles.
This different fluorophore location in the micellar solutions significantly
influences its sensing behavior to various explosives. Fluorescence
quenching studies reveal that the simple variation of micellar systems
leads to significant changes in the sensitivity and selectivity of
the fluorescent sensor to explosives. The sensor exhibits an on–off
response to multiple explosives with the highest sensitivity to picric
acid (PA) in the anionic SDS micelles. In the cationic DTAB micelles,
it displays the highest on–off responses to PYX. Both the sensitivity
and selectivity to PYX in the cationic micelles are enhanced compared
with that to PA in the anionic micelles. However, the poor encapsulation
in the neutral surfactant TX100 micelles leads to fluorescence instability
of the fluorophore and fails to function as a sensor system. Time-resolved
fluorescence decays in the presence of explosives reveal that the
quenching mechanism of two micellar sensor systems to explosives is
static in nature. The present work demonstrates that the electrostatic
interaction between the cationic fluorophore and differently charged
micelles plays a determinative role in adjusting its distribution
in micellar solutions, which further influences the sensing behavior
of the obtained micellar sensor systems