4 research outputs found
A BODIPY-Based Fluorescent Probe for Detection of Subnanomolar Phosgene with Rapid Response and High Selectivity
A new
type of phosgene probe with a limit of detection down to 0.12 nM,
response time of less than 1.5 s, and high selectivity over other
similarly reactive toxic chemicals was developed using ethylenediamine
as the recognition moiety and 8-substituted BODIPY unit as the fluorescence
signaling component. The probe undergoes sequential phosgene-mediated
nucleophilic substitution reaction and intramolecular cyclization
reaction with high rate, yielding a product with the intramolecular
charge transfer (ICT) process from amine to the BODIPY core significantly
inhibited. Owing to the emission feature of 8-substituted BODIPY that
is highly sensitive to the substituent′s electronic nature,
such inhibition on the ICT process strikingly generates strong fluorescence
contrast by a factor of more than 23 300, and therefore creates
the superhigh sensitivity of the probe for phosgene. Owing to the
high reactivity of ethylenediamine of the probe in nucleophilic substitution
reactions, the probe displays a very fast response rate to phosgene
Photoswitching Near-Infrared Fluorescence from Polymer Nanoparticles Catapults Signals over the Region of Noises and Interferences for Enhanced Sensitivity
As
a very sensitive technique, photoswitchable fluorescence not only
gains ultrasensitivity but also imparts many novel and unexpected
applications. Applications of near-infrared (NIR) fluorescence have
demonstrated low background noises, high tissue-penetrating ability,
and an ability to reduce photodamage to live cells. Because of these
desired features, NIR-fluorescent dyes have been the premium among
fluorescent dyes, and probes with photoswitchable NIR fluorescence
are even more desirable for enhanced signal quality in the emerging
optical imaging modalities but rarely used because they are extremely
challenging to design and construct. Using a spiropyran derivative
functioning as both a photoswitch and a fluorophore to launch its
periodically modulated red fluorescence excitation energy into a NIR
acceptor, we fabricated core–shell polymer nanoparticles exhibiting
a photoswitchable fluorescence signal within the biological window
(∼700–1000 nm) with a peak maximum of 776 nm. Live cells
constantly synthesize new molecules, including fluorescent molecules,
and also endocytose exogenous particles, including fluorescent particles.
Upon excitation at different wavelengths, these fluorescent species
bring about background noises and interferences covering nearly the
whole visible region and therefore render many intracellular targets
unaddressable. The oscillating NIR fluorescence signal with an on/off
ratio of up to 67 that the polymer nanoparticles display is beyond
the typical background noises and interferences, thus producing superior
sharpness, reliability, and signal-to-noise ratios in cellular imaging.
Taking these salient features, we anticipate that these types of nanoparticles
will be useful for in vivo imaging of biological tissue and other
complex specimens, where two-photon activation and excitation are
used in combination with NIR-fluorescence photoswitching
Beyond a Carrier: Graphene Quantum Dots as a Probe for Programmatically Monitoring Anti-Cancer Drug Delivery, Release, and Response
On
the basis of the unique physicochemical properties of graphene quantum
dots (GQDs), we developed a novel type of theranostic agent by loading
anticancer drug doxorubicin (DOX) to GQD’s surface and conjugating
Cy5.5 (Cy) dye to GQD though a cathepsin D-responsive (P) peptide.
Such type of agents demonstrated superior therapeutic performance
both in vitro and in vivo because of the improved tissue penetration
and cellular uptake. More importantly, they are capable of functioning
as probes for programmed tracking the delivery and release of anticancer
drug as well as drug-induced cancer cell apoptosis through GQD’s,
DOX’s, and Cy’s charateristic fluorescence, respectively
A Turn-On Fluorescent Probe for Detection of Sub-ppm Levels of a Sulfur Mustard Simulant with High Selectivity
A new
type of fluorescent probe capable of detecting a sulfur mustard
(SM) simultant at a concentration of 1.2 μM in solution and
0.5 ppm in the gas phase has been developed. Owing to its molecular
structure with a thiocarbonyl component and two piperidyl moieties
integrated into the xanthene molecular skeleton, this probe underwent
a highly selective nucleophilic reaction with the SM simultant and
generated a thiopyronin derivative emitting intensive pink fluorescence.
The distinct difference in electronic structure between the probe
and thiopyronin derivative generated a marked shift of the absorption
band from 445 to 567 nm, which enabled an optimal wavelength propitious
for exciting the thiopyronin derivative but adverse to the probe.
Such efficient separation of the excitation wavelength and tremendous
increase in fluorescence quantum yield, from less than 0.002 to 0.53,
upon conversion from the probe to the thiopyronin derivative, jointly
led to a distinct contrast in the beaconing fluorescence signal (up
to 850-fold) and therefore the unprecedented sensitivity for detecting
SM species