26 research outputs found
Sensing Performance Enhancement via Acetate-Mediated N-Acylation of Thiourea Derivatives: A Novel Fluorescent Turn-On Hg<sup>2+</sup> Chemodosimeter
A Hg<sup>2+</sup> chemodosimeter <b>P3</b> derived
from a
perylenebisimide scaffold and thiourea fragments was systematically
studied with focus on the photophysical, chemodosimetric mechanistic,
as well as fluorogenic behaviors toward various metal cations for
the sake of improving selectivity to Hg<sup>2+</sup>. As demonstrated,
Hg<sup>2+</sup> can promote a stepwise desulfurization and N-acylation
of <b>P3</b> with the help of an acetate anion (OAc<sup>â</sup>), resulting in an N-acylated urea derivative. Interestingly,
OAc<sup>â</sup> has the effect of improving the selectivity
of <b>P3</b> to Hg<sup>2+</sup> among other metal ions; that
is, in an acetone/BrittonâRobinson
buffer (9:1, v/v; pH 7.0) upon excitation at 540 nm, the relative
fluorescence intensity is increased linearly with increasing concentration
of Hg<sup>2+</sup> in the range of 2.5â20 ÎŒM with a detection
limit of 0.6 ÎŒM, whereas the fluorescence
intensity of <b>P3</b> to other metal ions, including Na<sup>+</sup>, K<sup>+</sup>, Mg<sup>2+</sup>, Ca<sup>2+</sup>, Mn<sup>2+</sup>, Fe<sup>2+</sup>, Ni<sup>2+</sup>, Co<sup>2+</sup>, Zn<sup>2+</sup> Ag<sup>+</sup>, Cd<sup>2+</sup>, Pb<sup>2+</sup>, and Cu<sup>2+</sup>, is negligible. The fluorescent bioimaging of chemodosimeter <b>P3</b> to detect Hg<sup>2+</sup> in living cells was also reported
A Multiaddressable Photochromic Bisthienylethene with Sequence-Dependent Responses: Construction of an INHIBIT Logic Gate and a Keypad Lock
A photochromic
bisthienylethene derivative (<b>BIT</b>) containing two imidazole
units has been synthesized and fully characterized. When triggered
by chemical ions (Ag<sup>+</sup>), protons, and light, <b>BIT</b> can behave as an absorbance switch, leading to a multiaddressable
system. <b>BIT</b> exhibits sequence-dependent responses via
efficient interaction of the specific imidazole unit with protons
and Ag<sup>+</sup>. Furthermore, an INHIBIT logic gate and a keypad
lock with three inputs are constructed with the unimolecular platform
by employing an absorption mode at different wavelengths as outputs
on the basis of an appropriate combination of chemical and photonic
stimuli
Screen-Printed Red Luminescent Copolymer Film Containing Cyclometalated Iridium(III) Complex as a High-Permeability Dissolved-Oxygen Sensor for Fermentation Bioprocess
The novel hydrophobic
luminescent copolymer PÂ(Ir-TFEMA) was developed
as an online dissolved-oxygen (DO) sensor. The phosphorescent moiety
of cyclometalated iridiumÂ(III) complex exhibits red emission near
650 nm with a large Stokes shift of about 245 nm and minimal optical
interference from the fermentation system. The covalent incorporation
of the chromophore into the polymeric matrix rather than physical
doping was used to avoid phase-separation and leaching problems. The
low molar ratio between the introduced chromophore and polymeric matrix
within the range of 1:135â1:250 was confirmed to have little
influence on the luminescence response ability. To assess its potential
utility, this copolymer was applied to the online monitoring of DO
during the cephalosporin C fermentation process. The screen-printing
technique was utilized as a rapid and reliable automatic approach
to preparing sensor films with good photostability and fatigue resistance,
showing promise in bioprocess monitoring as a low-cost DO indicator
for high-throughput microbioreactors
Optimizing the Chemical Recognition Process of a Fluorescent Chemosensor for 뱉Ketoglutarate
α-Ketoglutarate
(α-KA) can convert to 2-hydroxyglutarate
(2-HG), which is confirmed to be associated with many diseases, especially
with acute myeloid leukemia (AML). In this paper, a novel reaction-based
chemosensor DT based on the typical Schiff-base reaction was designed
for sensing the biomarker of α-KA, in which a diazanyl group
as the recognition group was linked with a benzothiadiazole unit as
the fluorophore moiety. Considering the typical Schiff-base reaction
to generate hydrazones suffering from slow kinetics, particularly
under neutral conditions, a series of parallel experiments was conducted
for optimizing the chemical recognition process, including varying
the solvent, reaction temperature, reactant concentration, and reaction
rate. The optimum condition was established as a pH value, temperature,
α-KA concentration, and response time of 5.7, 30 °C, 100
ÎŒM, and 20 min, respectively. Notably, in contrast with the
initial 6.3-fold fluorescence enhancement, the remarkable 75-fold
fluorescence enhancement ((<i>I</i> â <i>I</i><sub>0</sub>)/<i>I</i><sub>0</sub> at 560 nm) was observed
by optimizing the chemical recognition process of DT and α-KA.
Finally, DT was carried out for the chemical recognition processing
of α-KA in serum. We demonstrated that DT is selective for α-KA
over other potential biologically interferences with similar structures
and thus is suitable for detecting α-KA in serum. On the basis
of the optimized chemical recognition process, DT shows high potential
application for sensing α-KA with remarkable fluorescence
enhancement. This work provided a potential method that is quick and
convenient for sensing biomarker α-KA in serum. It is worth
noting that without complicated pretreatment, utilizing a novel reaction-based
fluorescent chemosensor may establish a new promising platform for
clinical diagnosis biomarker
Near-Infrared Colorimetric and Fluorescent Cu<sup>2+</sup> Sensors Based on IndolineâBenzothiadiazole Derivatives via Formation of Radical Cations
The
donorâacceptor system of indolineâbenzothiadiazole
is established as the novel and reactive platform for generating amine
radical cations with the interaction of Cu<sup>2+</sup>, which has
been successfully exploited as the building block to be highly sensitive
and selective near infrared (NIR) colorimetric and fluorescent Cu<sup>2+</sup> sensors. Upon the addition of Cu<sup>2+</sup>, an instantaneous
red shift of absorption spectra as well as the quenched NIR fluorescence
of the substrates is observed. The feasibility and validity of the
radical cation generation are confirmed by cyclic voltammetry and
electron paramagnetic resonance spectra. Moreover, the introduction
of an aldehyde group extends the electron spin density and changes
the charge distribution. Our system demonstrates the large scope and
diversity in terms of activation mechanism, response time, and property
control in the design of Cu<sup>2+</sup> sensors
<i>In Vivo</i> and <i>in Situ</i> Tracking Cancer Chemotherapy by Highly Photostable NIR Fluorescent Theranostic Prodrug
<i>In vivo</i> monitoring
of the biodistribution and
activation of prodrugs is urgently required. Near infrared (NIR) fluorescence-active
fluorophores with excellent photostability are preferable for tracking
drug release <i>in vivo</i>. Herein, we describe a NIR prodrug
DCM-S-CPT and its polyethylene glycolâpolylactic acid (PEG-PLA)
loaded nanoparticles as a potent cancer therapy. We have conjugated
a dicyanomethylene-4<i>H</i>-pyran derivative as the NIR
fluorophore with camptothecin (CPT) as the anticancer drug using a
disulfide linker. <i>In vitro</i> experiments verify that
the high intracellular glutathione (GSH) concentrations in tumor cells
cause cleavage of the disulfide linker, resulting in concomitantly
the active drug CPT release and significant NIR fluorescence turn-on
with large Stokes shift (200 nm). The NIR fluorescence of DCM-S-CPT
at 665 nm with fast response to GSH can act as a direct offâon
signal reporter for the GSH-activatable prodrug. Particularly, DCM-S-CPT
possesses much better photostability than ICG, which is highly desirable
for <i>in situ</i> fluorescence-tracking of cancer chemotherapy.
DCM-S-CPT has been successfully utilized for <i>in vivo</i> and <i>in situ</i> tracking of drug release and cancer
therapeutic efficacy in living animals by NIR fluorescence. DCM-S-CPT
exhibits excellent tumor-activatable performance when intravenously
injected into tumor-bearing nude mice, as well as specific cancer
therapy with few side effects. DCM-S-CPT loaded in PEG-PLA nanoparticles
shows even higher antitumor activity than free CPT, and is also retained
longer in the plasma. The tumor-targeting ability and the specific
drug release in tumors make DCM-S-CPT as a promising prodrug, providing
significant advances toward deeper understanding and exploration of
theranostic drug-delivery systems
Self-Assembly Solid-State Enhanced Red Emission of Quinolinemalononitrile: Optical Waveguides and Stimuli Response
The fluorescence of luminescent emitters is often quenched
in the solid state, because of the typical aggregation-caused quenching
(ACQ) effect, which is a thorny obstacle to high-performance organic
optoelectronic materials. The exploration of solid-state enhanced
long wavelength, red-emitting chromophores, especially possessing
one-dimensional (1D) assembly features, is of great importance. Interestingly,
an excellent solid-state enhanced red emission system (denoted as
ED) based on quinolinemalononitrile has been developed via the delicate
modification of the conventional ACQ dicyanomethylene-4<i>H</i>-pyran (DCM) derivative (denoted as BD) through crystal engineering.
ED exhibits extraordinary self-assembly property in a variety of solvents,
even realizing the âwaving ribbonsâ with a length of
6 mm and a diameter of 10 ÎŒm. Crystal analysis shows that the
CHÂ·Â·Â·Ï and CH···N supramolecular
interactions of ED contribute to the twisted self-assembly solid-state
enhanced emission phenomenon. However, for BD, strong face-to-face
stacking leads to fluorescence quenching in the solid state. Because
of such easy assembly and strong solid-state emission properties,
application for optical waveguides of ED is realized with a low optical
loss. Stimuli-responsive behavior is also elaborated with color change
between orange and red by grinding/fuming or pressing/heating
In Situ Ratiometric Quantitative Tracing of Intracellular Leucine Aminopeptidase Activity via an Activatable Near-Infrared Fluorescent Probe
Leucine aminopeptidase
(LAP), one of the important proteolytic enzymes, is intertwined with
the progress of many pathological disorders as a well-defined biomarker.
To explore fluorescent aminopeptidase probe for quantitative detection
of LAP distribution and dynamic changes, herein we report a LAP-targeting
near-infrared (NIR) fluorescent probe (DCMâLeu) for ratiometric
quantitative trapping of LAP activity in different kinds of living
cells. DCMâLeu is composed of a NIR-emitting fluorophore (DCM)
as a reporter and l-leucine as a triggered moiety, which
are linked together by an amide bond specific for LAP cleavage. High
contrast on the ratiometric NIR fluorescence signal can be achieved
in response to LAP activity, thus enabling quantification of endogenous
LAP with âbuild-in calibrationâ as well as minimal background
interference. Its ratiometric NIR signal can be blocked in a dose-dependent
manner by bestatin, an LAP inhibitor, indicating that the alteration
of endogenous LAP activity results in these obviously fluorescent
signal responses. It is worth noting that DCMâLeu features
striking characteristics such as a large Stokes shift (âŒ205
nm), superior selectivity, and strong photostability responding to
LAP. Impressively, not only did we successfully exemplify DCMâLeu
in situ ratiometric trapping and quantification of endogenous LAP
activity in various types of living cells, but also, with the aid
of three-dimensional confocal imaging, the intracellular LAP distribution
is clearly observed from different perspectives for the first time,
owing to the high signal-to-noise of ratiometric NIR fluorescent response.
Collectively, these results demonstrate preclinical potential value
of DCMâLeu serving as a useful NIR fluorescent probe for early
detection of LAP-associated disease and screening inhibitor
Facile Preparation of AIE-Active Fluorescent Nanoparticles through Flash Nanoprecipitation
Flash
nanoprecipitation (FNP) is an easily scalable and fast processing
method for the preparation of nanoparticles (NPs) with simple vortex
equipment. By using the FNP method, fluorescent NPs are prepared in
less than 1 s in a multi-inlet vortex mixer, in which hydrophobic
aggregation-induced emission (AIE)-active dye of EDP is incorporated
within the biocompatible block copolymer polyÂ(ethylene glycol)-<i>b</i>-polyÂ(Δ-caprolactone) for EDP NP assembly. The formulation
parameters of stream velocity, dyes, and loading and concentration
in FNP are optimized. The sizes of the NPs ranged from 20 to 60 nm
with a ratio change of mixed solvents. As a control, an aggregation-caused
quenching (ACQ) molecule of BDP was also synthesized for BDP NPs.
To gain insight into the effect of the polymer on the aggregation
state of hydrophobic dyes, the preparation of EDP and BDP NPs without
block copolymer was also investigated. Apparently, the sizes of the
NPs display large distributions without an amphiphilic block copolymer
as the engineering template, suggesting that the block of polymers
plays a key role in tuning the aggregation state of encapsulated dyes
in FNP processes. Moreover, the peak shifts of dye with different
microenvironments also confirmed the successful encapsulation of fluorescent
dye in the NP cores. Finally, by externally applied forces in the
FNP method, the engineered assembly of AIE-active fluorescent NPs
possessing a narrow size distribution with desirable fluorescence
properties was obtained. These features provide the possibility of
rapidly constructing controllable AIE-active fluorescent NPs as biomedical
tracers
Facile Preparation of AIE-Active Fluorescent Nanoparticles through Flash Nanoprecipitation
Flash
nanoprecipitation (FNP) is an easily scalable and fast processing
method for the preparation of nanoparticles (NPs) with simple vortex
equipment. By using the FNP method, fluorescent NPs are prepared in
less than 1 s in a multi-inlet vortex mixer, in which hydrophobic
aggregation-induced emission (AIE)-active dye of EDP is incorporated
within the biocompatible block copolymer polyÂ(ethylene glycol)-<i>b</i>-polyÂ(Δ-caprolactone) for EDP NP assembly. The formulation
parameters of stream velocity, dyes, and loading and concentration
in FNP are optimized. The sizes of the NPs ranged from 20 to 60 nm
with a ratio change of mixed solvents. As a control, an aggregation-caused
quenching (ACQ) molecule of BDP was also synthesized for BDP NPs.
To gain insight into the effect of the polymer on the aggregation
state of hydrophobic dyes, the preparation of EDP and BDP NPs without
block copolymer was also investigated. Apparently, the sizes of the
NPs display large distributions without an amphiphilic block copolymer
as the engineering template, suggesting that the block of polymers
plays a key role in tuning the aggregation state of encapsulated dyes
in FNP processes. Moreover, the peak shifts of dye with different
microenvironments also confirmed the successful encapsulation of fluorescent
dye in the NP cores. Finally, by externally applied forces in the
FNP method, the engineered assembly of AIE-active fluorescent NPs
possessing a narrow size distribution with desirable fluorescence
properties was obtained. These features provide the possibility of
rapidly constructing controllable AIE-active fluorescent NPs as biomedical
tracers