A highly selective colorimetric and turn-on fluorescent probe for cyanide anion

A new colorimetric and turn-on fluorescence chemosensor was developed for cyanide anion with high selectivity in the presence of other anions in an aqueous THF solution. The sensing mechanism is attributed to the interruption of π-conjugation by a nucleophilic addition of cyanide to the β-position of a dicyanoethylene unit.     

A turn-on fluorescent probe for selective and sensitive detection of hydrogen sulfide

An imidazolethione based turn-on fluorescent probe was synthesized for the detection of hydrogen sulfide, a biologically relevant molecule and an important air pollutant. The probe rapidly and selectively reacted with hydrogen sulfide to produce a strongly fluorescent product, resulting in the fluorescence enhancement of the system. The detection limit was determined to be 30 nM at the probe concentration of 1.0 μM. An indicating paper for visual detection of hydrogen sulfide gas has been fabricated by immobilizing the probe on a piece of appropriate paper substrate, and the detection limit of the visual method reached as low as 0.7 ppm. Moreover, the fluorescence turn-on/off of the system showed good reversibility when exposed alternately to hydrogen sulfide and mercuric ion, which was utilized to make an INHIBIT logic circuit for the presence of the two species.     

Aptamer-based turn-on fluorescent four-branched quaternary ammonium pyrazine probe for selective thrombin detection

In this thrombin detection system, the bright fluorescence of TASPI is almost eliminated by the DNA aptamer TBA (turn-off); however, in the presence of thrombin, it specifically binds to TBA by folding unrestricted TBA into an anti-parallel G-quadruplex structure and then releasing TASPI molecules, resulting in vivid and facile fluorescence recovery (turn-on).     

A novel AIEE and EISPT fluorescent probe for selective detection of cysteine

We designed and synthesized a simple and readily available fluorescent probe 3 for cysteine (Cys) based on naphthalene derivative. The probe is composed of a new class of aggregation-induced emission enhancement (AIEE) active dye 2 based on excited-state intramolecular proton transfer (ESIPT) and an acrylate group as the Cys recognition unit as well as the ESIPT blocking agent, which can be cut off by Cys from the probe in aqueous solution with mild conditions. The probe had great sensitivity and selectivity for the detection of Cys over homocysteine (Hcy) and glutathione (GSH) with a detection limit of 0.05 µM. In addition, we have successfully applied the probe for bioimaging studies of Cys in living cells, indicating that the probe holds great potential for biological applications.     

A turn-on two-photon fluorescent probe for ATP and ADP

An acedan derivative containing Zn(II)-DPA has been developed as a two-photon probe for nucleoside phosphates, which shows enhanced fluorescence toward ATP and ADP at physiological pH 7.4 among other competing anions including AMP; the probe is permeable to cell membranes and thus can be directly used for two-photon imaging of ATP and ADP in live cells.     

Real-time quantification for sulfite using a turn-on NIR fluorescent probe equipped with a portable fluorescence detector

Sulfur dioxide and its derivative sulfite widely existed in air, water as the environment pollutant. Sulfite is also commonly used as preservative and additive in fresh fruits, vegetables, wines and pharmaceutical materials. Due to sulfite is closely related with human diseases, it is very urgent for the sensitive and rapid quantification of sulfite in various samples. In our study, a turn-on near infrared (NIR) fluorescent probe (MDQ) was developed for sulfite detection based on a Michael addition reaction, with high sensitivity (LOD 4.16 nmol/L), selectivity and fast response time (400 s). Using MDQ, a quantify method for sulfite in traditional Chinese medicines (TCMs) was developed with the advantages of high precision, accuracy and convenient operation. Furthermore, according to the photophysical property of MDQ, a portable fluorescence detector is designed to quantify sulfite for TCMs and surface water in Dalian city of China. Therefore, the developed fluorescent probe MDQ and portable fluorescent detector as a rapid inspection instrument were successfully used to real-time monitor the sulfite in various complex samples.     

Highly selective fluorescence turn-on probe for glutathione

An activated coumarin-3-phenyl enone (1) by an intramolecular hydrogen bond has shown a selective and ratiometric response toward GSH and Cys over other natural amino acids through the Michael addition reaction of a thiol group to 1. When GSH was added to 1, a prominent color change together with a fluorescence turn-on property was observed so that submillimolar GSH was detectable.     

A boradiazaindacene-based turn-on fluorescent probe for cyanide detection in aqueous media

Turn on events: A molecular probe consisting of a boradiazaindacene unit conjugated with a dicyano-vinyl group has been designed for the selective and sensitive detection of cyanide by strong fluorescence enhancement in aqueous media (see scheme).     

一种新型快速检测半胱氨酸的荧光探针EI北大核心CSCD

基于三苯胺母体的强供电子能力,设计合成了一种共轭性良好的新型半胱氨酸(Cys)荧光探针。采用荧光光谱法和紫外-可见光谱法研究了目标探针T-Probe对半胱氨酸(Cys)的光谱响应。结果表明:目标探针分子与Cys作用后,荧光发射波长有约20 nm红移,荧光强度发生明显的增强,在365 nm紫外灯下,溶液由青色变为蓝色;探针分子选择性识别Cys的检测限为98.4 nmol/L,且灵敏度较高。     

Highly selective NIR fluorescent probe for acetylcholinesterase and its application in pesticide residues detection

A series of near-infrared (NIR) fluorescent substrates (NDRO-1～8) derived from fluorophore NDRH with different volumes of ester bond as the recognition group were designed and synthesized for the detection of acetylcholinesterase (AChE), among which NDRO-1 with the smallest acetate group displayed the highest activity toward AChE. The detection limit of NDRO-1 for sensing AChE was 0.32 µg/mL, and K_m was 6.40 µmol/L, indicating ultra-sensitivity and good affinity of NDRO-1 toward AChE. NDRO-1 was used to detect the inhibitory of four kinds of pesticides including methamidophos, dichlorvos, and the detection limit was lower than 50 µg/L, which was further used in pesticide residues detection.     

A selective turn-on fluorescent sensor for Fe and application to bioimaging

A novel compound FD1 was demonstrated as a turn-on fluorescent sensor for imaging of iron(III) ion in biological samples. Based on the spirolactam (nonfluorescence) to ring-open amide (fluorescence) equilibrium, FD1 exhibited high selectivity and sensitivity for Fe³⁺ over other metal ions. Moreover, fluorescent microscopy experiments further established that FD1 could be used for sensing Fe³⁺ within living cells.     

A selective turn-on fluorescent sensor for imaging copper in living cells

We present the synthesis, properties, and biological applications of Coppersensor-1 (CS1), a new water-soluble, turn-on fluorescent sensor for intracellular imaging of copper in living biological samples. CS1 utilizes a BODIPY reporter and thioether-rich receptor to provide high selectivity and sensitivity for Cu+ over other biologically relevant metal ions, including Cu2+, in aqueous solution. This BODIPY-based probe is the first Cu+-responsive sensor with visible excitation and emission profiles and gives a 10-fold turn-on response for detecting this ion. Confocal microscopy experiments further establish that CS1 is membrane-permeable and can successfully monitor intracellular Cu+ levels within living cells.     

A new spirobifluorene-bridged bipolar system for a nitric oxide turn-on fluorescent probe

A new spirobifluorene-bridged bipolar molecule (EDADO) as a nitric oxide (NO) turn-on fluorescent probe was designed and synthesized. The fluorescence of EDADO is strongly quenched by photoinduced electron transfer (PET) from the electron-donating o-phenylenediamine-containing biphenyl branch to the orthogonally arranged electron-accepting 1,3,4-oxadiazole-containing conjugated oligoaryl system. Upon reacting with NO, EDADO is converted to EDADO-T, which exhibits strong fluorescence due to the suppression of PET.     

Multi-organelle-targeting pH-dependent NIR fluorescent probe for lysosomal viscosity

The normal operation of lysosome, mitochondria, Golgi apparatus and endoplasmic reticulum plays a significant role in maintaining cell homeostasis. Reflecting the state and function of lysosomes, viscosity is a pivotal parameter to assess the stability of microenvironment. Herein, based on TICT mechanism, a new NIR pH-dependent fluorescent probe DCIC with push-pull electronic moiety was synthesized to identify the lysosomes viscosity. In viscous media, DCIC was highly sensitive to viscosity, fluorescence intensity increased by 180 times as viscosity increased from 1.0 cp to 438.4 cp. In addition, DCIC have high localization ability for lysosome, mitochondria, Golgi apparatus, and endoplasmic reticulum and can monitor lysosomal viscosity fluctuations with laser confocal microscopy.     

Highly selective and sensitive fluorescence turn-on probe for proline

A weakly fluorescent coumarinyl aldehyde was transformed into a strongly fluorescent aldol product by a catalytic amount of proline. The aldehyde probe has shown a highly selective fluorescence turn-on response toward proline over other amino acids with micromolar sensitivity.     

A highly selective fluorescent probe for thiol bioimaging

A new fluorescent turn-on probe (3) for the selective sensing and bioimaging of thiols is reported. In aqueous buffer solutions at physiological pH, thiols cleave the 2,4-dinitrobenzenesulfonyl group to release the red-emissive donor-acceptor fluorophore (4). The probe displays excellent immunity to interference from nitrogen and oxygen nucleophiles and the imaging of thiols in living cells is demonstrated.     

A highly selective turn-on fluorescent probe for hypochlorous acid based on hypochlorous acid-induced oxidative intramolecular cyclization of boron dipyrromethene-hydrazone

A BODIPY-based fluorescent probe, HBP, was developed for the detection of hypochlorous acid based on the specific hypochlorous acid-promoted oxidative intramolecular cyclization of heterocyclic hydrazone in response to the amount of HOCl. The reaction is accompanied by a 41-fold increase in the fluorescent quantum yield (from 0.004 to 0.164). The fluorescence intensity of the reaction between HOCl and HBP is linear in the HOCl concentration range of 1–8 μM with a detection limit of 2.4 nM (S/N = 3). Confocal fluorescence microscopy imaging using RAW264.7 cells showed that the new probe HBP could be used as an effective fluorescent probe for detecting HOCl in living cells.     

A new selective fluorescent probe for lead ions

A new fluorescent probe(BPbl) for Pb~(2+) has been synthesized,where diethanolamine(receptor) is linked with 4,4-difluoro-4-bora-3a, 4a-diaza-s-indacene(BODIPY)(fluorophore) via a methylene group(spacer).The absorption(496 nm) and emission (505 nm) wavelengths are in visible range.The fluorescence quantum yields of the lead-free and lead-bound states of BPb_1 in acetonitrile are 0.013 and 0.693,respectively.The large chelation enhanced fluorescence effect(CHEF) with Pb~(2+) can be explained by the blocki...     

A highly selective turn-on fluorescent chemosensor for copper(II) ion

A new pyrene derivative (1) containing a diaminomaleonitrile moiety exhibits high selectivity for Cu²⁺ detection. Significant fluorescence enhancement was observed with chemosensor 1 in the presence of Cu²⁺. However, the metal ions Ag⁺, Ca²⁺, Cd²⁺, Co²⁺, Fe²⁺, Fe³⁺, Hg²⁺, Mg²⁺, Mn²⁺, Ni²⁺, Pb²⁺, and Zn²⁺ produced only minor changes in fluorescence values for the system. The apparent association constant (K_a) of Cu²⁺ binding in chemosensor 1 was found to be 5.55×10³ M⁻¹. The maximum fluorescence enhancement caused by Cu²⁺ binding in chemosensor 1 was observed over the pH range 5-7.5.