An asymmetrical flavylium based probe with large Stokes shift and near infrared emission for highly sensitive detecting and visualizing cellular drug induced HS fluctuations.

Hydrogen sulfide (HS) has been recognized as an important gaseous signaling molecule in living systems, and is of great significance in many pathological and physiological processes. Misregulation of endogenous HS is implicated in various diseases in the neuronal, gastrointestinal, circulatory, and endocrine systems. Fluorescent probe with large Stokes shift and near infrared emission, is ideal candidate for imaging applications to prevent excitation scattering, autofluorescence interference, matrix absorption caused signal loss, and sample destruction.

Optimized self-immolative near-infrared probe based on hemicyanine for highly specific monitoring thiophenols in living systems.

In this paper, utilizing the same recognition group dinitrophenyl and hydroxyl functional NIR fluorophore hemicyanine, directly-linked probe CyNO and self-immolative probe CyBNO were developed for evaluation of sensing PhSH. Though CyNO was easily synthesized and sensitive to mercapto, the probe CyBNO showed higher selectivity, broader linear range from 1.0 × 10 to 7.

A novel weak acid activated probe for highly selective monitoring selenocysteine in living cells.

Selenocysteine (Sec, pK 5.8) is genetically encoded 21st amino acid into the active site of selenoproteins, which have broad functions relevant to various diseases, tissues or organs and subcellular organelles. However, many selenoproteins involved cellular functions still remains unclear.

A structure optimized fluorescent probe for highly sensitive monitoring drug induced lysosomal pH value changes.

Lysosomes generally maintain the weak acidic microenvironment, to ensure highly efficient activity and functions of hydrolytic enzymes and proteins. Aberrations of the lysosomal pH may result in cellular functional changes and influence human physiology, possibly causing serious diseases. Small-molecular fluorescent probes based imaging techniques capable of providing information on target locations are considerably appreciated.

A near-infrared fluorescent probe based on photostable Si-rhodamine for imaging hypochlorous acid during lysosome-involved inflammatory response.

Hypochloric acid (HClO) is mainly distributed in acidic lysosomes of phagocytes and closely associated with numerous physiological and pathological processes, especially inflammatory response. Fluorescent probe has become an important tool for imaging HClO in lysosomes, but suffered from interference from autofluorescence in vivo, phototoxicity to biosamples and photobleaching phenomenon due to their short-wavelength excitation and emission. Unfortunately, up to now, no near-infrared (NIR) lysosome-targetable fluorescent probe has been reported for imaging HClO.

A novel two-photon fluorescent probe with long-wavelength emission for monitoring HClO in living cells and tissues.

Hypochlorous acid (HClO), one of the most important reactive oxygen species (ROS), is a potent antimicrobial agent for the immune system against invasive bacteria and a wide range of pathogens. Therefore, it is critical to develop sensitive and selective methods for visualization of HClO in biological samples. In this work, a two-photon fluorescent probe HN2-TP) with long-wavelength emission (far-red: 630 nm) based on rhodamine analogue for bioimaging HClO was developed.

A unique approach toward near-infrared fluorescent probes for bioimaging with remarkably enhanced contrast.

Near-infrared (NIR) fluorescent probes are attractive molecular tools for bioimaging because of their low autofluorescence interference, deep tissue penetration, and minimal damage to sample. However, most previously reported NIR probes exhibit small Stokes shift, typically less than 30 nm, and low fluorescence quantum yield, strictly limited contrast and spatial resolution for bioimaging. Herein, by expanding the π-conjugated system of rhodamine B, while, at the same time, keeping its rigid and planar structure, we reported an efficient NIR dye, , with large stokes shift of 73 nm and fluorescence quantum yield as high as 0.

Rhodamine-based fluorescent probe for direct bio-imaging of lysosomal pH changes.

Intracellular pH plays a pivotal role in various biological processes. In eukaryotic cells, lysosomes contain numerous enzymes and proteins exhibiting a variety of activities and functions at acidic pH (4.5-5.

A simple and pH-independent and ultrasensitive fluorescent probe for the rapid detection of Hg2+.

Development of fluorescent probes for Hg(2+) has become a hot topic in modern chemical research due to its high toxicity. In this paper, we for the first time report the synthesis and application of a thioether spirocyclic rhodamine B derivative (TR) as an efficient fluorescent probe for Hg(2+). TR was synthesized using a simple procedure under mild condition.

Through bond energy transfer: a convenient and universal strategy toward efficient ratiometric fluorescent probe for bioimaging applications.

Fluorescence resonance energy transfer (FRET) strategy has been widely applied in designing ratiometric probes for bioimaging applications. Unfortunately, for FRET systems, sufficiently large spectral overlap is necessary between the donor emission and the acceptor absorption, which would limit the resolution of double-channel images. The through-bond energy transfer (TBET) system does not need spectral overlap between donor and acceptor and could afford large wavelength difference between the two emissions with improved imaging resolution and higher energy transfer efficiency than that of the classical FRET system.

Bifunctional fluoroionphore-ionic liquid hybrid for toxic heavy metal ions: improving its performance via the synergistic extraction strategy.

Several heavy metal ions (HMIs), such as Cd(2+), Pb(2+), and Hg(2+), are highly toxic even at very low concentrations. Although a large number of fluoroionphores have been synthesized for HMIs, only a few of them show detection limits that are below the maximum contamination levels in drinking water (usually in the nM range), and few of them can simultaneously detect and remove HMIs. In this work, we report a new fluoroionphore-ionic liquid hybrid-based strategy to improve the performance of classic fluoroionphores via a synergistic extraction effect and realize simultaneous instrument-free detection and removal of HMIs.

An efficient rhodamine thiospirolactam-based fluorescent probe for detection of Hg2+ in aqueous samples.

This paper described the optimized design, synthesis and application of a novel rhodamine thiospirolactam derivative as an 'off-on' fluorescent probe for the detection of Hg(2+) in aqueous samples. The 'off-on' fluorescence and color signal change of the probe is based on an Hg(2+)-triggered domino reaction which brings on the opened-ring form of the rhodamine spirolactam to regain the conjugated system of the rhodamine skeleton. In the well designed probe, the thiospirolactam serves as both Hg(2+) binding unit and electron-defect carbon centre, a phenolic hydroxyl with very strong nucleophilicity after deprotonation is chosen as the attacking unit, and a benzene ring is introduced on the linker to afford steric effects, which benefits an efficient nucleophilic reaction, with a high sensitivity towards Hg(2+).

Clicking fluoroionophores onto mesoporous silicas: a universal strategy toward efficient fluorescent surface sensors for metal ions.

Mesoporous SBA-15 silica is an excellent support for constructing fluorescent surface sensors. In this letter, we reported a two-step surface reaction involved strategy to construct efficient fluorescent surface sensors for metal ions by clicking fluoroionophores onto azide-functionalized SBA-15. Our experimental results indicate that such a strategy exhibits an obviously higher loading efficiency within commercial SBA-15 than a previously reported strategy.

Efficient fluorescence resonance energy transfer-based ratiometric fluorescent cellular imaging probe for Zn(2+) using a rhodamine spirolactam as a trigger.

This letter described the design and synthesis of a novel fluorescein-appended rhodamine spirolactam derivative and its preliminary application as a ratiometric fluorescent cellular imaging probe for Zn(2+). The ratiometric fluorescent signal change of the probe is based on an intramolecular fluorescence resonance energy transfer (FRET) mechanism modulated by a specific metal ion induced ring-opening process of the rhodamine spirolactam (acting as a trigger). In the new developed sensing system, the emission peaks of the two fluorophores are well-resolved, which can avoid the emission spectra overlap problem generally met by spectra-shift type probes and benefits for observation of fluorescence signal change at two different emission wavelengths with high resolution.

A ratiometric fluorescent sensor for zinc ions based on covalently immobilized derivative of benzoxazole.

In the present paper, we describe the fabrication and analytical characteristics of fluorescence-based zinc ion-sensing glass slides. To construct the sensor, a benzoxazole derivative 4-benzoxazol-2'-yl-3-hydroxyphenyl allyl ether (1) with a terminal double bond was synthesized and copolymerized with 2-hydroxyethyl methacrylate (HEMA) on the activated surface of glass slides by UV irradiation. In the absence of Zn(2+) at pH 7.