CO release with ratiometric fluorescence changes: a promising visible-light-triggered metal-free CO-releasing molecule.

The first visible-light-triggered metal-free and ratiometric fluorescent CORM is reported. This CORM can be used to release CO with distinct ratiometric fluorescence changes in aqueous solution, living cells, zebrafish, and mice, which provided an excellent controllable and trackable CORM for living systems.

A Fluorescent ESIPT Probe for Imaging CO-Releasing Molecule-3 in Living Systems.

CO-releasing molecule-3 (CORM-3) has been widely used recently as a convenient and safe CO donor to release exogenous CO in living cells and to study the effects of CO on cellular systems. Accordingly, development of effective methods for detecting and tracking CORM-3 in living systems is of great significance. In this work, a readily available fluorescent probe for detection of CORM-3 was reported for the first time. This probe is based on an excited-state intramolecular proton transfer (ESIPT) dye phthalimide and uses the reducing ability of CORM-3 to convert a nitro group to an amino group, and more importantly, it can be used for rapid, highly selective, and sensitive detection of CORM-3 with a distinct turn-on green fluorescence change in aqueous solution, living cells, and animals, thus providing a useful tool for studying CORM-3 in living systems.

Development of a near-infrared fluorescent sensor with a large Stokes shift for sensing pyrophosphate in living cells and animals.

The detection of pyrophosphate (PPi) in living systems has attracted considerable attention in recent years due to its biological significance. While many fluorescent PPi sensors were developed with emission changes in the visible region, near-infrared (NIR) fluorescent sensors for PPi are rather scarce. In this paper, a dicyanomethylene-benzopyran (DCMB) based phenol-bridged dinuclear Zn(II)-DPA (DPA: dipicolylamine) complex was prepared, which was found to be a promising NIR fluorescent sensor for PPi. This sensor features a remarkable large Stokes shift (>150 nm) and shows colorimetric and NIR fluorescence changes for PPi with high selectivity and sensitivity in 100% aqueous solution. The detection limit of this sensor for PPi was determined to be as low as 42 nM. In addition, this sensor exhibits low cytotoxicity and can be conveniently employed for bioimaging PPi in living cells and animals, indicating it has great potential for in vitro and in vivo detection of PPi.

Readily prepared iminocoumarin for rapid, colorimetric and ratiometric fluorescent detection of phosgene.

In this paper, a new colorimetric and ratiometric fluorescent probe for the rapid detection of phosgene is reported. This probe is based on a readily prepared and highly fluorescent iminocoumarin, which reacts rapidly with phosgene to form a cyclic carbamate product to produce, distinctive colorimetric and ratiometric fluorescent signal changes. The detection of phosgene with this probe is fast (complete within 2 min), highly selective and sensitive with a detection limit of 27 nM in solution. Moreover, this probe can be used to prepare easy-to-use paper test strips for convenient visual and fluorescent detection of phosgene gas even at a concentration of 0.1 mg/L. Overall, this work provides a very promising dual colorimetric and ratiometric fluorescent probe for rapid and sensitive detection of phosgene both in solution and in the gas phase.

Near-Infrared Fluorescent Turn-on Probe with a Remarkable Large Stokes Shift for Imaging Selenocysteine in Living Cells and Animals.

Selenocysteine (Sec) is the 21st naturally occurring amino acid and has emerged as an important sensing target in recent years. However, fluorescent detection of Sec in living systems is challenging. To date, very few fluorescent Sec probes have been reported and most of them respond fluorescence to Sec in the visible region. In this paper, a very promising near-infrared fluorescent probe for Sec was developed. This probe works in aqueous solution over a wide pH range under mild conditions and can be used for rapid, highly selective and sensitive detection of Sec with significant near-infrared fluorescent turn-on signal changes. In addition, it features a remarkable large Stokes shift (192 nm) and a low detection limit (60 nM) for Sec with a wide linear range (0-70 µM). Moreover, this probe can be conveniently used to detect Sec in serum samples, living cells, and animals, indicating it holds great promise for biological applications.

Allyl Fluorescein Ethers as Promising Fluorescent Probes for Carbon Monoxide Imaging in Living Cells.

Recently, the fluorescent detection of carbon monoxide (CO) in living cells has attracted great attention. However, due to the lack of effective ways to construct fluorescent CO probes, fluorescent detection of CO in living cells is still in its infancy. In this paper, we report for the first time the use of allyl ether as a reaction site for construction of fluorescent CO probes. By this way, two readily available allyl fluorescein ethers were prepared, which were found to be highly selective and sensitive probes for CO in the presence of PdCl2. These probes have the merits of good stability, good water-solubility, and rapid and distinct colorimetric and remarkable fluorescent turn-on signal changes. Moreover, a very low dose of these two probes can be used to detect and track CO in living cells, indicating that these two probes could be very promising biological tools for CO detection in living systems. Overall, this work provided not only two new promising fluorescent CO probes but also a new way to devise fluorescent CO probes.

Selenocysteine detection and bioimaging in living cells by a colorimetric and near-infrared fluorescent turn-on probe with a large stokes shift.

Selenocysteine (Sec) has emerged as an important sensing target in recent years. In this paper, a colorimetric and near-infrared fluorescent turn-on probe for Sec was developed. This probe features a remarkable large Stokes shift (146nm) and shows a rapid, highly selective detection process for Sec with obvious colorimetric and near-infrared fluorescent (Em 706nm with Ex 560nm) turn-on responses. In addition, this probe can be used to quantitatively detect Sec with high sensitivity with a detection limit of 62nM over a wide linear range (0.2-80µM). Moreover, it was further demonstrated that this NIR fluorescent probe can be employed to image both exogenous and endogenous Sec in living cells, indicating that this probe has great potential for biological applications.

Readily Available Fluorescent Probe for Carbon Monoxide Imaging in Living Cells.

Carbon monoxide (CO) is an important gasotransmitter in living systems and its fluorescent detection is of particular interest. However, fluorescent detection of CO in living cells is still challenging due to lack of effective probes. In this paper, a readily available fluorescein-based fluorescent probe was developed for rapid detection of CO. This probe can be used to detect CO in almost wholly aqueous solution under mild conditions and shows high selectivity and sensitivity for CO with colorimetric and remarkable fluorescent turn-on signal changes. The detection limit of this probe for CO is as low as 37 nM with a linear range of 0-30 µM. More importantly, this probe (1 µM dose) can be conveniently used for fluorescent imaging CO in living cells.