Probe For Carbon Monoxide Research Articles

Highly dispersed Pt nanoparticles onto dendritic silica as colorimetric probe for CO sensing in mainstream cigarette smokes

Carbon monoxide (CO) is a typical substance harmful to human body produced during cigarette smoking. Its content in cigarette smoke is one of the important indicators for evaluating its toxicity and the filtration effect of cigarette filter tips, which provides important guidance for its rational design. In this work, Pt nanoparticles with superior peroxidase catalytic ability were synthesized and loaded onto fibrous SiO2 nanoparticles as nanozymes to detect CO in cigarette smoke by taking advantage of the reduced catalytic performance of CO adsorption on the active sites of the nanozymes. The fibrous SiO2 not only provide abundant sites for the deposition and dispersion of Pt NPs, but also prevent their aggregation and thus maintain their high catalytic activity. Density functional theory calculations reveal that Pt nanoparticles exhibits superior peroxidase ability over Au and Pd nanoparticles, which can be significantly inhibited by CO. Accordingly, a nanozyme-inhibition based colorimetric method was developed for the detection of CO in cigarette smoke with the limit of detection of 0.15 mg/L. The applicability of this method was validated by analyzing the CO contents in 8 kinds of cigarette smoke with different types of filter tips. The concentrations of CO are in the range of 5.40–6.73 mg/branch, which are in good agreement with those of GC results, indicating the accuracy and reliability of our method. This assay is fast, convenient and sensitive for quantitatively assessing the CO content in cigarette smoke, and it lays the foundation for prompting the widespread use of nanozyme-inhibition in chemical sensing.

Sensing a CO-Releasing Molecule (CORM) Does Not Equate to Sensing CO: The Case of DPHP and CORM-3.

Carbon monoxide (CO) is an endogenous signaling molecule with demonstrated pharmacological effects. For studying CO biology, there is a need for sensitive and selective fluorescent probes for CO as research tools. In developing such probes, CO gas and/or commercially available metal-carbonyl-based "CO-releasing molecules" (CORMs) have been used as CO sources. However, new findings are steadily emerging that some of these commonly used CORMs do not release CO reliably in buffers commonly used for studying such CO probes and have very pronounced chemical reactivities of their own, which could lead to the erroneous identification of "CO probes" that merely detect the CORM used, not CO. This is especially true when the CO-sensing mechanism relies on chemistry that is not firmly established otherwise. Cu2+ can quench the fluorescence of an imine-based fluorophore, DPHP, presumably through complexation. The Cu2+-quenched fluorescence was restored through the addition of CORM-3, a Ru-based CORM. This approach was reported as a new "strategy for detecting carbon monoxide" with the proposed mechanism being dependent on CO reduction of Cu2+ to Cu1+ under near-physiological conditions ( Anal. Chem. 2022, 94, 11298-11306). The study only used CORM-3 as the source of CO. CORM-3 has been reported to have very pronounced redox reactivity and is known not to release CO in an aqueous solution unless in the presence of a strong nucleophile. To assess whether the fluorescent response of the DPHP-Cu(II) cocktail to CORM-3 was truly through detecting CO, we report experiments using both pure CO and CORM-3. We confirm the reported DPHP-Cu(II) response to CORM-3 but not pure CO gas. Further, we did not observe the stated selectivity of DPHP for CO over sulfide species. Along this line, we also found that a reducing agent such as ascorbate was able to induce the same fluorescent turn-on as CORM-3 did. As such, the DPHP-Cu(II) system is not a CO probe and cannot be used to study CO biology. Corollary to this finding, it is critical that future work in developing CO probes uses more than a chemically reactive "CO donor" as the CO source. Especially important will be to confirm the ability of the "CO probe" to detect CO using pure CO gas or another source of CO.

A novel red AIE fluorescent probe for ratiometric detection of carbon monoxide in vitro and in vivo.

As a significant signaling gas molecule, carbon monoxide (CO) has a crucial impact on various physiological and pathological processes in organisms, particularly in oxidative stress processes. Hence, designing and synthesizing a fluorescent probe that can effectively image CO in vivo holds immense significance. In this work, under the guidance of density functional theory (DFT) and time-dependent density functional theory (TDDFT), we designed and synthesized a red aggregation-induced emission (AIE) fluorescent probe THBTA-CO for CO detection and imaging. The fluorescent probe displayed green fluorescence emission at 535 nm before the CO response. However, upon CO response, with the involvement of Pd2+, the probe emitted red fluorescence at 630 nm. Furthermore, we successfully demonstrated the potential of THBTA-CO in visualizing both exogenous and endogenous CO in living cells. Significantly, THBTA-CO was effectively employed to image CO in lipopolysaccharide (LPS)-induced oxidative stress in mice. These findings convincingly establish THBTA-CO as a promising fluorescent probe for CO sensing and imaging, thereby facilitating a better understanding of CO's role in biomedical research.

A TCF-Based Carbon Monoxide NIR-Probe without the Interference of BSA and Its Application in Living Cells.

As toxic gaseous pollution, carbon monoxide (CO) plays an essential role in many pathological and physiological processes, well-known as the third gasotransmitter. Owning to the reducibility of CO, the Pd0-mediated Tsuji-Trost reaction has drawn much attention in CO detection in vitro and in vivo, using allyl ester and allyl ether caged fluorophores as probes and PdCl2 as co-probes. Because of its higher decaging reactivity than allyl ether in the Pd0-mediated Tsuji-Trost reaction, the allyl ester group is more popular in CO probe design. However, during the application of allyl ester caged probes, it was found that bovine serum albumin (BSA) in the fetal bovine serum (FBS), an irreplaceable nutrient in cell culture media, could hydrolyze the allyl ester bond, and thus give erroneous imaging results. In this work, dicyanomethylenedihydrofuran (TCF) and dicyanoisophorone (DCI) were selected as electron acceptors for constructing near-infrared-emission fluorophores with electron donor phenolic OH. An allyl ester and allyl ether group were installed onto TCF-OH and DCI-OH, constructing four potential CO fluorescent probes, TCF-ester, TCF-ether, DCI-ester, and DCI-ether. Our data revealed that ester bonds of TCF-ester and DCI-ester could completely hydrolyze in 20 min, but ether bonds in TCF-ether and DCI-ether tolerate the hydrolysis of BSA and no released fluorescence was observed even up to 2 h. Moreover, passing through the screen, it was concluded that TCF-ether is superior to DCI-ether due to its higher reactivity in a Pd0-mediated Tsuji-Trost reaction. Also, the large stokes shift of TCF-OH, absorption and emission at 408 nm and 618 nm respectively, make TCF-ether desirable for fluorescent imaging because of differentiating signals from the excitation light source. Lastly, TCF-ether has been successfully applied to the detection of CO in H9C2 cells.

Mitochondria-targetable ratiometric fluorescence probe for carbon monoxide based on naphthalimide derivatives.

The design of ratiometric probes for imaging of carbon monoxide (CO) in subcellular organelles is critical to elucidate its biological and pathological functions. In this work, we establish a ratiometric fluorescent probe (Mito-NIB-CO) for imaging of CO in mitochondria. The mitochondria-targeting unit (triphenylphosphonium moiety) and CO-responsive unit (allyl ether moiety) are covalently linking into the single molecule (Mito-NIB-CO) to achieve the multifunctional effect. Upon being treated with CO, Mito-NIB-CO underwent the cleavage of allyl ether element in the presence of PdCl2, resulting in the structural and spectral conversion. This characteristic afforded Mito-NIB-CO to be a ratiometric probe for CO with two fluorescent emission bands. Additionally, the probe Mito-NIB-CO exhibited other distinct merits, including preeminent selectivity and sensitivity. What's more, profiting from triphenylphosphonium moiety, the probe Mito-NIB-CO can specifically target the mitochondria and realize quantitative detection of exogenous/endogenous CO in mitochondria. Graphical abstract.

A Comparison of the Stellar, CO, and Dust-continuum Emission from Three Star-forming HUDF Galaxies at z ∼ 2

Abstract We compare the extent of the dust, molecular gas, and stars in three star-forming galaxies, at z = 1.4, 1.6, and 2.7, selected from the Hubble Ultra Deep Field based on their bright carbon monoxide (CO) and dust-continuum emission as well as their large rest-frame optical sizes. The galaxies have high stellar masses, , and reside on, or slightly below, the main sequence of star-forming galaxies at their respective redshifts. We probe the dust and molecular gas using subarcsecond Atacama Large Millimeter/submillimeter Array observations of the 1.3 mm continuum and CO line emission, respectively, and probe the stellar distribution using Hubble Space Telescope observations at 1.6 μm. We find that for all three galaxies the CO emission appears ≳30% more compact than the stellar emission. For the z = 1.4 and 2.7 galaxies, the dust emission is also more compact, by ≳50%, than the stellar emission, whereas for the z = 1.6 galaxy, the dust and stellar emission have similar spatial extents. This similar spatial extent is consistent with observations of local disk galaxies. However, most high-redshift observations show more compact dust emission, likely because of the ubiquity of central starbursts at high redshift and the limited sensitivity of many of these observations. Using the CO emission line, we also investigate the kinematics of the cold interstellar medium in the galaxies, and find that all three have kinematics consistent with a rotation-dominated disk.

A near-infrared fluorescence probe with a large Stokes shift for detecting carbon monoxide in living cells and mice

Carbon monoxide (CO) can be endogenously produced in mammalian cells and regarded as an essential cell signaling molecule in the body. And it is closely related with a range of physiological and pathological processes. Although some fluorescence probes for tracking CO are reported, near-infrared (NIR) fluorescence probe for CO with a large Stokes shift remains scarce. Herein, a NIR fluorescence probe named DCX-CO is designed and synthesized. In the probe, the allyl formate group is chosen as recognizing moiety and benzopyranonitrile-xanthene-based dye is selected as fluorophore. Upon the addition of CO, the probe shows NIR emission at 762 nm with a large Stokes shift (164 nm). Moreover, the probe displays high sensitivity for CO with 16-fold fluorescence enhancement and excellent selectivity to CO over other potential interference in biological sample. Based on the low cytotoxicity, the probe can be used for the detection of exogenous and endogenous CO in HepG2 cells and HCT116 cells. In addition, taking advantage of NIR emission with a large Stokes shift, DCX-CO is applied for monitoring CO in vivo.

Preparation of a Nile Red-Pd-based fluorescent CO probe and its imaging applications in vitro and in vivo.

Carbon monoxide (CO) is a key gaseous signaling molecule in living cells and organisms. This protocol illustrates the synthesis of a highly sensitive Nile Red (NR)-Pd-based fluorescent probe, NR-PdA, and its applications for detecting endogenous CO in tissue culture cells, ex vivo organs, and zebrafish embryos. In the NR-PdA synthesis process, 3-diethylamine phenol reacts with sodium nitrite in the acidic condition to afford 5-(diethylamino)-2-nitrosophenol hydrochloride (compound 1), which is further treated with 1-naphthalenol at a high temperature to provide the NR dye via a cyclization reaction. Finally, NR is reacted with palladium acetate to obtain the desired Pd-based fluorescent probe NR-PdA. NR-PdA possesses excellent two-photon excitation and near-IR emission properties, high stability, low background fluorescence, and a low detection limit. In addition to the chemical synthesis procedures, we provide step-by-step procedures for imaging endogenous CO in RAW 264.7 cells, mouse organs ex vivo, and live zebrafish embryos. The synthesis process for the probe requires ∼4 d, and the biological imaging experiments take ∼14 d.

Bioluminescence Imaging of Carbon Monoxide in Living Cells and Nude Mice Based on Pd0-Mediated Tsuji-Trost Reaction.

Carbon monoxide (CO) is highly toxic and lethal to humans and animals because of its strong affinity for hemoglobin, while this "silent killer" is constantly generated in the body as a cell-signaling molecule of the gasotransmitter family in various pathological and physiological conditions. Up to now, designing fluorescent probes for real-time imaging of CO in living species is a continuous challenge due to background interference, light scattering, and photoactivation/photobleaching. Herein, a novel type of bioluminescence probe (allyl-luciferin) was synthesized and exploited to realize CO imaging with high signal-to-noise ratios. Based on Pd0-mediated Tsuji-Trost reaction, allyl-luciferin specifically reacted with CO to yield D-luciferin and thus generate a turn-on bioluminescence response, exhibiting high selectivity against bioactive small molecules such as reactive nitrogen, oxygen, and sulfur species. Furthermore, the new probe can be easily employed to detect exogenous CO in Huh7 cells and MDA-MB-231 cells, and CO production was enhanced greatly in these living cells after pretreatment with [Ru(CO)3Cl-(glycinate)] (CORM-3). Through the use of PdCl2-containing liposomes to improve poor membrane permeability of PdCl2, endogenous CO stimulated by heme was also seen clearly. In addition, the probe was successfully used to monitor exogenous and endogenous CO in nude mice. Overall, our data proved that the allyl-luciferin is a promising tool for exogenous and endogenous CO detection and imaging within living species. This is the first demonstration of bioluminescence imaging obtained by a probe for CO. We anticipate that the good imaging properties of allyl-luciferin presented in this study will provide a potentially powerful approach for illuminating CO functions in the future.

A readily available colorimetric and near-infrared fluorescent turn-on probe for detection of carbon monoxide in living cells and animals

Since carbon monoxide (CO) was recognized as an important gasotransmitter, great interest has been given to develop probes for detection of this gas molecule in living systems. While several fluorescent probes have been developed very recently for imaging CO in living cells, probes for in vivo detection of CO have not yet been reported. Herein, we report a new NIR fluorescent CO probe that can be used for detection of CO both in vitro and in vivo. This probe works in almost wholly aqueous solution under mild conditions and shows high selectivity and sensitivity for CO in the presence of Pd2+, giving rapid (within few minutes) and distinct colorimetric and near-infrared (NIR) fluorescent turn-on signal changes with a detection limit as low as 3.2nM. Moreover, we also show that this probe has low cytotoxicity and can be conveniently used to image CO in both living cells and animals.

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.

A unique carbazole–coumarin fused two-photon platform: development of a robust two-photon fluorescent probe for imaging carbon monoxide in living tissues

Two-photon fluorescent probes are favorable as powerful molecular tools for studies in biology and medicine. To construct two-photon fluorescent probes, it is necessary to have suitable two-photon fluorescent platforms. Herein, we present the rational design, synthesis, and spectral properties of carbazole–coumarin (CC) derivatives, a unique family of two-photon fluorescent dyes. Significantly, the action cross-sections of CC are tunable by modifications at the 4′-position of the coumarin moiety, implying that CC could be exploited as a novel platform to design two-photon fluorescent probes. Carbon monoxide (CO) plays an important role in many physiological and pathological processes. Although the tracking of CO in living cells has been previously reported, the detection of CO in much thicker biosamples, for instance, living tissues, has not been realized. It is known that two-photon fluorescent probes are favorable for monitoring biomolecules in living tissues. Thus, based on the unique CC platform, we rationally engineered CC–CO as the first two-photon fluorescent CO probe, and we further demonstrated that CC–CO could monitor the changes of CO levels not only in living cells but also in living tissues for the first time, demonstrating the value of our two-photon fluorescent CO probe. The CC platform is complementary to the current two-photon fluorescent platforms and it may be used to develop a wide variety of two-photon fluorescent probes. In addition, we expect that CC–CO and its next generation analogues may be useful for unraveling the functions of CO in complicated living systems.