Comment on "Water-Soluble Fluorescent Probe with Dual Mitochondria/Lysosome Targetability for Selective Superoxide Detection in Live Cells and in Zebrafish Embryos"

Near-Infrared Fluorescent Probe for the In Situ Visualization of Oxidative Stress in the Brains of Neuroinflammatory and Schizophrenic Mice

Schizophrenia is a common mental disorder with unclear mechanisms. Oxidative stress and neuroinflammation play important roles in the pathological process of schizophrenia. Superoxide anion (O2•-) is an important oxidative stress biomarker in vivo. However, due to the existence of the blood-brain barrier (BBB), few near-infrared (NIR) fluorescent probes have been used for the sensing and detection of O2•- in the brain. With this research, we developed the first near-infrared fluorescent probe (named CT-CF3) for noninvasive detection of endogenous O2•- in the brain of mice. Enabling fluorescence monitoring of the dynamic changes in O2•- flux due to the prolonged activation of microglia in neuroinflamed and schizophrenic (SZ) mice brains, thereby providing direct evidence for the relationship between oxidative stress, neuroinflammation, and schizophrenia. Furthermore, we confirmed the O2•- burst in the brains of first-episode schizophrenic mice and assessed the effect of two atypical antipsychotic drugs (risperidone and olanzapine) on redox homeostasis.

Synthesis and Single Crystal X-ray Study of Phenylselenyl Embedded Coumarin-Based Sensors for Selective Detection of Superoxide

Selenium-coumarin based probe 4 was synthesized from the reaction of bromo derivative of coumarin with in situ prepared sodium phenyl selenide. Esterification of probe 4 resulted in the formation of...

Insights Into the Detection Selectivity of Redox and Non-redox Based Probes for the Superoxide Anion Using Coumarin and Chromone as the Fluorophores

In this study, we evaluated the applicability of various superoxide anion sensors which were designed based on either redox or non-redox mechanisms. Firstly, both redox- and non-redox-based superoxide anion probes were designed and synthesized using either coumarin or chromone as the fluorophores, and the photophysical properties of these probes were measured. Subsequently, the sensing preference of both types of probes toward various reactive oxygen species (ROS) was evaluated. We found that non-redox-based O2 •- probes exhibited broad sensing ability toward various ROS. By contrast, redox based O2 •- probes showed a clear reactivity hierarchy which was well correlated to the oxidizing strength of the ROS. Lastly, the detection selectivity of redox-based O2 •- recognizing probes was also observed when balancing various factors, such as reactant ROS concentrations, temperature, and changing reaction transformation rates. Herein, we concluded the selectivity advantage of redox-based O2 •- probes.

Recent progress in developing fluorescent probes for imaging cell metabolites

Cellular metabolites play a crucial role in promoting and regulating cellular activities, but it has been difficult to monitor these cellular metabolites in living cells and in real time. Over the past decades, iterative development and improvements of fluorescent probes have been made, resulting in the effective monitoring of metabolites. In this review, we highlight recent progress in the use of fluorescent probes for tracking some key metabolites, such as adenosine triphosphate, cyclic adenosine monophosphate, cyclic guanosine 5'-monophosphate, Nicotinamide adenine dinucleotide (NADH), reactive oxygen species, sugar, carbon monoxide, and nitric oxide for both whole cell and subcellular imaging.

Fluorescent probe for the imaging of superoxide and peroxynitrite during drug-induced liver injury

Drug-induced liver injury (DILI) is an important cause of potentially fatal liver disease. Herein, we report the development of a molecular probe (LW-OTf) for the detection and imaging of two biomarkers involved in DILI. Initially, primary reactive oxygen species (ROS) superoxide (O₂˙^-) selectively activates a near-infrared fluorescence (NIRF) output by generating fluorophore LW-OH. The C[double bond, length as m-dash]C linker of this hemicyanine fluorophore is subsequently oxidized by reactive nitrogen species (RNS) peroxynitrite (ONOO^-), resulting in cleavage to release xanthene derivative LW-XTD, detected using two-photon excitation fluorescence (TPEF). An alternative fluorescence pathway can occur through cleavage of LW-OTf by ONOO^- to non-fluorescent LW-XTD-OTf, which can react further with the second analyte O₂˙^- to produce the same LW-XTD fluorescent species. By combining NIRF and TPEF, LW-OTf is capable of differential and simultaneous detection of ROS and RNS in DILI using two optically orthogonal channels. Probe LW-OTf could be used to detect O₂˙^- or O₂˙^- and ONOO^- in lysosomes stimulated by 2-methoxyestradiol (2-ME) or 2-ME and SIN-1 respectively. In addition, we were able to monitor the chemoprotective effects of tert-butylhydroxyanisole (BHA) against acetaminophen (APAP) toxicity in living HL-7702 cells. More importantly, TPEF and NIRF imaging confirmed an increase in levels of both O₂˙^- and ONOO^- in mouse livers during APAP-induced DILI (confirmed by hematoxylin and eosin (H&E) staining).

Application of Fluorescence-Based Probes for the Determination of Superoxide in Water Treated with Air Non-thermal Plasma

Superoxide is one of the reactive oxygen species (ROS) in non-thermal plasmas generated by electrical discharges in air at room temperature and atmospheric pressure. One important application of such plasmas is the activation of advanced oxidation processes for air and water decontaminating treatments. When in contact with aqueous media, ROS and notably superoxide can react at the plasma/liquid interface or transfer and react into the liquid. While the detection of superoxide in plasma-treated water has been reported in the literature, to the best of our knowledge, quantitative determinations are lacking. We report here the determination of superoxide rate of formation and steady-state concentration in water subjected to air non-thermal plasma in a streamer discharge reactor used previously to treat various organic contaminants. After detecting the presence of superoxide by spin-trapping and electron paramagnetic resonance analyses, we applied superoxide-selective fluorescent probes to carry out quantitative determinations. The first probe tested, 3',6'-bis(diphenylphosphinyl) fluorescein (PF-1), was not sufficiently soluble, but the second one, fluorescein-bis-[(N-methylpyridinium-3-yl)sulfonate iodide] (FMSI), was applied successfully. Under typical plasma operating conditions, the rate of superoxide formation and its steady-state concentration were (0.27 ± 0.15) μM s^-1 and (0.007 ± 0.004) nM, respectively. The procedure outlined here can be usefully applied to detect and quantify superoxide in water treated by different plasma sources in various types of plasma reactors.

Taking advantage of the aromatisation of 7-diethylamino-4-methyl-3,4-dihydrocoumarin in the fluorescence sensing of superoxide anion

The aromatisation of 7-diethylamino-3,4-dihydrocoumarin provides an alternative fluorescent probing technique to selectively detect the concentration of superoxide anion in solution. In addition, we reported the advantage of evaluating O₂˙^- sensing probes in anhydrous DMSO instead of in aqueous buffers when using KO₂ as the surrogate of O₂˙^-.

Establishment of a Customizable Fluorescent Probe Platform for the Organelle-Targeted Bioactive Species Detection

A customizable fluorescent probe platform that can be used to detect various bioactive analytes offers significant potential for engineering a wide range of bioprobes with diverse sensing and imaging functions. Here, we show a facile and innovative strategy for introducing cis-amino-proline as a carrier scaffold, which is appended with three specific functional groups: a target group, a water-soluble group, and fluorophores with triggers. The potency of the designed strategy could be customized to generate variable multifunctional fluorescent probes for detecting bioactive species of interest, including reactive oxygen species (ROS), reactive nitrogen species (RNS), reactive sulfur species (RSS), ROS/RSS, and even enzymes. We designed and synthesized five representative water-soluble and organelle-targeted compounds, PMB, PMN, PMD, PRB, and PME, with emission wavelengths of these fluorescent probes varying from blue to red (465, 480, 535, 550, 565, and 640 nm). This strategy could be exemplified by its application to develop a mitochondria-/lysosome-targeting multifunctional fluorescent probe capable of imaging bioactive species of interest in live cells and nude mice.

Reply to Comment on "Water-Soluble Fluorescent Probe with Dual Mitochondria/Lysosome Targetability Superoxide Detection in Live Cells and in Zebrafish Embryos"

Recently, we published a paper on the detection of superoxide (O₂^•-) with a water-soluble fluorescent probe (ACS Sens. 2018, 3, 59-64), and Francesco Tampieri et al. provided comments on our publication, mostly on the detection medium (deionized water) we used. Herein we present our responses to the addressed questions to explain that although KO₂ decomposes in aqueous environment, the results we obtained did not affect the general trend, since evidence from the literature afforded the correlation between KO₂ in aqueous media as a surrogate of superoxide and enzymatically produced O₂^•- for the probes wherein the deprotection pathway operated. Moreover, fluorescence imaging on cells and zebrafish embryos under PMA stimulation confirmed the effectiveness of our probe to detect superoxide using KO₂ as a convenient source. The detailed studies from Francesco Tampieri and coauthors are scientifically meaningful for the reliable evaluation of fluorescent probes using KO₂ as a surrogate of superoxide.