A mitochondria-targeted near-infrared fluorescent probe for detection and imaging of HSO3- in living cells

A colorimetric fluorescent probe for reversible detection of HSO3-/H2O2 and effective discrimination of HSO3-/ClO- and its application in food and bioimaging

In view of the significant role of reactive sulfur species (RSS) and reactive oxygen species (ROS) in maintaining the redox homeostasis of organisms, we proposed a colorimetric fluorescent probe (HTN) for reversible detection of HSO3-/H2O2 and effective discrimination of HSO3-/ClO-. C = C is the active site for the Michael addition of HSO3- and the oxidation of ClO-. When HTN interacts with HSO3- and ClO-, it exhibits fluorescence quenching. The addition of oxidizing H2O2 to the system can restore the conjugate structure of the addition product of HSO3- (HTN-HSO3-) and the fluorescence recovery, but it cannot restore the structure of the oxidation product of ClO- (HTN-ClO-). By studying the change of the reversibility/non-reversibility of the probe structure with the addition of H2O2, the purpose of reversible detection of HSO3-/H2O2 and distinguishing HSO3-/ClO- is achieved. In addition, HTN can not only be used as a fluorescent ink to detect HSO3- on the test paper, but also has excellent detection effect on HSO3- and ClO- in real food samples and water samples. Meantime, HTN has good biocompatibility and can target mitochondria to achieve reversible detection of HSO3-/H2O2 and effective discrimination of HSO3-/ClO- in living cells. Therefore, HTN has great potential as a molecular tool for studying redox homeostasis in the interaction network of complex living systems.

A novel fluorescence probe for ultrafast detection of SO2 derivatives/biogenic amines and its multi-application: Detecting food and fish freshness, fluorescent dye and bioimaging

In this study, we have effectively prepared a novel fluorescent probe named HDXM based on benzopyran derivatives for the ultrafast detection (within 3 s) of SO2 derivatives or biogenic amines. HDXM showed a noticeable color change after the addition of SO2 derivatives (from purple to colorless) or biogenic amines (from purple to blue), indicating that HDXM can identify two analytes with the naked eye. It is worth noting that HDXM can be used to detect SO2 derivatives in actual sugar samples, and to image HSO3-/SO32- in living cells. More importantly, sensing labels (HDXM-loaded filter paper or agarose hydrogel) enable real-time visual monitoring of salmon freshness through colorimetric and fluorescence dual channels. Compared with the Chinese national standard method, the sensing label is an effective tool for evaluating the freshness of fish. Benefiting from its excellent solubility and fluorescence performance, HDXM can be used as a versatile fluorescent material in various applications, including flexible films, glass coatings, impregnating dyes, printing, and fingerprint ink. HDXM is expected to be a promising and valuable multifunctional tool for food safety and fluorescent materials.

Structure-regulated mitochondrial-targeted fluorescent probe for sensing and imaging SO2in vivo

SO2 and its derivatives play an important role in the antioxidation and anticorrosion of food and medicine. In biological systems, abnormal levels of SO2 lead to the occurrence of many biological diseases. Hence, the development of suitable tools for monitoring SO2 in mitochondria is beneficial for studying the biological effect of SO2 in subcellular organelles. In this research, DHX-1 and DHX-2 are fluorescent probes designed on the basis of dihydroxanthene skeletons. Importantly, DHX-1 (650 nm) and DHX-2 (748 nm) show near-infrared fluorescence response toward endogenous and exogenous SO2, which showed advantages of great selectivity, good sensitivity and low cytotoxicity, and the detection limit is 5.6 μM and 4.08 μM of SO2, respectively. Moreover, DHX-1 and DHX-2 realized SO2 sensing in HeLa cells and zebrafish. Moreover, cell imaging demonstrated that DHX-2 with a thiazole salt structure possesses good mitochondria-targeting ability. Additionally, DHX-2 was perfectly achieved by in situ imaging of SO2 in mice.

A mitochondria-targeted fluorescent probe for imaging of endogenous carbon monoxide in living cells

Carbon monoxide (CO), a vital gasotransmitter, plays critical functions in many physiological processes. Mitochondrial CO is closely related to mitochondrial respiration, thus the detection and imaging of mitochondrial CO in living cells is very important and has attracted much attention recently. In this paper, we developed a hemicyanine-based off-on fluorescent probe, CO-H1, which was used for monitoring endogenous mitochondrial CO levels in living cells. After reacted with CO in the presence of PdCl₂, the fluorescence of CO-H1 was enhanced notably, accompanied by a significant red shift of absorption. CO-H1 exhibits low cytotoxicity, high sensitivity (detection limit of 0.048 μM), and good selectivity for CO. When incubated with living cells, probe CO-H1 mainly entered the mitochondria. CO-H1 was successfully applied to imaging the exogenous/endogenous mitochondrial CO in living cells, suggesting its potential application for further studying the biological functions of mitochondrial CO in living cells.

Mitochondrial Targeting and Imaging with Small Organic Conjugated Fluorophores: A Review

The last decade has seen an increasingly large number of studies reporting on the development of novel small organic conjugated systems for mitochondrial imaging exploiting optical signal transduction pathways. Mitochondria are known to play a critical role in a number of key biological processes, including cellular metabolism. Importantly, irregularities on their working function are nowadays understood to be intimately linked to a range of clinical conditions, highlighting the importance of targeting mitochondria for therapeutic benefits. In this work we carry out an in-depth evaluation on the progress to date in the field to pave the way for the realization of superior alternatives to those currently existing. The manuscript is structured by commonly used chemical scaffolds and comprehensively covers key aspects factored in design strategies such as synthetic approaches as well as photophysical and biological characterization, to foster collaborative work among organic and physical chemists as well as cell biologists.