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In recent years, targeting drugs made by physical loading or chemical bonding of drugs on small molecular carriers have shown a very wide application prospect in the field of tumor and cancer treatment. How to achieve the release of drugs in cancer cells has become the core of this research. One of the most important bases for drug localization is to use the difference of small molecular biothiol concentration between cancer cells and normal cells. Details of the changes of biothiol levels in the growth and reproduction of cancer cells are still poorly understood, and the main reason is the lack of sensitive real-time imaging tools for biothiols in cancer cells. In this work, we reasonably designed and synthesized the combination of 4-hydroxy-1,8-naphthalimide and NBD-Cl as a concise fluorescent probe HN-NBD for imaging biothiols in live cells and zebrafish. In addition, due to the advantages of HN-NBD design, it is sufficiently sensitive to biothiols, and further imaging can distinguish cancer cells from normal cells. Probe HN-NBD would be of great significance to biomedical researchers for the study of biothiol-related diseases, the screening of new anticancer drugs, and the early diagnosis and treatment of cancers. [ABSTRACT FROM AUTHOR]

A novel pH-sensitive fluorescent probe has been designed and synthesized for sensing intracellular pH. This probe showed excellent water solubility, it was sensitive toward the pH range from 4 to 12, and it was especially sensitive in alkaline environments. During the pH changes from acidic to alkaline environments, the color of the solution turned from yellow to purple, thus the difference in color can be used to distinguish between acidic and alkaline systems. The other major features of probe pH-DCN including high selectivity, low toxicity, good reversibility and stability allowed pH-DCN to visualize fluctuations of the pH in live cells. Moreover, probe pH-DCN has successfully discriminated cancer cells from normal cells by monitoring their different intracellular pH levels. [ABSTRACT FROM AUTHOR]

Biothiols such as cysteine (Cys), homocysteine (Hcy), glutathione (GSH) and hydrogen sulfide (H2S) are widely found in mammalian cells. They are closely related to the production and metabolic pathways and play very important roles in physiological and pathological activities. Therefore, the quantitative detection of these biothiols is of great significance. Although many fluorescent probes have been successfully used to track biothiols in biological samples, the fluorescence method for simultaneously detecting these biothiols using separated fluorescence emission channels under single wavelength excitation is still immature. In this work, we prepared the conjugate of seminaphthorhodafluor (SNARF) dye and 7-nitro-1,2,3-benzoxadiazole (NBD) using as a simple long-wavelength fluorescent probe SNARF-NBD for specific detection of biothiols. Cys/Hcy and GSH/H2S were identified by two separated fluorescence emission channels under single wavelength excitation, which showed good selectivity and sensitivity. In addition, SNARF-NBD has low cytotoxicity and shows good imaging ability in living cells and zebrafish. [ABSTRACT FROM AUTHOR]

Peroxynitrite (ONOO−) has been proven to participate in various physiological and pathological processes, and may also be a contributing factor in many diseases. In view of this, there is a need to develop detection tools for unambiguously tracking a small amount of endogenous ONOO− to reveal its exact mechanisms. In this paper, a colorimetric and red-emitting fluorescent probe Red-PN, based on a rhodamine-type fluorophore and hydrazide reactive site is described. The probe Red-PN possesses the advantages of rapid response (within 5 s), visual color change (from colorless to pink), preeminent sensitivity (detection limit = 4.3 nM) and selectivity. Because of these outstanding performances, it was possible to accurately detect endogenous ONOO−. It was encouraging that the probe Red-PN could be used effectively for tracking the relatively low levels of endogenous and exogenous ONOO− in living cells and zebrafish. Thus, it is envisioned that the probe Red-PN would have promising prospects in applications for imaging ONOO− in a variety of biological settings. [ABSTRACT FROM AUTHOR]

The detection of ionic mercury (Hg2+) is very important because it is a highly toxic environmental pollutant that could cause serious diseases and threaten human health. Herein, we designed a new carbonothioate-based far-red fluorescent probe, CBRB, with a seminaphthorhodafluor dye as the fluorophore for the detection of Hg2+. The CBRB probe by itself exhibited very weak fluorescence due to the enhanced photo-induced electron transfer (PET) effect and inhibited the intramolecular charge transfer (ICT) process caused by the carbonothioate moiety. Upon addition of Hg2+, a tremendous fluorescence enhancement was achieved, attributed to the removal of the carbonothioate group via a specific mercury-promoted desulfurization reaction. Moreover, the probe displayed a large Stokes shift (about 105 nm) and was used to quantitatively measure the concentration of Hg2+ for concentrations ranging from 0 to 1 μM (DL = 3.6 nM). In addition, CBRB in our experiments responded exclusively to Hg2+, even in the presence of high concentrations other ions. Gratifyingly, this probe was successfully used to monitor Hg2+ in environmental water samples and to image Hg2+ in living cells as well as in zebrafish. [ABSTRACT FROM AUTHOR]