A 'double locked' ratiometric fluorescent probe for detection of cysteine in a viscous system and its application in cancer cells

Near-Infrared Fluorescent Turn-On Probe for Selective Detection of Hypochlorite in Aqueous Medium and Live Cell Imaging

Hypochlorite, as an important reactive oxygen species (ROS), plays a vital role in many physiological and pathological processes, but an excess concentration of hypochlorite (ClO-) may become toxic to humans and cause disease. Hence, the selective and rapid detection of hypochlorite (ClO-) is necessary for human safety. Here, we report a novel near-infrared (NIR) fluorescence "turn-on" and highly selective benzophenoxazinium chloride-based fluorescent probe, BPH (benzophenoxazinium dihydroxy benzaldehyde), for hypochlorite detection. Due to hypochlorite-induced vicinal diol oxidation to the corresponding ortho benzoquinone derivative, the photoinduced electron transfer (PET) process, which was operating from vicinal diol to the benzophenoxazinium chloride receptor moiety, was suddenly inhibited, as a result of which strong NIR fluorescence "turn-on" emission was observed. The detection limit of BPH was found to be 2.39 × 10-10 M, or 0.23 nM. BPH was successfully applied for exogenous and endogenous hypochlorite detection in live MDA-MB 231 cells.

A dual-channel fluorescence probe for simultaneously visualizing cysteine and viscosity during drug-induced hepatotoxicity

Cysteine (Cys), one of the important participants in protecting cells from oxidative stress, is closely associated with the occurrence and development of various diseases. Moreover, cell viscosity as a pivotal microenvironmental parameter has recently attracted increasing attention due to its dominant role in governing intracellular signal transduction and diffusion of reactive metabolites. Thus, simultaneous detection of Cys and viscosity is imperative for investigating their pathophysiological functions and cross-link. Herein we present a mitochondria-targetable dual-channel fluorescence probe ABDSP by grafting the acrylate modified pyridinium unit to dimethylaminobenzene. Whilst the probe is a seemingly simple, it could simultaneously discriminate Cys and viscosity in a fashion of distinguishable signals. Furthermore, the probe was successfully employed for visualizing mitochondrial Cys and viscosity, and probe into their cross-link during acetaminophen-induced hepatotoxicity.

A Single Organic Fluorescent Probe for the Discrimination of Dual Spontaneous ROS in Living Organisms: Theoretical Approach

Single-organic-molecule fluorescent probes with double-lock or even multi-lock response modes have attracted the attention of a wide range of researchers. The number of corresponding reports has rapidly increased in recent years. The effective application of the multi-lock response mode single-molecule fluorescent probe has improved the comprehensive understanding of the related targets' functions or influences in pathologic processes. Building a highly efficient functional single-molecule fluorescent probe would benefit the diagnosis and treatment of corresponding diseases. Here, we conducted a theoretical analysis of the synthesizing and sensing mechanism of this kind of functional single-molecule fluorescent probe, thereby guiding the design and building of new efficient probes. In this work, we discuss in detail the electronic structure, electron excitation, and fluorescent character of a recently developed single-molecule fluorescent probe, which could achieve the discrimination and profiling of spontaneous reactive oxygen species (ROS, •OH, and HClO) simultaneously. The theoretical results provide insights that will help develop new tools for fluorescent diagnosis in biological and medical fields.

Theoretical Insights into a Near-Infrared Fluorescent Probe NI-VIS Based on the Organic Molecule for Monitoring Intracellular Viscosity

So many biological functional disorders and diseases, such as atherosclerosis, hypertension, diabetes, Alzheimer's disease, as well as cell malignancy are closely related with the intracellular viscosity. A safe and effective intracellular viscosity detecting method is desired by the biomedical community. Recently, a novel near-infrared fluorescent probe NI-VIS with a twisting intramolecular charge transfer mechanism was developed. The capability of this probe to visualize the viscosity variation in cirrhotic liver tissues and map the micro viscosity in vivo were testified using an experiment. In this work, the twisting intramolecular charge transfer mechanism and fluorescent properties of the probe NI-VIS were studied in detail under quantum mechanical method. The low energy barrier among the different conformations of the probe indicated the occurrence of twisting intramolecular charge transfer due to the rotation of the aryl group in the probe molecule while within the low viscosity environment. The electronic structure analysis on different probe conformations revealed the electron transfer process of the probe under optical excitation. All these theoretical results could provide insights into understand in greater depth the principles and build highly effective fluorescent probe to monitor the viscosity in biological samples.