Kenjiro Hanaoka

Detection of chelatable zinc (Zn(2+)) in biological studies has attracted much attention recently, because chelatable Zn(2+) plays important roles in many biological systems. Lanthanide complexes (Eu(3+), Tb(3+), etc.) have excellent spectroscopic properties for biological applications, such as long luminescence lifetimes of the order of milliseconds, a large Stoke's shift of >200 nm, and high water solubility. Herein, we present the design and synthesis of a novel lanthanide sensor molecule, [E

Let it shine: New hypoxia-sensitive fluorescent probes were developed; they consist of a rhodamine moiety with an azo group directly conjugated to the fluorophore. Because of an ultrafast conformational change around the NN bond, the compounds are nonfluorescent under normoxia. However, under hypoxia, the azo group is reduced, and a strongly fluorescent rhodamine derivative is released.

Superior fluorescence imaging methods are needed for detailed studies on biological phenomena, and one approach that permits precise analyses is time-resolved fluorescence measurement, which offers a high signal-to-noise ratio. Herein, we describe a new fluorescence imaging system to visualize biomolecules within living biological samples by means of time-resolved, long-lived luminescence microscopy (TRLLM). In TRLLM, short-lived background fluorescence and scattered light are gated out, allowin

A remarkable enhancement of luminescence is observed in a solution of the TbIII complex 1 upon adding ZnII ions (see picture). Complex 1 has a high selectivity for ZnII and a long luminescence lifetime of the order of milliseconds, thus is an excellent lead compound for the development of ZnII-sensitive luminescent chemosensors with long luminescence lifetimes. A=light absorption, ET=energy transfer, E=light emission. Supporting information for this article is available on the WWW under http://w

Fluorescence imaging is a powerful tool for the visualization of biological molecules in living cells, tissue slices, and whole bodies, and is important for elucidating biological phenomena. Furthermore, zinc (Zn(2+)) is the second most abundant heavy metal ion in the human body after iron, and detection of chelatable Zn(2+) in biological studies has attracted much attention. Herein, we present a novel, highly sensitive off-on fluorescent chemosensor for Zn(2+) by using the internal charge trans

Fluorescence imaging is one of the most powerful techniques for visualizing temporal and spatial changes of biological phenomena in living cells, and many fluorescent probes have been developed. In particular, xanthene dyes such as fluorescein and rhodamines have favorable characteristics, such as high water solubility, high fluorescence quantum yield and high molar extinction coefficient, and they have been utilized as fluorescent cores for fluorescent probes working in the green to red wavelen

In biological systems, the pH in intracellular organelles or tissues is strictly regulated, and differences of pH are deeply related to key biological events such as protein degradation, intracellular trafficking, renal failure, and cancer. Ratiometric fluorescence imaging is useful for determination of precise pH values, but existing fluorescence probes have substantial limitations, such as inappropriate p K_a for imaging in the physiological pH range, inadequate photobleaching resist

Fluorogenic probes for bioimaging have become essential tools for life science and medicine, and the key to their development is a precise understanding of the mechanisms available for fluorescence off/on control, such as photoinduced electron transfer (PeT) and Förster resonance energy transfer (FRET). Here we establish a new molecular design strategy to rationally develop activatable fluorescent probes, which exhibit a fluorescence off/on change in response to target biomolecules, by controlli

Light-based microscope imaging techniques using fluorescence sensor molecules suffer from photobleaching and light scattering, but magnetic resonance imaging (MRI) can provide three-dimensional imaging without these problems. Recently, “smart” MRI contrast agents which modulate the access of water to a chelated gadolinium (Gd3+) ion in the presence or absence of a specific trigger have been reported. Zinc (Zn2+) is an essential component of many enzymes, transcription factors and synaptic vesicl

Silicon-substituted xanthene dyes, with Si in place of the O atom at the xanthene 10-position, are practically useful as far-red to near-infrared fluorophores. Many fluorescent probes based on them have recently been reported. These fluorophores retain the advantages of typical xanthene dyes and also show unique properties suitable for applications such as multi-color and super-resolution imaging.

Very recent studies indicate that sulfur atoms with oxidation state 0 or -1, called sulfane sulfurs, are the actual mediators of some physiological processes previously considered to be regulated by hydrogen sulfide (H₂S). 3-Mercaptopyruvate sulfurtransferase (3MST), one of three H₂S-producing enzymes, was also recently shown to produce sulfane sulfur (H₂S_n). Here, we report the discovery of several potent 3MST inhibitors by means of high-throughput sc

We report a reversible off/on fluorescent probe for monitoring concentration changes of sulfane sulfur by utilizing the unique ability of sulfane sulfur to bind reversibly to other sulfur atoms and the intramolecular spirocyclization reaction of xanthene dyes. It reversibly visualized sulfane sulfur in living A549 cells and primary-cultured hippocampal astrocytes.

We see red (and yellow and green): Probe 1 was developed for the visualization of cytoplasmic Ca2+, a pivotal second messenger in many biological responses. The new probe is suitable for multicolor imaging for the simultaneous detection of metal ions or proteins and is superior to the existing red fluorescent probe Rhod-2 for the monitoring of cytoplasmic Ca2+ oscillation in cultured cells (see fluorescence images of cells with 1 (top) and Rhod-2 (bottom)). As a service to our authors and reader