The role of intracellular magnesium ions is of high interest in the fields of pharmacology and cellular biology. To accomplish the dynamic and three-dimensional imaging of intracellular Mg2+, there is a strong desire for the development of optimized Mg2+ fluorescent probes. In this paper we describe the design, synthesis, and cellular application of the three novel Mg2+ fluorescent probes KMG-101, -103, and -104. The compounds of this series feature a charged beta-diketone as a binding site specific for Mg2+ and a fluorescein residue as the fluorophore that can be excited with an Ar+ laser such as is widely used in confocal scanning microscopy. This molecular design leads to an intensive off-on-type fluorescent response toward Mg2+ ions. The two fluorescent probes KMG-103 and -104 showed suitable dissociation constants (Kd,Mg2+ = 2 mM) and nearly a 10-fold fluorescence enhancement over the intracellular magnesium ion concentration range (0.1-6 mM), allowing high-contrast, sensitive, and selective Mg2+ measurements. For intracellular applications, the membrane-permeable probe KMG-104AM was synthesized and successfully incorporated into PC12 cells. Upon application of the mitochondria uncoupler FCCP to the probe-incorporated cells, the resulting increase in the free magnesium ion concentration could be followed over time. By using a confocal microscope, the intracellular 3D magnesium ion concentration distributions were satisfactorily observed.

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Diffuse thyroidal FDG uptake may be an indicator of chronic thyroiditis. The actual prevalence of the disorder was not low in this series, and such lesions may be found incidentally at FDG PET.

Novel fluorescent molecular probes possessing both a hydroxystyryl and a cyanopyranyl moieties were designed and synthesized to detect the proteins via noncovalent bonding. These fluorescent probes indicated very weak fluorescence emission in the absence of protein. On the other hand, the fluorescence spectra of these probes showed a large Stokes shift and dramatic increase of fluorescence intensity, and red emission was observed after addition of BSA. These fluorescence spectral changes upon binding proteins were caused by the ICT process. Fluorescence intensities of the probes were plotted as a function of protein concentrations. A good linear relationship was observed up to 1000 microg/mL of protein, and the detection limit was found to be 100 ng/mL at the given assay conditions. Similar results were observed for the measurements of not only BSA but also other proteins (BGG, etc.). The responses of these probes to various nonprotein substances (inorganic salts, chelating agents, etc.) were observed, the fluorescence intensity did not change before and after the addition of foreign substances, and correct protein monitoring was successful using these fluorescent probes. To demonstrate the application of these probes, proteins after the separation using SDS-PAGE were stained in the medium containing 1, and the imaging of the proteins in the gel was successful. The experimental results clearly showed that these probes are good protein indicators for easy and highly sensitive detection.