Fluorescence Imaging of Intracellular Cadmium Using a Dual-Excitation Ratiometric Chemosensor

Graduate School of Human and Environmental Studies, Kyoto University, Yoshida, Sakyo-ku, Kyoto 606-8501, Japan.
Journal of the American Chemical Society (Impact Factor: 12.11). 09/2008; 130(38):12564-5. DOI: 10.1021/ja803429z
Source: PubMed


We described here a coumarin-based dual-excitation ratiometric probe for cadmium, CadMQ. This fluorescence sensor has high quantum yields of 0.59 and 0.70 in the metal-free and Cd(2+) bound forms, respectively, and has a dissociation constant of 0.16 nM for Cd(2+). CadMQ is cell permeable and locates within the acidic compartments of the cells. We further show that CadMQ is a useful tool to ratiometrically probe the change in the intracellular Cd(2+) levels with the use of two excited wavelengths.

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    • "Therefore development of reliable chemo-sensors for detection and monitoring of cadmium in environment and biology is still in demand. However, numerous numbers of fluorescent sensors have been reported to detect and analyze different kinds of heavy toxic metal ions because of their simplicity, high sensitivity, and real-time detection [7] [8] but there are only a few reports of fluorescent sensors for cadmium ion [9] [10] [11] [12] [13] [14], and even rare examples are available in living cells [15] [16] [17] [18] [19] [20]. The paramount challenge in the detection of Cd 2+ is the interference of other transition metal ions, in particular Zn 2+ , which have similar properties to those of Cd 2+ because they are in the same group of the periodic table. "
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    ABSTRACT: A novel simple C3v-symmetric, completely water soluble quinoline based guanidinium Schiff's base system have been reported for the selective detection of Cd2+ in physiological environment through a turn-on fluorescence response. The cadmium complex is found to be highly selective toward iodide by turning off the fluorescence through the sequestration of Cd2+ from L1-Cd by the precipitation of CdI2. Detection limit for Cd2+ and iodide are found to be 51 ppb and 1 ppb, respectively. L1 is reversible toward Cd2+ and iodide and can be recycled. The receptor was used for the detection of Cd2+ in complex natural samples (tap, lake and river water).
    Sensors and Actuators B Chemical 12/2014; 204:474. DOI:10.1016/j.snb.2014.08.004 · 4.10 Impact Factor
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    • "(Met-cad: 2.1±0.02; reached to 2.5±0.06, about 1.19 fold increase, shown in Figure 4), and decreased its ratio to 0.74 upon TPEN chelation [23] (we also did this chelation test to confirm, ratio changed back to 2.2±0.03). However, the sensing ability of CadMQ was also affected by Zn2+ and Cu2+ (Zn2+ and Cu2+ did have certain influence on Met-cad sensing as shown in Figure S2) and even Hg2+. "
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    ABSTRACT: Cd(2+) causes damages to several human tissues. Although the toxicological and carcinogenetic mechanisms of Cd(2+) have been previously established, some basic questions on this toxicant remain unclear. In this study, we constructed Met-cad 1.57, a new fluorescent resonance energy transfer (FRET)-based Cd(2+) indicator, which contains a portion of a Cd(2+)-binding protein (CadR) obtained from Pseudomonas putida as the Cd(2+) sensing key. We produced a human embryonic kidney cell line HEK-MCD157 which stably expresses the Met-cad 1.57 for further investigations. Both fluorescence spectroscopy and FRET microscopic ratio imaging were used to monitor the Cd(2+) concentration within the living HEK-MCD157 cells. The dissociation constant of Met-cad 1.57 was approximately 271 nM. The function of Ca(2+) channels as a potential Cd(2+) entry gateway was further confirmed in the HEK-MCD157 cells. The organelle-targeted property of the protein-based Cd(2+) indicator directly reveals the nucleus accumulation phenomena. In summary, a human kidney cell line that stably expresses the FRET-based Cd(2+) indicator Met-cad 1.57 was constructed for reliable and convenient investigations to determine the Cd(2+) concentration within living cells, including the identification of the entry pathway of Cd(2+) and sub-cellular sequestration.
    PLoS ONE 06/2013; 8(6):e65853. DOI:10.1371/journal.pone.0065853 · 3.23 Impact Factor
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    ABSTRACT: A highly selective and sensitive OFF-ON fluorescent sensor 1, employing the PET mechanism, was designed and synthesized. It could be used to detect Cd(2+) ion in aqueous solution and to image Cd(2+) ion in living cells. The fluorescence intensity significantly enhanced about 195-fold and the quantum yield increased almost 100-fold. Moreover the fluorescence intensity of 1 increased linearly with high sensitivity (0-1 microM) toward Cd(2+).
    Journal of the American Chemical Society 12/2008; 130(48):16160-1. DOI:10.1021/ja806928n · 12.11 Impact Factor
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