Browsing by Author "Kao, Chai-Lin"

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[Gd(Try-TTDA)(H(2)O)](2-): A new MRI contrast agent for copper ion sensing
(2011-01-01)
Kasala, Dayananda
;
Lin, Tsung-Sheng
;
Chen, Chiao-Yun
;
Liu, Gin-Chung
;
Kao, Chai-Lin
In this study, we have developed two new L-tryptophan based contrast agents [Gd(Try-TTDA)(H(2)O)](2-) and [Gd(Try-ac-DOTA)(H(2)O)](-). Upon addition of Cu(II) to [Gd(Try-TTDA)(H(2)O)](2-), significant increases in the relaxivity (r(1)) and hydration number of [Gd(Try-TTDA)(H(2)O)](2-) were observed. However, it only induced a minute increase in the relaxivity (r(1)) in the case of [Gd(Try-ac-DOTA)(H(2)O)](-). Furthermore, the interaction of Cu(II) with the indole ring of Gd(III) complexes was explored by measuring the intrinsic fluorescence of the tryptophan of the Gd(III) complex. With the addition of one equivalent of Cu(II) to [Gd(Try-TTDA)(H(2)O)](2) the indole fluorescence was completely quenched. Moreover, the [Gd(Try-TTDA)(H(2)O)](2-) complex shows excellent selectivity towards Cu(II) over other metal ions (Cu(II) > La(III) > Mg(II)). Importantly, the significant signal intensity (2073 +/- 67) for in vitro MR imaging using [Gd(Try-TTDA)(H(2)O)](2-) in the presence of Cu(II) implicates that this new smart contrast agent ([Gd(Try-TTDA)(H(2)O)](2-)) can serve as a Cu(II) sensor for MR imaging.
[Gd(Try-TTDA)(H2O)](2-): A new MRI contrast agent for copper ion sensing
(2011-01-01)
Kasala, Dayananda
;
Lin, Tsung-Sheng
;
Chen, Chiao-Yun
;
Liu, Gin-Chung
;
Kao, Chai-Lin
In this study, we have developed two new L-tryptophan based contrast agents [Gd(Try-TTDA)(H2O)](2-) and [Gd(Try-ac-DOTA)(H2O)](-). Upon addition of Cu(II) to [Gd(Try-TTDA)(H2O)](2-), significant increases in the relaxivity (r(1)) and hydration number of [Gd(Try-TTDA)(H2O)](2-) were observed. However, it only induced a minute increase in the relaxivity (r(1)) in the case of [Gd(Try-ac-DOTA)(H2O)](-). Furthermore, the interaction of Cu(II) with the indole ring of Gd(III) complexes was explored by measuring the intrinsic fluorescence of the tryptophan of the Gd(III) complex. With the addition of one equivalent of Cu(II) to [Gd(Try-TTDA)(H2O)](2) the indole fluorescence was completely quenched. Moreover, the [Gd(Try-TTDA)(H2O)](2-) complex shows excellent selectivity towards Cu(II) over other metal ions (Cu(II) > La(III) > Mg(II)). Importantly, the significant signal intensity (2073 +/- 67) for in vitro MR imaging using [Gd(Try-TTDA)(H2O)](2-) in the presence of Cu(II) implicates that this new smart contrast agent ([Gd(Try-TTDA)(H2O)](2-)) can serve as a Cu(II) sensor for MR imaging.
Nitric oxide-release study of a bio-inspired copper(i)-nitrito complex under chemical and biological conditions
(2018-10-07)
Chuang, Wan-Jung
;
Narwane, Manmath
;
Chen, Hsing-Yin
;
Kao, Chai-Lin
;
Huang, Bin
The selective and efficient nitrite reduction process is ubiquitous in biological systems. To understand copper-mediated nitrite reduction, we developed a bio-inspired model system to investigate the mechanism of copper-containing nitrite reductase. A well-characterized copper(i)-nitrate complex with amino functionalized 2-(diphenylphosphino)aniline ligands, [(Ph2PC6H4(o-NH2))(2)Cu(ONO)], demonstrated the aniline protonation will cause NO release in an acidic environment. To further understand NO releasing ability, we also performed pH-dependency experiments and confocal imaging to release NO under physiological buffer conditions. According to titration and spectroscopic studies on the protonation reaction of complex [(Ph2PC6H4(o-NH2))(2)Cu(ONO)], we proposed a mechanistic pathway for proton transfer and NO release. Furthermore, DFT calculations predicted that the release of NO takes place via aniline in both organic and aqueous media. These results highlight the importance of the proton-rich microenvironment around the copper(i)-nitrite core to induce nitrate reduction in a chemical and biological environment.