Browsing by Author "Lin, Chein-Ming"

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A fully-aqueous red-fluorescent probe for selective optical sensing of Hg2+ and its application in living cells
(2016-07)
Pola, Murali Krishna
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Raju, Mandapati V. Ramakrishnam
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Lin, Chein-Ming
;
Putikam, Raghunath
;
Lin, Ming-Chang
A new red-fluorescent mercury ion sensor material is designed and synthesized, which is composed of at weezer-shaped hydrophilic probe containing bifurcated soft-base atoms N and S coupled with 2-dicyanomethylene-3-cyano-4,5,5-trimethyl-2,5-dihydrofuran (TCF) unit. By virtue of the strong electron-accepting nature of TCF unit (as a push pull chromophore), this designed sensor material can selectively detect Hg2+ over various tested metal ions in a 100% aqueous medium via naked-eye and photoluminescence (PL) observations. Theoretical and time-resolved photoluminescence measurements further confirmed the selectivity and reversibility of the probe towards Hg2+ via intramolocular charge transfer mechanism in this sensor material. Moreover, the living cell tests by confocal fluorescence images of this sensor material towards Hg2+ were also investigated. Finally, distinguished absorption changes and fluorescence quenching spectral appearances allowed us to present the selective optical indicator of Hg2+ via TCF moiety for the first time. (C) 2016 Elsevier Ltd. All rights reserved.
Novel pyrene containing monomeric and dimeric supramolecular AIEE active nano-probes utilized in selective "off-on" trivalent metal and highly acidic pH sensing with live cell applications
(2016)
Shellaiah, Muthaiah
;
Simon, Turibius
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Srinivasadesikan, Venkatesan
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Lin, Chein-Ming
;
Sun, Kien Wen
Two novel pyrene containing monomeric and dimeric Schiff base derivatives PCS1 and PCS2 have been synthesized via one-pot reaction and their nano-J-type aggregation induced emission enhancement (AIEE) was well demonstrated using UV-Vis/PL, transmission electron microscopy (TEM), dynamic light scattering (DLS), time resolved photoluminescence (TRPL), and live cell imaging studies. In contrast to PCS2, PCS1 in CH3CN exhibits fluorescence "off-on" sensor selectivity towards transition trivalent metal ions (Fe3+, Cr3+ and Al3+) among other metals, via PET inhibition with excimer PCS1-PCS1(star) formation. The 2 : 1 stoichiometry of PCS1 center dot center dot center dot M3+ (M = Fe/Cr/Al) sensor complexes was calculated from Job\'s plots based on their PL titrations. In addition, the binding sites of PCS1 center dot center dot center dot M3+ sensor complexes were well recognised from the H-1 NMR titrations and supported by ESI(+ve) mass and FTIR analysis. Additionally, fluorescence reversibilities of PCS1 center dot center dot center dot M3+ were observed via consequent addition of M3+ ions and PMDTA, respectively. Furthermore, the detection limits (LODs) and the association constant (K-a) values of PCS1 center dot center dot center dot M3+ complexes were calculated using standard deviation and linear fittings. Likewise, quantum yield (Phi) measurements, TEM analysis, determination of the effect of pH, density functional theory (DFT) and time resolved photoluminescence (TRPL) studies were performed for the PCS1 center dot center dot center dot M3+ sensor complexes. More importantly, confocal fluorescence microscopy imaging of Raw264.7 cells showed that PCS1 could be used as an effective fluorescent probe for detecting transition trivalent metal ions (Fe3+, Cr3+, and Al3+) in living cells. Impressively, both PCS1 and PCS2 showed "off-on" sensing at highly acidic pH values (1-3) with live cell applications.