Browsing by Author "Wu, Shu Pao"

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A triple action chemosensor for Cu2+ by chromogenic, Cr3+ by fluorogenic and CN- by relay recognition methods with bio-imaging of HeLa cells
(2017-09-01)
Vijay, Natarajan
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Balamurugan, Gopal
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Venkatesan, Parthiban
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Wu, Shu Pao
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Velmathi, Sivan
A triple action chemosensor (R1) bearing a rhodamine and thiophene moiety was synthesized by a simple condensation reaction. The sensing behaviour and selectivity of the synthesized chemosensor toward metal ions were studied by UV-Vis and fluorescence spectroscopy. The chemosensor recognized Cu2+ and Cr3+ ions with significant changes in UV-Vis absorbance and fluorescence intensity. The results showed that Cr3+ induced greater fluorescence enhancement whereas Cu2+ ions bound strongly with the receptor by showing a strong absorption band at 554 nm but with weak fluorescence. A visible colour change was observed by the addition of Cu2+ and that colour change is due to the opening of the spirolactam ring triggered by the addition of Cu2+ ions. Job's plot analysis indicated a 1 : 2 and 1 : 1 binding stoichiometry between the chemosensor and Cr3+/Cu2+. Subsequently, the R1 - Cu2+ complex chemosensor was employed to detect CN- in the presence of different anions, such as F-, Cl-, Br-, I-, AcO-, H2PO4-, HSO4-, NO3- and -OH. In addition, the live cell imaging of HeLa cells using R1 and Cr3+ was demonstrated successfully.
Highly Selective Detection of Cr3+ Ion with Colorimetric & Fluorescent Response Via Chemodosimetric Approach in Aqueous Medium
(2018-03-01)
Punithakumari, Ganesan
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Wu, Shu Pao
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Velmathi, Sivan
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應用化學系
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Department of Applied Chemistry
So far, very few numbers of chemosensors for Cr3+ ion have been reported. However, the main drawback of reported receptors are the lack of selectivity and other trivalent cations such as Fe3+, Al3+ and anions like F- and -OAc frequently interfere with such assays. This paper present the synthesis, characterization & sensor studies of Schiff base containing naphthalene moiety which selectively detect Cr3+ ion by chemodosimetric approach. Using FT-IR, H-1 NMR, C-13 NMR and ESI mass spectroscopic techniques the probe was characterized. This receptor exhibit more selectivity and sensitivity towards Cr3+ than other divalent and trivalent cations like Mn2+, Zn2+, Co2+, Ni2+, Cd2+, Cu2+, Hg2+, Fe3+, and Al3+ ions. After the addition of chromium ion the receptor get change from yellow to colorless in aqueous medium. But no color change was observed on the addition of other metal ions. Using UV-Vis and PL studies, it was confirmed that the selective hydrolysis of imine group of receptor by Cr3+ ions takes place with high fluorescence enhancement that is corresponding to 1-naphthylamine. Receptor acts as selective chemodosimeter for Cr3+ ions with 2:1 stoichiometry and micro molar detection limit. This chemodosimetric approach was applied successfully for bio-imaging of HeLa cells.
New phenazine based AIE probes for selective detection of aluminium(III) ions in presence of other trivalent metal ions in living cells
(2017-12-21)
Balamurugan, Gopal
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Velmathi, Sivan
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Thirumalaivasan, Natesan
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Wu, Shu Pao
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應用化學系
Phenazine fluorophore based imidazole derivatives (S1 and S2) were synthesized and sensor studies were carried out with various cations. Aggregation induced emission (AIE) was observed selectively for Al3+ among other cations under study in case of both sensors. H-1 NMR titration supported the aggregation induced emission of S2 with Al3+. ESI mass spectra successfully confirmed the aggregate formation. SEM images clearly showed the aggregation of receptor induced by Al3+ in a flower-like fashion. AIE probe was successfully applied for bio-imaging of RAW264.7 cells.
Novel ratiometric turn-on fluorescent probe for selective sensing of cyanide ions, effect of substitution and bio-imaging studies
(2016-01-01)
Balamurugan, Gopal
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Venkatesan, Parthiban
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Wu, Shu Pao
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Velmathi, Sivan
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應用化學系
Novel fluorogenic receptors S1-S4 (imidazo anthraquinone derivatives) were synthesized from o-substituted benzaldehyde and 1,2-diaminoanthraquinone and characterised with various spectroanalytical techniques. In the case of S1, the selectivity towards cyanide ions with turn-on fluorescence output among other anions, due to the inhibition of the twisted intramolecular charge transfer (TICT) mechanism. The effect of substitution was successfully compared with sensing studies of S2-S4. S1 showed a good binding constant with a 1 : 1 stoichiometric ratio and micromolar detection limit. The sensing behaviour was further supported by H-1 NMR titration, TD-DFT calculations and lifetime measurement studies. S1 was applied for the bio-imaging of the cell line RAW264.7 and successfully sensed cyanide ions under physiological conditions.
Turn on fluorescent chemosensor containing rhodamine B fluorophore for selective sensing and in vivo fluorescent imaging of Fe3+ ions in HeLa cell line and zebrafish
(2019-11-01)
Vijay, Natarajan
;
Wu, Shu Pao
;
Velmathi, Sivan
;
應用化學系
;
Department of Applied Chemistry
Rhodamine dyes are utilized effectively as a chemosensor to monitor biologically important metal ions and effectively applied for fluorescent imaging studies in living systems. Herein, rhodamine-B armed fluorescent chemosensor (RhBNC) was designed and synthesized by condensation reaction between rhodamine B hydrazide and naphthyl chromone with ONO binding site in good yield. Upon sensing study towards metal ions, the probe showed selective turn-on fluorescent change for Fe3+ over other cations even in the presence of competing trivalent metal ions as well. The fluorescence switch is "on" when Fe3+ ions binds to RhBNC with orange fluorescence. The probe can detect lower concentration of Fe3+ ions with detection limit of 0.16 mu M. Due to its lower detection limit; it can be applied to monitor Fe3+ ion presence in a living system by fluorescent imaging technique. The probe was employed effectively to ascertain the presence of Fe3+ and to image Fe3+ ions in HeLa cell line and zebrafish.