Browsing by Author "Velmathi, Sivan"

Now showing 1 - 15 of 15

A dual-mode chemosensor: Highly selective colorimetric fluorescent probe for Cu2+ and F- ions
(2014-12-01)
Udhayakumari, Duraisamy
;
Velmathi, Sivan
;
Chen, Wei-Chieh
;
Wu, Shu-Pao
;
應用化學系
N-Phenylthiosemicarbazones (R1-R4) have been synthesized and characterized by various spectroscopic techniques. The sensors (R1-R4) exhibited highly selective and sensitive recognition toward Cu2+ and F ions over other cations and anions via visual color change. Sensors showed a significant fluorescent enhancement toward Cu2+ in aqueous medium and found a sub-nanomolar detection limit with good quantum yield. R1 displayed high selectivity to Cu2+ over other interference ions with 89-fold fluorescence intensity enhancement upon the addition of 2 equiv. of Cu2+. In addition, the turn-on fluorescent changes upon the addition of Cu2+, is also applied in cell imaging. (C) 2014 Elsevier B.V. All rights reserved.
A highly fluorescent zinc complex of a dipodal N-acyl hydrazone as a selective sensor for H2PO4- ions and application in living cells
(2015-01-01)
Suganya, Sivalingam
;
Velmathi, Sivan
;
Venkatesan, Parthiban
;
Wu, Shu-Pao
;
Boobalan, Maria Susai
A dipodal N-acyl hydrazone receptor (R1) was synthesized in a single step, and utilized as a test probe for the selective sensing of metal ions as well as anions. Upon the exposure to various metal ions, R1 displays rapid colorimetric and absorption changes in the presence of Co2+, Ni2+, Cu2+ and Zn2+ ions. However, R1 shows a selective fluorescence response only in the presence of Zn2+ ions and no other metal ions showed obvious changes. In particular, zinc acetate showed higher sensitivity over other zinc sources. Upon the binding of Zn2+ ions with R1, the colorless solution changed into fluorescent yellow color accompanied by the conversion of the non-fluorescence nature into the highly fluorescence nature. The in situ formed R1-Zn2+ complex was further explored for the reversible recognition of H2PO4- ions selectively over other anions such as F-, Cl-, Br-, AcO-, CN-, HSO4- and NO3- ions. A strong and enhanced emission at 502 nm and 534 nm corresponding to the R1-Zn2+ complex was quenched completely in the presence of H2PO4- ions. Relay recognition of different phosphates such as mono, di and tri basic phosphate ions was also tested. Furthermore, R1 has good cell permeability and could serve as a bioprobe in living cells for the intracellular uptake of Zn2+ and H2PO4- ions. Time dependent density functional (TDDFT) calculation has been performed to demonstrate the binding of Zn2+ ions with R1.
A novel nanomolar highly selective fluorescent probe for imaging mercury (II) in living cells and zebrafish
(2018-12-20)
Liu, Yen-Yu
;
Naha, Sanay
;
Thirumalaivasan, Natesan
;
Velmathi, Sivan
;
Wu, Shu-Pao
A novel fluorescent probe, PES, which contains a bisethylsulfane moiety, displayed high specificity for Hg2+ detection. With Hg2+, PES showed significant blue fluorescence enhancement, while the metal ions Al3+, Ag+, Cr3+, Ca2+, Cu2+, Co2+, Cd2+, Fe3+, Fe2+, Mn2+, Mg2+, Ni2+, Zn2+, and Pb2+ exhibited only negligible fluorescence change. PES has been found to be an effective quantitative detector (LOD, 57 nM) for Hg2+ in semi-aqueous medium based on the Hg2+-induced removal of bisethylsulfane. It resulted in a turn-on blue fluorescence response. The fluorescence enhancement induced by Hg2+ was observed over the pH range of 4-10. Our fluorescence cell-imaging experiments revealed the applicability of the new probe, PES, to be a reliable and effective fluorescent marker for Hg2+ in living cells.
A pyrene-linked thiourea as a chemosensor for cations and simple fluorescent sensor for picric acid
(2015-01-01)
Udhayakumari, Duraisamy
;
Velmathi, Sivan
;
Venkatesan, Parthiban
;
Wu, Shu-Pao
;
應用化學系
A simple pyrene- linked thiourea 1 has been synthesized and shown to act as a fluorescent and visual sensor for the detection of Cu2+ and Hg2+ ions. The sensor showed effective detection of Cu2+ and Hg2+ at a low detection limit. Receptor 1 has been successfully applied in the fluorescence imaging of Cu2+ and Hg2+ ions in living cells. Receptor 1 also selectively detects picric acid via both color change and fluorescence change.
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
;
Balamurugan, Gopal
;
Venkatesan, Parthiban
;
Wu, Shu Pao
;
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.
Anthracene coupled thiourea as a colorimetric sensor for F-/Cu2+ and fluorescent sensor for Hg2+/picric acid
(2015-05-01)
Udhayakumari, Duraisamy
;
Velmathi, Sivan
;
Venkatesan, Parthiban
;
Wu, Shu-Pao
;
應用化學系
A new dual chemosensor (Z)-2-(anthracen-9-ylmethylene)-N-phenylhydrazinecarbothioamide R1 was synthesized by incorporating a thiourea derivative as a binding unit and an anthracene group as a fluorescence signalling unit. R1 selectively binds with Cu2+ and He2+ ions in aqueous medium. R1 exhibits highly selective recognition towards F- ion and picric acid in organic medium. Fluorescence quenching was observed in case of R1 with Cu2+ and He+ ions over commonly coexistent metal ions. Furthermore, fluorescence imaging experiments of Cu2+ and Hg2+ ions in living RAW 264.7 cells demonstrate its value of practical applications in biological systems. (C) 2015 Elsevier B.V. All rights reserved.
Coumarin-based Hg2+ fluorescent probe: Fluorescence turn-on detection for Hg2+ bioimaging in living cells and zebrafish
(2019-08-05)
Chen, Chong-Guang
;
Vijay, Natarajan
;
Thirumalaivasan, Natesan
;
Velmathi, Sivan
;
Wu, Shu-Pao
The need in developing fluorescent probes for trace metal ion detection in biological samples has been an important issue. Herein, a reaction-based fluorescent probe PIC containing a perimidine moiety was designed and synthesized for Hg2+ detection. The probe can selectively distinguish Hg2+ with 42-fold fluorescent enhancement from the other metal ions at physiological pH. This probe can detect Hg2+ with the detection limit of 1.08 mu M. The sensor PIC can be applied to real-time detection of Hg2+ in cells with blue emission. (C) 2019 Elsevier B.V. All rights reserved.
Heterocyclic ring based colorimetric and fluorescent chemosensor for transition metal ions in an aqueous medium
(2015-02-01)
Udhayakumari, Duraisamy
;
Velmathi, Sivan
;
Boobalan, Maria Susai
;
Venkatesan, Parthiban
;
Wu, Shu-Pao
Heterocyclic ring based R1-R3 have been synthesized from the simple condensation method. R1-R3 exhibit highly selective and sensitive recognition towards transition metal ions in an aqueous medium via visual color change and were further confirmed by UV-vis and fluorescent spectroscopic methods. Fluorescent turn on and turn off behavior was observed for receptors tested with transition metal ions. The interaction of transition metal ions and receptors R1-R3 was confirmed to adopt 1:1 binding stoichiometry. Micromolar detection limit was found for R1-R3 with metal ions. DFT theoretical calculations were employed to understand the sensing mechanism of the sensors towards the metal ions. R1 and R2 were also successfully demonstrated as a fluorescent probe for detecting Cu2+ ions in living cells. (C) 2014 Elsevier B.V. All rights reserved.
Highly fluorescent probe for copper (II) ion based on commercially available compounds and live cell imaging
(2014-07-01)
Udhayakumari, Duraisamy
;
Velmathi, Sivan
;
Sung, Yi-Ming
;
Wu, Shu-Pao
;
應用化學系
The commercially available 2, 3-diaminophenazine, 1,2-diamino-anthraquinone and 2, 4-dinitrophenylhydrazine (S1-S3) act as a colorimetric, fluorescent probes for selective detection of Cu2+ ions in aqueous medium over other metal ions. In presence of Cu2+, S1 shows fluorescent turn-on due to the inhibition of photoinduced electron transfer mechanism. The fluorescent probes S1-S3 detect Cu2+ ions in aqueous solution at nanomolar levels. Theoretical calculations were emploued to understand the sensing mechanism of the semsors towards Cu2+. S1, S2 and S3 were further applied for biological imaging to confirm that it can be used as a fluorescent probe for monitoring Cu2+ in living cells, and demonstrated its value in practical applications such as environmental and biological systems. (C) 2014 Elsevier B.V. All rights reserved.
Highly Selective Detection of Cr3+ Ion with Colorimetric & Fluorescent Response Via Chemodosimetric Approach in Aqueous Medium
(2018-03-01)
Punithakumari, Ganesan
;
Wu, Shu Pao
;
Velmathi, Sivan
;
應用化學系
;
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.
Nanomolar Detection of H2S in an Aqueous Medium: Application in Endogenous and Exogenous Imaging of HeLa Cells and Zebrafish
(2020-08-11)
Naha, Sanay
;
Thirumalaivasan, Natesan
;
Garai, Somenath
;
Wu, Shu-Pao
;
Velmathi, Sivan
The homeostasis of short-lived reactive species such as hydrogen sulfide/hypochlorous acid (H2S/HOCI) in biological systems is essential for maintaining intercellular balance. An unchecked increase in biological H2S concentrations impedes homeostasis. In this report, we present a molecular probe pyrenebased sulfonyl hydrazone derived from pyrene for the selective detection of H2S endogenously as well as exogenously through a "turn-off' response in water. The structure of the receptor is confirmed by Fourier-transform infrared spectroscopy, H-1 and C-13 nuclear magnetic resonance spectroscopy, electrospray ionization mass spectrometry, and single-crystal X-ray diffraction studies. The receptor shows excellent green emission in both the aqueous phase and solid state. Quenching of green emission of the receptor is observed only when H2S is present in water with a detection limit of 18 nM. Other competing anions and cations do not have any influence on the receptor's optical properties. The efficiency of H2S detection is not negatively impacted by other reactive sulfur species too. The sensing mechanism of H2S follows a chemodosimetric reductive elimination of sulfur dioxide, which is supported by product isolation. The receptor is found to be biocompatible, as evident by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and its utility is extended to endogenous and exogenous fluorescence imaging of HeLa cells and zebrafish.
Naphthalimide based smart sensor for CN-/Fe3+ and H2S. Synthesis and application in RAW264.7 cells and zebrafish imaging
(2020-03-01)
Naha, Sanay
;
Wu, Shu-Pao
;
Velmathi, Sivan
;
應用化學系
;
Department of Applied Chemistry
Achieving selective detection of target analytes in aqueous media continues to be an arduous proposition. Herein, we report the conceptualization and synthesis of a novel tailor-fit molecular probe R based on 1,8-naphthalimide which acts as a trifunctional molecular sensor for CN-, Fe3+ and H2S. R shows colorimetric and fluorometric "on-off" relay recognition for CN- (red colour and orange emission) and Fe3+ (no colour and no emission) in 5% H2O + DMSO medium which is experimentally ascertained to be a tandem deprotonation-protonation process and is supported by H-1-NMR titration. Among all RSS (Reactive Sulphur Species), R shows selectivity for H2S through red colouration. Other coexistent anions, cations and RSS cause no discernible perturbation to the detection process. The detection of H2S is attributed to a chemodosimetric reduction of the nitro to amino group as evidenced by a potentiometric titration assay. The experimental observations are well supported by DFT theoretical calculation. The K-a for CN-/Fe3+ are 1.4 x 10(4) M-1, 6.07 x 10(4) M-1 respectively and photochemical yield of R + CN- is 0.86. Limit of detections for CN-, Fe3+ and H2S are 17.5 nM, 8.69 mu M and 8.1 mu M respectively. Receptor R is effective for real time applications, bio-compatible and has been successfully employed for confocal fluorescence imaging of RAW264.7 cell and zebrafish.
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
;
Velmathi, Sivan
;
Thirumalaivasan, Natesan
;
Wu, Shu Pao
;
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
;
Venkatesan, Parthiban
;
Wu, Shu Pao
;
Velmathi, Sivan
;
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.