Daphnetin: A novel blue-green photonic switch for disodium phosphates that allows monitoring of polymerase chain reactions

Pandith, Anup,Koo, Jachoon,Seo, Young Jun Elsevier 2018 Spectrochimica acta. Part A, Molecular and biomole Vol.204 No.-

<P><B>Abstract</B></P> <P>This paper describes the very simple and robust ratiometric photonic switching properties of daphnetin (<B>DP</B>) toward HPO<SUB>4</SUB> <SUP>2−</SUP> ions selectively in complex biological fluids, without any interference from other relevant anions under physiological conditions. The sensing ability of <B>DP</B> toward HPO<SUB>4</SUB> <SUP>2−</SUP> ions was first demonstrated using UV–Vis and fluorescence spectroscopy, dynamic light scattering (DLS), and one- and two-dimensional NMR spectroscopy. <B>DP</B> can detect HPO<SUB>4</SUB> <SUP>2−</SUP> ions at concentrations up to the sub-micromolar/nanomolar level very effectively, with a ratiometric response resulting from intramolecular charge transfer aided by aggregated-induced emission. The interactions between <B>DP</B> and HPO<SUB>4</SUB> <SUP>2−</SUP> ions resulted in new bands appearing in the UV–Vis (at 385 nm) and emission (at 535 nm) spectra. The noncovalently held HPO<SUB>4</SUB> <SUP>2−</SUP> ions induced pronounced specific aggregation of <B>DP</B> molecules, resulting in the new excimer band at 535 nm while retaining the monomer band centered at 445 nm. In contrast, reciprocal absorptivity changes were observed at 320 and 385 nm, with exponential decrements and increments, respectively. This probe could effectively monitor the consumption of dNTPs during various cycles of the polymerase chain reaction performed with relatively short oligonucleotides as well as genomic DNA from <I>Agrobacterium tumefaciens</I> (AcH5α strain).</P> <P><B>Highlights</B></P> <P> <UL> <LI> A novel, simple and robust blue-green fluorescent probe <B>DP</B>, used to detect the HPO<SUB>4</SUB> <SUP>2−</SUP> ions using colorimetric and fluorimetric methods. </LI> <LI> <B>DP</B> able to sense the HPO<SUB>4</SUB> <SUP>2−</SUP> ions very selectively, through the ratiometric response, without any interferences from other biologically relevant anions at physiological conditions. </LI> <LI> For the first time HPO<SUB>4</SUB> <SUP>2−</SUP> ions sensing aided application were effectively demonstrated in polymerase chain reactions (PCR) monitoring process. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

Selective Detection of 2,4,6-Trinitrophenol Based on In Situ-generated Fluorescent Zn2+–Anthracene Ensembles in 80% Aqueous Dimethyl Sulfoxide

Anup Pandith,김홍석 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.1

Novel in situ-generated highly fluorescent chelated Zn2+–anthracene (Zn2+•P: 1:1) complex detected 2,4,6-trinitrophenol (TNP) more selectively by a “switch-off” response with a very high Stern–Volmer quenching constant (Ksv = 3.75 × 106 M−1) at a 1:2 stoichiometry in 80% aqueous DMSO. The selective quenching response that occurred with TNP is due to the effective destruction of the chelated complex by efficient protonation at secondary amines, which created an effective resonance energy transfer (RET) from the anthracene unit to the TNP. Formation of a stable P2+•(TNP)−2 ionic charge-transfer complex showed that the anthracene monomer band quenching resulted from efficient RET, accompanied by synergistic multiple hydrogen bonding, electron-rich–electron-deficient πAn–πTNP interactions, and columbic interactions. An application was demonstrated using the biocompatible ensemble-coated hydrogel for ultraviolet-assisted naked eye sensing, and its sensing mechanism was postulated. The lowest detection limit for TNP was 3.01 × 10−10 M in 80% aqueous DMSO.

Highly selective imidazole-appended 9,10-<i>N,N′</i>-diaminomethylanthracene fluorescent probe for switch-on Zn²⁺ detection and switch-off H₂PO₄ ⁻ and CN⁻ detection in 80% aqueous DMSO

Pandith, Anup,Uddin, Nizam,Choi, Cheol Ho,Kim, Hong-Seok Elsevier 2017 Sensors and actuators. B Chemical Vol.247 No.-

<P><B>Abstract</B></P> <P>A new imidazole-appended anthracene-based photoinduced electron transfer (PET) probe (<B>P</B>) was designed and synthesized. Probe <B>P</B> detected Zn<SUP>2+</SUP> selectively in an 80% aqueous solution of dimethyl sulfoxide (DMSO) through a switch-on response at pH 7.5 without any interference from other metal ions. Probe <B>P</B> exhibited a moderately strong association constant (<I>K<SUB>a</SUB> </I>) of 1.41×10<SUP>5</SUP> M<SUP>−1</SUP> and associated with Zn<SUP>2+</SUP> ions with 1:1 stoichiometry. The in situ-generated <B>P</B>•Zn<SUP>2+</SUP> (1:1) ensemble detected H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP> and CN<SUP>−</SUP> ions sequentially through switch-off responses. The selective discrimination of H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP> and CN<SUP>−</SUP> ions occurred both in the absence and presence of Ca<SUP>2+</SUP> ions at pH 7.5 in a <I>N</I>-2-hydroxyethylpiperazine-<I>N</I>-2-ethanesulfonic acid (HEPES) buffer. The switch-on response was driven by the selective complexation of <B>P</B> with Zn<SUP>2+</SUP> ions, mediated by the combined effects of PET and chelation-induced enhanced fluorescence, resulting in a more structurally rigid complex. Applications of <B>P</B> to real water sample analysis and sequential logic gate operations were demonstrated. The lowest detection limits for Zn<SUP>2+</SUP>, H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP>, and CN<SUP>−</SUP> ions in 80% aqueous DMSO were determined to be 1.0×10<SUP>−9</SUP>, 1.0×10<SUP>−9</SUP>, and 8.0×10<SUP>−9</SUP> M, respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Imidazole-appended anthracene probe P for sensing Zn<SUP>2+</SUP> was synthesized. </LI> <LI> Zn<SUP>2+</SUP> ions “<I>switched on</I>” the emission of P in 80% aqueous DMSO. </LI> <LI> In situ generated P-Zn<SUP>2+</SUP> (1:1) ensemble detected H<SUB>2</SUB>PO<SUB>4</SUB> <SUP>−</SUP> and CN<SUP>−</SUP> ions sequentially through “<I>switch off</I>” response in the absence and presence of Ca<SUP>2+</SUP> ions respectively. </LI> <LI> Sensing ability of P towards Zn<SUP>2+</SUP> is attributed to PET and CHEF upon complexation. </LI> <LI> Application of P to real water samples and sequential logic gate operations were demonstrated. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Novel fluorescent C₂-symmetric sequential <i>on-off-on</i> switch for Cu²⁺ and pyrophosphate and its application in monitoring of endogenous alkaline phosphatase activity

Pandith, Anup,Bhattarai, Kashi Raj,Guralamatta Siddappa, Ravi Kumara,Chae, Han-Jung,Seo, Young Jun Elsevier 2019 Sensors and actuators. B Chemical Vol.282 No.-

<P><B>Abstract</B></P> <P>A doubly armed hydrazone-based <B>FLRHYDDFP</B> probe selectively detects Cu<SUP>2+</SUP> and pyrophosphate (PPi) ions through an colorimetric response-<I>“colorless → yellow → colorless</I>”- as well as “<I>on-off-on</I>” photonic switching response under physiological conditions in a sequential manner. The binding stoichiometries of the analytes Cu<SUP>2+</SUP> and PPi were 1:2 and 2:4 for <B>FLRHYDDFP</B>-Cu<SUP>2+</SUP> and Cu<SUP>2+</SUP>/PPi, respectively. The sequential sensing ability of <B>FLRHYDDFP</B> toward Cu<SUP>2+</SUP> and PPi, attributed to effective complexation-aided d→π* electron transfer (ET) from Cu<SUP>2+</SUP> to <B>FLRHYDDFP</B> and intramolecular charge/electron transfer from <B>FLRHYDDFP</B> to <B>FLRHYDDFP<SUP>+</SUP> </B>, resulted in the formation of a non-symmetric Cu<SUP>2+</SUP> chelate that provided a yellow-colored solution with a significant bathochromic shift from 376 to 446 nm in the UV–vis spectrum and quenching in the emission spectrum. Upon addition of PPi, Cu<SUP>2+</SUP> was extruded from the complex, resulting in a revival of the fluorescence centered at 572 nm. Thus, sequential addition of Cu<SUP>2+</SUP> and PPi yielded a colorless–yellow–colorless transition under visible light and <I>on-off-on</I> switching under 365-nm light (fluorescence). The lowest detection limits for Cu<SUP>2+</SUP> and PPi, when using colorimetric and fluorimetric methods, were in the sub-micromolar and nanomolar levels, respectively. By exploiting this PPi sensing strategy, invitro as well as endogenous alkaline phosphatase activity could be monitored effectively, as demonstrated by exploiting the intracellular production or residual PPi in human salivary glands (normal) and cancer cell lines.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Novel and highly sensitive colorimetric and fluorimetric probe <B>FLRHYDDFP</B> designed and synthesized to identify the Cu<SUP>2+</SUP> and PPi ions in invitro studies with revsersibility. </LI> <LI> By the aid of PPi sensing strategy, alkaline phosphatase activities (ALP) were monitored with lowest detection limit of 0.012 U/mL. </LI> <LI> For the first time endogenous PPi productions aided ALP recognition demonstrated using fluorescence confocal image guided technique in the presence of ALP inhibitor. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

A new fluorogenic sensing platform for salicylic acid derivatives based on π-π and NH-π interactions between electron-deficient and electron-rich aromatics

Pandith, Anup,Hazra, Giridhari,Kim, Hong-Seok Elsevier 2017 Spectrochimica acta. Part A, Molecular and biomole Vol.178 No.-

<P><B>Abstract</B></P> <P>A novel simple fluorescent probe was designed for the recognition of electron-rich salicylic acid derivatives (SAs). The imidazole-appended aminomethyl perylene probe <B>1</B> selectively differentiated between electron-rich amino-SAs and electron-deficient nitro-SAs in EtOH, exhibiting the highest selectivity and sensitivity toward 5-aminosalicylic acid (5-ASA) and showing strong 1:1 binding (<I>K</I> <SUB>a</SUB> =1.37×10<SUP>7</SUP> M<SUP>−1</SUP>). This high selectivity and sensitivity resulted from the synergistic multiple hydrogen bonding interactions of secondary amine and imidazole units and π-π interactions between electron-rich and electron-deficient rings, along with the unusual NH-π interactions between 5-ASA and the perylene moiety of <B>1</B>. The limit of detection (LOD) for 5-ASA in EtOH was 0.012ppb.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Imidazole-appended aminomethyl perylene probe <B>1</B> for sensing 5-aminosalycylic acid (5-ASA) was synthesized. </LI> <LI> 5-ASA “<I>switched on</I>” the emission of probe <B>1</B>. </LI> <LI> Fluorescence mechanism explained by multiple hydrogen bonding, π-π, and unusual NH-π interactions between 5-ASA and <B>1</B>. </LI> <LI> The limit of detection for 5-ASA in EtOH was 0.012ppb. </LI> </UL> </P> <P><B>Graphical Abstract</B></P> <P>[DISPLAY OMISSION]</P>

A simple and robust PET-based anthracene-appended O-<i>N</i>-O chelate for sequential recognition of Fe³⁺/CN^– ions in aqueous media and its multimodal applications

Pandith, Anup,Choi, Jun-Hyeak,Jung, Ok-Sang,Kim, Hong-Seok Elsevier Sequoia [etc.] 2018 Inorganica chimica acta Vol.482 No.-

<P><B>Abstract</B></P> <P>A very simple, robust, and pico/nanomolar-sensitive 9,10-diethanolamine-substituted fluorescent Fe<SUP>3+</SUP>/CN<SUP>–</SUP> probe (<B>PD</B>) was synthesised, and its sensing abilities towards various ions were studied in mixed aqueous media. <B>PD</B> selectively recognised Fe<SUP>3+</SUP> ions through a ‘<I>turn on</I>’ response with an excellent binding constant (<I>K</I> <SUB>a</SUB>, 9.29 × 10<SUP>6</SUP> M<SUP>−1</SUP>) in 1:2 binding stoichiometry at pH 7.0 in phosphate-buffered saline (PBS). The <I>in situ</I> generated Fe<SUP>3+</SUP>·<B>PD</B> ensemble sequentially recognised CN<SUP>–</SUP> ions with an excellent binding constant (<I>K</I> <SUB>a</SUB> 1.72 × 10<SUP>8</SUP> M<SUP>−1</SUP>) via a ‘<I>turn off</I>’ mode by extruding Fe<SUP>3+</SUP> ions from the ensemble. The highly selective sequential ‘<I>on-off</I>’ responses towards Fe<SUP>3+</SUP> and CN<SUP>–</SUP> ions were attributed to inhibition and restoration of photoinduced electron transfer (PET) and chelation-induced enhanced fluorescence (CHEF) effects from the chelating N and O heteroatoms. <B>PD</B> was able to detect Fe<SUP>3+</SUP> and CN<SUP>–</SUP> ions in real water samples satisfactorily at picomolar to sub-nanomolar levels. A colorimetric assay based on pyrocatechol violet (<B>PCV</B>) was also able to detect Fe<SUP>3+</SUP>/CN<SUP>–</SUP> in a sequential manner (up to sub-micromolar level) by a change in colour from colourless to yellow/pale green without any interferences from other ions. Based on the complexation and decomplexation mechanism, bio-imaging photonic INHIBIT logic circuit strips were prepared for use under physiological conditions. In addition, solid-phase recognition of Fe<SUP>3+</SUP>/CN<SUP>–</SUP> ions was demonstrated using cost-effective paper-based strips.</P> <P><B>Highlights</B></P> <P> <UL> <LI> 9,10-Diethanolamine-appended anthracene probe PD was synthesized and sensing abilities were studied in aqueous medium. </LI> <LI> Probe PD detected Fe<SUP>3+</SUP> and CN<SUP>–</SUP> sequentially through ‘<I>switch-on</I>’ and ‘<I>switch-off</I>’ responses. </LI> <LI> Pyrocatechol violet based colorimetric assay also is able to detect Fe<SUP>3+</SUP>/CN<SUP>–</SUP> in sequential manner by changing the color from colorless to yellow/pale green. </LI> <LI> Bio-imaging, photonic INHIBIT logic circuit strips were demonstrated at physiological conditions based on complexations and decomplexation mechanism. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Al3+-Morpholine-appended Anthracene Ensemble as a Dual Photonic Switch for H2PO4? and CN? Ions and its Biological Applications

최준혁,Anup Pandith,다사그란디차크라다르,김학렬,김홍석 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.2

A highly selective Al3+-morpholine anthracene (1?Al 3+) chelate was designed as a novel fluorescent photonic switch for H2PO4? and CN? ions. The in situ-generated Al3+ chelate could be used to detect H2PO4? ions only in the absence of CN? ions. In contrast, CN? ions effectively extruded Al3+ from the chelate, resulting in the regeneration of probe 1 with a concomitant revival of PET, resulting in a turn-off response. By exploiting the complexation- and decomplexation-aided off?on switching system through the sequential addition of Al3+ followed by H2PO4? or CN?, combinational photonic logic circuits, as well as image-guided fluorogenic tracking, was demonstrated.

Electronically-tuned 2-(2′-Hydroxyphenyl)-4-pyrenylthiazole through Bond Energy Transfer Donor–Acceptor Couples: Sensing and Biological Applications

허준혁,Anup Pandith,조찬식,김홍석 대한화학회 2018 Bulletin of the Korean Chemical Society Vol.39 No.12

A novel pyrene-conjugated 2-(2?-hydroxyphenyl)thiazole probe (HPTP, 1) was prepared, and its photophysical and sensing properties were investigated and compared to those of four model compounds. HPTP effectively detects CN? and glycerol in DMSO, with ?turn off? at 425?nm and ?turn on? at 495?nm. The sensing ability of 1 towards CN? ions in DMSO, mediated by the hydrogen bonding-induced disaggregation of aggregates, resulted in the quenching of ESIPT emission at 425?nm. By contrast, in a DMSO?glycerol mixed medium, the aggregate size increased together with the increased degree of intermolecular π?π interactions between two pyrene units located on adjacent molecules, and resulted in partial inhibition of energy/charge transfer from the pyrene unit to the thiazole unit in the excited state. Excitation energy transfer with increased photostability of the ESIPT core was effectively demonstrated in Candida albicans cell lines.

Highly Selective Fluorescent Probe Based on 2-(2′-Dansylamidophenyl)-Thiazole for Sequential Sensing of Copper(II) and Iodide Ions

김보연,Anup Pandith,조찬식,김홍석 대한화학회 2019 Bulletin of the Korean Chemical Society Vol.40 No.2

A novel highly selective fluorescent probe based on 2-(2?-dansylamidophenyl)-4-phenylthiazole (1) is developed for sequential sensing of copper(II) and iodide ions in acetonitrile. The fluorescence mechanism is based on cation-induced inhibition of excited-state intramolecular hydrogen transfer, intramolecular charge transfer, and metal?ligand electron/charge transfer. Subsequent iodide-induced extrusion of copper(II) results in partial revival of fluorescence. Probe 1 and its ensemble with copper (II) show high selectivity for copper(II) and iodide ions, respectively, in acetonitrile solution.

Sclerotiorin: a Novel Azaphilone with Demonstrated Membrane Targeting and DNA Binding Activity against Methicillin-Resistant Staphylococcus aureus

( Chakradhar Dasagrandhi ),( Anup Pandith ),( Khalid Imran ) 한국미생물생명공학회(구 한국산업미생물학회) 2020 한국미생물·생명공학회지 Vol.48 No.4

The emergence of multi-drug resistant, pathogenic methicillin-resistant Staphylococcus aureus (MRSA) is a threat to global health and has created a need for novel functional therapeutic agents. In this study, we evaluated the underlying mechanisms of the anti-MRSA effect of an azaphilone pigment, sclerotiorin (SCL) from Penicillium sclerotiorum. The antimicrobial activity of SCL was evaluated using agar disc diffusion, broth microdilution, time-kill assays and biophysical studies. SCL exhibits selective activity against Gram positive bacteria including MRSA (range, MIC = 128-1028 μg/ml) and exhibited rapid bactericidal action against MRSA with a > 4 log reduction in colony forming units within three hours of administration. Biophysical studies, using fluorescent probes and laser or electron microscopy, demonstrated a SCL dose-dependent alternation in membrane potential (62.6 ± 5.0.4% inhibition) and integrity (> 95 ± 2.3%), and the release of UV₂₆₀ absorbing materials within 60 min (up to 3.2 fold increase, p < 0.01) of exposure. Further, SCL localized to the cytoplasm and hydrolyzed plasmid DNA. While in vitro checkerboard studies revealed that SCL potentiated the antimicrobial activity of topical antimicrobials such as polymixin, neomycin, and bacitracin (Fractional Inhibitory Concentration Index range, 0.26-0.37). Taken together these results suggest that SCL targets the membrane and DNA of MRSA to facilitate its anti- MRSA antimicrobial effect.