Highly Sensitive Ratiometric Fluorescent Detection of Indium(III) Using Fluorescent Probe Based on Phosphoserine as a Receptor

( Mehta Pramod Kumar ),이건형 한국공업화학회 2018 한국공업화학회 연구논문 초록집 Vol.2018 No.0

We synthesized a fluorescent probe (1) based on a novel receptor, phosphoserine for ratiometric detection of In(III). 1 selectively detected In(III) among various metal ions including Al(III) and Ga(III) in aqueous solutions through a ratiometric response. Upon addition of In(III), monomer emission of the pyrene at 395 nm decreased and the excimer emission at 476 nm increased significantly. About 2 equiv of In(III) completely induced the ratiometric response of 1. The detection limit was calculated to be 64 nM (R2 = 0.992) in aq. solution. Job’s plot analysis indicated that 1 formed a 2:1 complex with In(III) and the binding affinity of 1 for In(III) was measured to be 2.3 × 1012 M-2 (R2 = 0.989). The binding mode study showed that the phosphate group and two carbonyl groups of the amide bonds of 1 play an important role for the binding with In(III). Moreover, the fluorescent probe was suitable for the ratiometric detection of In(III) ions in ground water and tap water.

1P-586 Ratiometric Fluorescent Probe Based on a Peptide Receptor with Femtomolar Affinity for Cu(I) in Aqueous Buffered Solutions

( Mehta Pramod Kumar ),이건형 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.0

Highly Sensitive Ratiometric Fluorescent Detection of Indium(III) Using Fluorescent Probe Based on Phosphoserine as a Receptor

Mehta, Pramod Kumar,Hwang, Gi Won,Park, Joohee,Lee, Keun-Hyeung American Chemical Society 2018 ANALYTICAL CHEMISTRY - Vol.90 No.19

<P>Indium is one of the most widely used scarce metals for manufacturing various electronic devices including notebooks, mobile phones, and PC monitors. Recent studies revealed that indium and its compound could cause several toxicities to human beings and animals. However, there is no report about ratiometric fluorescent detection of In(III) in aqueous solutions. We synthesized a fluorescent probe (<B>1</B>) for In(III) based on a phosphoserine as a receptor with a pyrene fluorophore using solid phase synthesis. <B>1</B> showed highly sensitive ratiometric response to In(III) in purely aqueous solutions by increasing excimer emission intensity at 476 nm with a concomitant decrease in monomer emission intensity at 395 nm. <B>1</B> showed sensitive ratiometric responses to In(III) over a wide range of pH (2 < pH < 8) and exhibited a highly selective ratiometric response to In(III) among 18 tested metal including Al(III) and Ga(III). Job’s plot analysis indicated that <B>1</B> preferred to form a 2:1 complex with In(III) and the binding affinity for In(III) was measured to be 2.3 × 10<SUP>12</SUP> M<SUP>-2</SUP> (<I>R</I><SUP>2</SUP> = 0.989). <B>1</B> showed linear ratiometric responses to nanomolar concentrations (0-750 nM) of In(III) and the detection limit was calculated to be 64 nM (<I>R</I><SUP>2</SUP> = 0.992) in aqueous solution. The binding mode study using NMR, IR, and CD spectroscopies revealed that the phosphate and the amide groups of the receptor of <B>1</B> played an important role for the binding with In(III). Moreover, <B>1</B> was suitable for the ratiometric detection of In(III) in tap water and groundwater. <B>1</B> showed much better detection properties than those of the colorimetric methods using EDTA with Eriochrome black T (EBT) and 4-(2-pyridylazo) resorcinol (PAR) for the detection of In(III) in tap water and groundwater.</P> [FIG OMISSION]</BR>

Ratiometric detection of Cu⁺ in aqueous buffered solutions and in live cells using fluorescent peptidyl probe to mimic the binding site of the metalloprotein for Cu⁺

Mehta, Pramod Kumar,Oh, Eun-Taex,Park, Heon Joo,Lee, Keun-Hyeung Elsevier 2018 Sensors and actuators. B Chemical Vol.256 No.-

<P><B>Abstract</B></P> <P>Ratiometric detection of Cu<SUP>+</SUP> in aqueous buffered solutions and live cells is highly recomended. We synthesized a fluorescent probe (<B>1)</B> based on the peptide receptor to mimic the binding site of the metalloprotein (CusF) for Cu<SUP>+</SUP>. <B>1</B> sensitively and selectively detected Cu<SUP>+</SUP> among various biological relevant metal ions in aqueous solutions at physiological pH through a ratiometric response. Job’s plot analysis indicated that <B>1</B> formed a 2:1 complex with Cu<SUP>+</SUP> and the binding affinity of <B>1</B> for Cu<SUP>+</SUP> was measured to be 5.73×10<SUP>−21</SUP> M<SUP>2</SUP> from a competition experiment with bathocuproine disulfonate. The probe showed significant ratiometric responses to Cu<SUP>+</SUP> over a wide range of pH (6.5∼10.5). The binding mode study showed that the imidazole and indole groups of the peptide receptor played a critical role in the tight binding to Cu<SUP>+</SUP>. <B>1</B> penetrated successfully in living A549 cells and detected intracellular Cu<SUP>+</SUP> ions in Golgi apparatus through ratiometric response. Giving the recent growing interests in fluorescent imaging of Cu<SUP>+</SUP>, the development of a fluorescent ratiometric probe (<B>1)</B> based on the peptide receptor to mimic the binding site of the metalloprotein for Cu<SUP>+</SUP> will provide a potential tool for detection of intracellular metal ions in live cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The fluorescent peptidyl probe for Cu(I) was easily synthesized in high yield (75%). </LI> <LI> Highly sensitive and selective response to Cu(I) among various biological relevant metal ions. </LI> <LI> Ratiometric response to Cu(I) and the intensity ratio (I<SUB>472</SUB>/I<SUB>396</SUB>) at 472 and 396nm increased by about 130 fold. </LI> <LI> Cell penetration and ratiometric detection of intracellular Cu(I) in the Golgi apparatus in live cells. </LI> </UL> </P>

Highly sensitive ratiometric detection of heparin and its oversulfated chondroitin sulfate contaminant by fluorescent peptidyl probe

Mehta, Pramod Kumar,Lee, Hyeri,Lee, Keun-Hyeung Elsevier 2017 Biosensors & Bioelectronics Vol.91 No.-

<P><B>Abstract</B></P> <P>The selective and sensitive detection of heparin, an anticoagulant in clinics as well as its contaminant oversulfated chondroitin sulfate (OSCS) is of great importance. We first reported a ratiometric sensing method for heparin as well as OSCS contaminants in heparin using a fluorescent peptidyl probe (<B>Pep1</B>, pyrene-GSRKR) and heparin-digestive enzyme. <B>Pep1</B> exhibited a highly sensitive ratiometric response to nanomolar concentration of heparin in aqueous solution over a wide pH range (2~11) and showed highly selective ratiometric response to heparin among biological competitors such as hyaluronic acid and chondroitin sulfate. <B>Pep1</B> showed a linear ratiometric response to nanomolar concentrations of heparin in aqueous solutions and in human serum samples. The detection limit for heparin was calculated to be 2.46nM (R<SUP>2</SUP>=0.99) in aqueous solutions, 2.98nM (R<SUP>2</SUP>=0.98) in 1% serum samples, and 3.43nM (R<SUP>2</SUP>=0.99) in 5% serum samples. <B>Pep1</B> was applied to detect the contaminated OSCS in heparin with heparinase I, II, and III, respectively. The ratiometric sensing method using <B>Pep1</B> and heparinase II was highly sensitive, fast, and efficient for the detection of OSCS contaminant in heparin. <B>Pep1</B> with heparinase II could detect as low as 0.0001% (w/w) of OSCS in heparin by a ratiometric response.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Highly sensitive and selective ratiometric detection of heparin among various biological heparin competitors </LI> <LI> The detection limit for heparin was measured to be 2.46nM </LI> <LI> Highly sensitive ratiometric detection of OSCS in heparin using only one heparin-digestive enzyme (heparinase II) </LI> <LI> Ratiometric detection of as low as 0.0001% (w/w) of OSCS in heparin </LI> </UL> </P>

Ratiometric fluorescent probe based on symmetric peptidyl receptor with picomolar affinity for Zn²⁺ in aqueous solution

Mehta, Pramod Kumar,Oh, Eun-Taex,Park, Heon Joo,Lee, Keun-Hyeung Elsevier 2017 Sensors and actuators. B Chemical Vol.245 No.-

<P><B>Abstract</B></P> <P>It is still a significant challenge to synthesize ratiometric fluorescent probes based on the new receptor with potent and tunable binding affinities for Zn<SUP>2+</SUP>. A fluorescent probe (<B>1</B>) based on the symmetric peptide receptor bearing two imidazole and two sulfonamide groups was synthesized for the ratiometric detection of Zn<SUP>2+</SUP> in aqueous solution. <B>1</B> selectively and sensitively detected Zn<SUP>2+</SUP> among biological relevant metal ions by a ratiometric response. Upon addition of Zn<SUP>2+</SUP>, monomer emissions of the pyrenes at 379 and 399nm increased significantly and the excimer emission at 508nm decreased with a blue shift. About 1 equiv of Zn<SUP>2+</SUP> ions completely induced the ratiometric response of <B>1</B>. Job’s plot analysis indicated that <B>1</B> formed a 1:1 complex with Zn<SUP>2+</SUP>. The dissociation constant for Zn<SUP>2+</SUP> was found to be 300 pM. The binding mode study revealed that two imidazole and two sulfonamide groups of the peptide receptor played an important role in the binding with Zn<SUP>2+</SUP>. The peptidyl probe successfully penetrated and detected intracellular Zn<SUP>2+</SUP> in live cells.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The fluorescent probe based on the peptide receptor with tunable binding affinities for Zn<SUP>2+</SUP>. </LI> <LI> Highly sensitive ratiometric response to Zn<SUP>2+</SUP> in aqueous solutions at physiological pH. </LI> <LI> A picomolar binding affinity (300 pM) for Zn<SUP>2+</SUP> in aqueous solutions and formation of a 1:1 complex. </LI> <LI> Highly selective response to Zn<SUP>2+</SUP> among various biological relevant metal ions. </LI> <LI> Cell penetration and detection of intracellular Zn<SUP>2+</SUP> in live cells. </LI> </UL> </P>

Ratiometric red-emission fluorescence detection of Al³⁺ in pure aqueous solution and live cells by a fluorescent peptidyl probe using aggregation-induced emission

Neupane, Lok Nath,Mehta, Pramod Kumar,Oh, Semin,Park, See-Hyoung,Lee, Keun-Hyeung The Royal Society of Chemistry 2018 The Analyst Vol.143 No.21

<P>The development of a fluorescence method for the selective ratiometric detection of Al<SUP>3+</SUP> ions in pure aqueous solutions and live cells is still a significant challenge. In the present study, we synthesized a new type of fluorescent probe using an Al<SUP>3+</SUP>-triggered self-assembly based on the dipeptide receptor and an aggregation-induced emission fluorophore. The fluorescent probe (1) bearing cyanostilbene with excitation by visible light detected Al<SUP>3+</SUP> ions sensitively in pure aqueous buffered solution by ratiometric red-emission at 600 nm. 1 provided a highly selective ratiometric detection of Al<SUP>3+</SUP> among 16 metal ions in aqueous solution. 1 exhibited sensitive ratiometric response to Al<SUP>3+</SUP> in aqueous buffered solutions at pH ranging from 5 to 7.4. The detection limit (145 nM, <I>R</I><SUP>2</SUP> = 0.999) for Al<SUP>3+</SUP> ions in pure aqueous solution was much lower than the maximum allowable level of Al<SUP>3+</SUP> in drinking water demanded by the Environmental Protection Agency (EPA). The probe provided an efficient approach to detect low concentrations of Al<SUP>3+</SUP> in ground water, tap water, and live cells by ratiometric red-emissions at 600 nm. The binding study using dynamic light scattering, NMR, IR, and TEM revealed that the complex between 1 and Al<SUP>3+</SUP> self-assembled to form nanoparticles, resulting in the enhancement of the emission at 600 nm and a concomitant decrease in the emission at 535 nm.</P>

Dual Role of a Fluorescent Peptidyl Probe Based on Self-Assembly for the Detection of Heparin and for the Inhibition of the Heparin-Digestive Enzyme Reaction

Lee, Hyeri,In, Byunggyu,Mehta, Pramod Kumar,Kishore, Mallela Y. L. N.,Lee, Keun-Hyeung American Chemical Society 2018 ACS APPLIED MATERIALS & INTERFACES Vol.10 No.3

<P>The detection of fluorescent probes for biomolecules and control of the function of a complex through a recognition process have not been investigated intensively. A fluorescent peptidyl probe (1) based on the self-assembly stimulated by heparin was synthesized. The fluorescent probe with an aggregation-induced emission fluorophore formed a self assembling complex with heparin, resulting in a sensitive and selective turn-on response to heparin compared to its biological competitors. The detection limits for heparin were measured to be 138.0 pM (R-2 = 0.976) in aqueous solution and 2.6 nM (R-2 = 0.996) in aqueous solution containing human serum. Nanosized aggregates formed through the self-assembly of the complex showed potent resistance against the heparin-digestive enzyme. The dual role of the probe for the detection of heparin and the inhibition of heparinase-mediated digestion through the recognition process was used for the real-time monitoring of the enzyme activity of heparinase for the digestion of heparin. Furthermore, the dual role of the probe was applied for the detection of the oversulfated chondroitin sulfate contaminant in heparin.</P>

Selective red-emission detection for mercuric ions in aqueous solution and cells using a fluorescent probe based on an unnatural peptide receptor

Neupane, Lok Nath,Mehta, Pramod Kumar,Kwon, Joon-Uk,Park, See-Hyoung,Lee, Keun-Hyeung The Royal Society of Chemistry 2019 Organic & Biomolecular Chemistry Vol.17 No.14

<P>The selective ratiometric red-emission detection of Hg<SUP>2+</SUP> ions in aqueous buffered solutions and live cells is still a significant challenge. In the present study, we synthesized a fluorescent probe (1) based on an unnatural peptide receptor containing sulfonamide groups with an aggregation-induced emission and twisted internal charge transfer (TICT)-active fluorophore, cyanostilbene. 1 exhibited a highly selective ratiometric response to Hg<SUP>2+</SUP> among 14 metal ions tested by ratiometric red-emission at 600 nm, with a clear isoemissive point in purely aqueous solution containing 1% DMSO. The ratiometric response for Hg<SUP>2+</SUP> ions was complete within 3 min and the ratiometric responses induced by Hg<SUP>2+</SUP> ions did not suffer considerable interference from the other metal ions. The ratiometric response was complete for less than 7 μM Hg<SUP>2+</SUP> and 1 had a potent binding affinity (7.42 × 10<SUP>−6</SUP> M, <I>R</I><SUP>2</SUP> = 0.98) for Hg<SUP>2+</SUP> and a nanomolar detection limit. 1 detected Hg<SUP>2+</SUP> ions by ratiometric responses in aqueous buffered solutions over a wide range of pH (5.5-11.5). Binding mode studies using TEM, NMR, IR, and a mass spectrometer revealed that the sulfonamide groups of the unnatural peptide receptor played an important role in the complexation of Hg<SUP>2+</SUP> and in the complexation-induced nano-sized aggregates, which resulted in a significant increase in emissions at 600 nm and a decrease in emissions at 535 nm. 1 quantified micro-molar concentrations (0-6 μM) of Hg<SUP>2+</SUP> in tap water and groundwater by ratiometric detection. Furthermore, 1 passed through the lipid membranes of live cells and detected intracellular Hg<SUP>2+</SUP> ions at 2 μM by a ratiometric red-emission change.</P>