Development of peptide-based ratiometric fluorescent probe for sensing heparan sulfate and heparin in aqueous solutions at physiological pH and quantitative detection of heparan sulfate in live cells.

Heparan sulfate (HS) plays a critical role in various biological processes as a vital component of the extracellular matrix. In this study, we synthesized three fluorescent probes (1-3) comprising Arg-rich peptides as HS receptors and a fluorophore capable of exhibiting red-shifted emissions upon aggregation. All three probes demonstrated ratiometric responses to HS and heparin in aqueous solutions.

Ratiometric Fluorescence Sensing System for Lead Ions Based on Self-Assembly of Bioprobes Triggered by Specific Pb-Peptide Interactions.

Lead is one of the most toxic substances. However, there are few ratiometric fluorescent probes for sensing Pb in aqueous solution as well as living cells because specific ligands for Pb ions have not been well characterized. Considering the interactions between Pb and peptides, we developed ratiometric fluorescent probes for Pb based on the peptide receptor in two steps.

Development of ratiometric fluorescent probes based on peptides for sensing Pb in aquatic environments and human serum.

The detection of Pb ions in aquatic environments and biofluid samples is crucial for assessment of human health. Herein, we synthesized two fluorescent probes (1 and 2) consisting of the peptide receptor for Pb and a benzothiazolyl-cyanovinylene fluorophore that exhibited excimer-like emission when it aggregated. The peptide-based probes sensitively detected Pb in purely aqueous solution (1% DMF) through ratiometric fluorescent response with a decrease in monomer emission at 520 nm and an increase in excimer emission at 570 nm.

Ratiometric fluorescent detection of lead ions in aquatic environment and living cells using a fluorescent peptide-based probe.

Ratiometric fluorescent detection using dual emission bands is highly necessary to quantify Pb(II) in aquatic environment and live cells. We synthesized a ratiometric fluorescent peptidyl probe (1) by conjugation of a peptide receptor for Pb(II) with an excimer-forming benzothiazolylcyanovinylene fluorophore. The peptidyl probe dissolved well in aqueous solution and displayed an emission band at 538 nm (λ = 460 nm).

Ratiometric fluorescent detection of silver nanoparticles in aqueous samples using peptide-based fluorogenic probes with aggregation-induced emission characteristics.

The quantification of silver nanoparticles and Ag contamination in the aquatic ecosystem has attracted considerable interest. Benzoimidazolyl-cyanovinylene (1) was synthesized as an aggregation-induced emission fluorophore, and a fluorescent peptidyl probe (2 and 3) bearing this fluorophore was developed. The fluorescent peptidyl probes coordinated with Ag selectively among various metal ions, leading to a ratiometric response to Ag in pure aqueous solutions.

Selective ratiometric red-emission detection of In in aqueous solutions and in live cells using a fluorescent peptidyl probe and metal chelating agent.

Indium has been regarded as one of the most rarely used metal ions; however, the consumption of indium has increased intensively due to its increasing use in electrodes of liquid crystal displays (LCDs). In recent years, warnings have been issued about the toxicity of indium to aquatic ecosystems and humans. Thus, the development of efficient and selective detection methods for In in aquatic environments as well as in live cells is highly required.

Fluorescent Detection of Methyl Mercury in Aqueous Solution and Live Cells Using Fluorescent Probe and Micelle Systems.

It is highly challenging to develop fast and sensitive fluorescent methods for monitoring organic mercury in purely aqueous solutions as well as live cells. Especially, selective fluorescent detection of methylmercury over inorganic mercury ions has not been reported. We developed a fast and sensitive fluorescent detection method for Hg ions as well as methylmercury using an amino acid-based fluorescent probe () and SDS micelles.

Fast and sensitive fluorescent detection of inorganic mercury species and methylmercury using a fluorescent probe based on the displacement reaction of arylboronic acid with the mercury species.

We present a reaction-based fluorescent probe (1) for Hg and CHHg, based on the displacement reaction of the arylboronic acid with the mercury species. 1 showed promising sensing properties for Hg and CHHg, such as high selectivity and sensitivity, turn-on response, fast response to Hg (<2 min) and CHHg (<5 min), low detection limits and operation in purely aqueous solutions.

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

The selective ratiometric red-emission detection of Hg2+ 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 Hg2+ among 14 metal ions tested by ratiometric red-emission at 600 nm, with a clear isoemissive point in purely aqueous solution containing 1% DMSO.

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

The development of a fluorescence method for the selective ratiometric detection of Al3+ 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 Al3+-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 Al3+ ions sensitively in pure aqueous buffered solution by ratiometric red-emission at 600 nm.

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

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.

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.

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.

Tuning of the selectivity of fluorescent peptidyl bioprobe using aggregation induced emission for heavy metal ions by buffering agents in 100% aqueous solutions.

Smart fluorescent probes of which the detection of specific target molecules can be controlled are attracting remarkable interest. A fluorescent peptidyl bioprobe (1) was rationally synthesized by conjugating tetraphenylethylene, an aggregation-induced emission (AIE) fluorophore with a peptide receptor (AspHis) that acted as hard and intermediate bases. The selective detection of 1 for specific metal ion in 100% aqueous solutions was controlled by the buffering agents with the chelate effect without the change of pH.

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

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 (Pep1, pyrene-GSRKR) and heparin-digestive enzyme. Pep1 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.

Highly sensitive and selective detection of Al(III) ions in aqueous buffered solution with fluorescent peptide-based sensor.

A fluorescent sensor based on a tripeptide (SerGluGlu) with a dansyl fluorophore detected selectively Al(III) among 16 metal ions in aqueous buffered solutions without any organic cosolvent. The peptide-based sensor showed a highly sensitive turn on response to aluminium ion with high binding affinity (1.84×10(4)M(-1)) in aqueous buffered solutions.

Development of new peptide-based receptor of fluorescent probe with femtomolar affinity for Cu(+) and detection of Cu(+) in Golgi apparatus.

Developing fluorescent probes for monitoring intracellular Cu(+) is important for human health and disease, whereas a few types of their receptors showing a limited range of binding affinities for Cu(+) have been reported. In the present study, we first report a novel peptide receptor of a fluorescent probe for the detection of Cu(+). Dansyl-labeled tripeptide probe (Dns-LLC) formed a 1:1 complex with Cu(+) and showed a turn-on fluorescent response to Cu(+) in aqueous buffered solutions.

Selective and Sensitive Detection of Heavy Metal Ions in 100% Aqueous Solution and Cells with a Fluorescence Chemosensor Based on Peptide Using Aggregation-Induced Emission.

A fluorescent peptidyl chemosensor for the detection of heavy metal ions in aqueous solution as well as in cells was synthesized on the basis of the peptide receptor for the metal ions using an aggregation-induced emission fluorophore. The peptidyl chemosensor (1) bearing tetraphenylethylene fluorophore showed an exclusively selective turn-on response to Hg(2+) among 16 metal ions in aqueous buffered solution containing NaCl. The peptidyl chemosensor complexed Hg(2+) ions and then aggregated in aqueous buffered solution, resulting in the significant enhancement (OFF-On) of emissions at around 470 nm.

Efficient ensemble system based on the copper binding motif for highly sensitive and selective detection of cyanide ions in 100% aqueous solutions by fluorescent and colorimetric changes.

A peptide-based ensemble for the detection of cyanide ions in 100% aqueous solutions was designed on the basis of the copper binding motif. 7-Nitro-2,1,3-benzoxadiazole-labeled tripeptide (NBD-SSH, NBD-SerSerHis) formed the ensemble with Cu(2+), leading to a change in the color of the solution from yellow to orange and a complete decrease of fluorescence emission. The ensemble (NBD-SSH-Cu(2+)) sensitively and selectively detected a low concentration of cyanide ions in 100% aqueous solutions by a colorimetric change as well as a fluorescent change.

Pyrene Excimer-Based Peptidyl Chemosensors for the Sensitive Detection of Low Levels of Heparin in 100% Aqueous Solutions and Serum Samples.

Fluorescent chemosensors (1 and 2, Py-(Arg)nGlyGlyGly(Arg)nLys(Py)-NH2, n = 2 and 3) bearing two pyrene (Py) labeled heparin-binding peptides were synthesized for the sensitive ratiometric detection of heparin. The peptidyl chemosensors (1 and 2) sensitively detected nanomolar concentrations of heparin in aqueous solutions and in serum samples via a ratiometric response. In 100% aqueous solutions at pH 7.

Fluorescent peptide-based sensors for the ratiometric detection of nanomolar concentration of heparin in aqueous solutions and in serum.

New fluorescent peptide-based sensors (1-3) for monitoring heparin in serum sample were synthesized using short peptides (1∼3mer) as a receptor. The peptide-based sensors (2 and 3) showed a sensitive ratiometric response to heparin both in aqueous buffered solution (10 mM HEPES, pH 7.4) and in 2% human serum sample by increase of excimer emission of pyrene at 480 nm and concomitant decrease of monomer emission of pyrene at 376 nm, whereas the peptide-based sensor 1 showed a turn off response only by decrease of monomer emission at 376 nm.

Highly sensitive colorimetric detection of Hg(II) and Cu(II) in aqueous solutions: from amino acids toward solid platforms.

A chemosensor (NBD-H) based on an amino acid with 7-nitro-2,1,3-benzoxadiazole was used for selective detection of Hg(II) and Cu(II) among 15 metal ions in aqueous solutions by a colorimetric change. NBD-H sensitively differentiated Hg(II) and Cu(II) in aqueous solutions by a color change; a pink color for Hg(II) and an orange color for Cu(II). NBD-H showed nanomolar detection limits for Hg(II) (176 nM, R2 = 0.

Ethyl pyruvate inhibits HMGB1 phosphorylation and release by chelating calcium.

Ethyl pyruvate (EP), a simple aliphatic ester of pyruvic acid, has been shown to have antiinflammatory effects and to confer protective effects in various pathological conditions. Recently, a number of studies have reported EP inhibits high mobility group box 1 (HMGB1) secretion and suggest this might contribute to its antiinflammatory effect. Since EP is used in a calcium-containing balanced salt solution (Ringer solution), we wondered if EP directly chelates Ca(2+) and if it is related to the EP-mediated suppression of HMGB1 release.

Stimuli-responsive conformational conversion of peptide gatekeepers for controlled release of guests from mesoporous silica nanocontainers.

The use of peptides as gatekeepers for payloads of mesoporous silica nanoparticles would allow triggering the release of guests by various biological stimuli. We investigated the effect of peptide conformation on their gatekeeping capability by employing two model peptides with a turn or a random structure. The conformation-dependent gatekeeping properties provided an opportunity to utilize the conformational conversion of peptides as a valuable motif for stimuli-responsive gatekeepers.

Ratiometric fluorescence chemosensor based on tyrosine derivatives for monitoring mercury ions in aqueous solutions.

Ratiometric fluorescent chemosensors 1 and 2 were synthesized based on tyrosine amino acid derivatives with a pyrene fluorophore. 1 and 2 showed high selectivity for Hg(II) ions among 13 metal ions in aqueous solutions. Both 1 and 2 sensitively detected Hg(II) ions in aqueous solutions by ratiometric response without interference of any of the other tested metal ions including Cu(II), Cd(II), Pb(II), and Ag(I) ions.

Ratiometric detection of nanomolar concentrations of heparin in serum and plasma samples using a fluorescent chemosensor based on peptides.

A peptidyl fluorescent chemosensor for heparin was synthesized by conjugating a pyrene fluorophore with the heparin-binding peptide. The fluorescent chemosensor (Py12; pyrene-RKRLQVQLSIRT) showed a highly sensitive ratiometric response to nanomolar concentrations of heparin in aqueous solutions at physiological pH by increasing excimer emission intensity at 500 nm with a concomitant decrease in monomer emission intensity at 400 nm. Py12 showed a sensitive ratiometric response to heparin over a wide pH range (1.