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1.
Anal Chem ; 92(19): 13396-13404, 2020 10 06.
Artigo em Inglês | MEDLINE | ID: mdl-32867467

RESUMO

Rapid, accurate, reliable, and risk-free tracking of pathogenic microorganisms at the single-cell level is critical to achieve efficient source control and prevent outbreaks of microbial infectious diseases. For the first time, we report a promising approach for integrating the concepts of a remarkably large Stokes shift and dual-recognition into a single matrix to develop a pathogenic microorganism stimuli-responsive ratiometric fluorescent nanoprobe with speed, cost efficiency, stability, ultrahigh specificity, and sensitivity. As a proof-of-concept, we selected the Gram-positive bacterium Staphylococcus aureus (S. aureus) as the target analyte model, which easily bound to its recognition aptamer and the broad-spectrum glycopeptide antibiotic vancomycin (Van). To improve the specificity and short sample-to-answer time, we employed classic noncovalent π-π stacking interactions as a driving force to trigger the binding of Van and aptamer dual-functionalized near-infrared (NIR) fluorescent Apt-Van-QDs to the surface of an unreported blue fluorescent π-rich electronic carbon nanoparticles (CNPs), achieving S. aureus stimuli-responsive ratiometric nanoprobe Apt-Van-QDs@CNPs. In the assembly of Apt-Van-QDs@CNPs, the blue CNPs (energy donor) and NIR Apt-Van-QDs (energy acceptor) became close to allow the fluorescence resonance energy transfer (FRET) process, leading to a remarkable blue fluorescence quenching for the CNPs at ∼465 nm and a clear NIR fluorescence enhancement for Apt-Van-QDs at ∼725 nm. In the presence of S. aureus, the FRET process from CNPs to Apt-Van-QDs was disrupted, causing the nanoprobe Apt-Van-QDs@CNPs to display a ratiometric fluorescent response to S. aureus, which exhibited a large Stokes shift of ∼260 nm and rapid sample-to-answer detection time (∼30.0 min). As expected, the nanoprobe Apt-Van-QDs@CNPs showed an ultrahigh specificity for ratiometric fluorescence detection of S. aureus with a good detection limit of 1.0 CFU/mL, allowing the assay at single-cell level. Moreover, we also carried out the precise analysis of S. aureus in actual samples with acceptable results. We believe that this work offers new insight into the rational design of efficient ratiometric nanoprobes for rapid on-site accurate screening of pathogenic microorganisms at the single-cell level in the early stages, especially during the worldwide spread of COVID-19 today.


Assuntos
Bactérias/química , Infecções Bacterianas/diagnóstico , Infecções Bacterianas/microbiologia , Técnicas Biossensoriais/métodos , Corantes Fluorescentes/síntese química , Nanotecnologia/métodos , Antibacterianos/farmacologia , Aptâmeros de Nucleotídeos , Infecções por Coronavirus/complicações , Infecções por Coronavirus/microbiologia , Fluorescência , Transferência Ressonante de Energia de Fluorescência , Microbiologia de Alimentos/métodos , Humanos , Nanopartículas , Pandemias , Pneumonia Viral/complicações , Pneumonia Viral/microbiologia , Sensibilidade e Especificidade , Espectroscopia de Luz Próxima ao Infravermelho , Infecções Estafilocócicas/diagnóstico , Infecções Estafilocócicas/microbiologia , Staphylococcus aureus/química , Vancomicina/farmacologia
2.
J Med Chem ; 63(8): 3996-4004, 2020 04 23.
Artigo em Inglês | MEDLINE | ID: mdl-32227886

RESUMO

Constitutive proteolytic activity of MALT1 is associated with highly aggressive B-cell lymphomas. Chemical tools that detect active MALT1 have been reported, but suffer from poor cell permeability and/or cross-reactivity with the cysteine protease cathepsin B. Here, we report that the non-natural amino acid pipecolinic acid in the P2 position of substrates and chemical probes leads to improved selectivity toward MALT1 and results in cell-permeable fluorescent probes.


Assuntos
Aminoácidos/síntese química , Aminoácidos/metabolismo , Permeabilidade da Membrana Celular/efeitos dos fármacos , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Proteína de Translocação 1 do Linfoma de Tecido Linfoide Associado à Mucosa/metabolismo , Aminoácidos/farmacologia , Linhagem Celular Tumoral , Permeabilidade da Membrana Celular/fisiologia , Desenho de Fármacos , Corantes Fluorescentes/farmacologia , Humanos , Células Jurkat , Estrutura Secundária de Proteína , Estrutura Terciária de Proteína
3.
Org Biomol Chem ; 18(15): 2929-2937, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32239080

RESUMO

The actin cytoskeleton is crucial for endocytosis, intracellular trafficking, cell shape maintenance and a wide range of other cellular functions. Recently introduced cell-permeable fluorescent actin probes, such as SiR-actin, suffer from poor membrane permeability and stain some cell populations inhomogeneously due to the active efflux by the plasma membrane pumps. We analyzed a series of new probes composed of jasplakinolide and modified rhodamine fluorophores and found that rhodamine positional isomerism has a profound effect on probe performance. The probes based on the 6'-carboxy-carbopyronine scaffold are considerably less susceptible to efflux and allow efficient staining without efflux pump inhibitors. They can be used for 2D and 3D fluorescence nanoscopy at high nanomolar concentrations without significant cytotoxicity. We show that jasplakinolide-based fluorescent probes bind not only to actin filaments, but also to G-actin, which enables imaging highly dynamic actin structures. We demonstrate an excellent performance of the new probes in multiple organisms and cell types: human cell lines, frog erythrocytes, fruit fly tissues and primary neurons.


Assuntos
Actinas/análise , Depsipeptídeos/química , Corantes Fluorescentes/química , Imagem Óptica , Rodaminas/química , Células Cultivadas , Corantes Fluorescentes/síntese química , Células HeLa , Humanos , Estrutura Molecular
4.
Org Biomol Chem ; 18(15): 2938-2948, 2020 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-32242600

RESUMO

Two myo-inositol derivatives having an Nα,Nε-diacetyl-l-lysine (Ac2Lys) moiety linked to the inositol 1-O-position through a self-cleavable linker and a metabolically stable 2-azidoethyl group linked to the inositol 3-O- and 4-O-positions, respectively, were designed and synthesized. The Ac2Lys moiety blocking the inositol 1-O-position required for GPI biosynthesis was expected to be removable by a combination of two enzymes, histone deacetylase (HDAC) and cathepsin L (CTSL), abundantly expressed in cancer cells, but not in normal cells, to transform these inositol derivatives into biosynthetically useful products with a free 1-O-position. As a result, it was found that these inositol derivatives could be incorporated into the glycosylphosphatidylinositol (GPI) biosynthetic pathway by cancer cells, but not by normal cells, to express azide-labeled GPIs and GPI-anchored proteins on cell surfaces. Consequently, this study has established a novel strategy and new molecular tools for selective metabolic labeling of cancer cells, which should be useful for various biological studies and applications.


Assuntos
Corantes Fluorescentes/química , Proteínas Ligadas por GPI/metabolismo , Glicosilfosfatidilinositóis/metabolismo , Inositol/química , Lisina/química , Engenharia Metabólica , Imagem Óptica , Células Cultivadas , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Proteínas Ligadas por GPI/química , Glicosilfosfatidilinositóis/química , Células HEK293 , Humanos , Inositol/síntese química , Inositol/metabolismo , Lisina/síntese química , Lisina/metabolismo , Microscopia de Fluorescência
5.
Chem Pharm Bull (Tokyo) ; 68(3): 216-219, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32115528

RESUMO

A turn-on fluorescent traceable linker based on N-sulfanylethylcoumarinyl amide (SECmide) has been developed as an advanced cleavable linker. It was successfully employed for the enrichment and selective visualization of a target protein in cell lysate. The results demonstrated that the SECmide-based traceable linker is potentially applicable to the identification of low molecular weight target proteins, a factor which has been problematic for a previously developed N-sulfanylethylanilide-based traceable linker.


Assuntos
Amidas/química , Cumarínicos/química , Fluorescência , Corantes Fluorescentes/química , Proteínas/análise , Corantes Fluorescentes/síntese química , Estrutura Molecular
6.
J Med Chem ; 63(7): 3596-3609, 2020 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-32159953

RESUMO

Opioid receptors (ORs) are among the best-studied G protein-coupled receptors due to their involvement in neurological disorders and important role in pain treatment. Contrary to the classical monomeric model, indirect evidence suggests that ORs might form dimers, which could be endowed with a distinct pharmacological profile, and, thus, be targeted to develop innovative pharmacological therapies. However, direct evidence for the spontaneous formation of OR dimers in living cells under physiological conditions is missing. Despite a growing interest in the κ opioid receptor (KOR), KOR-selective fluorescent probes are particularly scarce in the literature. Herein, we present the first set of fluorescent KOR-selective probes with antagonistic properties. Two of these were employed in single-molecule microscopy (SMM) experiments to investigate KOR homodimerization, localization, and trafficking. Our findings indicate that most KORs labeled with the new fluorescent probes are present as apparently freely diffusing monomers on the surface of a simple cell model.


Assuntos
Corantes Fluorescentes/farmacologia , Naltrexona/análogos & derivados , Naltrexona/farmacologia , Multimerização Proteica/efeitos dos fármacos , Receptores Opioides kappa/antagonistas & inibidores , Animais , Células CHO , Cricetulus , Corantes Fluorescentes/síntese química , Células HEK293 , Humanos , Ligantes , Naltrexona/síntese química , Receptores Opioides kappa/metabolismo , Imagem Individual de Molécula
7.
J Med Chem ; 63(7): 3563-3576, 2020 04 09.
Artigo em Inglês | MEDLINE | ID: mdl-32207938

RESUMO

In an effort to seek novel agents targeting prostate-specific membrane antigen (PSMA), 16 ligands (L1-L16) with structural modifications in S1' binding pocket were synthesized and evaluated for PSMA inhibition. (S)-3-(Carboxyformamido)-2-(3-(carboxymethyl)ureido)propanoic acids proved to be potent PSMA ligands with Ki values ranging from 0.08 nM to 8.98 nM, which are in the range of or are higher in potency compared to previously published urea-based ligands. Computational docking was performed to study the binding mode of the two most potent ligands discovered. FITC-conjugated L14 could selectively stain PSMA+ LNCaP cells over PSMA- PC3 cells. IRDye800CW conjugated L16 can effectively image tumors in a murine xenograft model of prostate cancer.


Assuntos
Corantes Fluorescentes/farmacologia , Neoplasias da Próstata/diagnóstico por imagem , Ureia/análogos & derivados , Ureia/farmacologia , Animais , Antígenos de Superfície/metabolismo , Linhagem Celular Tumoral , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Glutamato Carboxipeptidase II/metabolismo , Humanos , Masculino , Camundongos Endogâmicos BALB C , Simulação de Acoplamento Molecular , Imagem Óptica/métodos , Estudo de Prova de Conceito , Ligação Proteica , Ureia/metabolismo
8.
J Med Chem ; 63(6): 3359-3369, 2020 03 26.
Artigo em Inglês | MEDLINE | ID: mdl-32142286

RESUMO

Cytotoxic T-lymphocytes (CTLs) and natural killer cells (NKs) kill compromised cells to defend against tumor and viral infections. Both effector cell types use multiple strategies to induce target cell death including Fas/CD95 activation and the release of perforin and a group of lymphocyte granule serine proteases called granzymes. Granzymes have relatively broad and overlapping substrate specificities and may hydrolyze a wide range of peptidic epitopes; it is therefore challenging to identify their natural and synthetic substrates and to distinguish their localization and functions. Here, we present a specific and potent substrate, an inhibitor, and an activity-based probe of Granzyme A (GrA) that can be used to follow functional GrA in cells.


Assuntos
Cumarínicos/farmacologia , Corantes Fluorescentes/farmacologia , Granzimas/análise , Oligopeptídeos/farmacologia , Inibidores de Serino Proteinase/farmacologia , Linhagem Celular Tumoral , Cumarínicos/síntese química , Cumarínicos/toxicidade , Desenho de Fármacos , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/toxicidade , Granzimas/química , Humanos , Oligopeptídeos/síntese química , Oligopeptídeos/toxicidade , Inibidores de Serino Proteinase/síntese química , Inibidores de Serino Proteinase/toxicidade , Especificidade por Substrato
9.
Chem Commun (Camb) ; 56(21): 3199-3202, 2020 Mar 12.
Artigo em Inglês | MEDLINE | ID: mdl-32068200

RESUMO

We have developed a propargylamine-selective dual fluorescence turn-on system, using ylidenemalononitrile enamines, for post-synthetic DNA labeling, allowing the direct monitoring of DNA using dual emission in living cells.


Assuntos
DNA/química , Fluorescência , Corantes Fluorescentes/síntese química , Pargilina/análogos & derivados , Propilaminas/química , Linhagem Celular Tumoral , Corantes Fluorescentes/química , Humanos , Estrutura Molecular , Imagem Óptica , Pargilina/química , Coloração e Rotulagem
10.
Nat Commun ; 11(1): 793, 2020 02 07.
Artigo em Inglês | MEDLINE | ID: mdl-32034152

RESUMO

Fluorescence-based technologies have revolutionized in vivo monitoring of biomolecules. However, significant technical hurdles in both probe chemistry and complex cellular environments have limited the accuracy of quantifying these biomolecules. Herein, we report a generalizable engineering strategy for dual-emission anti-Kasha-active fluorophores, which combine an integrated fluorescein with chromene (IFC) building block with donor-π-acceptor structural modification. These fluorophores exhibit an invariant near-infrared Kasha emission from the S1 state, while their anti-Kasha emission from the S2 state at around 520 nm can be finely regulated via a spirolactone open/closed switch. We introduce bio-recognition moieties to IFC structures, and demonstrate ratiometric quantification of cysteine and glutathione in living cells and animals, using the ratio (S2/S1) with the S1 emission as a reliable internal reference signal. This de novo strategy of tuning anti-Kasha-active properties expands the in vivo ratiometric quantification toolbox for highly accurate analysis in both basic life science research and clinical applications.


Assuntos
Bioquímica/métodos , Corantes Fluorescentes/química , Imagem Molecular/métodos , Células A549 , Animais , Benzopiranos/química , Cisteína/análise , Feminino , Fluoresceína/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Glutationa/análise , Células Hep G2 , Humanos , Camundongos Endogâmicos BALB C , Estrutura Molecular , Neoplasias Experimentais/diagnóstico por imagem , Piranos/química , Espectroscopia de Luz Próxima ao Infravermelho/métodos , Espironolactona/química
11.
J Fluoresc ; 30(2): 301-308, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32002726

RESUMO

Copper is an important trace element involved in several physiological processes. The deficiency or excess of Cu in the human body may cause some serious diseases. EDTA has been widely employed in many industry fields owing to its excellent chelating ability. The poor biodegradability of EDTA makes itself a persistent substance in the natural environment. This work provided a fluorescence "on-off-on" strategy for the sequential determination of trace Cu2+ and EDTA. Amino-functionalized graphene quantum dots (afGQDs) were synthetized via the thermal pyrolysis of citric acid. Fluorescence resonance energy transfer (FRET) between afGQDs and 1-(2-pyridylazo)-2-naphthol (PAN) effectively quenched the fluorescence of this carbon-based nanomaterial. The generation of the Cu2+-PAN complex caused the increased FRET efficiency and the further fluorescence decline. The change of the fluorescence intensity sensitively responded to copper ions. The linear range and the limit of detection (LOD) were 1 nM-10 µM and 0.87 nM, respectively. EDTA could decompose the Cu2+-PAN complex and liberate PAN, which weakened the FRET efficiency and led to the fluorescence recovery. The increasing degree of the fluorescence intensity was closely related to EDTA within a concentration range from 10 nM to 10 µM with a LOD at 4 nM. Copper ions in the water and human serum samples and EDTA in the trypsin-EDTA sample were successfully detected based on the proposed fluorescence method.


Assuntos
Cobre/análise , Ácido Edético/análise , Corantes Fluorescentes/química , Grafite/química , Pontos Quânticos/química , Fluorescência , Corantes Fluorescentes/síntese química , Concentração de Íons de Hidrogênio , Íons/análise , Estrutura Molecular , Tamanho da Partícula , Espectrometria de Fluorescência , Propriedades de Superfície
12.
J Fluoresc ; 30(2): 317-327, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32016910

RESUMO

Herein, we report the preparation of a fluorescent sensor based on coumarin derivative for copper (II) ion sensing in CH3CN/HEPES media. 6,7-dihydroxy-3-(4-(trifluoro)methylphenyl)coumarin (HMAC) sensor was fabricated and analyzed by spectroscopic techniques. The sensor demonstrates "turn on-off" fluorescence quenching in the presence of copper (II) ions at 458 nm. A clear complex between the chemosensor HMAC and copper (II) ions was characterized by ESI-MS as well as the Job's method. Also, the limit of detection (LOD, 3σ/k) value was determined as 24.5 nM in CH3CN/HEPES (95/5, v/v) buffer media (pH = 7.0). This value is lower than the admissible level of copper (II) ions in drinking water (maximum 31.5 µM) reported by EU Water Framework Directive (WFD) and World Health Organization (WHO) guidelines. The theoretical calculations (density functional theory, DFT) have been performed for the geometric optimized structures. As a final stage, real sample analyses have successfully been performed by using HMAC, as well as ICP-OES method. The relative standard deviation for copper (II) in mineral and drinking water samples has been determined to be below 0.15% and recovery values are in the range of 95.48-109.20%.


Assuntos
Cobre/análise , Cumarínicos/química , Teoria da Densidade Funcional , Água Potável/química , Corantes Fluorescentes/química , Minerais/química , Cumarínicos/síntese química , Fluorescência , Corantes Fluorescentes/síntese química , Íons/análise , Estrutura Molecular , Espectrometria de Fluorescência
13.
J Fluoresc ; 30(2): 347-356, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32040795

RESUMO

A novel fluorescence chemosensor XYQ for detecting Zn(II) was synthesized. XYQ showed fluorescence turn-on to Zn(II) with high sensitivity and selectivity in aqueous media among 19 metal ions. Its binding structure was demonstrated by ESI-MS, Job plot, and 1H NMR titration. The detection limit of XYQ to Zn(II) was 0.53 µM. It is much below WHO drinking water standard (76.0 µM). XYQ could be applied successfully to the test kit and real samples. The fluorescence turn-on process was possibly explained as a chelation-enhanced fluorescence (CHEF) effect with theoretical calculations.


Assuntos
Corantes Fluorescentes/química , Quinolinas/química , Zinco/análise , Teoria da Densidade Funcional , Corantes Fluorescentes/síntese química , Íons/análise , Estrutura Molecular , Quinolinas/síntese química , Espectrometria de Fluorescência
14.
J Fluoresc ; 30(2): 375-387, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-32086710

RESUMO

Fluorescent molecularly imprinted polymer (FMIP) optosensor was utilized for the selective identification of 2,4-dichlorophenoxacetic acid (2,4-D) due to worldwide pollution caused by using herbicides in agricultural industry. In this regards, two derivatives of polymerizable 1,8-naphthalimide namely, 1,8-naphthalimide containing thiourea (NI) and diethyl amine tagged 1,8-naphthalimide (NII) were used as the receptors and 2,4-D was applied as a template. Also, precipitation polymerization was applied to prepare the fluorescent molecularly imprinted polymer (FMIP). The morphological, structural and thermal analysis was carried out using SEM, TEM, EDS, BET, FTIR, DSC and TGA for characterizing the fluorescent optosensor. The adsorption efficiency of FMIP and FNIP was studied using Langmuir, Freundlich, BET and Redlich Peterson isotherms. The results represented that the adsorption of 2,4-D on FMIP and FNIP agreed the Freundlich adsorption isotherm with correlation coefficient of 0.9935 and 0.9801, respectively. The prepared sensor was able for the selective determination of 2,4-D salt in the linear range of 5 × 10-7-1 × 10-3 M with a limit of detection of 16.8 nM. The present study revealed that the FMIP prepared by 1,8-naphthalimide derivative (NI) could potentially recognize the trace concentration of 2,4-D. Graphical Abstract Graphical abstract of flourescene switching mechanism in a fluorescent molecularly imprinted polymer sensor.


Assuntos
Ácido 2,4-Diclorofenoxiacético/análise , Corantes Fluorescentes/química , Herbicidas/análise , Impressão Molecular , Naftalimidas/química , Polímeros/química , Poluentes Químicos da Água/análise , Corantes Fluorescentes/síntese química , Naftalimidas/síntese química , Tamanho da Partícula , Polímeros/síntese química , Espectrometria de Fluorescência , Propriedades de Superfície
15.
Chem Commun (Camb) ; 56(16): 2431-2434, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31995041

RESUMO

A composite nanosensor based on Zr(iv)-MOFs and PNPP was developed, and was successfully applied for the in situ fluorescence imaging of phosphate and ALP levels in mice with parathyroid dysfunction. The current work provides new ideas for further development of the diagnosis of parathyroid diseases.


Assuntos
Fosfatase Alcalina/análise , Corantes Fluorescentes/química , Estruturas Metalorgânicas/química , Nanopartículas/química , Doenças das Paratireoides/diagnóstico por imagem , Fosfatos/análise , Zircônio/química , Fosfatase Alcalina/metabolismo , Animais , Modelos Animais de Doenças , Corantes Fluorescentes/síntese química , Estruturas Metalorgânicas/síntese química , Camundongos , Doenças das Paratireoides/metabolismo
16.
Chem Commun (Camb) ; 56(16): 2455-2458, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31996872

RESUMO

A group of asymmetric Si-rhodamine scaffolds was designed for protease-activated NIR probes. Dual pH-inertia for both spirocyclized fluorescent probes and fluorescent products of zwitterions form over a wide range of pH (4.0-11.0). Leucine aminopeptidase (LAP) and γ-glutamyl transpeptidase (GGT) were monitored by fluorescent imaging in vivo.


Assuntos
Corantes Fluorescentes/química , Imagem Óptica , Peptídeo Hidrolases/análise , Rodaminas/química , Silício/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/metabolismo , Células HeLa , Humanos , Concentração de Íons de Hidrogênio , Raios Infravermelhos , Estrutura Molecular , Peptídeo Hidrolases/metabolismo , Rodaminas/metabolismo , Silício/metabolismo , Espectrometria de Fluorescência
17.
Chem Commun (Camb) ; 56(16): 2463-2466, 2020 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-31996881

RESUMO

We report an aptamer-tethered, self-assembled DNA nanowire as a multivalent vehicle for the intracellular delivery of FRET flares. The FRET flares are bound to the nanowire and fluorescently labeled donors and acceptors at two ends, respectively. In the absence of targets, the flares are captured by binding with the nanowires, separating the donor and acceptor (low FRET). However, in the presence of target miRNAs, the flares are displaced from the nanowire, subsequently forming hairpin structures that bring the donor and acceptor into close proximity (high FRET).


Assuntos
Aptâmeros de Nucleotídeos/química , Transferência Ressonante de Energia de Fluorescência , Corantes Fluorescentes/química , MicroRNAs/análise , Imagem Óptica , Aptâmeros de Nucleotídeos/síntese química , Corantes Fluorescentes/síntese química , Humanos , Células MCF-7
18.
Photochem Photobiol Sci ; 19(1): 105-113, 2020 Jan 22.
Artigo em Inglês | MEDLINE | ID: mdl-31930262

RESUMO

We report on the light-switch behaviour of two head-to-tail expanded bipyridinium species as a function of their interaction with calf thymus DNA and polynucleotides. In particular, both DNA and polynucleotides containing exclusively adenine or guanine moieties quench the luminescence of the fused expanded bipyridinium species. This behaviour has been rationalized demonstrating that a reductive photoinduced electron transfer process takes place involving both adenine or guanine moieties. The charge separated state so produced recombines in the tens of picoseconds. These results could help in designing new organic substrates for application in DNA probing technology and lab on chip-based sensing systems.


Assuntos
Sondas de DNA/química , DNA/análise , Corantes Fluorescentes/química , Imagem Óptica , Compostos de Piridínio/química , Animais , Bovinos , Sondas de DNA/síntese química , Corantes Fluorescentes/síntese química , Estrutura Molecular , Oxirredução , Compostos de Piridínio/síntese química , Espectroscopia de Luz Próxima ao Infravermelho , Raios Ultravioleta
19.
Food Chem ; 314: 126172, 2020 Jun 01.
Artigo em Inglês | MEDLINE | ID: mdl-31951890

RESUMO

Instant detection of antibiotic residues in dairy products has been remained a challenge. Current methods require careful samples storage and handling, skilled personnel, and expensive instrumentations. Herein, we report the preparation of a ratiometric fluorescent sensor that contains different colored Carbon dots (CDs) as dual fluorophores, and a mesoporous structured molecularly imprinted polymer as a receptor (B/YCDs@mMIP) for penicillin-G (PNG) detection in milk. Upon PNG addition, only the fluorescence of yellow emissive CDs was quenched due to analyte blockage, while that of the blue emissive CDs stayed almost constant, which led to an obvious change in the fluorescence color from the yellow to blue. A linear response in the range of 1-32 nM with a detection limit of 0.34 nM and excellent recognition specificity for PNG over its analogs were also observed. Comparing our sensor with its counterparts, it exhibited a promising potential in the in-situ PNG detection in milk.


Assuntos
Contaminação de Alimentos/análise , Leite/química , Penicilina G/análise , Polímeros/química , Espectrometria de Fluorescência/métodos , Animais , Carbono/química , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/química , Análise de Alimentos/instrumentação , Análise de Alimentos/métodos , Limite de Detecção , Impressão Molecular/métodos , Nanocompostos/química , Pontos Quânticos/química
20.
J Enzyme Inhib Med Chem ; 35(1): 498-505, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31914836

RESUMO

Brain butyrylcholinesterase (BChE) is an attractive target for drugs designed for the treatment of Alzheimer's disease (AD) in its advanced stages. It also potentially represents a biomarker for progression of this disease. Based on the crystal structure of previously described highly potent, reversible, and selective BChE inhibitors, we have developed the fluorescent probes that are selective towards human BChE. The most promising probes also maintain their inhibition of BChE in the low nanomolar range with high selectivity over acetylcholinesterase. Kinetic studies of probes reveal a reversible mixed inhibition mechanism, with binding of these fluorescent probes to both the free and acylated enzyme. Probes show environment-sensitive emission, and additionally, one of them also shows significant enhancement of fluorescence intensity upon binding to the active site of BChE. Finally, the crystal structures of probes in complex with human BChE are reported, which offer an excellent base for further development of this library of compounds.


Assuntos
Amidas/farmacologia , Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/farmacologia , Corantes Fluorescentes/farmacologia , Amidas/síntese química , Amidas/química , Animais , Butirilcolinesterase/isolamento & purificação , Inibidores da Colinesterase/síntese química , Inibidores da Colinesterase/química , Cristalografia por Raios X , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/química , Humanos , Camundongos , Modelos Moleculares , Estrutura Molecular
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