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1.
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
2.
Biochim Biophys Acta Biomembr ; 1862(2): 183109, 2020 02 01.
Artigo em Inglês | MEDLINE | ID: mdl-31785235

RESUMO

Small fluorescent molecules are widely used as probes of biomembranes. Different probes optically indicate membrane properties such as the lipid phase, thickness, viscosity, and electrical potential. The detailed molecular mechanisms behind probe signals are not well understood, in part due to the lack of tools to determine probe position and orientation in the membrane. Optical measurements on aligned biomembranes and lipid bilayers provide some degree of orientational information based on anisotropy in absorption, fluorescence, or nonlinear optical properties. These methods typically find the polar tilt angle between the membrane normal and the long axis of the molecule. Here we show that solution-phase surface enhanced Raman scattering (SERS) spectra of lipid membranes on gold nanorods can be used to determine molecular orientation of molecules within the membrane. The voltage sensitive dye 4-(2-(6-(dibutylamino)-2-naphthalenyl)ethenyl)-1-(3-sulfopropyl)-hydroxide, known as di-4-ANEPPS, is studied. Through the analysis of several peaks in the SERS spectrum, the polar angle from the membrane normal is found to be 66°, and the roll angle around the long axis of the molecule to be 305° from the original orientation. This structural analysis method could help elucidate the meaning of fluorescent membrane probe signals, and how they are affected by different lipid compositions.


Assuntos
2-Naftilamina/análogos & derivados , Corantes Fluorescentes/química , Lauratos/química , Bicamadas Lipídicas/química , Compostos de Piridínio/química , 2-Naftilamina/química , Ouro/química , Nanotubos/química , Fosfolipídeos/química , Análise Espectral Raman/métodos
3.
Mikrochim Acta ; 186(12): 783, 2019 11 15.
Artigo em Inglês | MEDLINE | ID: mdl-31732804

RESUMO

Porous carbon was prepared from wheat flour by alkali treatment and carbonization. The resulting biomass-derived porous carbon (BPC) was employed to prepare a Pt-Au-BPC nanocomposite by a hydrothermal method. The material was then placed on the surface of a carbon ionic liquid electrode (CILE). The Pt-Au-BPC was characterized by SEM, XPS, and the modified CILE by electrochemical methods. They revealed a porous structure, a large specific surface with high conductivity. Pt-Au-BPC/CILE was applied to the sensitive determination of quercetin. Electrochemical response was studied by cyclic voltammetry and differential pulse voltammetry (DPV). Under optimized experimental conditions, the oxidation peak current (measured at 0.48 V vs. Ag/AgCl by DPV) increases linearly in the 0.15 to 6.0 µM and in the 10.0 to 25.0 µM quercetin concentration range. The detection limit is 50.0 nM (at 3σ). The Pt-Au-BPC/CILE was applied to the direct determination of quercetin in ginkgo tablets sample and gave satisfactory results. Graphical abstract A Pt-Au-BPC nanocomposite modified carbon ionic liquid electrode was applied to differential pulse voltammetric determination of quercetin. BPC: biomass-derived porous carbon.


Assuntos
Carbono/química , Nanocompostos/química , Quercetina/análise , Biomassa , Técnicas Eletroquímicas/instrumentação , Técnicas Eletroquímicas/métodos , Eletrodos , Farinha , Ginkgo biloba/química , Ouro/química , Líquidos Iônicos/química , Limite de Detecção , Nanopartículas Metálicas/química , Platina/química , Porosidade , Compostos de Piridínio/química , Reprodutibilidade dos Testes , Comprimidos/análise , Triticum/química
4.
Chem Commun (Camb) ; 55(94): 14135-14138, 2019 Dec 07.
Artigo em Inglês | MEDLINE | ID: mdl-31687696

RESUMO

We report a novel nanostructured chemosensing ensemble PyNp-C13/UD, obtained by self-assembling uranine dye (UD) and an amphiphilic pyridinium salt PyNp-C13. The ensemble was developed for the fluorescence turn-on sensing of ATP in aqueous solutions and inside living cells. The assembly operates via an indicator displacement assay (IDA) method with an ultra-low detection limit of 6.8 nM.


Assuntos
Trifosfato de Adenosina/análise , Fluoresceína/química , Corantes Fluorescentes/química , Nanoestruturas/química , Técnicas Biossensoriais , Fluoresceína/síntese química , Corantes Fluorescentes/síntese química , Compostos de Piridínio/química , Sais/química , Espectrometria de Fluorescência , Tensoativos/química
5.
Chem Commun (Camb) ; 55(81): 12235-12238, 2019 Oct 08.
Artigo em Inglês | MEDLINE | ID: mdl-31552940

RESUMO

A new calixpyridinium-based light-responsive host-guest recognition motif was found in this work. This host-guest recognition motif was further discovered to be applied as a selective turn-on fluorescent sensor for lysine over other natural amino acids.


Assuntos
Corantes Fluorescentes/química , Lisina/química , Compostos Macrocíclicos/química , Fotólise , Compostos de Piridínio/química , Técnicas Biossensoriais/métodos , Interações Hidrofóbicas e Hidrofílicas , Conformação Molecular , Espectrometria de Fluorescência , Água
6.
Environ Toxicol Pharmacol ; 71: 103218, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31302432

RESUMO

A novel panel of oximes were synthesized, which have displayed varying degree of reactivation ability towards different organophosphorus (OP) modified cholinesterases. In the present article, we report a comparative reactivation profile of a series of quaternary pyridinium-oximes for electric eel acetylcholinesterase (EEAChE) inhibited by the organophosphorus (OP) inhibitors methyl paraoxon (MePOX), ethyl paraoxon (POX; paraoxon) and diisopropyl fluorophosphate (DFP) that are distinguishable as dimethoxyphosphoryl, diethoxyphosphoryl and diisopropoxyphosphoryl AChE-OP-adducts. Most of the 59-oximes tested led to faster and more extensive reactivation of MePOX- and POX-inhibited EEAChE as compared to DFP-modified EEAChE. All were effective reactivators of three OP-modified EEAChE conjugates showing 18-21% reactivation for DFP-inhibited AChE and ≥45% reactivation for MePOX- and POX-inhibited EEAChE. Oximes 7 and 8 showed kr values better than pralidoxime (1) for DFP-inhibited EEAChE. Reactivation rates determined at different inhibition times showed no significant change in kr values during 0-90 min incubation with three OPs. However, a 34-72% decrease in kr for MePOX and POX and > 95% decrease in kr for DFP-inhibited EEAChE was observed after 24 h of OP-exposure (aging).


Assuntos
Acetilcolinesterase/metabolismo , Inibidores da Colinesterase/química , Reativadores da Colinesterase/farmacologia , Compostos Organofosforados/química , Oximas/farmacologia , Compostos de Piridínio/farmacologia , Animais , Reativadores da Colinesterase/síntese química , Reativadores da Colinesterase/química , Desenho de Fármacos , Electrophorus , Simulação de Acoplamento Molecular , Estrutura Molecular , Agentes Neurotóxicos/química , Intoxicação por Organofosfatos/enzimologia , Intoxicação por Organofosfatos/prevenção & controle , Oximas/síntese química , Oximas/química , Compostos de Piridínio/síntese química , Compostos de Piridínio/química
7.
Molecules ; 24(12)2019 Jun 25.
Artigo em Inglês | MEDLINE | ID: mdl-31242559

RESUMO

We report a new one-pot synthesis of 2-trifluoromethylated/2-perfluoroalkylated N-aryl-substituted pyridiniums, 5,6,7,8-tetrahydroquinoliniums and 6,7,8,9-tetrahydro-5H-cyclohepta[b]-pyridinium compounds starting from an activated ß-dicarbonyl analogue (here a perfluoro-alkylated gem-iodoacetoxy derivative), an aromatic amine and a (cyclic or acyclic) ketone. The key step of this multicomponent reaction, involves the formation of a 3-perfluoroalkyl-N,N'-diaryl-1,5-diazapentadiene intermediate, various examples of which were isolated and characterized for the first time, together with investigation of their reactivity. We propose a mechanism involving a concurrent inverse electron demand Diels-Alder or Aza-Robinson cascade cyclisation, followed by a bis-de-anilino-elimination. Noteworthy, a meta-methoxy substituent on the aniline directs the reaction towards a 2-perfluoroalkyl-7-methoxyquinoline, resulting from the direct cyclization of the diazapentadiene intermediate, instead of pyridinium formation. This is the first evidence of synthesis of pyridinium derivatives from activated ß-dicarbonyls, ketones, and an aromatic amine, the structures of which (both reactants and products) being analogous to species involved in biological systems, especially upon neurodegenerative diseases such as Parkinson's. Beyond suggesting chemical/biochemical analogies, we thus hope to outline new research directions for understanding the mechanism of in vivo formation of pyridiniums, hence possible pharmaceutical strategies to better monitor, control or prevent it.


Assuntos
Técnicas de Química Sintética , Compostos de Piridínio/síntese química , Fenômenos Químicos , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Compostos de Piridínio/química , Compostos de Piridínio/isolamento & purificação
8.
Colloids Surf B Biointerfaces ; 181: 814-821, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31247406

RESUMO

A series of novel gemini pyridinium surfactants with different alkyl chains were synthesized and characterized. The surface properties and aggregation behavior of the gemini surfactants in solution were studied. The gemini pyridinium salts exhibit higher surface activity than quaternary ammonium salts and can form vesicles above critical micellization concentration (CMC). The antimicrobial performance of these surfactants against E. coli was investigated and compared with those of quaternary ammonium salts. Alkyl chain length has a significant effect on the antimicrobial activity of the gemini surfactants, and the surfactant with decyl group showed more effective antimicrobial activity than quaternary ammonium salts. The high cationic charge density on the polar head group and the strong adsorption tendency confer relatively high antimicrobial of the gemini surfactants.


Assuntos
Antibacterianos/farmacologia , Escherichia coli/efeitos dos fármacos , Compostos de Piridínio/farmacologia , Tensoativos/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Escherichia coli/crescimento & desenvolvimento , Testes de Sensibilidade Microbiana , Estrutura Molecular , Tamanho da Partícula , Compostos de Piridínio/síntese química , Compostos de Piridínio/química , Compostos de Amônio Quaternário/química , Compostos de Amônio Quaternário/farmacologia , Propriedades de Superfície , Tensoativos/síntese química , Tensoativos/química
9.
Talanta ; 201: 330-334, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31122431

RESUMO

A novel ratiometric fluorescence probe for hypochlorous acid was constructed by coumarin and pyridinium fluorophore based on the Forster resonance energy transfer (FRET) and intramolecular charge transfer (ICT) platform. In this ICT/FRET system, the energy transfer efficiency is high to 94.3%. Moreover, the probe could respond to hypochlorous acid with high selectivity and sensitivity, and exhibited a large Stokes shift. It was interesting to find that the probe could recognize hypochlorous acid via a new mechanism, in which the α-position of carbonyl group was oxidized to form a diketone derivative. More importantly, the probe was successfully applied to the ratiometric imaging of both exogenous and endogenous hypochlorous acid in living RAW 264.7 cells, with low toxicity and high photo-stability.


Assuntos
Cumarínicos/química , Corantes Fluorescentes/química , Ácido Hipocloroso/análise , Ácido Hipocloroso/metabolismo , Compostos de Piridínio/química , Animais , Cumarínicos/síntese química , Cumarínicos/efeitos da radiação , Desenho de Fármacos , Fluorescência , Transferência Ressonante de Energia de Fluorescência/métodos , Corantes Fluorescentes/síntese química , Corantes Fluorescentes/efeitos da radiação , Concentração de Íons de Hidrogênio , Luz , Limite de Detecção , Camundongos , Imagem Óptica/métodos , Compostos de Piridínio/síntese química , Compostos de Piridínio/efeitos da radiação , Células RAW 264.7
10.
Talanta ; 199: 140-146, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952238

RESUMO

Small molecules emitting in the NIR for tracking mitochondrial pH alteration with super-resolution are expected to play an essential role in biomedical applications. Herein, two small molecules based on pyridinium salt (P1 and P2) have been synthesized and systematically investigated. It was found that pyridinium salts P1 and P2 emitted in the NIR (about 610 nm), which could detect pH changes from 2.0 to 11.0 with good linearity and high sensitivity. Importantly, P2 could precisely target cellular mitochondria in a real-time manner under stimulated emission depletion (STED). These results implied a chemical strategy with a potential application in super-resolution imaging and mitochondrial pH determination.


Assuntos
Mitocôndrias/química , Compostos de Piridínio/química , Bibliotecas de Moléculas Pequenas/química , Cristalografia por Raios X , Células Hep G2 , Humanos , Concentração de Íons de Hidrogênio , Raios Infravermelhos , Microscopia de Fluorescência , Modelos Moleculares , Estrutura Molecular , Compostos de Piridínio/síntese química , Teoria Quântica , Bibliotecas de Moléculas Pequenas/síntese química
11.
Chem Biol Interact ; 307: 16-20, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-31004594

RESUMO

Bispyridinium oximes with one (K865, K866, K867) or two (K868, K869, K870) ortho-positioned chlorine moiety, analogous to previously known K027, K048 and K203 oximes, and potent reactivators of human acetylcholinesterase (AChE) inhibited by nerve agents, were tested in the reactivation of human butyrylcholinesterase (BChE) inhibited by sarin, cyclosarin, VX, and tabun. A previously highlighted AChE reactivator, dichlorinated bispyridinium oxime with propyl linker (K868), was tested in more detail for reactivation of four nerve agent-BChE conjugates. Its BChE reactivation potency was showed to be promising when compared to the standard oximes used in medical practice, asoxime (HI-6) and pralidoxime (2-PAM), especially in case of sarin and tabun. This finding could be used in the pseudo-catalytic scavenging of the most nerve agents due to its cumulative capacity to reactivate both AChE and BChE.


Assuntos
Butirilcolinesterase/metabolismo , Inibidores da Colinesterase/metabolismo , Agentes Neurotóxicos/metabolismo , Oximas/metabolismo , Butirilcolinesterase/química , Inibidores da Colinesterase/química , Ativação Enzimática/efeitos dos fármacos , Halogenação , Humanos , Cinética , Agentes Neurotóxicos/química , Oximas/química , Oximas/farmacologia , Compostos de Piridínio/química , Sarina/química , Sarina/metabolismo
12.
Org Lett ; 21(8): 2941-2946, 2019 04 19.
Artigo em Inglês | MEDLINE | ID: mdl-30917282

RESUMO

A nickel-catalyzed reductive cross-coupling of alkylpyridinium salts and aryl bromides has been developed using Mn as the reductant. Both primary and secondary alkylpyridinium salts can be used, and high functional group and heterocycle tolerance is observed, including for protic groups. Mechanistic studies indicate the formation of an alkyl radical, and controlling its fate was key to the success of this reaction.


Assuntos
Aminas/química , Bromo , Piridinas/química , Ácidos Borônicos/química , Catálise , Radicais Livres/química , Cloreto de Magnésio , Manganês/química , Níquel/química , Oxirredução , Compostos de Piridínio/química
13.
J Colloid Interface Sci ; 543: 307-316, 2019 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-30825679

RESUMO

In this work the impact of molecular inter-linker size on gold nanoparticle (AuNP) mono-/multilayer structural properties, density and homogeneity has been investigated. These characteristics are of great importance for functional binding of biomolecules. Positively charged high or low molecular weight inter-linkers, poly-L-lysine (PLL) or N-(6-mercapto)hexylpyridinium (MHP), were used to attach negatively charged AuNPs on a planar gold surface as well as to further interlink into a multilayer structure via layer-by-layer deposition. The inter-particle interaction within the assembled AuNP films was adjusted by the ionic strength in the AuNPs dispersions. The AuNP layer density and structural/viscoelastic properties were evaluated by the quartz crystal microbalance with dissipation (QCM-D) technique. The validity of the commercial Voigt model, specifically developed for quantitative QCM-D data analysis of homogeneous viscoelastic films, was evaluated by a model independent analysis when comparing the assembled AuNP films with a homogeneous layer of a mucin from bovine submaxillary glands. Both AuNP mono- and multilayers, attached/interlinked via long flexible PLL molecules assembled to denser and more soft/viscous structures compared to those interlinked by short MHP compounds. Thus, PLL-interlinked AuNP mono-/multilayer structures were further investigated as a platform for laccase enzyme functional adsorption via qualitative assessment of bioelectrochemical characteristics of the enzyme.


Assuntos
Ouro/química , Nanopartículas Metálicas/química , Mucinas/química , Polilisina/química , Compostos de Piridínio/química , Animais , Sítios de Ligação , Bovinos , Físico-Química , Peso Molecular , Tamanho da Partícula , Propriedades de Superfície
14.
Biosci Biotechnol Biochem ; 83(6): 1136-1145, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30822216

RESUMO

Advanced glycation end products (AGEs) are implicated in the development of diabetic complications via the receptor for AGEs (RAGE). We have reported that the 3-hydroxypyridinium (3HP)-containing AGEs derived from α-hydroxyaldehydes physically interact with RAGE and show cytotoxicity. Lactaldehyde (LA) is formed from a reaction between threonine and myeloperoxidase, but no LA-derived AGEs have been characterized. Here, we identify the structure and physiological effects of an AGE derived from LA. We isolated a novel 3HP derivative, 2-acetamido-6-(3-hydroxy-5-methyl-pyridin-1-ium-1-yl)hexanoate, named as N-acetyl-LAPL (lactaldehyde-derived pyridinium-type lysine adduct), from a mixture of LA with Nα-acetyl-L-lysine. LAPL was also detected in the LA-modified protein. LAPL elicited toxicity in PC12 neuronal cells, but the effect was suppressed by the soluble form of RAGE as a decoy receptor. Moreover, surface plasmon resonance-based analysis revealed that LAPL specifically binds to recombinant RAGE. These results indicate that LA generates an AGE containing the 3HP moiety and contributes to RAGE-dependent cytotoxicity. Abbreviations: AGEs: advanced glycation end products; RAGE: receptor for advanced glycation end products; 3HP: 3-hydroxypyridinium; LA: lactaldehyde; LAPL: lactaldehyde-derived pyridinium-type lysine adduct; BSA: bovine serum albumin; GLAP: glyceraldehyde-derived pyridinium; MPO: myeloperoxidase; HFBA: heptafluorobutyric acid; TFA: trifluoroacetic acid; HPLC: high performance liquid chromatography; LC-ESI-QTOF-MS: liquid chromatography-electrospray ionization-quadrupole time-of-flight-mass spectrometry; NMR: nuclear magnetic resonance; LA-BSA: lactaldehyde-modified bovine serum albumin; PBS: phosphate buffered saline, GST, glutathione S-transferase; SPR: surface plasmon resonance; OP-lysine: 2-ammonio-6-(3-oxidopyridinium-1-yl)hexanoate; GLO1: glyoxalase 1; MG, methylglyoxal.


Assuntos
Aldeídos/química , Produtos Finais de Glicação Avançada/química , Produtos Finais de Glicação Avançada/fisiologia , Aldeídos/toxicidade , Animais , Lisina/análogos & derivados , Lisina/química , Estrutura Molecular , Neurônios/efeitos dos fármacos , Células PC12 , Compostos de Piridínio/química , Ratos , Receptor para Produtos Finais de Glicação Avançada/química , Soroalbumina Bovina/química , Propriedades de Superfície
15.
ACS Appl Mater Interfaces ; 11(12): 11227-11237, 2019 Mar 27.
Artigo em Inglês | MEDLINE | ID: mdl-30843393

RESUMO

Recently, luminogens with the aggregation-induced emission characteristic (AIEgens) have received much attention in the field of bioimaging and therapeutic applications. However, the development of AIEgens that are derived from the simple core skeleton with emission color tuning for imaging and therapy is still a formidable challenge. To address this constraint, we present a series of cationic AIEgens based on cyanopyridinium salts (CP1-CP5). The AIEgens can be facilely prepared by varying the aromatic electron donor while fixing the cyanopyridinium group as the electron acceptor within a single benzene ring. The obtained AIEgens possess wide color tunability, large Stokes shifts, and bright emission in the condensed state. Due to their good biocompatibility and cationic nature, these AIEgens can be utilized for multiple-color imaging of intracellular mitochondria as well as Gram-negative and Gram-positive bacteria. Importantly, these AIEgens exhibit remarkable structure-dependent singlet-oxygen generation ability under white light illumination (25 mW cm-2), and CP4 was optimized to serve as an excellent photosensitizer for photodynamic anticancer and antibacterial therapy.


Assuntos
Antibacterianos/química , Corantes Fluorescentes/química , Fármacos Fotossensibilizantes/química , Antibacterianos/farmacologia , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/efeitos da radiação , Desenho de Fármacos , Corantes Fluorescentes/farmacologia , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Células HeLa , Humanos , Luz , Microscopia Confocal , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/patologia , Fármacos Fotossensibilizantes/farmacologia , Compostos de Piridínio/química , Teoria Quântica , Oxigênio Singlete/metabolismo
16.
Bioorg Med Chem ; 27(5): 686-691, 2019 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-30709643

RESUMO

The ene reaction involves the addition of an 'ene' to an 'enophile.' The retro-ene reaction is the reverse of the ene reaction. In recent years various biological molecules have been found to form covalent intermediates (ene-adducts) that might be the result of an ene reactions. Such adducts have been characterized or implicated for dihydropyridines and pyridininum cofactors derived from vitamin B3, such as the reduced and oxidized forms of nicotinamide adenine dinucleotide (NADH/NAD); flavin cofactors derived from vitamin B2, such as flavin adenine dinucleotide, FAD, and flavin mononucleotide, FMN; vitamin C; the oxime intermediate of nitric oxide synthase; tyrosine; and other biomolecules. Given the ubiquitous nature of these cofactors, it might be speculated that the formation of ene-adducts is a more common principle in biochemistry.


Assuntos
Bioquímica , Di-Hidropiridinas/metabolismo , Flavinas/metabolismo , Compostos de Piridínio/metabolismo , Ácido Ascórbico/química , Di-Hidropiridinas/química , Flavinas/química , Modelos Químicos , Monoaminoxidase/metabolismo , Óxido Nítrico Sintase/metabolismo , Compostos de Piridínio/química , Tirosina/química
17.
ACS Appl Mater Interfaces ; 11(11): 10567-10577, 2019 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-30801178

RESUMO

The cell membrane is the protecting frontier of cells, which is crucial for maintaining cell integrity, and has a close relationship with cell growth and death. There is a growing need for cell membrane imaging and monitoring in both living and dying cells. Herein, we report a new amphiphilic tetraphenylethene-based pyridinium salt (TPE-MEM) with aggregation-induced emission features for discriminatory cell membrane imaging. The fluorogenic probe with high yield was synthesized following asymmetric McMurry reaction, Williamson ether synthesis reaction, Suzuki coupling, and aldol condensation between a double-charged pyridinium salt and hexyloxytetraphenylethene benzaldehyde. TPE-MEM shows good water solubility, biocompatibility, and cell membrane specificity. Interestingly, a reactive oxygen species (ROS) is produced by the molecule (TPE-MEM) under room-light irradiation, which could destroy the integrity of the plasma membrane and cause cell necrosis. This enables a visible observation of cell necrosis and the phototherapeutic effect under a mild condition. Preliminary animal investigations also demonstrated the photodynamic therapy (PDT) effectiveness of TPE-MEM in tumor growth inhibition. We conclude that TPE-MEM is potentially a cell membrane-selective photosensitizer for PDT and it is worthy of further exploration of the phototherapeutic effect on animals systematically.


Assuntos
Membrana Celular/química , Luz , Fármacos Fotossensibilizantes/química , Compostos de Piridínio/química , Estilbenos/química , Animais , Membrana Celular/metabolismo , Sobrevivência Celular/efeitos dos fármacos , Corantes Fluorescentes/química , Células HeLa , Humanos , Camundongos , Camundongos Nus , Microscopia Confocal , Neoplasias/tratamento farmacológico , Neoplasias/patologia , Fotoquimioterapia , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/uso terapêutico , Espécies Reativas de Oxigênio/química , Espécies Reativas de Oxigênio/metabolismo , Sais/química , Transplante Heterólogo
18.
J Labelled Comp Radiopharm ; 62(3): 139-145, 2019 03.
Artigo em Inglês | MEDLINE | ID: mdl-30644121

RESUMO

Copper-mediated radiofluorination provides a quick and versatile approach for 18 F-labeling of arenes and heteroarenes. However, this method is known to be base sensitive, which has been a barrier for preparative scale radiosynthesis. In this report, we provide an approach for copper-mediated radiofluorination without azeotropic drying or adding a base. [18 F]Fluoride trapped on a PS-HCO3 Sep-Pak was quantitatively eluted with a solution of 4-dimethylaminopyridinium trifluoromethanesulfonate (DMAP·OTf) in anhydrous N,N-dimethylformamide (DMF). The eluted solution was directly used for copper-mediated radiofluorination. Twelve boronic ester substrates were tested, yielding fluorinated products in 27% to 83% radiochemical yield based on HPLC analysis. This approach was successfully applied to the radiosynthesis of [18 F]flumazenil, a well-known positron emission tomography (PET) tracer for imaging central benzodiazepine receptors, with a radiochemical yield of 47%. This highly efficient protocol significantly augments the powerful copper-mediated radiofluorination approach.


Assuntos
Flumazenil/síntese química , Radioisótopos de Flúor/química , Compostos Radiofarmacêuticos/síntese química , Cobre/química , Dimetilformamida/química , Compostos de Piridínio/química
19.
Colloids Surf B Biointerfaces ; 176: 325-333, 2019 Apr 01.
Artigo em Inglês | MEDLINE | ID: mdl-30641304

RESUMO

The diblock copolymer polystyrene-block-poly(N-methyl 4-vinylpyridine iodide) (PS-b-P4VPQ) with the molecular weight of PS 3.5 × 103 g/mol and P4VPQ 11.6 × 103 g/mol forms core-shell polymer micelles in aqueous solution. The cationic brush shell of the polymer micelle can be used to accommodate hydrophilic drugs and biomolecules, such as DNA, for biomedical applications. It is essential to understand how biomolecules are adsorbed within the brush layer. Here we investigated the interaction of the cationic brush of the polymer micelle with DNA by small angle X-ray scattering (SAXS) and transmission electron microscopy (TEM). It is found when adding only relatively small amounts of on average 30 base pairs (bp) DNA, at 19.6 and 39.2 µM for 0.1 mM PS-b-P4VPQ, most of the polymer micelle/DNA complexes remain well dispersed. The brush layer of the polymer micelles are slightly swelled due to the adsorption of DNA within the brush layer. When the DNA concentration is increased to 58.8 µM or higher, the polymer micelle/DNA complexes form closely packed agglomerates. At high DNA concentrations, some adsorbed DNA will start to build up at the edge or surface of the brush layer which could induce aggregation of the polymer micelle/DNA complexes. This means that it is possible to prepare mostly dispersed polymer/DNA complexes by keeping the DNA concentration below the aggregation concentration. The well dispersed polymer micelle/DNA complexes are advantageous for many DNA related biomedical applications.


Assuntos
DNA/química , Micelas , Poliestirenos/química , Compostos de Piridínio/química , Adsorção , Cátions , Poliestirenos/síntese química , Compostos de Piridínio/síntese química , Espalhamento a Baixo Ângulo , Difração de Raios X
20.
Molecules ; 24(2)2019 Jan 10.
Artigo em Inglês | MEDLINE | ID: mdl-30634707

RESUMO

Electron transfer reactions play a key role for artificial solar energy conversion, however, the underlying reaction mechanisms and the interplay with the molecular structure are still poorly understood due to the complexity of the reaction pathways and ultrafast timescales. In order to investigate such light-induced reaction pathways, a new spectroscopic tool has been applied, which combines UV-vis and resonance Raman spectroscopy at multiple excitation wavelengths with electrochemistry in a thin-layer electrochemical cell to study [RuII(tbtpy)2]2+ (tbtpy = tri-tert-butyl-2,2':6',2''-terpyridine) as a model compound for the photo-activated electron donor in structurally related molecular and supramolecular assemblies. The new spectroscopic method substantiates previous suggestions regarding the reduction mechanism of this complex by localizing photo-electrons and identifying structural changes of metastable intermediates along the reaction cascade. This has been realized by monitoring selective enhancement of Raman-active vibrations associated with structural changes upon electronic absorption when tuning the excitation wavelength into new UV-vis absorption bands of intermediate structures. Additional interpretation of shifts in Raman band positions upon reduction with the help of quantum chemical calculations provides a consistent picture of the sequential reduction of the individual terpyridine ligands, i.e., the first reduction results in the monocation [(tbtpy)Ru(tbtpy•)]⁺, while the second reduction generates [(tbtpy•)Ru(tbtpy•)]0 of triplet multiplicity. Therefore, the combination of this versatile spectro-electrochemical tool allows us to deepen the fundamental understanding of light-induced charge transfer processes in more relevant and complex systems.


Assuntos
Fotoquímica/métodos , Compostos de Piridínio/química , Rutênio/química , Transporte de Elétrons , Modelos Químicos , Estrutura Molecular , Energia Solar , Análise Espectral Raman
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