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Azo-Based Fluorogenic Probes for Biosensing and Bioimaging: Recent Advances and Upcoming Challenges.Chemistry, An Asian Journal Aug 2017The use of nonfluorescent azo dyes as dark quenchers in activatable optical bioprobes based on the Förster resonance energy transfer (FRET) mechanism and designed to... (Review)
Review
The use of nonfluorescent azo dyes as dark quenchers in activatable optical bioprobes based on the Förster resonance energy transfer (FRET) mechanism and designed to target a wide range of enzymes has been established for over two decades. The key value of the azo moiety (-N=N-) to act as an efficient "ON-OFF" switch of fluorescence once introduced within the core structure of conventional organic-based fluorophores (mainly fluorescent aniline derivatives) has recently been exploited in the development of alternative reaction-based small-molecule probes based on the "profluorescence" concept. These unprecedented "azobenzene-caged" fluorophores are valuable tools for the detection of a wide range of reactive (bio)analytes. This review highlights the most recent and relevant advances made in the design and biosensing/bioimaging applications of azo-based fluorogenic probes. Emphasis is also placed on relevant achievements in the synthesis of bioconjugatable/biocompatible azo dyes used as starting building blocks in the rational and rapid construction of these fluorescent chemodosimeters. Finally, a brief glimpse of possible future biomedical applications (theranostics) of these "smart" azobenzene-based molecular systems is presented.
Topics: Azo Compounds; Biosensing Techniques; Fluorescent Dyes; Optical Imaging
PubMed: 28594477
DOI: 10.1002/asia.201700682 -
Mini Reviews in Medicinal Chemistry 2019In this review, specific therapeutic and medicinal advantages including antiviral, antibacterial, antifungal and antitumor, strategies for drug designing,... (Review)
Review
In this review, specific therapeutic and medicinal advantages including antiviral, antibacterial, antifungal and antitumor, strategies for drug designing, structure-activity relationship, advances in the syntheses of azo and hippuric acid derivatives of more than 50 compounds have been discussed since 2009-2018. It is found that phenyl-diazenyl azo derivatives and pyridinyl substituted hippuric acid derivatives showed promising antiretroviral potential. The incorporation of azo functionality to the respective quinolones and coumarin moieties and the insertion of thiocarbazone to hippuric acid displayed immense antibacterial activities. While, azo and hippuric acid derivatives of triazole and phenyl species gave maximum fungicidal as well as cytotoxic activities.
Topics: Animals; Anti-Infective Agents; Antineoplastic Agents; Azo Compounds; Bacterial Infections; Drug Design; Hippurates; Humans; Mycoses; Neoplasms; Structure-Activity Relationship; Virus Diseases
PubMed: 30058483
DOI: 10.2174/1389557518666180727162018 -
Chemistry (Weinheim An Der Bergstrasse,... Nov 2022Molecular switches have been used as delivery vehicles for various molecular and ionic species. The ones that reversibly operate with light are arguably the best... (Review)
Review
Molecular switches have been used as delivery vehicles for various molecular and ionic species. The ones that reversibly operate with light are arguably the best candidates for the purpose as they can be operated using light. The two states of these photoswitchable systems often possess remarkable differences in terms of their structural features and electronic properties. Photochromic systems with the appropriate embellishment of functionalities at suitable positions have thus been used as photoresponsive receptors. The use of light-driven alterations of the structural features has led to differential molecular recognition with these switchable host molecules. In this article, we discuss the use of such supramolecular systems as the delivery vehicles for ions and molecules that started with the pioneering work by Shinkai back in 1979. This review will explicitly cover the development from 2001 to 2022 with some past background and the future prospects of the field.
Topics: Azo Compounds; Ions
PubMed: 35959934
DOI: 10.1002/chem.202201902 -
Organic & Biomolecular Chemistry Feb 2015Carbohydrate-protein binding is a supramolecular recognition process that underpins myriad biological events. However, the precise conformational and configurational... (Review)
Review
Carbohydrate-protein binding is a supramolecular recognition process that underpins myriad biological events. However, the precise conformational and configurational requirements for biomolecular recognition are often poorly understood, since such phenomena often occur in a strongly spatiotemporal manner. Photoswitchable glycoconjugates have emerged as promising investigational tools for probing carbohydrate-protein recognition and for controlling bacterial adhesion. Reversible photoisomerisation, in particular that of azobenzene glycoconjugates, has also been exploited as a promising strategy for controlling supramolecular self-assembly and macroscopic properties, thereby facilitating the development of light responsive carbohydrate-based materials. The following review will highlight the recent advances in the design and applications of photoswitchable glycoconjugates, paying particular attention to the application of light as a stimulus for modulating protein and cellular adhesion, amphiphilicity and supramolecular assembly of carbohydrate-based materials.
Topics: Azo Compounds; Glycoconjugates; Light; Photochemical Processes
PubMed: 25573270
DOI: 10.1039/c4ob02296c -
ChemSusChem Jan 2015Diazo compounds are very versatile reagents in organic chemistry and meet the challenge of selective assembly of structurally complex molecules. Their leaving group is... (Review)
Review
Diazo compounds are very versatile reagents in organic chemistry and meet the challenge of selective assembly of structurally complex molecules. Their leaving group is dinitrogen; therefore, they are very clean and atom-efficient reagents. However, diazo compounds are potentially explosive and extremely difficult to handle on an industrial scale. In this review, it is discussed how continuous flow technology can help to make these powerful reagents accessible on large scale. Microstructured devices can improve heat transfer greatly and help with the handling of dangerous reagents safely. The in situ formation and subsequent consumption of diazo compounds are discussed along with advances in handling diazomethane and ethyl diazoacetate. The potential large-scale applications of a given methodology is emphasized.
Topics: Azo Compounds; Diazomethane; Diazonium Compounds; Safety
PubMed: 25488620
DOI: 10.1002/cssc.201402874 -
Molecules (Basel, Switzerland) Jul 2022The rational design of small building block molecules and understanding their molecular assemblies are of fundamental importance in creating new stimuli-responsive...
The rational design of small building block molecules and understanding their molecular assemblies are of fundamental importance in creating new stimuli-responsive organic architectures with desired shapes and functions. Based on the experimental results of light-induced conformational changes of four types of triangular azo dyes with different terminal functional groups, as well as absorption and fluorescence characteristics associated with their molecular assemblies, we report that aggregation-active emission enhancement (AIEE)-active compound () substituted with sterically crowded -butyl (-Bu) groups showed approximately 35% light-induced molecular switching and had a strong tendency to assemble into highly stable hexagonal structures with AIEE characteristics. Their sizes were regulated from nanometer-scale hexagonal rods to micrometer-scale sticks depending on the concentration. This is in contrast to other triangular compounds with bromo (Br) and triphenylamine (TPA) substituents, which exhibited no photoisomerization and tended to form flexible fibrous structures. Moreover, non-contact exposure of the fluorescent hexagonal nanorods to ultraviolet (UV) light led to a dramatic hexagonal-to-amorphous structure transition. The resulting remarkable variations, such as in the contrast of microscopic images and fluorescence characteristics, were confirmed by various microscopic and spectroscopic measurements.
Topics: Azo Compounds; Fluorescent Dyes; Spectrum Analysis
PubMed: 35889253
DOI: 10.3390/molecules27144380 -
International Microbiology : the... May 2020Azo dyes are aromatic compounds with one to many -N=N- groups as well as the leading class of synthetic dyes utilised in commercial solicitations. Azo dyes, released in... (Review)
Review
Azo dyes are aromatic compounds with one to many -N=N- groups as well as the leading class of synthetic dyes utilised in commercial solicitations. Azo dyes, released in the environment through textile effluents, have hazardous effects on the aquatic as well as human life. Their persistence and discharge into the environment are becoming a global concern; thus, the remediation of these contaminants has acquired great attention. The current review comprehensively discusses some of the main aspects of biodegradation of azo dyes. A variety of physicochemical approaches has already been utilised for treatment of textile effluents counting filtration, coagulation and chemical flocculation. Though these conventional techniques are effective, yet they are lavish and also comprise formation of concentrated sludge that makes a secondary disposal problem. In this regard, microbial usage is an effective, economical, bio-friendly and ecologically benign approach.
Topics: Azo Compounds; Bacteria; Biodegradation, Environmental; Fungi; Humans; Industrial Waste; Microalgae; Plants; Water Pollutants, Chemical
PubMed: 31741129
DOI: 10.1007/s10123-019-00103-2 -
Nature Methods May 2019We report the identification of a photocleavable anionic surfactant, 4-hexylphenylazosulfonate (Azo), which can be rapidly degraded by ultraviolet irradiation, for...
We report the identification of a photocleavable anionic surfactant, 4-hexylphenylazosulfonate (Azo), which can be rapidly degraded by ultraviolet irradiation, for top-down proteomics. Azo can effectively solubilize proteins with performance comparable to that of sodium dodecyl sulfate (SDS) and is compatible with mass spectrometry. Azo-aided top-down proteomics enables the solubilization of membrane proteins for comprehensive characterization of post-translational modifications. Moreover, Azo is simple to synthesize and can be used as a general SDS replacement in SDS-polyacrylamide gel electrophoresis.
Topics: Azo Compounds; Electrophoresis, Polyacrylamide Gel; Hydrophobic and Hydrophilic Interactions; Mass Spectrometry; Membrane Proteins; Photolysis; Proteomics; Sodium Dodecyl Sulfate; Solubility; Surface-Active Agents; Ultraviolet Rays
PubMed: 30988469
DOI: 10.1038/s41592-019-0391-1 -
European Journal of Pharmacology Jan 2023NMDA receptors play critical roles in numerous physiological and pathological processes in CNS that requires development of modulating ligands. In particular,...
NMDA receptors play critical roles in numerous physiological and pathological processes in CNS that requires development of modulating ligands. In particular, photoswitchable compounds that selectively target NMDA receptors would be particularly useful for analysis of receptor contributions to various processes. Recently, we identified a light-dependent anti-NMDA activity of the azobenzene-containing quaternary ammonium compounds DENAQ (diethylamine-azobenzene-quaternary ammonium) and DMNAQ (dimethylamine-azobenzene-quaternary ammonium). Here, we developed a series of light-sensitive compounds based on the DENAQ structure, and studied their action on glutamate receptors in rat brain neurons using patch-clamp method. We found that the activities of the compounds and the influence of illumination strongly depended on the structural details, as even minor structural modifications greatly altered the activity and sensitivity to illumination. The compound PyrAQ (pyrrolidine-azobenzene-quaternary ammonium) was the most active and produced fast and fully reversible inhibition of NMDA receptors. The IC values under ambient and monochromic light conditions were 2 and 14 μM, respectively. The anti-AMPA activity was much weaker. The action of PyrAQ did not depend on NMDA receptor activity, agonist concentration, or membrane voltage, making it a useful tool for photopharmacological studies.
Topics: Animals; Rats; Ammonium Compounds; Azo Compounds; Receptors, Glutamate; Receptors, N-Methyl-D-Aspartate
PubMed: 36470444
DOI: 10.1016/j.ejphar.2022.175448 -
Soft Matter Jan 2023Fluorescent protein biomaterials have important applications such as bioimaging in pharmacological studies. Self-assembly of proteins, especially into fibrils, is known...
Fluorescent protein biomaterials have important applications such as bioimaging in pharmacological studies. Self-assembly of proteins, especially into fibrils, is known to produce fluorescence in the blue band. Capable of self-assembly into nanofibers, we have shown we can modulate its aggregation into mesofibers by encapsulation of a small hydrophobic molecule. Conversely, azobenzenes are hydrophobic small molecules that are virtually non-fluorescent in solution due to their highly efficient photoisomerization. However, they demonstrate fluorogenic properties upon confinement in nanoscale assemblies by reducing the non-radiative photoisomerization. Here, we report the fluorescence of a hybrid protein-small molecule system in which azobenzene is confined in our protein assembly leading to fiber thickening and increased fluorescence. We show our engineered protein Q encapsulates AzoCholine, bearing a photoswitchable azobenzene moiety, in the hydrophobic pore to produce fluorescent mesofibers. This study further investigates the photocontrol of protein conformation as well as fluorescence of an azobenze-containing biomaterial.
Topics: Proteins; Protein Conformation; Azo Compounds
PubMed: 36538008
DOI: 10.1039/d2sm01578a