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1.
Chem Commun (Camb) ; 56(7): 1105-1108, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31894766

RESUMO

A series of hydrogen-bonded liquid crystals based on resveratrol and resveratrone is reported and investigated with respect to their photo-switchability (at 405 nm) and photo-cyclisation (at 300 nm).

2.
Soft Matter ; 15(36): 7117-7121, 2019 Sep 18.
Artigo em Inglês | MEDLINE | ID: mdl-31503269

RESUMO

In this contribution we describe a novel hydrogelator based on four guadiniumcarbonylpyrrole units in combination with aggregation-induced emission active aromatic thioethers which undergo self-assembly into fibrills in aqueous media as visible in AFM and TEM measurements. These fibrills are weakly luminescent and unable to induce gelation. Upon addition of malonic acid a cross-linking of the single fibres was detected leading to the formation of a highly emissive stable hydrogel. This gel responds to several external stimuli such as heat, shaking as well as pH changes.

3.
Chem Asian J ; 14(6): 814-820, 2019 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-30478991

RESUMO

In this contribution, we present the synthesis and self-assembly of alkylated thioethers with interesting photophysical properties. To this end, the emission, absorption and excitation spectra in organic solvents and as aggregates in water were measured as well as the corresponding photoluminescence quantum yields and lifetimes. The aggregates in aqueous media were visualized and measured using transmission electron microscopy. Besides that, crystal structures of selected compounds allowed a detailed discussion of the structure-property relationship. Furthermore, the mesomorphic behavior was investigated using polarized optical microscopy (POM) as well as differential scanning calorimetry (DSC).

4.
ACS Appl Mater Interfaces ; 11(1): 104-114, 2019 Jan 09.
Artigo em Inglês | MEDLINE | ID: mdl-30560648

RESUMO

Fungal infections are a growing global health and agricultural threat, and current chemical antifungals may induce various side-effects. Thus, nanoparticles are investigated as potential novel antifungals. We report that nanoparticles' antifungal activity strongly depends on their binding to fungal spores, focusing on the clinically important fungal pathogen Aspergillus fumigatus as well as common plant pathogens, such as Botrytis cinerea. We show that nanoparticle-spore complex formation was enhanced by the small nanoparticle size rather than the material, shape or charge, and could not be prevented by steric surface modifications. Fungal resistance to metal-based nanoparticles, such as ZnO-, Ag-, or CuO-nanoparticles as well as dissolution-resistant quantum dots, was mediated by biomolecule coronas acquired in pathophysiological and ecological environments, including the lung surfactant, plasma or complex organic matters. Mechanistically, dose-dependent corona-mediated resistance occurred via reducing physical adsorption of nanoparticles to fungal spores. The inhibitory effect of biomolecules on the antifungal activity of Ag-nanoparticles was further verified in vivo, using the invertebrate Galleria mellonella as an A. fumigatus infection model. Our results explain why current nanoantifungals often show low activity in realistic application environments, and will guide nanomaterial designs that maximize functionality and safe translatability as potent antifungals for human health, biotechnology, and agriculture.


Assuntos
Antifúngicos , Aspergillus fumigatus/crescimento & desenvolvimento , Farmacorresistência Fúngica/efeitos dos fármacos , Nanopartículas Metálicas , Coroa de Proteína/química , Animais , Antifúngicos/química , Antifúngicos/farmacologia , Botrytis , Modelos Animais de Doenças , Humanos , Nanopartículas Metálicas/química , Nanopartículas Metálicas/uso terapêutico , Camundongos , Mariposas , Doenças das Plantas , Aspergilose Pulmonar/tratamento farmacológico , Aspergilose Pulmonar/metabolismo , Aspergilose Pulmonar/patologia
5.
Soft Matter ; 14(30): 6166-6170, 2018 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-29966031

RESUMO

Functionalising AIE-active aromatic thioethers with self-complementary zwitterionic binding sites leads to a dual pH-responsive supramolecular organogelator with aggregation-induced emission (AIE) properties. The self-assembled fibrillar gel network is highly fluorescent (λem = 490 nm), whereas the addition of both acid and base leads to the sol state with a loss of emission. More over, the gel was found to be thermo- and mechanoresponsive.

6.
Chemistry ; 24(47): 12221-12230, 2018 Aug 22.
Artigo em Inglês | MEDLINE | ID: mdl-29573003

RESUMO

This minireview deals with the phenomenon of room-temperature phosphorescence induced by aggregation or crystallisation. Recent achievements, as well as novel classes of these unique luminophores, are put in to focus. In this fashion, different compounds, which reveal delayed fluorescence or phosphorescence upon fixation in a crystal lattice or within aggregates are described. Furthermore, the photophysical properties, the origin of the long-lived triplet states, and the possible applications of these fascinating classes of molecules are also discussed. To conclude, a short overview about the state of art in the field of pure organic phosphors at room temperature is presented.

7.
NPJ Sci Food ; 2(1): 22, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30882042

RESUMO

Nanotechnology provides the food industry with new ways to modulate various aspects of food. Hence, engineered nanoparticles (NPs) are increasingly added to food and beverage products as functional ingredients. However, the impact of engineered as well as naturally occurring NPs on both commensal and pathogenic microorganisms within the gastrointestinal tract (GI) is not fully understood. Here, well-defined synthetic NPs and bacterial models were used to probe nanoparticle-bacteria interactions, from analytical to in situ to in vitro. NP-bacteria complexation occurred most efficiently for small NPs, independent of their core material or surface charge, but could be reduced by NPs' steric surface modifications. Adsorption to bacteria could also be demonstrated for naturally occurring carbon NPs isolated from beer. Complex formation affected the (patho)biological behavior of both the NPs and bacteria, including their cellular uptake into epithelial cells and phagocytes, pathogenic signaling pathways, and NP-induced cell toxicity. NP-bacteria complex formation was concentration-dependently reduced when the NPs became coated with biomolecule coronas with sequential simulation of first oral uptake and then the GI. However, efficient NP adsorption was restored when the pH was sufficiently low, such as in simulating the conditions of the stomach. Collectively, NP binding to enteric bacteria may impact their (patho)biology, particularly in the stomach. Nanosized-food additives as well as naturally occurring NPs may be exploited to (rationally) shape the microbiome. The information contained in this article should facilitate a "safe by design" strategy for the development and application of engineered NPs as functional foods ingredients.

8.
Langmuir ; 33(43): 12443-12452, 2017 10 31.
Artigo em Inglês | MEDLINE | ID: mdl-28980816

RESUMO

We have developed a model system for membrane fusion that utilizes lipidated derivatives of a heterodimeric coiled-coil pair dubbed E3 (EIAALEK)3 and K3 (KIAALKE)3. In this system, peptides are conjugated to a lipid anchor via a poly(ethylene glycol) (PEG) spacer, and this contribution studies the influence of the PEG spacer length, coupled with the type of lipid anchor, on liposome-liposome fusion. The effects of these modifications on peptide secondary structure, their interactions with liposomes, and their ability to mediate fusion were studied using a variety of different content mixing experiments and CD spectroscopy. Our results demonstrate the asymmetric role of the peptides in the fusion process because alterations to the PEG spacer length affect E3 and K3 differently. We conclude that negatively charged E3 acts as a "handle" for positively charged K3 and facilitates liposome docking, the first stage of the fusion process, through coiled-coil formation. The efficacy of this E3 handle is enhanced by longer spacer lengths. K3 directs the fusion process via peptide-membrane interactions, but the length of the PEG spacer plays two competing roles: a PEG4/PEG8 spacer length is optimal for membrane destabilization; however, a PEG12 spacer increases the fusion efficiency over time by improving the peptide accessibility for successive fusion events. Both the anchor type and spacer length affect the peptide structure; a cholesterol anchor appears to enhance K3-membrane interactions and thus mediates fusion more efficiently.


Assuntos
Peptídeos/química , Lipídeos , Lipossomos , Fusão de Membrana , Estrutura Secundária de Proteína
9.
Chemistry ; 23(63): 16059-16065, 2017 Nov 13.
Artigo em Inglês | MEDLINE | ID: mdl-28885759

RESUMO

We report the inclusion of carboxy- and amine-substituted molecular nanodiamonds (NDs) adamantane, diamantane, and triamantane by ß-cyclodextrin and γ-cyclodextrin (ß-CD and γ-CD), which have particularly well-suited hydrophobicity and symmetry for an optimal fit of the host and guest molecules. We studied the host-guest interactions in detail and generally observed 1:1 association of the NDs with the larger γ-CD cavity, but observed 1:2 association for the largest ND in the series (triamantane) with ß-CD. We found higher binding affinities for carboxy-substituted NDs than for amine-substituted NDs. Additionally, cyclodextrin vesicles (CDVs) were decorated with d-mannose by using adamantane, diamantane, and triamantane as non-covalent anchors, and the resulting vesicles were compared with the lectin concanavalin A in agglutination experiments. Agglutination was directly correlated to the host-guest association: adamantane showed lower agglutination than di- or triamantane with ß-CDV and almost no agglutination with γ-CDV, whereas high agglutination was observed for di- and triamantane with γ-CDV.


Assuntos
Nanodiamantes/química , Nanoestruturas/química , beta-Ciclodextrinas/química , gama-Ciclodextrinas/química , Adamantano/química , Calorimetria , Espectroscopia de Ressonância Magnética , Manose/química , Rotação Ocular , Termodinâmica
10.
Chemistry ; 23(55): 13660-13668, 2017 Oct 04.
Artigo em Inglês | MEDLINE | ID: mdl-28661014

RESUMO

Here we report on a novel system based on aromatic thioethers with unique luminescence properties. Fifteen different compounds were investigated in detail on their luminescence properties using UV/Vis absorption and steady-state and time-resolved luminescence spectroscopy. Excited state lifetimes as well as quantum yields were determined, and the toxicity towards HeLa cells was investigated. Besides X-ray analyses also quantum chemical calculations were performed to gain deeper insights in the unique behavior of this facile system. The studied compounds reveal remarkable fluorescence emission ranging from 437 to 588 nm as well as phosphorescence (up to 5 µs).

11.
RSC Adv ; 7(86): 54341-54346, 2017 Nov 29.
Artigo em Inglês | MEDLINE | ID: mdl-29568508

RESUMO

Supramolecular amphiphiles, consisting of ternary complexes of cucurbit[8]uril (CB[8]), an alkylated paraquat derivative and a tetraethylene glycol-functionalized azobenzene, self-assemble into vesicles of about 200 nm in diameter. The outer surface of the vesicles was functionalized with cell-targeting ligands. These vesicles were employed for loading and delivery of proteins into cells. Supramolecular amphiphile-derived vesicles show great promise as nanocarriers of functional molecules to be transferred into cells.

13.
Org Biomol Chem ; 14(24): 5574-9, 2016 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-26972230

RESUMO

The synthesis and self-assembly of a new C2-symmetric oligohistidine amphiphile equipped with an aggregation induced emission luminophore is reported. We observe the formation of highly stable and ordered rod-like micelles in phosphate buffered saline, with a critical aggregation concentration below 200 nM. Aggregation induced emission of the luminophore confirms the high stability of the anisotropic assemblies in serum.


Assuntos
Histidina/química , Luminescência , Histidina/análogos & derivados , Histidina/síntese química , Micelas , Tamanho da Partícula
14.
Chem Commun (Camb) ; 52(9): 1964-6, 2016 Jan 31.
Artigo em Inglês | MEDLINE | ID: mdl-26685989

RESUMO

Surface immobilised polymer brushes containing azobenzene units were prepared using a combination of microcontact chemistry and surface-initiated atom transfer radical polymerisation (SI-ATRP). These brushes were investigated using AFM, XPS and UV/vis spectroscopy. It was shown that two surfaces bearing azobenzene brushes can be glued together in the presence of a ß-cyclodextrin polymer and hold as much as 700 ± 150 g cm(-2).

15.
Small ; 11(46): 6187-96, 2015 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-26469773

RESUMO

In this work, the development of a photoresponsive platform for the presentation of bioactive ligands to study receptor-ligand interactions has been described. For this purpose, supramolecular host-guest chemistry and supported lipid bilayers (SLBs) have been combined in a microfluidic device. Quartz crystal microbalance with dissipation monitoring (QCM-D) studies on methyl viologen (MV)-functionalized oligo ethylene glycol-based self-assembled monolayers, gel and liquid-state SLBs have been compared for their nonfouling properties in the case of ConA and bacteria. In combination with bacterial adhesion test, negligible nonspecific bacterial adhesion is observed only in the case of methyl-viologen-modified liquid-state SLBs. Therefore, liquid-state SLBs have been identified as most suitable for studying specific cell interactions when MV is incorporated as a guest on the surface. The photoswitchable supramolecular ternary complex is formed by assembling cucurbit[8]uril (CB[8]) and an azobenzene-mannose conjugate (Azo-Man) onto MV-functionalized liquid-state SLBs and the assembly process has been characterized using QCM-D and fluorescence techniques. Mannose has been found to enable binding of E. coli via cell-surface receptors on the nonfouling supramolecular SLBs. Optical switching of the azobenzene moiety allows us to "erase" the bioactive surface after bacterial binding, providing the potential to develop reusable sensors. Localized photorelease of bacterial cells has also been shown indicating the possibility of optically guiding cellular growth, migration, and intercellular interactions.


Assuntos
Aderência Bacteriana/efeitos da radiação , Hidrocarbonetos Aromáticos com Pontes/farmacologia , Escherichia coli/citologia , Imidazóis/farmacologia , Bicamadas Lipídicas/química , Raios Ultravioleta , Aderência Bacteriana/efeitos dos fármacos , Células Imobilizadas/citologia , Células Imobilizadas/efeitos dos fármacos , Células Imobilizadas/efeitos da radiação , Escherichia coli/efeitos dos fármacos , Escherichia coli/efeitos da radiação , Isomerismo , Paraquat/farmacologia , Técnicas de Microbalança de Cristal de Quartzo , Espectrometria de Fluorescência
16.
Chemistry ; 21(8): 3271-7, 2015 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-25585879

RESUMO

The development of an effective and general delivery method that can be applied to a large variety of structurally diverse biomolecules remains a bottleneck in modern drug therapy. Herein, we present a supramolecular system for the dynamic trapping and light-stimulated release of both DNA and proteins. Self-assembled ternary complexes act as nanoscale carriers, comprising vesicles of amphiphilic cyclodextrin, the target biomolecules and linker molecules with an azobenzene unit and a charged functionality. The non-covalent linker binds to the cyclodextrin by host-guest complexation with the azobenzene. Proteins or DNA are then bound to the functionalized vesicles through multivalent electrostatic attraction. The photoresponse of the host-guest complex allows a light-induced switch from the multivalent state that can bind the biomolecules to the low-affinity state of the free linker, thereby providing external control over the cargo release. The major advantage of this delivery approach is the wide variety of targets that can be addressed by multivalent electrostatic interaction, which we demonstrate on four types of DNA and six different proteins.


Assuntos
Compostos Azo/química , Ciclodextrinas/química , DNA/química , Proteínas/química , DNA/metabolismo , Luz , Estrutura Molecular , Ligação Proteica , Proteínas/metabolismo , Eletricidade Estática
17.
Soft Matter ; 10(48): 9746-51, 2014 Dec 28.
Artigo em Inglês | MEDLINE | ID: mdl-25367891

RESUMO

Controlled fusion events between natural membranes composed of phospholipids with synthetic unnatural membranes will yield valuable fundamental information on the mechanism of membrane fusion. Here, fusion between vastly different phospholipid liposomes and cyclodextrin amphiphile based vesicles (CDVs) controlled by a pair of coiled coil forming lipidated peptides was investigated. Fusion events were characterized using lipid and content mixing assays and the resulting hybrid assemblies were characterized with cryo-TEM imaging. The secondary/quaternary structure of the lipidated peptides at the membrane interface was studied using circular dichroism spectroscopy. This is the first example of targeted fusion between natural and non-natural bilayer membranes and the in situ formation of hybrid CDV-liposome structures is of interest as it yields fundamental information about the mechanism through which fusion proceeds.


Assuntos
Ciclodextrinas/química , Lipossomos/química , Fusão de Membrana , Peptídeos/química , Fosfolipídeos/química
18.
Angew Chem Int Ed Engl ; 53(13): 3400-4, 2014 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-24615852

RESUMO

Supramolecular nanoparticles (SNPs) encompass multiple copies of different building blocks brought together by specific noncovalent interactions. The inherently multivalent nature of these systems allows control of their size as well as their assembly and disassembly, thus promising potential as biomedical delivery vehicles. Here, dual responsive SNPs have been based on the ternary host-guest complexation between cucurbit[8]uril (CB[8]), a methyl viologen (MV) polymer, and mono- and multivalent azobenzene (Azo) functionalized molecules. UV switching of the Azo groups led to fast disruption of the ternary complexes, but to a relatively slow disintegration of the SNPs. Alternating UV and Vis photoisomerization of the Azo groups led to fully reversible SNP disassembly and reassembly. SNPs were only formed with the Azo moieties in the trans and the MV units in the oxidized states, respectively, thus constituting a supramolecular AND logic gate.

19.
Curr Opin Chem Biol ; 18: 1-7, 2014 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-24534746

RESUMO

Microcontact printing (µCP) techniques are powerful tools to print molecules on reactive surfaces in a covalent or non-covalent manner to produce well-defined patterns, in shape and spot morphology, of bioactive molecules such as carbohydrates, peptides and proteins. These printed biofunctional surfaces have nowadays found increased use in a range of bioanalytical and biomedical applications, for example, in the investigation of eukaryotic cell and bacteria behavior on solid supports. This review focuses on advances in techniques of µCP over the past three years and some recent appealing applications of the printed arrays are illustrated.


Assuntos
Carboidratos/análise , Análise em Microsséries/métodos , Peptídeos/análise , Proteínas/análise , Humanos
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