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1.
Bioconjug Chem ; 35(8): 1200-1206, 2024 Aug 21.
Artigo em Inglês | MEDLINE | ID: mdl-38982902

RESUMO

Glycoamphiphiles have attracted considerable interest in a broad range of application fields owing to their solution and bulk-state self-assembly abilities. Despite their importance, the straightforward synthesis of glycoamphiphiles consisting of a hydrophilic carbohydrate linked to a hydrophobic aglycone remains one of the major challenges in glycosciences. Here, a rapid, simple, and efficient synthetic access to chemically stable glycoamphiphiles at physiological pH, namely, N-(ß-d-glycosyl)-2-alkylbenzamide, is reported. It leverages the nonreductive amination of unprotected carbohydrates with ortho-substituted aniline derivatives which could be readily obtained by reacting commercially available primary alkylamines with isatoic anhydride. This strategy avoids protection and deprotection of sugar hydroxyl groups and the use of reductive agents, which makes it advantageous in terms of atom and step economy. Moreover, in order to circumvent the cons of classical N-aryl glycosylation, we investigate the use of microwave as a heat source that provides fast, clean, and high-yield ß-N-arylation of unprotected carbohydrates. Their self-assembly into water led to multiple morphologies of dynamic supramolecular glycoamphiphiles that were characterized to assess their ability to bind to lectins from pathogenic bacteria. Biophysical interactions probed by isothermal titration microcalorimetry revealed micromolar affinities for most of the synthesized glycoamphiphiles.


Assuntos
Lectinas , Micro-Ondas , Lectinas/química , Glicosilação , Carboidratos/química
2.
Molecules ; 27(9)2022 Apr 28.
Artigo em Inglês | MEDLINE | ID: mdl-35566173

RESUMO

Background: Parkinson's disease (PD) is the second most common age-related neurodegenerative disorder. Levodopa (L-DOPA) remains the gold-standard drug available for treating PD. Curcumin has many pharmacological activities, including antioxidant, anti-inflammatory, antimicrobial, anti-amyloid, and antitumor properties. Copolymers composed of Poly (ethylene oxide) (PEO) and biodegradable polyesters such as Poly (ε-caprolactone) (PCL) can self-assemble into nanoparticles (NPs). This study describes the development of NH2-PEO-PCL diblock copolymer positively charged and modified by adding glutathione (GSH) on the outer surface, resulting in a synergistic delivery of L-DOPA curcumin that would be able to pass the blood-brain barrier. Methods: The NH2-PEO-PCL NPs suspensions were prepared by using a nanoprecipitation and solvent displacement method and coated with GSH. NPs were submitted to characterization assays. In order to ensure the bioavailability, Vero and PC12 cells were treated with various concentrations of the loaded and unloaded NPs to observe cytotoxicity. Results: NPs have successfully loaded L-DOPA and curcumin and were stable after freeze-drying, indicating advancing into in vitro toxicity testing. Vero and PC12 cells that were treated up to 72 h with various concentrations of L-DOPA and curcumin-loaded NP maintained high viability percentage, indicating that the NPs are biocompatible. Conclusions: NPs consisting of NH2-PEO-PCL were characterized as potential formulations for brain delivery of L-DOPA and curcumin. The results also indicate that the developed biodegradable nanomicelles that were blood compatible presented low cytotoxicity.


Assuntos
Curcumina , Nanopartículas , Doença de Parkinson , Animais , Curcumina/farmacologia , Portadores de Fármacos , Levodopa , Doença de Parkinson/tratamento farmacológico , Poliésteres/farmacologia , Polietilenoglicóis , Polímeros , Ratos
3.
Chemistry ; 27(67): 16716-16721, 2021 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-34622999

RESUMO

Ordered molecular self-assembly of glycoamphiphiles has been regarded as an attractive, practical and bottom-up approach to obtain stable, structurally well-defined, and functional mimics of natural polysaccharides. This study describes a versatile and rational design of carbohydrate-based hydrogelators through N,N'-substituted barbituric acid-mediated Knoevenagel condensation onto unprotected carbohydrates in water. Amphiphilic N-substituted ß-C-maltosylbarbiturates self-assembled into pH- and calcium-triggered alginate-like supramolecular hydrogel fibers with a multistimuli responsiveness to temperature, pH and competitive metal chelating agent. In addition, amphiphilic N,N'-disubstituted ß-C-maltosylbarbiturates formed vesicle gels in pure water that were scarcely observed for glyco-hydrogelators. Finally, barbituric acid worked as a multitasking group allowing chemoselective ligation onto reducing-end carbohydrates, structural diversity, stimuli-sensitiveness, and supramolecular interactions by hydrogen bonding.


Assuntos
Alginatos , Hidrogéis , Ligação de Hidrogênio , Temperatura , Água
4.
Soft Matter ; 16(37): 8647-8654, 2020 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-32856677

RESUMO

Introducing macromolecular micelles into a biocompatible hyaluronic acid (HA) hydrogel is a promising strategy to improve its mechanical properties for biomedical applications. However, it is still unclear whether the solvent nature has an influence on the structure and property of HA gels especially when they are used for those cases containing binary solvents because reversible hydrophobic association within micelles could be weakened or even dissociated by organic solvents. In this work, we demonstrated that a binary solvent consisting of water and low-toxic dimethyl sulfoxide (DMSO), a commonly used cryoprotectant agent in biomedicine, can enhance the mechanical properties of hydrophobic-associated methacrylated hyaluronate (MeHA) gels crosslinked by diacrylated PEO99-PPO65-PEO99 (F127DA) macromolecular micelles, namely FH gels. The resulting FH hydro/organo-gels showed a crystalline structure due to polymer/solvent interactions. The FH gels showed a low swelling degree and the maximum strength (10.12 MPa), modulus (106.8 kPa) and toughness (1540 J m-2) in DMSO with a volume fraction of around 0.6. Moreover, the FH gels displayed a rapid recoverability under cyclic loading-unloading stress particularly in the presence of DMSO within the network due to their dual-dynamic dissipation networks. Such novel hydrophobic associated polysaccharide gels with tunable mechanical properties in binary solvents would be attractive in a cryopreservation system for cell-based applications.


Assuntos
Dimetil Sulfóxido , Micelas , Géis , Hidrogéis , Solventes , Água
5.
Bioconjug Chem ; 30(3): 647-656, 2019 03 20.
Artigo em Inglês | MEDLINE | ID: mdl-30590917

RESUMO

The approach developed here offers a straightforward and efficient access to ß- C-glycosyl barbiturate ligands, spanning from glycomimetics to multivalent C-neoglycoconjugates, with the aim of deciphering structural parameters impacting the binding to pathogenic lectins. We reinvestigated the Knoevenagel condensation of barbituratic acid on protecting-group free carbohydrates and successfully designed sodium and 5,5-disubstituted N, N-dimethyl barbiturate forms of D-galactose, L-fucose, melibiose, 2'-fucosyllactose, and maltose and evaluated their binding affinity by isothermal titration calorimetry with LecA (galactose-binding lectin) and LecB (fucose-binding lectin) from Pseudomonas aeruginosa and RSL (fucose-binding lectin) from Ralstonia solanacearum. The barbiturate ring was shown to be detrimental for binding to LecA ( KD in mM range) and even more to LecB (noninteraction) while RSL is much more tolerant especially in the presence of an aromatic group ( KD in µM range). However, distancing the barbiturate ring from the recognition carbohydrate residue by using oligosaccharides increased affinity up to low micromolar range. Extension of our convenient synthetic approach led in two steps to melibiose-based C-glycosyl barbiturate cluster and C-glycosyl barbiturate glycopolymers exhibiting a dramatic enhancement of binding avidity for LecA.


Assuntos
Adesinas Bacterianas/metabolismo , Barbitúricos/síntese química , Glicoconjugados/síntese química , Lectinas/metabolismo , Pseudomonas aeruginosa/metabolismo , Ralstonia solanacearum/metabolismo , Barbitúricos/química , Barbitúricos/farmacologia , Técnicas de Química Sintética , Glicoconjugados/química , Glicoconjugados/farmacologia , Glicosilação , Humanos , Ligantes , Simulação de Acoplamento Molecular , Doenças das Plantas/microbiologia , Infecções por Pseudomonas/microbiologia , Pseudomonas aeruginosa/efeitos dos fármacos , Ralstonia solanacearum/efeitos dos fármacos
6.
Chembiochem ; 18(2): 206-212, 2017 Jan 17.
Artigo em Inglês | MEDLINE | ID: mdl-27862786

RESUMO

Glycan-protein interactions play a crucial role in physiological and pathological events. Hence, improving the isolation of carbohydrate-binding proteins (i.e., lectins and anti-glycan antibodies) from complex media might not only lead to a better understanding of their function, but also provide solutions for public health issues, such as water contamination or the need for universal blood plasma. Here we report a rapid and efficient method for producing carbohydrate-based affinity adsorbents combining enzymatic synthesis and metal-free click chemistry. Both simple and complex glycans (maltose, blood group antigens A, B, and H) were readily modified by the addition of a furyl group at the reducing end without the need for protecting groups and were then efficiently conjugated to maleimide-activated Sepharose particles through Diels-Alder cycloaddition. These neoglycoconjugates showed high efficiency for the purification of lectins (concanavalin A and Ulex europaeus agglutinin), as well as for the capture of anti-A and anti-B blood group antibodies, opening new prospects for glycoproteomics and for the development of universal blood plasma.


Assuntos
Furanos/química , Maleimidas/química , Oligossacarídeos/química , Polímeros/química , Receptores de Superfície Celular/química , Química Click , Concanavalina A/química , Concanavalina A/metabolismo , Reação de Cicloadição , Fluoresceína-5-Isotiocianato/química , Lectinas/química , Lectinas/metabolismo , Microscopia de Fluorescência , Ligação Proteica , Receptores de Superfície Celular/metabolismo , Sefarose/química , Espectrofotometria Infravermelho
7.
Biomacromolecules ; 18(10): 3410-3417, 2017 Oct 09.
Artigo em Inglês | MEDLINE | ID: mdl-28910094

RESUMO

We report in this contribution that while low molecular weight hemicellulosic building blocks are known not to interact with cellulosic materials, their multivalent presentation on a polymeric scaffold significantly enhanced the binding interactions that are remarkably in the same range as those usually observed for lectin-carbohydrate interactions. We developed a poly(propargyl methacrylate) scaffold on which we conjugated, by "post-click" reaction, a variety of azide reducing-end functionalized xyloglucan oligosaccharides with controlled enzymatic-mediated rate of degalactosylation. Bottlebrush-like xyloglucan oligosaccharide glycopolymers (poly(XGOn)) were obtained and their self-assemblies in aqueous solution were investigated using dynamic light scattering (DLS). We demonstrated that increasing the extent of degalactosylation promoted self-association of poly(XGOn), which we attribute to the appearance of hydrophobic domains. A sharp thermoresponsiveness, which corresponds to a decrease in aggregate size with increasing temperature, was observed when the extent of degalactosylation was 30% or greater. Importantly, isothermal titration calorimetry (ITC) and polarized/depolarized DLS revealed that poly(XGOn) exhibit a significant capacity to interact with nanocrystalline cellulose (NCC) surfaces particularly for the nondegalactosylated form, emphasizing the important role of galactosyl residues in the binding mechanism and in the 3-dimensional structures of glycopolymers.


Assuntos
Materiais Biomiméticos/síntese química , Celulose/análogos & derivados , Glucanos/química , Xilanos/química , Nanopartículas/química
8.
Chembiochem ; 15(2): 293-300, 2014 Jan 24.
Artigo em Inglês | MEDLINE | ID: mdl-24376024

RESUMO

We report the enzymatic synthesis of α-D-glucopyranosyl-(1→4)-α-L-rhamnopyranoside and α-D-glucopyranosyl-(1→3)-α-L-rhamnopyranoside by using a wild-type transglucosidase in combination with glucoamylase and glucose oxidase. It was shown that Bacillus circulans 251 cyclodextrin glucanotransferase (CGTase, EC 2.1.4.19) can efficiently couple an α-L-rhamnosyl acceptor to a maltodextrin molecule with an α-(1→4) linkage, albeit in mixture with the α-(1→3) regioisomer, thus giving two glucosylated acceptors in a single reaction. Optimisation of the CGTase coupling reaction with ß-cyclodextrin as the donor substrate and methyl or allyl α-L-rhamnopyranoside as acceptors resulted in good conversion yields (42-70%) with adjustable glycosylation regioselectivity. Moreover, the efficient chemical conversion of the products of CGTase-mediated cis-glucosylation into protected building blocks (previously used in the synthesis of O-antigen fragments of several Shigella flexneri serotypes) was substantiated. These novel chemoenzymatic strategies towards useful, convenient intermediates in the synthesis of S. flexneri serotypes 2a and 3a oligosaccharides might find applications in developments towards synthetic carbohydrate-based vaccine candidates against bacillary dysentery.


Assuntos
Biocatálise , Glucosiltransferases/metabolismo , Haptenos/química , Oligossacarídeos/química , Oligossacarídeos/síntese química , Shigella flexneri , Bacillus/enzimologia , Sequência de Carboidratos , Estabilidade Enzimática , Glicosilação , Cinética , Dados de Sequência Molecular , Temperatura , beta-Ciclodextrinas/química
9.
Biomacromolecules ; 15(7): 2691-700, 2014 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-24857763

RESUMO

Despite a growing interest in amphiphilic polysaccharide-based diblock copolymers as functional polymeric drug delivery nanosystems, biologically relevant sulfated glycosaminoglycan systems were not yet investigated. Here, we report the synthesis and the self-assembly properties in water of chondroitin sulfate-b-poly(lactic acid) (CS-b-PLA(n)). The CS-b-PLA(n) were synthesized using click-grafting onto method implying reducing-end alkynation of low-molecular weight depolymerized CS (M(w) = 5000 g·mol(-1)) and azide-terminated functionalization of PLAn (M(w) = 6500 g·mol(-1) (n = 46) and M(w) = 1700 g·mol(-1) (n = 20)). The diblock copolymer self-assembled in water giving rise to spherical micelles that were characterized in solution using dynamic/static light scattering and at dry state by TEM technique. In vitro assays on healthy cells showed that at high concentrations, up to 10 µg·mL(-1), CS-b-PLA(n) were noncytotoxic. Those preliminary studies are promising in the perspective to use them as biocompatible nanovehicles for anticancer drug delivery.


Assuntos
Dermatan Sulfato/análogos & derivados , Dermatan Sulfato/síntese química , Portadores de Fármacos/síntese química , Ácido Láctico/química , Polímeros/química , Animais , Configuração de Carboidratos , Sobrevivência Celular/efeitos dos fármacos , Chlorocebus aethiops , Química Click , Dermatan Sulfato/toxicidade , Portadores de Fármacos/toxicidade , Camundongos , Micelas , Tamanho da Partícula , Poliésteres , Células Vero
10.
Bioconjug Chem ; 24(4): 544-9, 2013 Apr 17.
Artigo em Inglês | MEDLINE | ID: mdl-23458450

RESUMO

Functionalized oligosaccharides are useful intermediates to prepare products for biological research or for the development of advanced functional materials. Here, we report the unprecedented use of aniline as an efficient organocatalyst reaction with "clickable" (azide or alkyne) amine for the transimination-mediated reductive amination of a chitooligosaccharide. Moreover, we demonstrate that alkyne-bearing aniline constitutes an excellent tool for the easy derivatization of chitosan oligosaccharides. Evidence for such improvement has been illustrated by the straightforward design of a FRET substrate to probe chitinase activity and of amphiphilic polycaprolactone-grafted-chitosan. This efficient methodology paves the way to the preparation of novel chitosan oligosaccharide-based advanced materials.


Assuntos
Compostos de Anilina/química , Química Click , Oligossacarídeos/síntese química , Aminação , Configuração de Carboidratos , Catálise , Dados de Sequência Molecular , Oligossacarídeos/química , Oxirredução
11.
Chem Asian J ; 18(12): e202300258, 2023 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-37092331

RESUMO

Latent cyclic carbon-centered nucleophiles (latent C-nucleophiles) are recently proving their value in the field of reaction-based fluorescent probes, far beyond their primary utility in organic synthesis. They are typically used to introduce a Michael acceptor moiety acting as a recognition/reaction site for analyte to be detected or as a kinetic promoter of fluorogenic cascade reactions triggered by a reactive species. C-nucleophiles bearing a further reactive handle offer an additional opportunity for tuning the physicochemical/targeting properties or providing drug-releasing capabilities to these probes, through the covalent attachment of ad hoc chemical moiety. In order to implement such strategy to fluorogenic/chromogenic enzyme substrates based on the "covalent-assembly" principle, we have explored the potential of some functionalized derivatives of barbituric acid, piperidine-2,4-dione and Meldrum's acid. Our investigations based on the rational design and analytical validations of enzyme-responsive caged precursors of fluorescent pyronin dyes and 7-(diethylamino)coumarin-3-carboxylic acid, led to identify a versatile candidate suitable for this late-stage structural optimization approach. This Meldrum's acid derivative enables to either enhance water solubility or achieve the reversible conjugation of a targeting ligand, while promoting in situ formation of fluorophore upon enzymatic activation. This study opens the way to novel multifunctional fluorescence imaging probes and optically modulated small conjugate-based theranostics.


Assuntos
Dioxanos , Corantes Fluorescentes , Dioxanos/química , Sítios de Ligação
12.
Bioresour Technol ; 368: 128312, 2023 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-36372384

RESUMO

This study highlights the microfibrillation potential of three deep eutectic solvents (DES) composed of betaine hydrochloride-urea, choline chloride-urea and choline chloride-monoethanolamine. Cellulose fibres (eucalyptus and cotton) were first treated in DES (100 °C for 4 h) and then ground with an ultra-fine grinder to produce microfibrillated cellulose (MFC). DES pre-treatment especially betaine hydrochloride-urea system has significantly improved the microfibrillation process with reduced energy consumption comparable to that of enzymatic treatment (reference pre-treatment). Long and thin microfibril bundles (widths around 50 nm) and individualised microfibrils (widths between 5 and 10 nm) were obtained. MFC gels and nanopapers were characterised using several techniques. Nanopapers produced from DES treated MFC showed good mechanical properties with Young's modulus higher than 10 GPa. In addition, they exhibited higher quality index (between 73 and 76) than those produced from enzymatic hydrolysis (quality index around 68). DES pre-treatment is a promising way to produce MFC with high aspect ratio.


Assuntos
Celulose , Solventes Eutéticos Profundos , Solventes , Betaína , Colina , Ureia
13.
ACS Appl Mater Interfaces ; 15(19): 23736-23748, 2023 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-37134266

RESUMO

Top and bottom interfaces of high-χ cylinder-forming polystyrene-block-maltoheptaose (PS-b-MH) diblock copolymer (BCP) thin films are manipulated using cross-linked copolymer underlayers and a fluorinated phase-preferential surface-active polymer (SAP) additive to direct the self-assembly (both morphology and orientation) of BCP microdomains into sub-10 nm patterns. A series of four photo-cross-linkable statistical copolymers with various contents of styrene, a 4-vinylbenzyl azide cross-linker, and a carbohydrate-based acrylamide are processed into 15 nm-thick cross-linked passivation layers on silicon substrates. A partially fluorinated analogue of the PS-b-MH phase-preferential SAP additive is designed to tune the surface energy of the top interface. The self-assembly of PS-b-MH thin films on top of different cross-linked underlayers and including 0-20 wt % of SAP additive is investigated by atomic force microscopy and synchrotron grazing incidence small-angle X-ray scattering analysis. The precise manipulation of the interfaces of ca. 30 nm thick PS-b-MH films not only allows the control of the in-plane/out-of-plane orientation of hexagonally packed (HEX) cylinders but also promotes epitaxial order-order transitions from HEX cylinders to either face-centered orthorhombic or body-centered cubic spheres without modifying the volume fraction of both blocks. This general approach paves the way for the controlled self-assembly of other high-χ BCP systems.

14.
Carbohydr Polym ; 313: 120904, 2023 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-37182937

RESUMO

Delayed or chronic wound healing is one of severe clinical issues. Developing scaffold materials capable of supporting cells and inducing tissue regeneration remains a challenge. Here, a polysaccharide-based hydrogel is constructed for promoting full-thickness skin wound healing in mouse model. The engineering hydrogel consists of a dynamic crosslinking network formed by the Schiff base reaction between aldehyde-containing xyloglucan and methacrylated chitosan. Its reversible gel-sol-gel transition upon shearing force is highly beneficial to completely cover and fill irregular wound shape. The second covalent cross-linking network achieved by photo-initiated polymerization offers a feasible way to tune the mechanical property of hydrogel after injection, with an ideal mechanical adaptivity for clinical application. Remarkably, both in vitro and in vivo evaluations demonstrate that the hydrogel with endogenously bioactive galactoside units can promote cell spheroid formation and accelerate wound healing by expediting re-epithelialization, collagen deposition, angiogenesis as well as the formation of hair follicles.


Assuntos
Quitosana , Camundongos , Animais , Quitosana/farmacologia , Hidrogéis/farmacologia , Cicatrização , Glucanos/farmacologia
15.
Biomacromolecules ; 13(4): 1129-35, 2012 Apr 09.
Artigo em Inglês | MEDLINE | ID: mdl-22397388

RESUMO

The preparation of biocompatible nanocarriers that have potential applications in the cosmetic and health industries is highly desired. The self-assembly of amphiphilic block copolymers displaying biosourced polysaccharides at the surface is one of the most promising approaches. In the continuity of our works related to the preparation of "hybrid" amphiphilic oligosaccharide-based block copolymers, we present here the design of a new generation of self-assembled nanoparticles composed entirely of oligosaccharide-based amphiphilic block co-oligomers (BCO). These systems are defined by a covalent linkage of the two saccharidic blocks through their reducing end units, resulting in a sweet "head-to-head" connection. As an example, we have prepared and studied a BCO in which the hydrophilic part is composed of a free maltoheptaosyl derivative clicked to a hydrophobic part composed of a peracetylated maltoheptaosyl derivative. This amphiphilic BCO self-assembles to form spherical micelles in water with an average diameter of 30 nm. The efficient enzymatic hydrolysis of the maltoheptaose that constitutes the shell of the micelles was followed by light scattering and colorimetric methods.


Assuntos
Biopolímeros/química , Nanopartículas/química , Oligossacarídeos/síntese química , Tensoativos/síntese química , Aspergillus niger/enzimologia , Biopolímeros/metabolismo , Configuração de Carboidratos , Glucana 1,4-alfa-Glucosidase/química , Glucana 1,4-alfa-Glucosidase/metabolismo , Glucanos/química , Glucanos/metabolismo , Hidrólise , Interações Hidrofóbicas e Hidrofílicas , Micelas , Oligossacarídeos/química , Oligossacarídeos/metabolismo , Tamanho da Partícula , Propriedades de Superfície , Tensoativos/química , Tensoativos/metabolismo
16.
Biomacromolecules ; 13(5): 1458-65, 2012 May 14.
Artigo em Inglês | MEDLINE | ID: mdl-22439973

RESUMO

This paper discusses the thermoresponsive nanoparticles obtained by self-assemblies of nonlinear oligosaccharide-based diblock copolymer systems. These diblock copolymers were synthesized by Cu(I)-catalyzed 1,3-dipolar azide/alkyne cycloaddition ("click" reaction) of propargyl-functionalized ß-cyclodextrin (ßCyD) and xyloglucooligosaccharide (XGO) with poly(N-isopropylacrylamide) (PNIPAM) having a terminal azido group prepared by atom transfer radical polymerization (ATRP). Elastic and quasi-elastic light scattering analysis of the dibock copolymers in H(2)O indicated that thermodynamic phase transitions of the PNIPAM blocks at their cloud points (T(cp)s ≈ 34 °C), around lower critical solution temperatures (LCSTs), triggered their self-assemblies into the nanoparticles. These nanoparticles had narrow size distributions and small interphases (i.e., sharp boundaries). The mean hydrodynamic radii (R(h)s) of the ßCyD and XGO-based nanoparticles were determined to be around 150 and 250 nm upon slow heating (i.e., step-by-step heating), and 364 and 91.5 nm upon fast heating, respectively, depending on a predominance of the interchain association or the intrachain contraction. Transmission electron microscope (TEM) and field emission gun-scanning electron microscopy (FEG-SEM) images of the nanoparticles clearly showed compact spherical nanoparticles whose cores are mainly made with the PNIPAM blocks, whereas the rough shells consist in the oligosaccharidic blocks.


Assuntos
Acrilamidas/química , Nanopartículas/química , Oligossacarídeos/síntese química , Polímeros/química , Temperatura , Acrilamidas/síntese química , Resinas Acrílicas , Catálise , Cobre/química , Ciclização , Estrutura Molecular , Oligossacarídeos/química , Polímeros/síntese química
17.
Carbohydr Polym ; 292: 119606, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35725149

RESUMO

This work aims to study the effects of Deep Eutectic Solvents (DES) on cellulosic fibre structure. A focus was made on the induced fibrillation phenomena which could facilitate the further production of microfibrillated cellulose. Three DES of different pH (acid, neutral and alkaline), namely betaine hydrochloride-urea, choline chloride-urea and choline chloride-monoethanolamine, were tested. Eucalyptus and cotton pulps were used to investigate the effects of DES on both hemicelluloses and cellulose. Interestingly, cellulose was esterified during acidic DES treatment. Moreover, an internal and external fibrillation occurred with DES treatment without a great extent of modification in terms of chemical composition, crystallinity and degree of polymerisation. Compared to enzymatic hydrolysis (used as a conventional pre-treatment for cellulose microfibrillation), DES have significantly enhanced the mechanical properties of resulting papers. To conclude, DES treatment can be considered as a soft and green "chemical" refining that could be applied as a pre-treatment for cellulose microfibrillation.


Assuntos
Celulose , Solventes Eutéticos Profundos , Celulose/química , Colina/química , Solventes/química , Ureia/química
18.
Langmuir ; 27(7): 4098-103, 2011 Apr 05.
Artigo em Inglês | MEDLINE | ID: mdl-21395269

RESUMO

This paper discusses the self-assembly of rod-coil amylose-b-polystyrene (Mal-b-PS) block copolymer thick and thin films. The nano-organization falls in an interdomain spacing d of about 10 nm, much smaller than flexible-flexible petrol block copolymer systems. Additionally, hydrogen-bonding interactions between carbohydrate rods (amylose) and 4',4-bipyridine (bipy) molecules induces phase transitions. Indeed, adding bipy in maltooctadecaose-block-polystyrene (Mal18-b-PS) copolymers results, at room temperature, in the formation of a lamellar phase having Mal18 bipy-rich nanodomains instead of hexagonal close-packed (HCP) of cylinders made of Mal18, whereas a coexistence of Mal7bipy-rich cylindrical and spherical nanodomains are formed from maltoheptaose-b-polystyrene (Mal7-b-PS) copolymers instead of a poorly organized array of Mal7-based cylinders. On heating, the Mal7bipy-b-PS system shows more rich phase behavior as compared to the Mal7-b-PS one due to weakening of hydrogen bonding with temperature. Such a system is of great interest in developing active layers in light-emitting diodes (LEDs) or in photovoltaic cells to realize devices with an optimal structure, that is, having large interface area and domain size with similar exciton diffusion length (10 nm).

19.
Langmuir ; 26(4): 2325-32, 2010 Feb 16.
Artigo em Inglês | MEDLINE | ID: mdl-20141199

RESUMO

This work discusses the self-assembly properties of thermoresponsive hybrid oligosaccharide-block-poly(N-isopropylacrylamide) copolymer systems: maltoheptaose-block-poly(N-isopropylacrylamide) (Mal(7)-b-PNIPAM(n)) copolymers. Those systems at different molar masses and volume fractions were synthesized using Cu(I)-catalyzed 1,3-dipolar azide/alkyne cycloaddition, so-called "click" chemistry, between an alkynyl-functionalized maltoheptaose (1) and poly(N-isopropylacrylamide) having a terminal azido group (N(3)-PNIPAM(n)) prepared by atom transfer radical polymerization (ATRP). While the cloud point (T(cp)) of the N(3)-PNIPAM(n) ranged from 36.4 to 51.5 degrees C depending on the degree of polymerization, those obtained of the diblock copolymers ranged from 39.4 to 73.9 degrees C. The self-assembly of such systems is favored due to the hydrophobicity of the PNIPAM in water above the T(cp). While the N(3)-PNIPAM(n) present polydisperse globular shape with a mean diameter of 500 nm, well-defined vesicular morphologies with an approximate diameter of 300 nm are obtained in diblock copolymer systems. These results were obtained and confirmed using static and dynamic light scattering as well as imaging techniques such as transmission electron microscope experiments.


Assuntos
Acrilamidas/química , Glucanos/química , Oligossacarídeos/química , Oligossacarídeos/síntese química , Polímeros/química , Temperatura , Resinas Acrílicas , Catálise , Cobre/química
20.
Carbohydr Polym ; 212: 222-228, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30832851

RESUMO

The promising carbohydrate-based block copolymer maltoheptaose-block-polystyrene (MH-b-PS) has been used for high-performance memory transistors and next generation nanolithography. In order to realize the potential of MH-b-PS especially in microelectronic applications, we firstly improved its synthetic method for obtaining large amount of copper-free MH-b-PS. The main improvement relies on the removal of the residual copper catalyst by using a chelating resin. Then, the microphase separation of copper-free MH-b-PS in both thin film and bulk states under different solvent vapor annealing conditions were investigated comprehensively and compared with our previous report by using both real-space and reciprocal-space techniques. A phase transition of MH-b-PS from hexagonal close-packed horizontal cylinders to face-centered cubic were observed when increasing the amount of tetrahydrofuran in the mixture annealing solvent of tetrahydrofuran and H2O. More details about self-assembled MH-b-PS nanostructures were analyzed by comparing grazing incidence small angle X-ray scattering patterns with corresponding atomic force microscopy phase images.

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