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Amphiphilic poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol)]-co-(ethyl cyanoacrylate)} graft copolymer nanoparticles as carriers for transdermal drug delivery

Xing, Jinfeng; Deng, Liandong; Li, Jun; Dong, Anjie
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
542.19945%
In this study, the transdermal drug delivery properties of D,L-tetrahydropalmatine (THP)-loaded amphiphilic poly{[α-maleic anhydride-ω-methoxy-poly(ethylene glycol)]-co-(ethyl cyanoacrylate)} (PEGECA) graft copolymer nanoparticles (PEGECAT NPs) were evaluated by skin penetration experiments in vitro. The transdermal permeation experiments in vitro were carried out in Franz diffusion cells using THP-loaded PEGECAT NPs as the donor system. Transmission electron microscopy and Fourier transform infrared spectroscopy were used to characterize the receptor fluid. The results indicate that the THP-loaded PEGECAT NPs are able to penetrate the rat skin. Fluorescent microscopy measurements demonstrate that THP-loaded PEGECAT NPs can penetrate the skin not only via appendage routes but also via epidermal routes. This nanotechnology has potential application in transdermal drug delivery.

The nanofibrous architecture of poly(L-lactic acid)-based functional copolymers

Liu, Xiaohua; Ma, Peter X.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
203.41777%
It remains a challenge to synthesize functional materials that can develop advanced scaffolding architectures for tissue engineering. In this study, a series of biodegradable amphiphilic poly(hydroxyalkyl (meth)acrylate)-graft-poly(L-lactic acid) (PHAA-g-PLLA) copolymers have been synthesized and fabricated into nano-fibrous scaffolds. These copolymers can be further functionalized, are more hydrophilic, and have faster degradation rates than the PLLA homopolymer, which are advantageous for certain tissue engineering applications. First, PLLA-based macromonomers were prepared by using functional hydroxyalkyl (meth)acrylates (HAA) as initiators. The PHAA-g-PLLA copolymers were then synthesized using free radical copolymerization of PLLA-based macromonomers and HAA. Nano-fibrous architecture was created using a thermally induced phase separation technique from these functional PHAA-g-PLLA copolymers. The nano-fibrous structure mimics the architecture of natural collagen matrix at the nanometer scale. The effects of the macromonomer composition, copolymer composition, blending ratio, and solvent selection on nano-scale structures were studied. In general, the nano-fibrous structure was created when the amount of HAA in the macromonomer was low. By increasing the amount of HAA in the macromonomer...

Amphiphilic graft copolymer based on poly(styrene-co-maleic anhydride) with low molecular weight polyethylenimine for efficient gene delivery

Duan, Xiaopin; Xiao, Jisheng; Yin, Qi; Zhang, Zhiwen; Mao, Shirui; Li, Yaping
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
403.41777%

Presentation and accessibility of surface bound ligands on amphiphilic graft copolymer films

Kuhlman, William A
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 144 p.
ENG
Relevância na Pesquisa
549.7704%
Amphiphilic comb-type graft copolymers comprising a poly(methyl methacrylate) (PMMA) backbone and short, polyethylene oxide (PEO) side chains, PMMA-g-PEO, are proposed to self-organize at the polymer/water interface, resulting in quasi-2D confinement of the backbone at the immediate surface. The branched architecture and amphiphilic chemistry of these polymers results in a dense PEO brush that resists cell adhesion. To facilitate specific cell-surface interactions, small biological molecules such as adhesion peptides can be selectively tethered to PEO chain ends. Quasi-2D confinement of the polymer backbone results in clustering of tethered epitopes on a length scale dictated by the backbone. The present work investigates two aspects of this polymer architecture on organization of tethered ligands: nanometer length-scale clustering through backbone 2D confinement, and tether length effects on the availability of tethered peptides for cell adhesion.; (cont.) To directly probe 2D confined polymer conformations, combs at the film/water interface were labeled with gold nanoparticles and observed by transmission electron microscopy. A 2D radius of gyration (Rg) was calculated by reconstructing nanoparticle-decorated chain trajectories, and compared with Monte Carlo simulations of a 2D melt of similarly broad length distribution. The 2D Rg calculated from observed conformations scaled with the number of backbone segments (N) as Rg - N.69-0.02 Monte Carlo simulations yielded a scaling exponent v = 0.67 + 0.03...

Physicochemical characterization of PEG-based comb-like amphiphilic copolymer structures for possible imaging and therapeutic applications; Physicochemical characterization of polyethylene glycol-based comb-like amphiphilic copolymer structures for possible imaging and therapeutic applications

Dawson, Jin Zhou
Fonte: Massachusetts Institute of Technology Publicador: Massachusetts Institute of Technology
Tipo: Tese de Doutorado Formato: 267 p.
ENG
Relevância na Pesquisa
459.73277%
Comb-like copolymer structures, also known as graft/comb copolymers, have obtained a significant amount of attention in biomedical and industrial applications because of their unique compositional flexibility, which can lead to versatile structures in bulk, melt, and solution states. With biomedical applications (cancer diagnosis and treatment) as the context, this thesis is aimed at characterizing a series of polyethylene glycol (PEG) -based highly adaptable amphiphilic comb copolymer structures in their solution state that can serve as carriers and potentially contrast enhancement agent in magnetic resonance imaging (MRI). To successfully develop and implement such a delivery/contrast agent system, an adequate understanding is needed concerning their physicochemical properties: stability, size, morphology, local structural information, and magnetic resonance characteristics. The stability of these copolymer structures was characterized by their critical micelle concentration (the lower this concentration, the higher the stability), which was determined by total intensity light scattering and surface tension measurement. The size, morphology, and detailed structural information were studied by a combination of techniques, i.e., dynamic light scattering...

Self-assembly in aqueous solution of amphiphilic graft copolymers from oxidized carboxymethylcellulose

Bordallo, Eduardo; Rieumont, Jacques; Tiera, Marcio José; Gómez, Manuel; Lazzari, Massimo
Fonte: Elsevier B.V. Publicador: Elsevier B.V.
Tipo: Artigo de Revista Científica Formato: 43-49
ENG
Relevância na Pesquisa
737.5615%
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES); A series of oxidized carboxymethylcellulose-graft-poly(ethylene glycol)-dodecylamine (0CMC-g-PEG-DDA) was prepared by using an appositely prepared PEG with terminal amino groups and different amounts of DDA. The nanoaggregates formed in aqueous solution were characterized by surface tension measurements, fluorescence spectroscopy, dynamic light scattering (DES) and scanning electron microscopies (SEM and TEM). The micelles showed narrow hydrodynamic size distributions and diameters varying from 163 to 193 nm depending on the ratio of DDA to PEG chains. The DDA content in the graft copolymers also affected the core shell interfacial compactness.

MULTIVARIATE CHARACTERIZATION OF LIGNOCELLULOSIC BIOMASS AND GRAFT MODIFICATION OF NATURAL POLYMERS

KRASZNAI, DANIEL
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
331.534%
The plant cell wall contains significant quantities of renewable polymers in the form of cellulose, hemicellulose, and lignin. These three renewable polymers have the potential to complement or replace synthetic polymers in a variety of applications. Rapidly determining the quantities of these polysaccharides in lignocellulosic biomass is important yet difficult since plant biomass is recalcitrant and highly variable in composition. Part of this contribution outlines a novel compositional analysis protocol using infrared spectroscopy and multivariate regression techniques that is rapid and inexpensive. Multivariate regression models based on calibration mixtures can be used to discern between populations of lignocellulosic biomass or to predict cellulose, hemicellulose, and lignin quantities. Thus, the compositional analysis step can be expedited so that other processes, like fractionation of the lignocellulose polymers, can be tuned accordingly to maximize the value of the final product. Hybrid materials were also generated using a variety of polymerization techniques and post-polymerization modifications. A novel controlled/living radical polymerization initiator was synthesized (2-bromo-2-methylpropane hydrazide) containing a hydrazide functionality that was covalently linked to the reducing-end of dextran. Despite the rapid coupling of the hydrazide- based initiator to the reducing-end of dextran...

Mesoporous TiO2 Bragg Stack Templated by Graft Copolymer for Dye-sensitized Solar Cells

Park, Jung Tae; Chi, Won Seok; Kim, Sang Jin; Lee, Daeyeon; Kim, Jong Hak
Fonte: Nature Publishing Group Publicador: Nature Publishing Group
Tipo: Artigo de Revista Científica
Publicado em 01/07/2014 EN
Relevância na Pesquisa
514.08324%
Organized mesoporous TiO2 Bragg stacks (om-TiO2 BS) consisting of alternating high and low refractive index organized mesoporous TiO2 (om-TiO2) films were prepared to enhance dye loading, light harvesting, electron transport, and electrolyte pore-infiltration in dye-sensitized solar cells (DSSCs). The om-TiO2 films were synthesized via a sol-gel reaction using amphiphilic graft copolymers consisting of poly(vinyl chloride) backbones and poly(oxyethylene methacrylate) side chains, i.e., PVC-g-POEM as templates. To generate high and low index films, the refractive index of om-TiO2 film was tuned by controlling the grafting ratio of PVC-g-POEM via atomic transfer radical polymerization (ATRP). A polymerized ionic liquid (PIL)-based DSSC fabricated with a 1.2-μm-thick om-TiO2 BS-based photoanode exhibited an efficiency of 4.3%, which is much higher than that of conventional DSSCs with a nanocrystalline TiO2 layer (nc-TiO2 layer) (1.7%). A PIL-based DSSC with a heterostructured photoanode consisting of 400-nm-thick organized mesoporous TiO2 interfacial (om-TiO2 IF) layer, 7-μm-thick nc-TiO2, and 1.2-μm-thick om-TiO2 BS as the bottom, middle and top layers, respectively, exhibited an excellent efficiency of 7.5%, which is much higher than that of nanocrystaline TiO2 photoanode (3.5%).

Hydrogels based on modified chitosan, 1 - Synthesis and swelling behavior of poly(acrylic acid) grafted chitosan

Retuert de la Torre, Pedro Jaime; Yazdani-Pedram Zobeiri, Mehrdad
Fonte: WILEY-V C H VERLAG GMBH Publicador: WILEY-V C H VERLAG GMBH
Tipo: Artículo de revista
EN
Relevância na Pesquisa
303.41777%
A large number of carboxylic groups were introduced onto chitosan by grafting with poly(acrylic acid) as an efficient way of modification. The reactions were carried out in a homogeneous aqueous phase by using potassium persulfate and ferrous ammonium sulfate as the combined redox initiator system. The efficiency of grafting was found to depend on monomer, initiator, and ferrous ion concentrations as well as reaction time and temperature. It was observed that the level of grafting could be controlled to some degree by varying the amount of ferrous ion used as a co-catalyst in the reaction. Evidence of grafting was obtained by comparison of FTIR spectra of chitosan and the graft copolymer as well as solubility characteristics of the products. The swelling behavior of chitosan samples, grafted the 115% and 524% poly(acrylic acid), was studied as function of pH, in distilled water and in aqueous NaCl solution. The sample that has 115% grafting swells considerably more both in distilled water (pH 5.8) as well as higher pH values than the sample with 524% grafting. In contrast, an inverse swelling behavior at pH 2 was observed. An unusual swelling behavior at pH 2 was found for the sample with 524% grafting, which swells to a greater extent than in distilled water. This was attributed to the amphiphilic nature of the modified chitosan from which complex inter- and/or intramolecular interactions could originate.

Modification of Alginate and Development of Polymeric Nanocarriers by Living Radical Polymerization for Controlled/Targeted Drug Delivery

Kapishon, Vitaliy
Fonte: Quens University Publicador: Quens University
Tipo: Tese de Doutorado
EN; EN
Relevância na Pesquisa
436.1078%
Alginate-based amphiphilic graft copolymers were synthesized by single electron transfer living radical polymerization (SET-LRP), forming stable micelles during polymerization induced self-assembly (PISA). First, alginate macroinitiator was prepared by partial depolymerization of native alginate, solubility modification and attachment of initiator. Then, methyl methacrylate was polymerized from the alginate macroinitiator in mixtures of water and methanol forming poly(methyl methacrylate) grafts, prior to self-assembly. PISA of the amphiphilic graft-copolymer resulted in the formation of micelles with diameters of 50-300 nm. As the first reported case of LRP from alginate, this work introduces a synthetic route to of alginate-based hybrid polymers with a precise macromolecular architecture and desired functionalities. LRP from alginate can be applied to improve alginate-based hydrogel systems such as nano- and micro-hydrogel particles, islet encapsulation materials, hydrogel implants and topical applications. Such modified alginates can also improve the function and application of native alginates in food and agricultural technologies. Targeted drug delivery using polymeric nanostructures has been at the forefront of cancer research engineered for safer...