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Chitosan-reinforced alginate microspheres obtained through the emulsification/internal gelation technique

Ribeiro, António J.; Silva, Catarina; Ferreira, Domingos; Veiga, Francisco
Fonte: Universidade de Coimbra Publicador: Universidade de Coimbra
Tipo: Artigo de Revista Científica Formato: aplication/PDF
ENG
Relevância na Pesquisa
26.36%
Alginate microspheres prepared by emulsification/internal gelation were chosen as carriers for a model protein, hemoglobin (Hb). Reinforced chitosan-coated microspheres were obtained by an uninterrupted method, in order to simplify the coating process, minimize protein losses during production and to avoid Hb escape under acidic conditions. Microspheres recovery was evaluated as well as its morphology by determination of Hb encapsulation efficiency and microscopic observation, respectively. The formation of chitosan membrane made of it interaction with alginate was assessed by DSC (differential scanning calorimetry) and FT-IR (Fourier-transform infrared spectrometry) studies. Spherical uncoated microspheres with a mean diameter of 20 [mu]m and encapsulation efficiency above 89% were obtained. Coated microspheres provided similar encapsulation efficiency but a higher mean diameter was obtained due to microspheres clumping during the coating step. Protein loss occurred mainly during emulsification rather than recovery. FT-IR and DSC together indicated electrostatic interactions between alginate carboxylate and chitosan ammonium groups as the main forces for complex formation.; http://www.sciencedirect.com/science/article/B6T25-4FM5CXS-1/1/2db2be842f728a0541def21ac050a44e

Aplicação do óleo de buriti no desenvolvimento de emulsões e estudo da citotoxicidade e potencial foto-protetor em cultivo celular; Application of Buriti oil (Mauritia flexuosa) on emulsions development and cytotoxic and photoprotector potential evaluation in cell culture.

Zanatta, Cinthia Fernanda
Fonte: Biblioteca Digitais de Teses e Dissertações da USP Publicador: Biblioteca Digitais de Teses e Dissertações da USP
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 07/05/2008 PT
Relevância na Pesquisa
16.22%
Nos últimos anos intensificou-se o estudo sobre sistemas criados para veicular princípios ativos, como nanoemulsões, dispersões contendo cristais líquidos e emulsões múltiplas, bem como o emprego de matérias-primas da biodiversidade brasileira na produção destes sistemas, a exemplo dos óleos de andiroba, copaíba, urucum e buriti, cuja fruta amazônica é rica em micro-nutrientes com propriedades anti-oxidante, hidratante e fotoprotetora. Durante o desenvolvimento de novas formulações cosméticas, o potencial de irritação dérmica deve ser investigado antes que o produto seja disponibilizado ao consumidor, a fim de identificar compostos que possam causar reações adversas na pele. O objetivo deste trabalho foi avaliar cientificamente o emprego do óleo de buriti na obtenção de emulsões contendo cristais líquidos, nanoemulsões e emulsões múltiplas estáveis e estudar o possível potencial citotóxico e fotoprotetor destas formulações em culturas de células epidérmicas (fibroblastos e queratinócitos), bem como o potencial irritante em modelo organotípico (HET-CAM). Foi estabelecido como valor de EHL crítico igual a 7,25 e selecionados dois pares de tensoativos (Steareth-2 associado aos Ceteareth- 5 e Ceteareth-20) para produção das macroemulsões contendo cristal líquido pela técnica do diagrama ternário. Os testes preliminares em centrifuga...

Desenvolvimento tecnológico e avaliação da atividade antioxidante de sistemas nano e microparticulados contendo melatonina; Technological development and evaluation of the antioxidant activity of melatonin-loaded nano- and microparticulated systems

Schaffazick, Scheila Rezende
Fonte: Universidade Federal do Rio Grande do Sul Publicador: Universidade Federal do Rio Grande do Sul
Tipo: Tese de Doutorado Formato: application/pdf
POR
Relevância na Pesquisa
16.13%
Este trabalho centrou-se no desenvolvimento tecnológico e na caracterização de nanopartículas poliméricas (nanocápsulas ou nanoesferas) contendo melatonina, empregando diferentes composições, métodos de preparação e concentrações de melatonina. De uma maneira geral, as diferentes suspensões nanoparticuladas foram caracterizadas segundo a determinação dos teores totais de melatonina, a determinação das taxas de associação da melatonina aos nanocarreadores, a análise morfológica, a determinação dos diâmetros médios de partículas e polidispersões, além da determinação dos valores de potenciais zeta. As suspensões de nanocápsulas ou de nanoesferas foram preparadas pelos métodos de deposição interfacial ou de nanoprecipitação, respectivamente. Foram avaliadas as influências do tipo de polímero [Eudragit® S100, Eudragit® RS100, poli(ε-caprolactona) ou poli(lactideo)], de óleo (triglicerídeos dos ácidos cáprico e caprílico, óleo mineral ou Eutanol G®) e de tensoativos (polissorbato 80, poloxamer 188, monooleato de sorbitano, monoestearato de sorbitano ou lecitina) sobre as características físico-químicas das suspensões. Os resultados demonstraram que as nanopartículas apresentaram diâmetros inferiores a 350 nm...

Avaliação da permeabilidade em membrana tubular de TiO2/AL2O3 dos constituintes do sistema reacional heterogêneo para produção de biodiesel; Assessment of tubular membrane permeability in the constituents TiO2/AL2O3 reaction heterogeneous system for the production of biodiesel

Paulo Jardel Pereira Araujo
Fonte: Biblioteca Digital da Unicamp Publicador: Biblioteca Digital da Unicamp
Tipo: Tese de Doutorado Formato: application/pdf
Publicado em 19/08/2011 PT
Relevância na Pesquisa
36.17%
O biodiesel além de ser biodegradável e obtido de fontes renováveis, apresenta propriedades físico-químicas muito semelhantes ao diesel de petróleo, não necessitando de um novo motor para utilização do mesmo. A rota química mais comumente usada para obtenção do biodiesel é a transesterificação. Nesta, pela reação de um álcool com os triacilgliceróis (TAG) presentes principalmente em óleos vegetais e gordura animal, são produzidos o biodiesel e, como produto secundário, o glicerol em grandes quantidades. A presença deste glicerol é indesejada, pois além de diminuir a produtividade do biodiesel pelo equilíbrio termodinâmico estabelecido no processo, também aumenta seu custo pelo alto tempo de decantação e/ou uso de centrífugas para remover o glicerol do biodiesel. Devido a este inconveniente, o presente trabalho propõe rota alternativa para separação do glicerol, utilizando membrana de microfiltração (TiO2/Al2O3). Vários sistemas foram analisados, focando a separação do glicerol, o aumento do fluxo permeado e da conversão de TAG na catálise heterogênea. Inicialmente estudou-se a permeabilidade e seletividade dos reagentes e produtos obtidos na síntese do biodiesel com a membrana, através de experimentos binários. A partir destes resultados...

Desenvolvimento e avaliação da permeação e retenção cutânea de sistemas nanoemulsionados do ácido linoléico conjugado (CLA)

Zen, Bianca Steffen
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Dissertação de Mestrado Formato: 120 p.| il., grafs., tabs.
POR
Relevância na Pesquisa
15.97%
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Farmácia, Florianópolis, 2012.; O ácido linoléico conjugado (CLA) é um componente presente em produtos lácteos oriundos de ruminantes, que possui efeitos benéficos para a saúde humana e na prevenção de doenças. Vários estudos têm destacado e comprovado os benefícios do CLA à saúde. Os efeitos antilipogênicos, antiinflamatório e anti-carcinogênico estão fortemente aliados ao CLA e fazem dele um nutriente de enorme interesse a ser utilizado em formulações de uso tópico capazes de permear o extrato córneo, tornando-se assim, uma interessante opção no tratamento de processos inflamatórios da pele, na prevenção dos danos causados pela exposição à radiação solar e no combate à celulite. No entanto, a pele é uma barreira muito eficaz contra a penetração de substâncias ativas, que quando veiculadas normalmente não conseguem alcançar concentrações apreciáveis nos tecidos-alvo. Nos últimos anos, nanocarreadores lipídicos surgiram como uma estratégia promissora para aumentar a penetração de compostos ativos através da pele. Nanoemulsões consistem em emulsões muito finas...

Uso de membranas cerâmicas microporosas na produção de emulsões óleo de girassol em água

Zanatta, Vanessa
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Dissertação de Mestrado Formato: 111 p.| il., grafs., tabs.
POR
Relevância na Pesquisa
26.64%
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-Graduação em Engenharia de Alimentos, Florianópolis, 2014.; Emulsificação com membrana é um método simples quando comparado aos métodos convencionais, que tem recebido atenção crescente ao longo dos últimos anos, com aplicações potenciais em muitas áreas. Este trabalho teve como objetivo avaliar o preparo e a estabilidade de emulsões do tipo O/A (óleo em água) utilizando o processo de emulsificação com membranas cerâmicas. Membranas cerâmicas microporosas de tamanho médio de poros 0,2 µm e 0,8 µm foram utilizadas com sucesso para a produção de emulsões de óleo de girassol em água com tamanho médios de gotas variando de 2,9 µm a 11,6 µm, para a membrana de 0,2 µm; e de 4,8 a 16,2 µm para a membrana de 0,8 µm. O presente estudo demonstrou que o tamanho das gotas é largamente dependente do tamanho dos poros da membrana, da pressão, da concentração de óleo, do surfactante e da velocidade tangencial. Quanto à estabilidade das emulsões, pode-se dizer que as emulsões obtidas com a membrana de 0,2 µm são mais estáveis que aquelas obtidas com a membrana de 0,8 µm. Por um planejamento experimental do tipo Plackett & Burman...

Study of membrane emulsification process as a pre-step for the microencapsulation of lipid compounds by spray drying

Candéa, Tatiana Vidal
Fonte: Faculdade de Ciências e Tecnologia Publicador: Faculdade de Ciências e Tecnologia
Tipo: Dissertação de Mestrado
Publicado em //2013 ENG
Relevância na Pesquisa
66.91%
Dissertation presented to Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa for obtaining the master degree in Membrane Engineering; Food emulsions play an important role in product development and formulation, as well as to encapsulation of food additives. Conventional methods for emulsion production may present some drawbacks, such as the use of high shear stress, high energy demanding and polydisperse droplet size distribution. In this sense, membrane emulsification emerges as an alternative method to overcome all this issues and to produce fine and stable emulsions. Linseed oil has been widely studied in the last years, due to its nutritional composition, being the richest ω-3 vegetable source and for that reason it was used as the raw material for emulsion production. Premix and direct (cross flow) membrane emulsification were carried out using three different membrane materials: polissulphone, cellulose ester and α-alumina membrane. For premix membrane emulsification (PME) the variables transmembrane pressure, membrane material, surfactant type and membrane mean pore size were evaluated. The membrane mean pore size was the crucial factor to achieve emulsions by PME, once it was not possible to achieve stable emulsion with mean pore sizes lower than 0.8 μm. For direct membrane emulsification...

Electron microscopic evidence for nucleation and growth of 3D acetylcholine receptor microcrystals in structured lipid–detergent matrices

Paas, Yoav; Cartaud, Jean; Recouvreur, Michel; Grailhe, Regis; Dufresne, Virginie; Pebay-Peyroula, Eva; Landau, Ehud M.; Changeux, Jean-Pierre
Fonte: National Academy of Sciences Publicador: National Academy of Sciences
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.07%
Nicotinic acetylcholine receptors (AChRs) belong to a superfamily of oligomeric proteins that transduce electric signals across the cell membrane on binding of neurotransmitters. These receptors harbor a large extracellular ligand-binding domain directly linked to an ion-conducting channel-forming domain that spans the cell membrane 20 times and considerably extends into the cytoplasm. Thus far, none of these receptor channels has been crystallized in three dimensions. The crystallization of the AChR from Torpedo marmorata electric organs is challenged here in lipidic–detergent matrices. Detergent-soluble AChR complexed with α-bungarotoxin (αBTx), a polypeptidic competitive antagonist, was purified. The AChR–αBTx complex was reconstituted in a lipidic matrix composed of monoolein bilayers that are structured in three dimensions. The αBTx was conjugated to a photo-stable fluorophore, enabling us to monitor the physical behavior of the receptor–toxin complex in the lipidic matrix under light stereomicroscope, and to freeze fracture regions containing the receptor–toxin complex for visualization under a transmission electron microscope. Conditions were established for forming 2D receptor–toxin lattices that are stacked in the third dimension. 3D AChR nanocrystals were thereby grown inside the highly viscous lipidic 3D matrix. Slow emulsification of the lipidic matrix converted these nanocrystals into 3D elongated thin crystal plates of micrometer size. The latter are stable in detergent-containing aqueous solutions and can currently be used for seeding and epitaxial growth...

The SC3 Hydrophobin Self-Assembles into a Membrane with Distinct Mass Transfer Properties

Wang, X.; Shi, Fuxin; Wösten, H. A. B.; Hektor, H.; Poolman, B.; Robillard, G. T.
Fonte: Biophysical Society Publicador: Biophysical Society
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
26.13%
Hydrophobins are a class of small proteins that fulfill a wide spectrum of functions in fungal growth and development. They do so by self-assembling into an amphipathic membrane at hydrophilic-hydrophobic interfaces. The SC3 hydrophobin of Schizophyllum commune is the best-studied hydrophobin. It assembles at the air-water interface into a membrane consisting of functional amyloid fibrils that are called rodlets. Here we examine the dynamics of SC3 assembly at an oil-water and air-water interface and the permeability characteristics of the assembled layer. Hydrophobin assembled at an oil-water interface is a dynamic system capable of emulsifying oil. It accepts soluble-state SC3 oligomers from water in a unidirectional process and sloughs off SC3 vesicles back into the water phase enclosing a portion of the oil phase in their hydrophobic interior. The assembled layer is impermeable to solutes >200 Da from either the water phase or the oil phase; however, due to the emulsification process, oil and the hydrophobic marker molecules in the oil phase can be transferred into the water phase, thus giving the impression that the assembled layer is permeable to the marker molecules. By contrast, the layer assembled at an air-water interface is permeable to water vapor from either the hydrophobic or hydrophilic side.

Mucoadhesive Microparticles Engineered for Ophthalmic Drug Delivery

Bin Choy, Young; Park, Jung-Hwan; Prausnitz, Mark R.
Fonte: PubMed Publicador: PubMed
Tipo: Artigo de Revista Científica
Publicado em /05/2008 EN
Relevância na Pesquisa
15.97%
Although topical drug delivery is a convenient route of administration to treat various eye diseases, it has serious limitations due to rapid clearance of the formulation from the surface of the eye. In this study, we engineered microparticles for both sustained drug delivery and prolonged residence time on the extraocular surface. Microparticles were fabricated by emulsification using poly(lactic-co-glycolic acid) (PLG) and poly(ethylene glycol) (PEG) as the core material and mucoadhesion promoter, respectively. The particle size was controlled to be less than 10 µm to avoid eye irritation and for eventual clearance through the lacrimal canals. In vitro mucoadhesion tests showed that PLG microparticles with PEG adhered better to the mucous membrane under the conditions employed in this study compared to the microparticles without PEG. When an aqueous suspension of microparticles with PEG was administered topically to the rabbit eye in vivo, microparticles were seen for up to 30 min on the ocular surface in the cul-de-sac, which was a dramatic increase in residence time as compared to conventional eye drop formulations. We conclude that mucoadhesive microparticles are promising vehicles for ophthalmic drug delivery.

Bolaform surfactants with polyoxometalate head groups and their assembly into ultra-small monolayer membrane vesicles

Landsmann, Steve; Luka, Martin; Polarz, Sebastian
Fonte: Nature Pub. Group Publicador: Nature Pub. Group
Tipo: Artigo de Revista Científica
Publicado em 18/12/2012 EN
Relevância na Pesquisa
26.07%
Surfactants are indispensable in established technologies as detergents or emulsification agents, and also in recent studies for controlling the growth of nanoparticles or for creating nanocarriers. Although the properties of conventional, organic surfactants are thoroughly explored, strong interest persists in surfactants that possess unique features inaccessible for ordinary systems. Here we present dipolar, bolaform surfactants with a head group comprising of 11 tungsten atoms. These novel compounds are characterized by an exceptionally low critical self-organization concentration, which leads to monolayer vesicles with a diameter of only 15 nm, that is, substantially smaller than for any other system. The membrane of the vesicles is impermeable for water-soluble and oil-soluble guests. Control over release kinetics, which can be followed via the quantitative fluorescence quenching of confined fluorophores, is gained by means of pH adjustments.

Antitumor activity of docetaxel-loaded polymeric nanoparticles fabricated by Shirasu porous glass membrane-emulsification technique

Yu, Yunni; Tan, Songwei; Zhao, Shuang; Zhuang, Xiangting; Song, Qingle; Wang, Yuliang; Zhou, Qin; Zhang, Zhiping
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
46.39%
Docetaxel (DTX) has excellent efficiency against a wide spectrum of cancers. However, the current clinical formulation has limited its usage, as it causes some severe side effects. Various polymeric nanoparticles have thus been developed as alternative formulations of DTX, but they have been mostly fabricated on a laboratory scale. Previously, we synthesized a novel copolymer, poly(lactide)-D-α-tocopheryl polyethylene glycol 1000 succinate (PLA-TPGS), and found that it exhibited great potential in drug delivery with improved properties. In this study, we applied the Shirasu porous glass (SPG) membrane-emulsification technique to prepare the DTX-loaded PLA-TPGS nanoparticles on a pilot scale. The effect of several formulation variables on the DTX-loaded nanoparticle properties, including particle size, zeta potential, and drug-encapsulation efficiency, were investigated based on surfactant type and concentration in the aqueous phase, organic/aqueous phase volumetric ratio, membrane-pore size, transmembrane cycles, and operation pressure. The DTX-loaded nanoparticles were obtained with sizes of 306.8 ± 5.5 nm and 334.1 ± 2.7 nm (mean value ± standard deviation), and drug-encapsulation efficiency of 81.8% ± 4.5% and 64.5% ± 2.7% for PLA-TPGS and poly(lactic-co-glycolic acid) (PLGA) nanoparticles...

Self-Nanoemulsifying Drug Delivery System of Lutein: Physicochemical Properties and Effect on Bioavailability of Warfarin

Yoo, Juno; Baskaran, Rengarajan; Yoo, Bong-Kyu
Fonte: The Korean Society of Applied Pharmacology Publicador: The Korean Society of Applied Pharmacology
Tipo: Artigo de Revista Científica
Publicado em /03/2013 EN
Relevância na Pesquisa
15.97%
Objective of present study was to prepare and characterize self-nanoemulsifying drug delivery system (SNEDDS) of lutein and to evaluate its effect on bioavailability of warfarin. The SNEDDS was prepared using an oil, a surfactant, and co-surfactants with optimal composition based on pseudo-ternary phase diagram. Effect of the SNEDDS on the bioavailability of warfarin was performed using Sprague Dawley rats. Lutein was successfully formulated as SNEDDS for immediate self-emulsification and dissolution by using combination of Peceol as oil, Labrasol as surfactant, and Transcutol-HP or Lutrol-E400 as co-surfactant. Almost complete dissolution was achieved after 15 min while lutein was not detectable from the lutein powder or intra-capsule content of a commercial formulation. SNEDDS formulation of lutein affected bioavailability of warfarin, showing about 10% increase in Cmax and AUC of the drug in rats while lutein as non-SNEDDS did not alter these parameters. Although exact mechanism is not yet elucidated, it appears that surfactant and co-surfactant used for SNEDDS formulation caused disturbance in the anatomy of small intestinal microvilli, leading to permeability change of the mucosal membrane. Based on this finding, it is suggested that drugs with narrow therapeutic range such as warfarin be administered with caution to avoid undesirable drug interaction due to large amount of surfactants contained in SNEDDS.

Ultrasound-Triggered Phase Transition Sensitive Magnetic Fluorescent Nanodroplets as a Multimodal Imaging Contrast Agent in Rat and Mouse Model

Cheng, Xin; Li, Huan; Chen, Yunchao; Luo, Binhua; Liu, Xuhan; Liu, Wei; Xu, Haibo; Yang, Xiangliang
Fonte: Public Library of Science Publicador: Public Library of Science
Tipo: Artigo de Revista Científica
Publicado em 31/12/2013 EN
Relevância na Pesquisa
25.97%
Ultrasound-triggered phase transition sensitive nanodroplets with multimodal imaging functionality were prepared via premix Shirasu porous glass (SPG) membrane emulsification method. The nanodroplets with fluorescence dye DiR and SPIO nanoparticles (DiR-SPIO-NDs) had a polymer shell and a liquid perfluoropentane (PFP) core. The as-formed DiR-SPIO-NDs have a uniform size of 385±5.0 nm with PDI of 0.169±0.011. The TEM and microscopy imaging showed that the DiR-SPIO-NDs existed as core-shell spheres, and DiR and SPIO nanoparticles dispersed in the shell or core. The MTT and hemolysis studies demonstrated that the nanodroplets were biocompatible and safe. Moreover, the proposed nanodroplets exhibited significant ultrasound-triggered phase transition property under clinical diagnostic ultrasound irradiation due to the vaporization of PFP inside. Meanwhile, the high stability and R2 relaxivity of the DiR-SPIO-NDs suggested its applicability in MRI. The in vivo T2-weighted images of MRI and fluorescence images both showed that the image contrast in liver and spleen of rats and mice model were enhanced after the intravenous injection of DiR-SPIO-NDs. Furthermore, the ultrasound imaging (US) in mice tumor as well as MRI and fluorescence imaging in liver of rats and mice showed that the DiR-SPIO-NDs had long-lasting contrast ability in vivo. These in vitro and in vivo findings suggested that DiR-SPIO-NDs could potentially be a great MRI/US/fluorescence multimodal imaging contrast agent in the diagnosis of liver tissue diseases.

GPBA: a GPCR for bile acids and an emerging therapeutic target for disorders of digestion and sensation

Lieu, T; Jayaweera, G; Bunnett, N W
Fonte: Blackwell Publishing Ltd Publicador: Blackwell Publishing Ltd
Tipo: Artigo de Revista Científica
EN
Relevância na Pesquisa
16.07%
Bile acids (BAs) are digestive secretions that are necessary for the emulsification and absorption of dietary fats. Given the episodic nature of BA secretion and intestinal re-absorption, the circulating and tissue levels of BAs, like those of the gut hormones, fluctuate in fasting and fed states, and BA levels and forms are markedly affected by disease. BAs exert widespread hormonal-like effects by activating receptors in the nucleus and at the plasma membrane. The nuclear steroid receptors mediate the genomic actions of BAs on BA, glucose and lipid homeostasis. GPBA (TGR5) is a G-protein coupled plasma membrane receptor for BAs that mediates many of the rapid, non-genomic actions of BAs. GPBA has been implicated in the control of glucose homeostasis, inflammation and liver functions. Recent observations have revealed an unexpected role for GPBA in the nervous system. GPBA is expressed by enteric neurons and enterochromaffin cells that control peristalsis, and GPBA mediates the prokinetic actions of BAs in the colon that have been known for millennia. GPBA is also present on primary spinal afferent and spinal neurons that are necessary for sensory transduction. BA-induced activation of GPBA in the sensory nervous system promotes scratching behaviours and analgesia...

Intracellular uptake of etoposide-loaded solid lipid nanoparticles induces an enhancing inhibitory effect on gastric cancer through mitochondria-mediated apoptosis pathway

Wang, Jiao; Zhu, Rongrong; Sun, Xiaoyu; Zhu, Yanjing; Liu, Hui; Wang, Shi-Long
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
Publicado em 20/08/2014 EN
Relevância na Pesquisa
15.97%
The objective of this study was to prepare and characterize etoposide (VP16)-loaded solid lipid nanoparticles (SLNs) and evaluate their antitumor activity in vitro. VP16-SLNs were prepared using emulsification and low-temperature solidification methods. The physicochemical properties of the VP16-SLNs were investigated by particle-size analysis, zeta potential measurement, drug loading, drug entrapment efficiency, stability, and in vitro drug-release behavior. In contrast to free VP16, the VP16-SLNs were well dispersed in aqueous medium, showing a narrow size distribution at 30–50 nm, a zeta potential value of −28.4 mV, high drug loading (36.91%), and an ideal drug entrapment efficiency (75.42%). The drug release of VP16-SLNs could last up to 60 hours and exhibited a sustained profile, which made it a promising vehicle for drug delivery. Furthermore, VP16-SLNs could significantly enhance in vitro cytotoxicity against SGC7901 cells compared to the free drug. Furthermore, VP16-SLNs could induce higher apoptotic rates, more significant cell cycle arrest effects, and greater cellular uptake in SGC7901 cells than free VP16. Moreover, results demonstrated that the mechanisms of VP16-SLNs were similar to those claimed for free VP16, including induction of cellular apoptosis by activation of p53...

Enhanced local bioavailability of single or compound drugs delivery to the inner ear through application of PLGA nanoparticles via round window administration

Cai, Hui; Wen, Xingxing; Wen, Lu; Tirelli, Nicola; Zhang, Xiao; Zhang, Yue; Su, Huanpeng; Yang, Fan; Chen, Gang
Fonte: Dove Medical Press Publicador: Dove Medical Press
Tipo: Artigo de Revista Científica
Publicado em 01/12/2014 EN
Relevância na Pesquisa
15.97%
In this paper, the potential of poly(d,l-lactide-co-glycolide acid) (PLGA) nanoparticles (NPs) for carrying single or compound drugs traversing the round window membrane (RWM) was examined after the round window (RW) administration of different NPs to guinea pigs. First, coumarin-6 was incorporated into PLGA NPs as a fluorescent probe to investigate its ability to cross the RWM. Then, PLGA NPs with salvianolic acid B (Sal B), tanshinone IIA (TS IIA), and total panax notoginsenoside (PNS) including notoginsenoside R1 (R1), ginsenoside Rg1 (Rg1), and ginsenoside Rb1 (Rb1) were developed to evaluate whether NPs loaded with compound drugs would pass through the RWM and improve the local bioavailability of these agents. PLGA NPs loaded with single or compound drugs were prepared by the emulsification solvent evaporation method, and their particle size distribution, particle morphology, and encapsulation efficiency were characterized. In vitro release study showed sustained-release profiles of Sal B, TS IIA, and PNS from the NPs. The pharmacokinetic results showed that NPs applied to the RWM significantly improved drug distribution within the inner ear. The AUC0–t of coumarin-6 in the perilymph (PL) following RW administration of NPs was 4.7-fold higher than that of coumarin-6 solution...

Desenvolvimento e caracterização de micropartículas de cloridrato de quitosana contendo nistatina visando a libertação tópica

Konell, Camila Fernanda
Fonte: Universidade Federal de Santa Catarina Publicador: Universidade Federal de Santa Catarina
Tipo: Dissertação de Mestrado Formato: 114 p.| il., grafs., tabs.
POR
Relevância na Pesquisa
15.97%
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Farmácia, Florianópolis, 2014.; O uso indiscriminado de antimicrobianos na terapêutica tem desencadeado diversos tipos de mecanismos de resistência, o que tem impulsionado cada vez mais pesquisas focando na obtenção de novos fármacos, desenvolvimento ou melhoramento das formulações disponíveis no mercado. A nistatina é um antifúngico poliênico amplamente utilizado no tratamento de candidíases. Seu mecanismo de ação deve-se à ligação ao ergosterol, esteróide presente na membrana celular de fungos patogênicos como a Candida sp, promovendo a desestruturação e liberação do seu conteúdo celular. Além disso, a nistatina pertence à classe IV do Sistema de Classificação Biofarmacêutica, de modo que sua atividade biológica é impactada por sua baixa solubilidade e baixa permeabilidade. Neste contexto, sistemas microparticulados de cloridrato de quitosana destinados à via tópica foram desenvolvidos através de spray drying e emulsificação/evaporação de solvente seguida de liofilização objetivando um aumento da retenção cutânea e melhorias na atividade microbiológica da nistatina. Os sistemas foram obtidos em diferentes proporções de fármaco:polímero (1:1; 1:2 e 1:3...

Performance evaluation of organic emulsion liquid membrane on phenol removal

Ng, Y. S.; Jayakumar, N. S.; Hashim, M. A.
Fonte: Universidade Cornell Publicador: Universidade Cornell
Tipo: Artigo de Revista Científica
Publicado em 30/11/2014
Relevância na Pesquisa
26.45%
The percentage removal of phenol from aqueous solution by emulsion liquid membrane and emulsion leakage was investigated experimentally for various parameters such as membrane:internal phase ratio, membrane:external phase ratio, emulsification speed, emulsification time, carrier concentration, surfactant concentration and internal agent concentration. These parameters strongly influence the percentage removal of phenol and emulsion leakage. Under optimum membrane properties, the percentage removal of phenol was as high as 98.33%, with emulsion leakage of 1.25%. It was also found that the necessity of carrier for enhancing phenol removal was strongly dependent on the internal agent concentration.

Nanocomposite polymer beads for cell detection

Jacinto, João Paulo Palma
Fonte: Universidade Nova de Lisboa Publicador: Universidade Nova de Lisboa
Tipo: Dissertação de Mestrado
Publicado em //2015 ENG
Relevância na Pesquisa
46.52%
Circulating tumor cells (CTCs) may induce metastases when detached from the primary tumor. The numbers of these cells in blood offers a valuable prognostic indication. Magnetoresistive sensing is an attractive option for CTC counting. In this technique, cells are labeled with nancomposite polymer beads that provide the magnetic signal. Bead properties such as size and magnetic content must be optimized in order to be used as a detection tool in a magnetoresistive platform. Another important component of the platform is the magnet required for proper sensing. Both components are addressed in this work. Nanocomposite polymer beads were produced by nano-emulsion and membrane emulsification. Formulations of the oil phase comprising a mixture of aromatic monomers and iron oxide were employed. The effect of emulsifier (surfactant) concentration on bead size was studied. Formulations of polydimethilsiloxane (PDMS) with different viscosities were also prepared with nano-emulsion method resulting in colloidal beads. Polycaprolactone (PCL) beads were also synthetized by the membrane emulsification method. The beads were characterized by different techiques such as dynamic light scattering (DLS), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Additionally...