Estruturas vesiculares em misturas de surfactantes catiônicos

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Cetyltrimethylammonium chloride (CTAC) effect on the thermal stability of oxy-HbGp: Dynamic light scattering (DLS) and small angle X-ray scattering (SAXS) studies

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Transição vesícula-micela em mistura aquosa de sais dialquilados de amônio quaternário com Pluronic® F127

Pós-graduação em Biofísica Molecular - IBILCE

Systematic analysis of protein-detergent complexes applying dynamic light scattering to optimize solutions for crystallization trials

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Produção de matéria seca em pastagem de Tifton 85 irrigada, com diferentes doses de dejeto líquido de suíno

O dejeto líquido de suíno (DLS) pode constituir-se em excelente fonte de adubação em pastagem, com aplicação por aspersão, desde que seja assegurada a proteção do meio ambiente. Apesar de seu comprovado potencial para uso em sequeiro, pouco se conhece sobre o comportamento da cultivar Tifton 85 em sistemas sob irrigação e sob aplicação de DLS. Para determinar a produção de matéria seca pré-pastejo de Tifton 85 com DLS, foi conduzido um experimento na Fazenda-Escola da Universidade de Uberaba, irrigado por aspersão em malha, com aplicação de 0; 50; 100 e 200 m³ ha-1 ano-1 de DLS. Houve efeito significativo das doses de DLS em relação à produção de matéria seca pré-pastejo, ocorrendo acréscimos de produção com o aumento das doses. O fornecimento de 200 m³ ha-1 ano-1 de DLS possibilitou produção de 5.928 kg de matéria seca (MS) da forrageira por ciclo de 28 dias.

Preparation of polymeric micelles for use as carriers of tuberculostatic drugs

Purpose: This paper focuses on the characterization of polymeric micelle-forming tuberculostatic prodrugs and the antimycobacterial activity of these prodrugs.Method: By the condensation of hydroxymethylpyrazinamide, isoniazid and rifampin with free carboxyl groups on the copolymer poly(ethyleneglycol)-poly(aspartic acid), micelle-forming carrier-drug conjugates were obtained. These micelles were characterized by dynamic light scattering, to measure the micelle diameter; by acid-base titration, to determine the percentage of carboxylic groups occupied by the tuberculostatic; by Sudan III solubility tests, to estimate the critical micelle concentration (CMC); and visual control and spectrophotometric measurement, to determine the stability of micelles. These micelles were tested in vitro against several Mycobacterium strains.Results: As expected, the size and distribution of the micelle-forming tuberculostatic prodrugs found to be small (78.2nm, 84.2nm and 98.9 nm) while the level of the drug conjugated was high (65.02-85.7%). Furthermore, the micelles were stable in vitro, exhibiting a low level of CMC and stronger antimycobacterial activity than the original drugs.Conclusion: the results demonstrate that polymeric micelles can be used as efficient carriers for drugs, which alone, exhibit undesired pharmacokinetics, poor solubility, and low stability. The synthesized micelle-forming tuberculostatic prodrugs opens a perspective of alternative prodrugs that prolong action and decrease the toxicity of the tuberculostatic drugs of choice.

Molecular assay optimized by Taguchi experimental design method for venous thromboembolism investigation

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Structure, properties and applications of rhamnolipids produced by Pseudomonas aeruginosa L2-1 from cassava wastewater

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of C/N Ratio and Physicochemical Conditions on the production of Rhamnolipids by Pseudomonas Aeruginosa LBI

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Cassava wastewater as a substrate for the simultaneous production of rhamnolipids and polyhydroxyalkanoates by Pseudomonas aeruginosa

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Biochemical and Functional Characterization of a Metalloprotease from the Thermophilic Fungus Thermoascus aurantiacus

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Properties of a biosurfactant produced by Bacillus pumilus using vinasse and waste frying oil as alternative carbon sources

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Interaction of octaethylene glycol n-dodecyl monoether with dioctadecyldimethylammonium bromide and chloride vesicles

Several different methods were used to investigate the vesicle-to-micelle transition induced by the addition of the nonionic surfactant octaethylene glycol n-dodecyl monoether (C12E8) to spontaneously formed vesicle dispersions of dioctadecyldimethylammonium bromide and chloride (DODAX, X = Cl- and Br-). Dynamic light scattering reveals that fast mode micelles are formed upon addition of C12E6. The micellar mode becomes progressively dominant as the C12E8/DODAX molar ratio (R) is increased until the vesicle-to-micelle transition is complete. Turbidity, calorimetry, fluorescence quantum yield, and anisotropy measurements indicate two critical compositions: the first, R-sat, when the vesicle bilayer is saturated with C12E8 and the second, R-sol, which corresponds to the complete vesicle-to-micelle transition. Below R-sat the vesicles swell due to incorporation of the surfactant into the vesicle bilayer, and above R-sat mixed micelles and bilayer structures coexist, the determined R-sat and R-sol range from 0 to 1 and 4 to 6, respectively, depending on the surfactant counterion and the experimental method used. Cryo-transmission electron microscopy micrographs show that when R approximate to 4, micelles coexist with extended bilayer fragments. In pure DODAX (1.0 mM) dispersions, unilamellar vesicles are observed. According to the DSC results, C12E8 lowers the gel-to-liquid crystalline transition temperature, T-m, of DODAX and broadens the main transition peak which disappears around R approximate to 5 and 6 for DODAC and DODAB, respectively.

The interaction between heparin and Lys49 phospholipase A(2) reveals the natural binding of heparin on the enzyme

We have studied at a molecular level the interaction of heparins on bothropstoxin-1 (BthTx-1), a phospholipase A(2) toxin. The protein was monitored using gel filtration chromatography, dynamic light scattering (DLS), circular dichroism (CD), attenuated total reflectance Fourier transform infrared (ATR-FTIR) and intrinsic tryptophan fluorescence emission (ITFE) spectroscopy. The elution profile of the protein presents a displacement of the protein peak to larger complexes when interacting with higher concentration of heparin. The DLS results shows two R-h at a molar ratio of 1, one to the distribution of the protein and the second for the action of heparin on BthTx-I structures, and a large distribution with the increase of protein. The interaction is accompanied by significant changes in the CD spectra, showing two common features: a decrease in signal at 208 nm (3 and 6 kDa heparins) and an isodichroic point near 226 nm (3 kDa heparin). FTIR spectra indicate that only a few amino acid residues are involved in this interaction. Alterations in the ITFE by binding heparins suggest that the initial binding occurs on the ventral face of BthTx-1. Together, these results add an experimental and structural basis on the action mechanism of the heparins over the phospholipases A(2) and provide a molecular model to elucidate the interaction of the enzyme-heparin complex at a molecular level. (c) 2005 Elsevier B.V. All rights reserved.

The effect of chain length on the melting temperature and size of dialkyldimethylammonium bromide vesicles

Differential scanning calorimetry (DSc) and dynamic light scattering (DLS) were used to obtain the gel to liquid-crystalline phase transition temperature (T-m) and the apparent hydrodynamic radius (R-h) of spontaneously formed cationic vesicles of dialkyldimethylammonium bromide salts (CnH2n+1)(2)(CH3)(2)N+center dot Br-, with varying chain lengths. The preparation of cationic vesicles from aqueous solution of these surfactants, for n = 12, 14, 16 and 18 (DDAB, DTDAB, DHDAB and DODAB, respectively), requires the knowledge of the surfactant gel to liquid-crystalline phase transition temperature, or melting temperature (T-m) since below this temperature these surfactants are poorly or not soluble in water. That series of cationic surfactants has been widely investigated as vesicle-forming surfactants, although C-12 and C-18, DDAB and DODAB are by far the most investigated from this series. The dependence of T-m of these surfactants on the number n of carbons in the surfactant tails is reported. The T-m obtained by DSC increases non-linearly with n, and the vesicle apparent radius R-h is about the same for DHDAB and DODAB, but much smaller for DDAB. (c) 2006 Elsevier B.V.. All rights reserved.