RESUMO
Cryo-transmission electron microscopy (cryo-TEM) was used to image the microstructure in dilute sonicated dispersions of monoolein and oleic acid. The aim of the study was to explore how different experimental parameters, such as sample composition, total lipid concentration, pH, and ageing affect the phase behaviour and aggregate structure. Our investigations show that a rich variety of lamellar and non-lamellar structures, including liposomes and particles of cubic and inverted hexagonal phase, may form depending on the experimental conditions. The results are analyzed and discussed in relation to existing phase diagrams and earlier investigations concerning phase- and structural behaviour in monoolein/oleic acid/water systems.
Assuntos
Coloides/química , Glicerídeos/química , Ácido Oleico/química , Microscopia Crioeletrônica , Concentração de Íons de Hidrogênio , Lipossomos , Cristais Líquidos , Microscopia Eletrônica de Transmissão/métodos , Sonicação , Fatores de Tempo , Água/químicaRESUMO
Inclusion complexes of rifampicin (RP) were prepared with hydroxypropyl-ß-cyclodextrin (HPßCD). The aqueous solubility of RP increased linearly with cyclodextrin concentration in all range of the solubility diagram. The data was analyzed using the framework of Higuchi and Connors. The stability constant (K) values for RP/HPßCD complex at pH 6.9 were 18 and 120-125 M-1 for ionic strength 0.01 and 0.18M, respectively. The analysis of the chemical shift data of 1H and 15N for free RP and RP/HPßCD inclusion complex reveal that only peaks of the side chain related to the piperazine ring of RP change substantially, probably due to interaction of this region of RP molecule with the hydrophobic core of HPßCD...