RESUMO
The adsorption of bovine serum albumin (BSA) to lecithin was investigated by ATR-FTIR spectroscopy. Lecithin films were prepared by casting aliquots of 3.2 microg lecithin in methanol onto ZnSe ATR prisms. Surface morphology and the thickness of the films were investigated by laser scanning confocal electron microscopy and scanning electron microscopy and the thickness of the films used for adsorption studies was estimated to be 40 A. The dependency of the CO peak area on the lecithin mass in the calibration curve confirms that the thickness of the film is below the penetration depth of the infrared evanescent wave. Size exclusion HPLC and fluorescence spectroscopy show that BSA conformation in up to 1M NaCl and CaCl(2) solutions is similar to that in water with no aggregation or changes in protein conformation seen over 4h. The kinetics of BSA adsorption on the lecithin film from water, NaCl and CaCl(2) solutions demonstrates that ions promote the protein adsorption. BSA bound more in the presence of NaCl compared to CaCl(2) at equivalent concentrations. The adsorption appeared greatest at a 0.1M concentration for both NaCl and CaCl(2). The results are explained in terms of absorptive reactivity of BSA and lecithin surfaces upon salt addition.
Assuntos
Cloreto de Cálcio/química , Excipientes/química , Fosfatidilcolinas/química , Soroalbumina Bovina/química , Cloreto de Sódio/química , Espectroscopia de Infravermelho com Transformada de Fourier , Tecnologia Farmacêutica/métodos , Adsorção , Animais , Bovinos , Química Farmacêutica , Cromatografia em Gel/métodos , Cromatografia Líquida de Alta Pressão , Cinética , Metanol/química , Microscopia Confocal , Microscopia Eletrônica de Varredura , Fosfatidilcolinas/metabolismo , Ligação Proteica , Conformação Proteica , Compostos de Selênio/química , Soroalbumina Bovina/metabolismo , Espectrometria de Fluorescência , Propriedades de Superfície , Água/química , Compostos de Zinco/químicaRESUMO
FT-Raman spectroscopy has been used to investigate interactions between lecithin and cholesterol. Raman spectra of lecithin show multiple peaks which can be classified into three regions: hydrophobic chain, interfacial, and headgroup regions. Binary lipid mixtures (1:1, w/w, lecithin:cholesterol) were prepared by physical mixing, granulation, coprecipitation, hydration and heating (65 degrees C), and heating (120 degrees C). Regardless of the preparation method, no changes in the spectra were observed in the hydrophobic region. A shift in the wavenumber of the choline methyl asymmetric stretching mode was observed when the samples were prepared by coprecipitation, hydration and heating (65 degrees C), and heating (120 degrees C). This may indicate a modification of phospholipids in the headgroup region in these samples. The difference in degrees of frequency shift (physical mixing approximately granulationAssuntos
Colesterol/química
, Fosfatidilcolinas/análise
, Fosfatidilcolinas/química
, Química Farmacêutica/métodos
, Análise dos Mínimos Quadrados
, Membranas Artificiais
, Conformação Molecular
, Pós
, Análise Espectral Raman
, Temperatura
, Água/química
