Rheology and transition shapes of elastic liposomes in nanopores membranes / Reologia e transição de formas de lipossomas elasticos em membranas de nanoporos

AUTOR(ES)
DATA DE PUBLICAÇÃO

2007

RESUMO

In this work, liposomes prepared with comercial egg lecithin and octaoxyethylenelaurate-ester (PEG-8L) were characterized and studied in respect to PEG-8L incorporation, shape transitions, elasticity and rheology in nanopores membranes. Conventional liposomes (without PEG-8L) were used as control. The concentrated caffeine, extracted of guarana seeds, was incorporated with efficiency of 11,0%, 41,9% e 39,9%, for conventional and elastic liposomes with 25% and 40% of PEG-8L, respectively. The kinetic of PEG-8L incorporation in liposomes, its rheology and shape transitions were characterized through average diameter measurements, sizes distribution, phosphate concentration and surface tension of dispersions. The rheology was studied in synthetic nanoporous membranes and dermatomized ear pig skin. Average diameter and sistribution wre monitored during 24 hours for evaluation of liposomes stability. The results show PEG-8L incorporation in 20,4% and 15,4% for initial molar ratios lipid:PEG-8L 75:25 and 60:40. The rheology of elastic liposome across nanoporous membranes shows linear behavior between flow and pressure drop, in the range of 2,5 to 20 atm, with effect permeability dependent of liposome concentration and deformation. The rheological model of membranes for conventional liposomes was modified to contemplate the elastic liposome flow and to discuss its application. The surface tension, deformation and electron micrographs of elastic liposome with 40% of PEG-8L after permeation, suggested that the elasticity and its integrity maintenance were due to PEG-8L chains packing at its surface. This results contribute for knowledge of liposomes permeation mechanisms across skin and development of liposome formulation for drug transdermal transport

ASSUNTO(S)

agentes ativos de superficies elastic liposomes medicação transcutanea transdemal transport lipossomos peg-8l

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