High-sensitivity differential scanning calorimetry for measurement of steroid entrapment in nebulised liposomes generated from proliposomes

Elhissi, A.M.A., O'Neill, M.A.A., Ahmed, W. and Taylor, K.M.G. (2011) High-sensitivity differential scanning calorimetry for measurement of steroid entrapment in nebulised liposomes generated from proliposomes. Micro and Nano Letters, 6 (8). pp. 694-697. 10.1049/mnl.2011.0086.

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DOI: 10.1049/mnl.2011.0086

Abstract

A novel approach to the determination of steroid entrapment in the bilayers of aerosolised liposomes has been introduced using high-sensitivity differential scanning calorimetry (DSC). Proliposomes were dispersed in water within an air-jet nebuliser and the energy produced during atomisation was used to hydrate the proliposomes and generate liposome aerosols. Proliposomes that included the steroid beclometasone dipropionate (BDP) produced lower aerosol and lipid outputs than steroid-free proliposomes. Size analysis and transmission electron microscopy showed an evidence of liposome formation within the nebuliser, which was followed by deaggregation and size reduction of multilamellar liposomes on nebulisation to a two-stage impinger. For each formulation, no difference in thermal transitions was observed between delivered liposomes and those remaining in the nebuliser. However, steroid (5mole) lowered the onset temperature and the enthalpy of the pretransition, and produced a similar onset temperature and larger enthalpy of the main transition, with broadened pretransition and main transitions. This indicates that BDP was entrapped and exhibited an interaction with the liposome phospholipid membranes. Since the pretransition was depressed but not completely removed and no phase separation occurred, it is suggested that the bilayers of the multilamellar liposomes can entrap more than 5mole BDP. Overall, liposomes were generated from proliposomes and DSC investigations indicated that the steroid was entrapped in the bilayers of aerosolised multilamellar vesicles.

Item Type:Article
Departments, units and centres:Department of Pharmaceutics > Department of Pharmaceutics
ID Code:2799
Journal or Publication Title:Micro and Nano Letters
Deposited By:Library Staff
Deposited On:10 Feb 2012 11:25
Last Modified:10 Feb 2012 11:25

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