Young's Moduli of Surface-Bound Liposomes by Atomic Force Microscopy Force Measurements

Mechanical properties of layers of intact liposomes attached by specific interactions on solid surfaces were studied by atomic force microscopy (AFM) force measurements. Force−distance measurements using colloidal probe tips were obtained over liposome layers and used to calculate Young's modul...

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Bibliographic Details
Published in:Langmuir 2008-03, Vol.24 (5), p.2009-2014
Main Authors: Brochu, Heïdi, Vermette, Patrick
Format: Article
Language:English
Subjects:
Chemistry
Colloidal state and disperse state
Elasticity
Exact sciences and technology
General and physical chemistry
Liposomes - chemistry
Membranes
Microscopy, Atomic Force
Surface physical chemistry
Surface Properties
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Summary:Mechanical properties of layers of intact liposomes attached by specific interactions on solid surfaces were studied by atomic force microscopy (AFM) force measurements. Force−distance measurements using colloidal probe tips were obtained over liposome layers and used to calculate Young's moduli by using the Hertz contact theory. A classical Hertz model and a modified Hertz one have been used to extract Young's moduli from AFM force curves. The modified model, proposed by Dimitriadis, is correcting for the finite sample thickness since Hertz's classical model is assuming that the sample is infinitely thick. Values for Young's moduli of 40 and 8 kPa have been obtained using the Hertz model for one and three layers of intact liposomes, respectively. Young's moduli of approximately 3 kPa have been obtained using the corrected Hertz model for both one and three layers of surface-bound liposomes. Compression work performed by the colloidal probe to compress these liposome layers has also been calculated.
ISSN:0743-7463
1520-5827
DOI:10.1021/la702382d