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|Main Title:||Control of the stability and structure of liposomes by means of nanoparticles|
|Abstract:||The interaction of bilayer vesicles with hard nanoparticles is of great relevance to the field of nanotechnology, e.g., its impact on health and safety matters, and also as vesicles are important as delivery vehicles. In this work we describe hybrid systems composed of zwitterionic phospholipid vesicles (DPPC), which are below the phase transition temperature, and added silica nanoparticles (SiNPs) of much smaller size. The initial DPPC unilamellar vesicles, obtained by extrusion, are rather unstable and age but the rate of ageing can be controlled over a large time range by the amount of added SiNPs. For low addition they become destabilized whereas larger amounts of SiNPs enhance the stability largely as confirmed by dynamic light scattering (DLS). ζ-Potential and DSC measurements confirm the binding of the SiNPs onto the phospholipid vesicles, which stabilizes the vesicles against flocculation by rendering the ζ-potential more negative. This effect appears above a specific SiNP concentration, and is the result of the adsorption of the negatively charged nanoparticles onto the outer surface of the liposome leading to decorated vesicles as proven by cryogenic transmission electron microscopy (cryo-TEM). Small amounts of surface-adsorbed SiNPs initially lead to a bridging of vesicles thereby enhancing flocculation, while higher amounts render the vesicles much more negatively charged and thereby long-time stable. This stability has an optimum at neutral pH and for low ionic strength. Thus we show that the addition of the SiNPs is a versatile way to control the stability of gel-state phospholipid vesicles and also to modulate their surface structure in a systematic fashion. This is not only of importance for understanding the fundamental interaction between SiNPs and bilayer vesicles, but also with respect to using silica particles as formulation aids for phospholipid dispersions.|
|DDC Class:||530 Physik|
|Sponsor/Funder:||DFG, GRK 1524, Self-Assembled Soft-Matter Nanostructures at Interfaces|
|Usage rights:||Terms of German Copyright Law|
|Journal Title:||Soft matter|
|Publisher:||Royal Society of Chemistry|
|Notes:||Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG geförderten) Allianz- bzw. Nationallizenz frei zugänglich.|
This publication is with permission of the rights owner freely accessible due to an Alliance licence and a national licence (funded by the DFG, German Research Foundation) respectively.
|Appears in Collections:||Technische Universität Berlin » Fakultäten & Zentralinstitute » Fakultät 2 Mathematik und Naturwissenschaften » Institut für Chemie » Publications|
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