Liposome fractionation and size analysis by asymmetrical flow field-flow fractionation/multi-angle light scattering: influence of ionic strength and osmotic pressure of the carrier liquid

Hupfeld, Stefan; Moen, Helene; Ausbacher, Dominik; Haas, Heinrich; Brandl, Martin

doi:10.1016/j.chemphyslip.2009.10.009

Cited by 71 publications

(38 citation statements)

References 28 publications

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“…The observed influence of cholesterol on vesicle size is in agreement with earlier literature, where a stronger mechanical stability (higher lysis tension) during extrusion was made responsible for larger vesicle diameters of cholesterol-containing vesicles as compared with vesicles made of PC only (Patty & Frisken, 2003). Noteworthy, the geometric diameters of all vesicle dispersions appear to exceed the pore size of the filter used in the final extrusion step, indicating reversible elastic deformation of the vesicles during passage through the pores; see Hupfeld et al (2010) and cited therein for discussion of the elastic deformation phenomenon.…”

Section: Effect Of Phosphatidylcholine-/cholesterol-ratiosupporting

confidence: 91%

Filter-extruded liposomes revisited: a study into size distributions and morphologies in relation to lipid-composition and process parameters

Hinna

Steiniger

Hupfeld³

et al. 2015

Journal of Liposome Research

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Filter-extrusion is a widely used technique for down-sizing of phospholipid vesicles. In order to gain a detailed insight into size and size distributions of filter-extruded vesicles composed of egg phosphatidyl-choline (with varying fractions of cholesterol)--in relation to extrusion-parameters (pore-size, number of filter passages, and flow-rate), flow field-flow fractionation in conjunction with multi-angle laser light scattering (AF4-MALLS, Wyatt Technology Corp., Santa Barbara, CA) was employed. Liposome size-distributions determined by AF4-MALLS were compared with those of dynamic light scattering and correlated with cryo-transmission electron microscopy and (31)P-NMR-analysis of lamellarity. Both the mean size of liposome and the width of size distribution were found to decrease with sequential extrusion through smaller pore size filters, starting at a size range of ≈70-415 nm upon repeated extrusion through 400 nm pore-filters, eventually ending with a size range from ≈30 to 85 nm upon extrusion through 30 nm pore size filters. While for small pores sizes (50 nm), increased flow rates resulted in smaller vesicles, no significant influence of flow rate on mean vesicle size was seen with larger pores. Cholesterol at increasing mol fractions up to 0.45 yielded bigger vesicles (at identical process conditions). For a cholesterol mol fraction of 0.5 in combination with small filter pore size, a bimodal size distribution was seen indicating cholesterol micro-crystallites. Finally, a protocol is suggested to prepare large (∼ 300 nm) liposomes with rather narrow size distribution, based on the filter extrusion at defined flow-rates in combination with freeze-/thaw-cycling and bench-top centrifugation.

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Section: Effect Of Phosphatidylcholine-/cholesterol-ratiosupporting

confidence: 91%

Filter-extruded liposomes revisited: a study into size distributions and morphologies in relation to lipid-composition and process parameters

Hinna

Steiniger

Hupfeld³

et al. 2015

Journal of Liposome Research

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“…AFFF has been used for characterization and size fractionation of vesicles [22][23][24][25][26], including applications to biological vesicles [27,28]. The dispersed particles travel along a channel with a parabolic velocity profile in the principal flow direction.…”

Section: Asymmetric-flow Field-flow Fractionationmentioning

confidence: 99%

Synaptic vesicles studied by dynamic light scattering

et al. 2011

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Abstract. The size polydispersity distribution of synaptic vesicles (SVs) is characterized under quasiphysiological conditions by dynamic light scattering (DLS). Highly purified fractions of SVs obtained from rat brain still contain a small amount of larger contaminant structures, which can be quantified by DLS and further reduced by asymmetric-flow field-flow (AFFF) fractionation. The intensity autocorrelation functions g 2(τ ) recorded from these samples are analyzed by a constrained regularization method as well as by an alternative direct modeling approach. The results are in quantitative agreement with the polydispersity obtained from cryogenic electron microscopy of vitrified SVs. Next, different vesicle fusion assays based on samples composed of SVs and small unilamellar proteoliposomes with the fusion proteins syntaxin 1 and SNAP-25A are characterized by DLS. The size increase of the proteoliposomes due to SNARE-dependent fusion with SVs is quantified by DLS under quasi-physiological conditions.

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“…This "swelling" of the liposomes should be attributed to the co-existence of Dox and PG1, with probable Dox-PG1 complex formation in the interior cavity of the liposome, as this effect did not take place upon the presence of either just Dox or PG1. A possible explanation is the increased osmotic pressure of the aqueous interior of the vesicles due to the large quantity of the entrapped molecules (Gardikis et al, 2010b;Hupfeld et al, 2010).…”

Section: Discussionmentioning

confidence: 99%

New chimeric advanced Drug Delivery nano Systems (chi-aDDnSs) as doxorubicin carriers

Gardikis¹,

Tsimplouli²,

Dimas³

et al. 2010

International Journal of Pharmaceutics

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Liposome fractionation and size analysis by asymmetrical flow field-flow fractionation/multi-angle light scattering: influence of ionic strength and osmotic pressure of the carrier liquid

Cited by 71 publications

References 28 publications

Filter-extruded liposomes revisited: a study into size distributions and morphologies in relation to lipid-composition and process parameters

Filter-extruded liposomes revisited: a study into size distributions and morphologies in relation to lipid-composition and process parameters

Synaptic vesicles studied by dynamic light scattering

New chimeric advanced Drug Delivery nano Systems (chi-aDDnSs) as doxorubicin carriers

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