Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles

Beitrag in einer Fachzeitschrift


Details zur Publikation

Autor(en): Schmiele M, Gehrer S, Westermann M, Steiniger F, Unruh T
Zeitschrift: Journal of Chemical Physics
Verlag: AMER INST PHYSICS
Jahr der Veröffentlichung: 2014
Band: 140
Heftnummer: 21
ISSN: 0021-9606


Abstract


Suspensions of platelet-like shaped tripalmitin nanocrystals stabilized by the pure lecithin DLPC and the lecithin blend S100, respectively, have been studied by small-angle x-ray scattering (SAXS) and optical observation of their birefringence at different tripalmitin (PPP) concentrations phi(PPP). It could be demonstrated that the platelets of these potential drug delivery systems start to form a liquid crystalline phase already at pharmaceutically relevant concentrations phi(PPP) of less than 10 wt. %. The details of this liquid crystalline phase are described here for the first time. As in a previous study [A. Illing et al., Pharm. Res. 21, 592 (2004)] some platelets are found to self-assemble into lamellar stacks above a critical tripalmitin concentration phi(st)(PPP) of 4 wt. %. In this study another critical concentration phi(lc)(PPP) approximate to 7 wt. % for DLPC and phi(lc)(PPP) approximate to 9 wt. % for S100 stabilized dispersions, respectively, has been observed phi(lc)(PPP) describes the transition from a phase of randomly oriented stacked lamellae and remaining non-assembled individual platelets to a phase in which the stacks and non-assembled platelets exhibit an overall preferred orientation. A careful analysis of the experimental data indicates that for concentrations above phi(lc)(PPP) the stacked lamellae start to coalesce to rather small liquid crystalline domains of nematically ordered stacks. These liquid crystalline domains can be individually very differently oriented but possess an overall preferred orientation over macroscopic length scales which becomes successively more expressed when further increasing phi(PPP). The lower critical concentration for the formation of liquid crystalline domains of the DLPC-stabilized suspension compared to phi(lc)(PPP) of the S100-stabilized suspension can be explained by a larger aspect ratio of the corresponding tripalmitin platelets. A geometrical model based on the excluded volumes of individual platelets and stacked lamellae has been developed and successfully applied to reproduce the critical volume fractions for both, the onset of stack formation and the appearance of the liquid crystalline phase. (C) 2014 AIP Publishing LLC.



FAU-Autoren / FAU-Herausgeber

Gehrer, Simone
Lehrstuhl für Kristallographie und Strukturphysik
Schmiele, Martin
Professur für Nanomaterialcharakterisierung (Streumethoden)
Unruh, Tobias Prof. Dr.
Professur für Nanomaterialcharakterisierung (Streumethoden)


Autor(en) der externen Einrichtung(en)
Universitätsklinikum Jena


Zitierweisen

APA:
Schmiele, M., Gehrer, S., Westermann, M., Steiniger, F., & Unruh, T. (2014). Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles. Journal of Chemical Physics, 140(21). https://dx.doi.org/10.1063/1.4880723

MLA:
Schmiele, Martin, et al. "Formation of liquid crystalline phases in aqueous suspensions of platelet-like tripalmitin nanoparticles." Journal of Chemical Physics 140.21 (2014).

BibTeX: 

Zuletzt aktualisiert 2018-06-08 um 19:54