Joseph, S, Rappolt, M, Schoenitz, M et al. (4 more authors) (2015) Stability of the metastable α-polymorph in solid triglyceride drug carrier nanoparticles. Langmuir. ISSN 0743-7463
Abstract
Colloidal dispersions of crystalline nonpolar lipids are under intensive investigation as carrier systems in pharmaceutics and nutrition. In this context, the controlled preparation of particles in a metastable polymorphic state is of some interest for the delivery of active substances. In the present study, tristearin particles stabilized with three α-polymorph preserving emulsifier regimes ((I) sodium glycocholate/saturated long-chain phospholipids, (II) sodium glycocholate, (III) poly(vinyl alcohol) (PVA)) were investigated concerning the stability of the metastable α-polymorph after controlled crystallization of the particles from the melt. Upon long-term storage, the α-polymorph was preserved best in PVA-stabilized dispersions, followed by those stabilized with the glycocholate/phospholipid mixture and finally those stabilized solely with the bile salt. In particular for rapidly crystallized nanoparticles, the formation of an α-polymorph with highly reduced lamellarity was observed. According to time-/temperature-resolved synchrotron X-ray diffraction analysis with simultaneous DSC (differential scanning calorimetry) studies this less-ordered α-polymorph transformed into the common, lamellar α-form upon heating. Although the presence of the less-ordered form is probably related to the extraordinarily high stability of the metastable α-polymorph observed in some of the dispersions, it could not completely prevent the transition into the stable β-polymorph. The higher the transition temperature of the less-ordered α-form to the ordered one, the slower was the polymorphic transition to the stable β-polymorph. To estimate the polymorphic stability of the differently stabilized particles upon isothermal long-term storage, standard DSC measurements on samples stored at 23 °C for four weeks seem to be of predictive value.
Metadata
Item Type: | Article |
---|---|
Authors/Creators: |
|
Dates: |
|
Institution: | The University of Leeds |
Academic Units: | The University of Leeds > Faculty of Environment (Leeds) > School of Food Science and Nutrition (Leeds) |
Depositing User: | Symplectic Publications |
Date Deposited: | 11 Jun 2015 11:21 |
Last Modified: | 03 Nov 2016 08:44 |
Published Version: | http://dx.doi.org/10.1021/acs.langmuir.5b00874 |
Status: | Published |
Publisher: | American Chemical Society |
Identification Number: | 10.1021/acs.langmuir.5b00874 |
Related URLs: | |
Open Archives Initiative ID (OAI ID): | oai:eprints.whiterose.ac.uk:87001 |