Structural characterization of lipidic systems under nonequilibrium conditions
This review covers recent studies on the characterization of the dynamics of lipidic nanostructures formed via self-assembly processes. The focus is placed on two main topics: First, an overview of advanced experimental small-angle X-ray scattering (SAXS) setups combined with various sample manipulation techniques including, for instance, stop-flow mixing or rapid temperature-jump perturbation is given. Second, our recent synchrotron SAXS findings on the dynamic structural response of gold nanoparticle-loaded vesicles upon exposure to an ultraviolet light source, the impact of rapidly mixing negatively charged vesicles with calcium ions, and in situ hydration-induced formation of inverted-type liquid-crystalline phases loaded with the local anesthetic bupivacaine are summarized. These in situ time-resolved experiments allow real-time monitoring of the dynamics of the structural changes and the possible formation of intermediate states in the millisecond to second range. The need for investigating self-assembled systems, mainly stimuli-responsive drug nanocarriers, under nonequilibrium conditions is discussed. For pharmaceutically relevant applications, it is essential to combine these investigations with appropriate in vitro and in vivo studies.
KeywordsPhase transitions Inverted-type liquid-crystalline phases Nonequilibrium conditions Time-resolved SAXS Stop-flow mixing Temperature-jump
- Caffrey M (1989) Structural, mesomorphic and time-resolved studies of biological liquid crystals and lipid membranes using synchrotron X-radiation. In: Mandelkow E (ed) Topics in Current Chemistry. Springer, Berlin, pp 75–109Google Scholar
- Laggner P (1988) X-ray studies on biological membranes using synchrotron radiation. In: Mandelkow E (ed) Topics in Current Chemistry. Springer, Berlin, pp 173–202Google Scholar
- Laggner P, Kriechbaum M, Rappolt M, Pabst G, Amenitsch H, Johs A, Lohner K, Zweytick D, Koschuch R, Abuja P (2005) Pharmaceutical solid-state characterization by small-and wide-angle X-ray scattering. In: Zakrzewski A, Zakrzewski M (eds) Solid State Characterization of Pharmaceuticals. Assa International, Danbury, pp 407–448Google Scholar
- Nguyen TH, Hanley T, Porter CJH, Larson I, Boyd BJ (2010) Phytantriol and glyceryl monooleate cubic liquid crystalline phases as sustained-release oral drug delivery systems for poorly water soluble drugs I. Phase behaviour in physiologically-relevant media. J Pharm Pharmacol 62:844–855PubMedGoogle Scholar
- Yaghmur A, Rappolt M (2011) Recent advances in the characterization of lipid-based nanocarriers. In: Garti N, Amar-Yuli I (eds) Nanotechnologies for solubilization and delivery in foods, cosmetics and pharmaceuticals. DEStech, Lancaster, pp 187–208Google Scholar