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SAXS studies on dispersions from liquid crystalline systems

Otto Glatter, Department of Chemistry, Graz University of Technology, Austria

2019.05.21 | Trine Møller Hansen

Date Tue 18 Jun
Time 13:00 13:25
Location iNANO AUD (1593-012), Gustav Wieds Vej 14, 8000 Aarhus C

Otto Glatter, Department of Chemistry, Graz University of Technology, Austria

SAXS studies on dispersions from liquid crystalline systems

Glycerolmonolinolein (MLO), Glycerolmonoolein (GMO), Phytantriol (PT) and a few other lipophilic molecules self-assemble in bulk in presence of water to form well defined liquid crystalline phases. Their structure can be tuned by temperature variation and/or by addition of oils. This leads to gel-like or fluid systems with a large internal interface between water and oil domains with different viscosities.

These nanostructured phases can be dispersed in the excess water phase by addition of an external stabilizer and energy input leading to internally self-assembled particles, so-called Isasomes [1-6]. These Isasomes are potential carrier systems for hydrophilic, amphiphilic and lipophilic functional molecules, but similar structures are also formed in the intestine during digestion of fat [7]. Their internal nanostructure can be best characterized by SAXS, supported by polarization spectroscopy, while particle sizes are usually determined by dynamic light scattering (DLS) and Cryo-TEM.

The hierarchical structure can be extended to a next level by gelling the continuous aqueous phase by the addition of polymers like *–Carrageenan or Methylcellulose. This leads to a new type of hydrogel, loaded with ISAsomes [8-9].

These gels can even be dried into foils and re-dispersed on demand. During drying, the nanostructure is lost, but upon re-hydration it forms again within a few minutes. Even the emulsion droplets survive the drying and re-hydration process [10].

Finally, we can form inverted Isasomes like reverse hexosomes existing of an hydrophilic liquid crystal dispersed in an oil like alkane [11].

All these systems have a great potential as delivery systems for functional molecules in very different fields like pharmaceutical and cosmetic applications, food science and agro-chemistry.

References:
[1] L. de Campo, et al., 2004 Langmuir 20, 5254. Reversible Phase Transitions in Emulsified Nanostructured Lipid Systems.
[2] A. Yaghmur, et al., 2005 Langmuir 21, 569. Emulsified Microemulsions and Oil-Containing Liquid Crystalline Phases
[3] A. Yaghmur, et al., 2006 Langmuir 22, 517. Oil-Loaded Monolinolein-Based Particles with Confined Inverse Discontinuous Cubic Structure (Fd3m)
[4] A. Salonen, et al., 2008 Langmuir 24, 5306. Dispersions of Internally Liquid Crystalline Systems Stabilized by Charged Disklike Particles as Pickering Emulsions: Basic Properties and Time-Resolved Behavior
[5] Ch. Moitzi, et al., 2007 Adv. Materials 19, 1352. Phase Reorganization in Self-Assembled Systems Through Interparticle Material Transfer
[6] F. Muller, et al., 2010 J. Colloid and Interface Sci. 342, 392. Phase behavior of Phytantriol/water bicontinuous cubic Pn3m cubosomes stabilized by Laponite disc-like particles
[7] S. Salentinig et al. 2011 Soft Matter 7, 650. Transitions in the internal structure of lipid droplets during fat digestion
[8] S. Guillot, et al., 2009 J. Colloid and Interface Sci. 330, 175. Internally self-assembled particles entrapped in thermoreversible hydrogels
[9] M. Tomšič, et al., 2009 Langmuir, 25, 9525. Internally Self-Assembled Thermoreversible Gelling Emulsions: ISAsomes in Methylcellulose, K-Carrageenan, and Mixed Hydrogels
[10] Ch. Kulkarni et al., 2011 Langmuir. 27, 9541. Immobilization of Nanostructured Lipid Particles in Polysaccharide Films
[11] F. Pirolt, et al., (2018), Langmuir, 34, 8379. “Reverse-Hexosome Dispersions in Alkanes – The Challenge of Inverting Structures” .


The lecture is part of the symposium Recent progress in small-angle scattering from soft matter and biological systems on the occasion of Professor Jan Skov Pedersen's 60th birthday.    

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