Super-resolution.org.au
The Bell Single Molecule and Fluorescence Lab
Single particle tracking within liquid crystal structures
Lyotropic liquid crystal (LC) systems exhibit both the maintained structural properties of solids and the flow properties of liquids. LCs are formed by mixtures of water, oils and surfactants, and can form a variety of complex three-dimensional structures, including, but not limited to, lamellar bilayers, aligned micellar systems, or bicontinuous cubic phases. One of the simpler LCs, the lamellar bilayer phase, is best described as alternating oil and water layers separated by surfactant layers. These systems are therefore structurally analogous to lipid structures in biological systems, which, alongside their unique rheological properties, makes them useful in biotechnology as models, as delivery and transport devices, and as solvents or sensors in microfluidic devices. For the design, synthesis, and assessment of new LC systems, innovative and complementary experimental approaches are used, including small-angle neutron or x-ray scattering (SANS/SAXS) for structural analysis, polarising light microscopy (PLM) for phase identification, and a suite of rheological techniques in tandem with single particle tracking (SPT) for an understanding of the particle transport capabilities and flow properties.
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SPT visualises the movement of fluorescent species through a fluid sample, and can be used to examine the movement of various types of cargo, including molecules, complexes, organelles, or viruses, in systems ranging from pure solvents to complex cellular landscapes. SPT has been applied to many of these systems previously, for example to study the pore wall permeability of mesoporous silica and to study intracellular transport. In depth analysis of SPT data reveals both the mass transport properties and structure of the medium. SPT can also elucidate how species within the system behave, including the dimensionality and directionality of diffusion. Though there is interest in the use of SPT to understand the diffusion of particles within LC systems, current studies are limited primarily to diblock copolymers or one-dimensional structures rather than surfactant systems that more closely resemble lipid structures.
