Proceedings

EPJ E Highlight - Sac with spiral surface patterns facilitate substance delivery through biological membranes

Introducing bend in the liquid crystal layers.

Faceted microfilms made up of liquid crystals arranged in spiral patterns can help squeeze through membranes and deliver helpful molecules

Imagine a micron-sized ball of fluid enclosed in a thin film, similar to the film in soap bubbles, but made up of molecules resembling liquid crystal. These molecules can lower their overall energy by aligning their directions with their ever-changing neighbours—a state referred to as smectic phase. This means stacks of parallel stripe-like liquid-crystal layers form in the film. In a new study published in EPJ E, Francesco Serafin, affiliated with both Syracuse University, New York, and the Kavli Institute for Theoretical Physics (KITP) at UCSB, USA, together with his advisor Mark Bowick, also at the KITP, and Sid Nagel, from the University of Chicago, IL,USA, map out all the possible smectic patterns of such spherical films, or sac, at zero temperature. They determine the conditions under which it becomes easier for such sacs to pass through biological membranes and, potentially, deliver molecules attached to them at specific locations.

The constraints imposed on mapping parallel liquid crystals molecules onto a spherical shape produce defects in the liquid-crystal. In this study, the authors predict the existence of four defects, creating distortions that are accommodated as the shell bends in the defects' surroundings. The spherical film is most flexible, they note, when its lowest energy shape looks like a faceted tetrahedron with sharp edges and defects localised at the four vertices. The defects are natural candidate sites for attaching molecules with a special function for delivery into the body using such ball-shaped films.

Depending on the tilt angle between the stripe-like layers of the liquid-crystal-like molecules and the tetrahedron’s edge, the authors identify various patterns: lines of latitude, parallel spirals or a combination of the two. At zero or 30° tilt angle, all layers form closed latitutinal loops that are not easily deformed. At other tilt angles, the layers form spirals that allow localised compression to propagate a long distance along the film, making it easier for this spherical films to deform and squeeze through biological membranes.

This was our first experience of publishing with EPJ Web of Conferences. We contacted the publisher in the middle of September, just one month prior to the Conference, but everything went through smoothly. We have had published MNPS Proceedings with different publishers in the past, and would like to tell that the EPJ Web of Conferences team was probably the best, very quick, helpful and interactive. Typically, we were getting responses from EPJ Web of Conferences team within less than an hour and have had help at every production stage.
We are very thankful to Solange Guenot, Web of Conferences Publishing Editor, and Isabelle Houlbert, Web of Conferences Production Editor, for their support. These ladies are top-level professionals, who made a great contribution to the success of this issue. We are fully satisfied with the publication of the Conference Proceedings and are looking forward to further cooperation. The publication was very fast, easy and of high quality. My colleagues and I strongly recommend EPJ Web of Conferences to anyone, who is interested in quick high-quality publication of conference proceedings.

On behalf of the Organizing and Program Committees and Editorial Team of MNPS-2019, Dr. Alexey B. Nadykto, Moscow State Technological University “STANKIN”, Moscow, Russia. EPJ Web of Conferences vol. 224 (2019)

ISSN: 2100-014X (Electronic Edition)

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