Surface-Adhered Biomembrane Networks Formed on High Energy Surfaces of SiC and Al₂O₃

Reservoirs of lipid molecules, specifically onion shell vesicles, spread on high energy surfaces, e.g. Al₂O₃, to form a stack of molecular films (double bilayer). Eventually, the spreading lipid exhausts the reservoir, and rising tension ruptures of the films [1]. Gözen and later Köksal <i>et al</i>. discovered that this disruptive process generates a network of nanotubes, which redistributes lipid material in order to alleviate local tension (Marangoni flow), and vesicles grow from the tubes [2,3]. We have shown that local heating accelerate the growth and transformation of containers, and initiates their fusion. Similar processes might have occurred in warm environments on the Early Earth. Our current work aims to utilize this system and <b>control</b> soft matter <b>transformations with IR light</b> to design and construct reconfigurable chemical reaction networks (CRNs) on engineered surfaces.<br/>In the context of the origin of life, the formation of the earliest primitive compartments and their transformation to biological cells is not known in detail, and is a subject of intensive research. Köksal <i>et al. </i>suggested the involvement of solid high energy surfaces as source of energy for autonomous shape transformations of lipid assemblies, protocell and nanotube network formation, and encapsulation of solutes therein. Such surface-supported networks of vesicles and soft nano-conduits might have functioned as primitive CRNs in the prebiotic world. Their simplicity and ease of formation inspired further development as a soft matter reactor nanotechnology. We combined an inverted laser induced fluorescence microscope with a focused 1470 nm IR-B laser and a spatial light modulator (SLM) for generating designed irradiation patterns (digital holography) in order to elevate the temperature locally at the surface and simultaneously observe lipid film transformations.<br/>Membrane compartment formation, growth, and merging was accelerated by local heating with an IR fibre. We developed an <i>in situ </i>temperature measurement setup and confirmed consistency with conditions in warm natural environments, such as the “Lost City” hydrothermal vents (~70°C) [4]. Thermocouple absorption of IR energy was taken into account. The actual temperature in the proximity of the fibre ending (distance to the protocell) was determined by linear approximation. We further employ thermally evaporated SiC surfaces for improved adhesion control, which allows for efficient MLV spreading into double bilayer structures and rapid growing of protocells colonies [5], even without additional fusogenic agents, such as Ca⁺⁺ ions. Further research aims to implement chemical/enzymatic reactions within such networks in order to gain new insights into possible protocell development scenarios in the context of the origins of life.<br/><br/><b>References</b><br/>[1] I. Gözen, P. Dommersnes, I. Czolkos, A. Jesorka, T. Lobovkina, and O. Orwar, "Fractal avalanche ruptures in biological membranes," Nature Materials, vol. 9, pp. 908-912, 2010/11/01 2010.<br/>[2] I. Gozen, M. Shaali, A. Ainla, B. Ortmen, I. Poldsalu, K. Kustanovich, et al., "Thermal migration of molecular lipid films as a contactless fabrication strategy for lipid nanotube networks," Lab on a Chip, vol. 13, pp. 3822-3826, 2013 2013.<br/>[3] E. S. Köksal, S. Liese, L. Xue, R. Ryskulov, L. Viitala, A. Carlson, et al., "Rapid growth and fusion of protocells in surface-adhered membrane networks," bioRxiv, p. 2020.03.10.980417, 2020.<br/>[4] I. Gözen, E. S. Köksal, I. Põldsalu, L. Xue, K. Spustova, E. Pedrueza-Villalmanzo<i>, et al.</i>, "Protocells: Milestones and Recent Advances," <i>Small, </i>vol. n/a, p. 2106624, 2022/03/23 2022.<br/>[5] K. Spustova, C. Katke, E. Pedrueza Villalmanzo, R. Ryskulov, C. N. Kaplan, and I. Gözen, "Colony-like Protocell Superstructures," bioRxiv, p. 2021.09.16.460583, 2021.