engleski

From algal cells to ideally reconstructed, fluorescent vesicles

From the biotechnological perspective, it is of interest to explore the hidden potentials of bio-available algal cell products and in such a way to link the ocean and human health. The purpose of our study is to compare qualitatively molecular transport of fluorescent dyes through membrane systems of different level of complexities (algal plasma membrane vs. model phospholipid membrane). Plasma membrane vesicles were reconstructed from the native membrane material released upon rupturing algal cells by osmotic stress. Reconstructed plasma membranes retain the natural heterogeneous composition of proteins, lipids and carbohydrates, which is a step up from simple, artificial phospholipid vesicles. Reconstructed vesicles are of sufficient size to be observable under a microscope, and their membrane curvature and tension are close to natural systems. Structural characterization of reconstructed vesicles shows a thick envelope with nearly empty vesicle interior. The envelope contains surface globular structures which may be derived from surface coat proteins. Confocal imaging shows that plasma membrane vesicles are auto-fluorescent due to the chlorophyll pigments within the membrane. Physico-chemical characterization of plasma membrane vesicles in terms of adhesion behavior at the interface shows that vesicles are soft and easily deformable, which is in line with the low stiffness of a few kPa measured for algal cells. Transport of fluorescent dyes into the plasma membrane vesicle or into giant unilamellar vesicles shows striking differences in process spontaneity, probably due to membrane structural features and physicochemical properties. Naturally reconstructed plasma membrane models appear highly relevant and convenient to probe membrane-related processes, since complex biochemical processes within the cells are eliminated. This study may contribute to the design of bio-inspired carriers for advanced biotechnological applications. Acknowledgment This work is supported by the Croatian Science Foundation Project No IP-2018-01-5840. PTV is supported by United States Air Force Office of Scientific Research (AFOSR) grant FA9550-14-1- 0023 (a collaborative effort with FA9550-14-1- 0018) and by AFOSR MURI grant FA9550-15-1-0517 on "Nanoelectropulse- Induced Electromechanical Signaling and Control of Biological Systems", administered through Old Dominion University.

algal cell ; ghost vesicle ; marine inspired carriers ; permeability

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