Protocells: Milestones and Recent Advances

The origin of life is still one of humankind\u27s great mysteries. At the transition between nonliving and living matter, protocells, initially featureless aggregates of abiotic matter, gain the structure and functions necessary to fulfill the criteria of life. Research addressing protocells as a central element in this transition is diverse and increasingly interdisciplinary. The authors review current protocell concepts and research directions, address milestones, challenges and existing hypotheses in the context of conditions on the early Earth, and provide a concise overview of current protocell research methods

Repair of large area pores in supported double bilayers

We describe an experimental system where we can generate, and subsequently close, multiple large membrane ruptures in supported double bilayers. We show in this study for the first time that large membrane pores (similar to 10-150 mu m in size) in flat phospholipid vesicles can be reduced in size or completely closed by a pore edge tension driven area reduction mechanism. We can dynamically control the membrane tension of a flat giant unilamellar vesicle and its interplay with the surface adhesion to a solid support. Adhesion to the support surface causes increased membrane tension, which eventually relaxes by the formation of several pores in the membrane. We show that the tension propagation time tau(max) is exceptionally long in this system, which allows for simultaneous opening of multiple pores. The pores can be stabilized by Ca2+-mediated pinning sites in the interior of the flat giant unilamellar vesicle. After pore formation followed by pinning, we depleted Ca2+ ions resulting in removal of pinning and relaxation of membrane tension. This allows the pore to close, driven by the pore edge tension

Mechanical and electro-mechanical properties of EAP actuators with inkjet printed electrodes

Electrically conductive polymer (CP) based ionic electromechanically active polymer composites (IEAP-s) are attractive as bending and linear actuators in compliant and miniature devices due to low operating voltage. Ink-jet printing is a promising technology for fabrication of microscale CP-based IEAP-s with customized shapes and geometries. The current study investigates tailoring of the mechanical and electromechanical properties of the actuators by controlled growth of ink-jet printed poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate) (PEDOT:PSS) based electrodes on commercial poly(vinylidene fluoride) (PVdF) membranes. In parallel with PEDOT:PSS, hybrid actuators with ink-jet printed PEDOT:PSS and activated carbon aerogel electrodes were investigated. Cumulative growth of electrodes with each deposited layer was achieved in the case of both electrode materials. The strain, blocking force and capacitance of the actuators were in linear correlation with the thickness of the electrodes. Simple method of control encourages implementation of ink-jet-printing technology for manufacturing of IEAP micro-actuators with desired mechanical and electromechanical properties

Thermal migration of molecular lipid films as a contactless fabrication strategy for lipid nanotube networks

We demonstrate the contactless generation of lipid nanotube networks by means of thermally induced migration of flat giant unilamellar vesicles (FGUVs), covering micro-scale areas on oxidized aluminum surfaces. A temperature gradient with a reach of 20 mm was generated using a focused IR laser, leading to a surface adhesion gradient, along which FGUVs could be relocated. We report on suitable lipid-substrate combinations, highlighting the critical importance of the electrostatic interactions between the engineered substrate and the membrane for reversible migration of intact vesicles