Project Details
Projekt
Wetting of bio-inspired, stimulus-responsive polymer surfaces by lipid vesicles
Subject Area
Experimental and Theoretical Physics of Polymers
Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
Statistical Physics, Nonlinear Dynamics, Complex Systems, Soft and Fluid Matter, Biological Physics
Term
since 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 422801301
Analog to liquid drops, the shape of a vesicle is dictated by its enclosed volume, the membrane-substrate interaction (interface potential), and the properties of the interface (membrane) between the interior and exterior. Unique to wetting by vesicles is the importance of the membrane’s intrinsic bending rigidity and the buoyancy of the enclosed liquid.The experimental Tanaka team has established a bio-inspired polymer brush platform, capable of switching the adhesion of vesicles, and has monitored the large-scale vesicle shape by 3D confocal microscopy. This setup will be complemented by a micro-interferometry technique, providing information about the local geometry of the edge of the brush-vesicle contact zone. The theoretical Müller team has implemented a highly coarse-grained particle model of the switchable polymer brush and a triangulated Helfrich-Hamiltonian of the thin lipid membrane in a parallel, GPU-accelerated MD program and has generalized the Helfrich description to include a finite-ranged interface potential and buoyancy. In the new period, they will explicitly include solvents to account for viscous dissipation.Both teams will jointly investigate the dynamic change of vesicle shapes in response to a switch in adhesion and the adaptation of the brush to the contact with a vesicle by time-dependent measurements of the vesicle geometry. Thermodynamic forces (bending energy, adhesion, and buoyancy) and dissipation mechanisms (e.g., dissipation at the contact zone and of the surrounding liquids) exhibit different dependencies on the vesicle size, whose systematic variation will allow us to distinguish between different dissipation mechanisms and aid the comparison between experiment and simulation. Additionally, we will consider how transport of membrane species (e.g., positively charged lipids, binding to -COOH groups of the brush) toward the contact zone influences the dynamics of the vesicle. This line of study will be extended to heterogeneous substrates, where a wettability gradient may result in a pining of the contact zone or a gradual variation may induce a translation and spreading of the vesicle. We will also study time-periodic switches of the wettability and wettability gradients that move over the substrate. The lateral motion of vesicles will give rise to additional dynamics such as e.g. sliding or rolling motion/tank-treading of the vesicle.
DFG Programme
Priority Programmes
