title: Posing for a picture: vesicle immobilization in agarose gel.
abstract: Taking a photo typically requires the object of interest to stand still. In science, imaging is potentiated by optical and electron microscopy. However, living and soft matter are not still. Thus, biological preparations for microscopy usually include a fixation step. Similarly, immobilization strategies are required for or substantially facilitate imaging of cells or lipid vesicles, and even more so for acquiring high-quality data via fluorescence-based techniques. Here, we describe a simple yet efficient method to immobilize objects such as lipid vesicles with sizes between 0.1 and 100 μm using agarose gel. We show that while large and giant unilamellar vesicles (LUVs and GUVs) can be caged in the pockets of the gel meshwork, small molecules, proteins and micelles remain free to diffuse through the gel and interact with membranes as in agarose-free solutions, and complex biochemical reactions involving several proteins can proceed in the gel. At the same time, immobilization in agarose has no adverse effect on the GUV size and stability. By applying techniques such as FRAP and FCS, we show that the lateral diffusion of lipids is not affected by the gel. Finally, our immobilization strategy allows capturing high-resolution 3D images of GUVs.
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil.|Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
authors.forename: Rafael B
authors.initials: RB
authors.lastname: Lira
authors.affiliation: Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Steinkühler
authors.affiliation: Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
authors.forename: Roland L
authors.initials: RL
authors.lastname: Knorr
authors.affiliation: Department of Theory and Bio-Systems, Max Planck Institute of Colloids and Interfaces, Potsdam, Germany.
authors.forename: Rumiana
authors.initials: R
authors.lastname: Dimova
authors.affiliation: Departamento de Biofísica, Universidade Federal de São Paulo, São Paulo, Brazil.
authors.forename: Karin A
authors.initials: KA
authors.lastname: Riske
mesh_terms: D004587:Electrophoresis, Agar Gel / Q000379:methods*; D021621:Imaging, Three-Dimensional; D010316:Particle Size; D053835:Unilamellar Liposomes / Q000737:chemistry / Q000302:isolation & purification*
chemical_list: D053835:Unilamellar Liposomes