Optische Pinzette
Final Report Abstract
The instrument JPK NanoTracker II is an optical tweezer setup, which allows to manipulate objects and to measure forces in the piconewton range. It has been primarily used to i) examine the rheological properties of active actin networks in 2D and 3D, ii) quantify the fusion of lipid bilayers assisted by SNARE-proteins and synaptotagmin, and iii) to investigate the mechanical properties of hydrogels derived from proteins of the nuclear pore complex. With the help of this instrument we could demonstrate the active motion of cytoskeleton networks if motor proteins such as myosin were added and investigate the rheological properties of artificial cell cortices attached to plasma membrane mimics. Moreover, it was possible to elucidate the fusion of membranes triggered by the calcium sensor synaptotagmin-1. By monitoring the motion of trapped beads, we could unequivocally discern the crucial steps in membrane fusion comprising crossing the barrier associated with hydration of the membrane, hemifusion and eventually full fusion. The instrument has also been successfully used to assess the rheological properties of protein assemblies and giant vesicles.
