Quantification and regulation of the material properties of synapsin condensates in vitro and in live cells

The material properties of biomolecular condensates regulate many cell functions and play pivotal pathological roles. For example, the interfacial tension of condensates influences the interaction between condensates and other cellular structures, while viscoelasticity is crucial in aberrant phase transitions and dictates the kinetics of biochemical reactions within condensates. Here, we employ micropipette aspiration (MPA) to quantify the properties of synapsin condensates in vitro, revealing noteworthy effects of synapsin domains, crowding agents, synaptic vesicles (SVs), and alpha-synuclein (aSyn) on the condensates' material properties.