Determining Thermodynamic and Material Properties of Biomolecular Condensates by Confocal Microscopy and Optical Tweezers

While the roles of biomolecular condensates in health and disease are being intensely studied, it is equally important that their physical properties are characterized in order to achieve mechanistic understanding. Here we share some of the protocols developed in our lab for measuring thermodynamic and materials properties of condensates. These include a simple method for determining the droplet-phase concentrations of condensate components on a confocal microscope, and a method for determining the viscoelasticity of condensates by optical tweezers. These protocols are either generally applicable to biomolecular condensates or are unique for their characterization.