Probing biomolecular condensates with a minimally perturbative experimental readout framework.

Biomolecular condensates are membrane-less compartments formed through phase separation that concentrate and organize biomolecules within cells. Far from being static droplets, they are dynamic molecular assemblies whose internal dynamics, structure, mechanics, and composition can evolve over time during cellular aging, disease-associated aggregation, or engineered material formation. These changes are often described using state descriptors such as liquid-like, gel-like, aged, or solid-like, yet similar apparent states can be interpreted differently depending on whether they are assessed in terms of morphology, dynamics, structure, mechanical response, or composition. The present review article summarizes an experimental framework used to probe biomolecular condensates and their transitions across complementary dimensions while minimizing perturbation to the system. A diverse suite of label-free optical, scattering, spectroscopic, mechanical, and microfluidic approaches is discussed, highlighting how integrated strategies can connect these readouts to enable more rigorous interpretations of condensate behavior. This framework is intended to guide researchers to move beyond broad material descriptors toward understanding the mechanisms underlying condensate evolution, the resolution of phase transitions, and their implications for biological function, pathology, and biomaterial design.