Biomolecular condensates, formed by liquid-liquid phase separation, coordinate key cellular activities. Recent work has revealed the role of sub-micron assemblies, or nanocondensates, in the organisation of a significant portion of the proteome. Here, we introduce a single particle fluorescence spectroscopy framework to visualise and quantify individual nanocondensates in real time. Using the low-complexity domain of TAR DNA-binding protein 43 (TDP-43) as a model system, we show that this approa...