Stabilized real-time Brillouin microscopy reveals fractal organization of protein condensates in living cells

Journal article

Mechanical alterations of protein condensates are increasingly recognized in the etiology of several neurodegenerative diseases, yet their characterization remains technically challenging. Although Brillouin microscopy could offer a promising solution, its use is hindered by instrumental instabilities demanding frequent adjustments and manual calibrations with reference materials. Here, we present an enhanced Brillouin Microscope that incorporates an electro-optic modulator, serving simultaneously as frequency reference, spectrometer calibrator, and temporal stabilizer. This integration enables robust, real-time spectral stability over multiple days in a fully automated workflow. Using this system, we quantify Brillouin shifts of several protein condensates in living cells and validate our findings with FRAP. The correlation between techniques reveals a fractal internal architecture of the condensates, providing important insights into their physical nature while probing the mechanical behavior of entire compartments containing multiple protein species. Our method offers a unique framework for distinguishing physiological from pathological condensates, paving the way for long-term, user-independent, high-precision mechanical measurements in living cells.

Authors: Testi, C; Pontecorvo, E; Bartoli, C; Marzaro, C; Gala, F

• Publication status: Published
• Peer review status: Peer reviewed
• Publisher: Nature Research
• Journal: Nature Communications
• Publication date: 2026-02-05
• DOI: 10.1038/s41467-026-68984-2
• EISSN: 2041-1723
• ISSN: 2041-1723
• Language: English
• Keywords: Fractal; Living systems; Optical microscope; Microscopy; Brillouin scattering; Brillouin zone; Spectrometer; Characterization (materials science)