RT Journal Article
SR Electronic
T1 Combined fluorescence, optical diffraction tomography and Brillouin microscopy
JF bioRxiv
FD Cold Spring Harbor Laboratory
SP 2020.10.30.361808
DO 10.1101/2020.10.30.361808
A1 Raimund Schlüßler
A1 Kyoohyun Kim
A1 Martin Nötzel
A1 Anna Taubenberger
A1 Shada Abuhattum
A1 Timon Beck
A1 Paul Müller
A1 Shovamayee Maharana
A1 Gheorghe Cojoc
A1 Salvatore Girardo
A1 Andreas Hermann
A1 Simon Alberti
A1 Jochen Guck
YR 2021
UL http://biorxiv.org/content/early/2021/09/15/2020.10.30.361808.abstract
AB Quantitative measurements of physical parameters become increasingly important for understanding biological processes. Brillouin microscopy (BM) has recently emerged as one technique providing the 3D distribution of viscoelastic properties inside biological samples — so far relying on the implicit assumption that refractive index (RI) and density can be neglected. Here, we present a novel method (FOB microscopy) combining BM with optical diffraction tomography and epi-fluorescence imaging for explicitly measuring the Brillouin shift, RI and absolute density with specificity to fluorescently labeled structures. We show that neglecting the RI and density might lead to erroneous conclusions. Investigating the nucleoplasm of wild-type HeLa cells, we find that it has lower density but higher longitudinal modulus than the cytoplasm. Thus, the longitudinal modulus is not merely sensitive to the water content of the sample — a postulate vividly discussed in the field. We demonstrate the further utility of FOB on various biological systems including adipocytes and intracellular membraneless compartments. FOB microscopy can provide unexpected scientific discoveries and shed quantitative light on processes such as phase separation and transition inside living cells.Competing Interest StatementThe authors have declared no competing interest.