Viscoelastic properties of biopolymer hydrogels determined by Brillouin spectroscopy: a probe of tissue micromechanics

Abstract

Many problems in mechanobiology urgently require characterisation of the micromechanical properties of cells and tissues. Brillouin light scattering has been proposed as a new optical elastography technique to meet this need. However, the information contained in the Brillouin spectrum is still a matter of debate due to fundamental problems in understanding the role of water in biomechanics and in relating the Brillouin data to low-frequency macroscopic mechanical parameters. Here we investigate this question using gelatin as a model system in which the macroscopic physical properties can be manipulated to mimic all the relevant biological states of matter, ranging from the liquid to the gel and the glassy phase. We demonstrate that Brillouin spectroscopy is able to reveal both the elastic and viscous properties of biopolymers that are central to the structure and function of biological tissues.