Concentration
Dependence of Elastic and Viscoelastic
Properties of Aqueous Solutions of Ficoll and Bovine Serum Albumin
by Brillouin Light Scattering Spectroscopy
Version 2 2024-02-23, 20:09Version 2 2024-02-23, 20:09
Version 1 2024-02-22, 22:33Version 1 2024-02-22, 22:33
journal contribution
posted on 2024-02-23, 20:09authored byStephen J. Spencer, Venketesh Thrithamara Ranganathan, Anand Yethiraj, G. Todd Andrews
The cellular environment is crowded with macromolecules
of different
shapes and sizes. The effect of this macromolecular crowding has been
studied in a variety of synthetic crowding environments: two popular
examples are the compact colloid-like Ficoll macromolecule and the
globular protein bovine serum albumin (BSA). Recent studies have indicated
that a significant component of bound or surface-associated water
in these crowders reduces the available free volume. In this work,
Brillouin light scattering experiments were performed on aqueous solutions
of Ficoll 70 and Ficoll 400 with concentrations ranging from 1 to
35 wt % and BSA with concentrations of 1 to 27 wt %. From the dependence
of spectral peak parameters on polymer concentration, we determined
fundamental solution properties: hypersound velocity, adiabatic bulk
modulus and compressibility, apparent viscosity, and hypersound attenuation.
The existing theory that ignores intermolecular interactions can capture
only the observed linear trends in the frequency shift up to a threshold
concentration, beyond which a quadratic term accounting for intermolecular
interactions is necessary. This likely indicates a transition from
the dilute to semidilute regime. In the Ficoll solutions (but not
BSA), we see evidence for a central mode, which is indicative of relaxation
in the hydration shell of Ficoll.