Fluid-crystal coexistence for proteins and inorganic nanocolloids: dependence on ionic strength

Abstract

We investigate theoretically the fluid-crystal coexistence of solutions of globular charged nanoparticles like proteins and inorganic colloids. The thermodynamic properties of the fluid phase are computed via the optimized Baxter model. This is done specifically for lysozyme and silicotungstates for which the bare adhesion parameters are evaluated via the experimental second virial coefficients. The electrostatic free energy of the crystal is approximated by supposing the cavities in the interstitial phase between the particles are spherical in form. In the salt-free case a Poisson-Boltzmann equation is solved to calculate the effective charge on a particle and a Donnan approximation is used to derive the chemical potential and osmotic pressure in the presence of salt. The coexistence data of lysozyme and silicotungstates are analyzed within this scheme, especially with regard to the ionic-strength dependence of the chemical potentials. The latter agree within the two phases provided some upward adjustment of the effective charge is allowed for.

arXiv comment15 pages, 9 figures

References in corpus (2)

• Effective charge versus bare charge for colloids in the infinite dilution limit
• Optimized Baxter Model of Protein Solutions: Electrostatics versus Adhesion

Cited by in corpus (4)

• A simple patchy colloid model for the phase behavior of lysozyme dispersions
• Energetically favoured defects in dense packings of particles on spherical surfaces
• Electrostatics and aggregation: how charge can turn a crystal into a gel
• Collective diffusion coefficient of proteins with hydrodynamic, electrostatic and adhesive interactions