Ergodic and non-ergodic phase transitions in globular protein suspensions

Area of Science:

• Biophysics
• Soft Matter Physics
• Materials Science

Background:

• Protein suspensions are complex fluids with rich phase behavior.
• Understanding their equilibrium and nonequilibrium states is crucial for applications.
• Interparticle attraction strength and protein concentration are key factors influencing phase transitions.

Purpose of the Study:

• To investigate the equilibrium and nonequilibrium phase behavior of protein suspensions.
• To determine the influence of interparticle attraction strength and protein concentration on gelation and crystallization.
• To test the predictive power of mode coupling theories for gelation dynamics.

Main Methods:

• Studied protein suspension phase behavior as a function of attraction strength and concentration.
• Utilized mode coupling theories adapted for low volume fractions and square well fluids.
• Investigated gel dynamics to validate theoretical predictions.

Main Results:

• Phase behavior depends on the interplay between gelation and crystallization rates.
• At low attraction, suspensions gel before crystallizing; at high attraction, crystallization can precede gelation.
• Mode coupling theories accurately predict the gel line at low volume fractions.

Conclusions:

• The observed phase behavior arises from the competition between gelation and crystallization kinetics.
• Mode coupling theories provide a good framework for understanding gelation in protein suspensions.
• The range of attractions significantly impacts the observed phase transitions.