Suppressing convection strength using confinement during protein crystallization

Abstract: Fluid convection during protein crystallization plays a significant role in determining crystal growth rate and crystal quality. Crystals grown in reduced flow strength gives better quality crystal. Hence, tuning the flow strength is very essential in the crystal growth process. In this work, we have demonstrated a new method to suppress the flow strength using confinement effect during vapor diffusion method of protein crystallization where the crystal is grown inside an evaporating droplet. Flow study is carried out at four different confinement conditions to study the effect of confinement. Flow inside the droplet is caused by evaporation induced natural convection which is measured by micro-PIV method. Also concentration gradient generated around the growing crystal also induces buoyancy driven flow around the protein crystal during the crystal growth phase. The evaporation rate from the droplet and the flow strength inside the droplet get suppressed by increasing confinement. Hence, the flow strength can be tuned by adjusting the confinement which is a very simple method to tune the flow strength.