Self pinning protein-laden drops

Proteins dissolved in a drop induce and enhance the pinning of the drop contact line. This effect dramatically increases volume of drops that are vertically pinned on a flat siliconized substrate. The drop pinning behavior exhibits two regimes: for low protein content in a drop the pinning increases as the contact angle hysteresis increases, and for high protein content the pinning decreases as the surface tension of the protein solution decreases.