Crystallization of organic materials by using membrane crystallizers

Protein crystallization methodologies aiming to promote heterogeneous nucleation have been increased their significance in recent years. Among them, solid substrates may improve nucleation rate through the combination of different mechanisms: modification of the supersaturation profile nearby the surface due to concentration polarization; template effects due to adsorption of solutes at the surface; influence of surface characteristics leading to specific interactions with the solute. In this respect, solid porous or hydrophobic substrates have showed their effectiveness. Membrane crystallization has been recently proposed as an innovative technique for producing also protein crystals, starting from insatured solution, where the effect of the membrane as a solid support separating two liquid subsystem which experience a mass interchange in the vapour phase and the action of the porous and hydrophobic polymeric substrate as promoter of heterogeneous nucleation are combined.