Reversible control of solubility using functionalized nanoparticles†
The paper provides a novel method for the reversible control of solubility by use of functionalized nanoparticles. The nanoparticles are functionalized with functional groups that can act as a co-solvent or anti-solvent and thus can induce either dissolution or crystallization. The process is reversible, as the solution will go back to its original state when the nanoparticles are removed. The use of magnetic nanoparticles facilitates this reversibility. Reductions in solubility (and thus crystallization) were demonstrated for D-mannitol–water, sodium chloride–water and fenofibrate–ethyl acetate systems. An increase in solubility (and thus dissolution) was demonstrated for the benzoic acid–water system and the 4-nitrophenol–water system. Reversible manipulation of solubility can be used to reduce solvent usage in dissolution and crystallization by elimination of the need for an antisolvent or co-solvent.