I’m trying to conjugate mercaptohexanol to citrate-stabilised particles >13nm in diameter but I’m running into a few problems. As far as I am aware, both mercaptohexanol (MCH) and mercaptohexanol-stabilised particles are water soluble; however, mixing MCH and the particles in aqueous solution seems to invariably lead to immediate precipitation. I’ve tried doing this place exchange in DMF and it seems to work well, but I would rather like to avoid using any organic solvents altogether as the particles need to be eventually resuspended in water.
So, are these observations in an aqueous environment to be expected? and any other tips for performing this type of place exchange reaction would be most welcome!