Thermally reversible hydrogels: II. Delivery and selective removal of substances from aqueous solutions

Hydrogels have been synthesized which exhibit a lower critical solution temperature (LCST) and which shrink and deswell in aquous solutions when the temperature is raised through their LCST. This phenomenon is reversible on cooling below the LCST, when the gels reswell and expand. In this study we have shown that such gels may be used to absorb and/or release (deliver) a variety of biologically and industrially important substances. This action may be simulated by relatively small temperature changes in the environment. We have also shown how a specific binding ligand may be incorporated into the gel for selective binding (and removal or recovery) of specific solutes in aqueous solutions. Important applications of these novel gel systems are proposed for drug delivery, toxin removal, assay of selected solutes, bioprocess or industrial process product recovery and affinity separations in general.