Polymer Hydrogels for Glutathione-Mediated Protein Release

The use of amine-terminated poly(ethylene glycol) star polymers as macroinitiators for the N-carboxyanhydride ring-opening polymerisation of S-tert-butylmercapto-L-cysteine N-carboxahydride is described to yield amphiphilic copolymers that are capable of forming discrete particles in aqueous solution. Poly(amino acid) deprotection liberates the pendant thiol groups that can then form covalent disulfide crosslinks with adjacent thiol groups and yield a crosslinked polymer that is capable of hydrogel formation. The model protein albumin–fluorescein isothiocyanate conjugate was encapsulated within the hydrogels produced, prior to its release upon hydrogel interaction with the reducing agent glutathione. Consequently, the stimuli-responsive polymers formed hold great promise as biomaterials capable of releasing a protein molecular cargo upon interaction with glutathione.