One-pot precipitation polymerisation strategy for tuneable injectable Laponite®-pNIPAM hydrogels: Polymerisation, processability and beyond

Highly processable hydrogels loaded with active components for localised drug delivery and/or live cells for regenerative medicine are an attractive target for biotechnology research. We describe a single-pot precipitation polymerisation of poly (N-isopropylacrylamide) (pNIPAM) from the surface of dispersed Laponite® platelets in aqueous media above its lower critical solution temperature (LCST), yielding tightly packed pNIPAM globules that resist aggregation and can be maintained for long periods of time as a low viscosity colloidal suspension. Upon cooling, the pNIPAM chains transform from the ‘globule’ to the ‘coil’ conformation, establishing multiple physical interactions and chain entanglement leading to irreversible gel formation. We have shown that the temperature and rate of phase transition and the rheological and mechanical properties of Laponite®-pNIPAM hydrogel can be tailored by addition of N, N′-dimethylacrylamide (DMAc) comonomer and other biologically relevant additives. The tuneable properties of Laponite®-pNIPAM hydrogel confirms its excellent potential for a wide range of therapeutic applications.