Multicompartment aqueous microgels with degradable hydrophobic domains

In this work we successfully synthesized degradable microgels based on poly(N-vinylcaprolactam) (PVCL) with hydrophobic pockets for the uptake/release of poorly water-soluble molecules. The degradability as well as the presence of hydrophobic pockets in the microgel structure are ensured by incorporation of a star-shaped acrylate-functionalised poly(e-caprolactone) (starPCL) crosslinkers. Microgels with variable amount of star PCL crosslinker, narrow size distribution and a hydrodynamic radius of 200-400 nm were obtained by miniemulsion polymerisation. The microgel size and size distribution was characterised by means of dynamic light scattering (DLS), field emission scanning electron microscopy (FESEM) and sedimentation analysis. The obtained microgels undergo enzymatic degradation in aqueous medium as evidenced by DLS, nuclear magnetic resonance (NMR) and FESEM. Additionally, the uptake of hydrophobic molecules like the dye Nile-Red (model system) and the drug Ibuprofen into the starPCL-based microgels was proven by ultraviolet-visible spectroscopy (UV/Vis). The experimental data indicate that the solubilisation ability of microgels can be regulated by the amount of crosslinker in the microgel structure.