Microgel Surface Modification with Self-Assembling Peptides.

We describe the fabrication of peptide-coated microgels, where a fibrillizing peptide (RADA)4 self-assembles on the surface of hydrogel microparticles. The incorporation of an anionic comonomer into the microgel network is required for a stable colloidal dispersion to be obtained when particles are incubated with (RADA)4, suggesting that the assembly is dependent on Coulombic interactions. We further demonstrate the modification of the (RADA)4 shell by preparing coassemblies of (RADA)4 and a fluorescently labeled (RADA)4 peptide. Additionally, the (RADA)4 shell can be modified through postassembly conjugation of a cysteine residue or a non-natural amino acid bearing an alkyne moiety. Fluorescence and atomic force microscopy and circular dichroism spectroscopy were employed to characterize the assembly and modification of the peptide shell. Finally, our attempt to utilize a different fibrillizing peptide (Q11) in the formation of peptide-coated microgels was unsuccessful, demonstrating that the identity of the building blocks is important in the fabrication of these composite assemblies.