Self-assembled hydrogels from poly[N-(2-hydroxypropyl)methacrylamide] grafted with beta-sheet peptides.

A new hybrid hydrogel based on poly[N-(2-hydroxypropyl)methacrylamide] grafted with a beta-sheet peptide, Beta11, was designed. Circular dichroism spectroscopy indicated that the folding ability of beta-sheet peptide was retained in the hybrid system, whereas the sensitivity of the peptide toward temperature and pH variations was hindered. The polymer backbone also prevented the twisting of the fibrils that resulted from the antiparallel arrangement of the beta-strands, as proved by Fourier transform infrared spectroscopy. Thioflavin T binding experiments and transmission electron microscopy showed fibril formation with minimal lateral aggregation. As a consequence, the graft copolymer self-assembled into a hydrogel in aqueous environment. This process was mediated by association of beta-sheet domains. Scanning electron microscopy revealed a particular morphology of the network characterized by long-range order and uniformly aligned lamellae. Microrheology results confirmed that concentration-dependent gelation occurred.