Soft Hydrogels from Nanotubes of Poly(ethylene oxide)−Tetraphenylalanine Conjugates Prepared by Click Chemistry

A new poly(ethylene oxide)−tetraphenylalanine polymer−peptide conjugate has been prepared via a “click” reaction between an alkyne-modified peptide and an azide-terminated PEO oligomer. Self-assembled nanotubes are formed after dialysis of a THF solution of this polymer−peptide conjugate against water. The structure of these nanotubes has been probed by circular dichroism, IR, TEM, and SAXS. From these data, it is apparent that self-assembly involves the formation of antiparallel β-sheets and π−π-stacking. Nanotubes are formed at concentrations between 2 and 10 mg mL−1. Entanglement between adjacent nanotubes occurs at higher concentrations, resulting in the formation of soft hydrogels. Gel strength increases at higher polymer−peptide conjugate concentration, as expected.