FT-IR characterization. Fibril, furan-fibril and fibril cluster (PF-4) were dialyzed against ultrapure water for 4 days at room temperature. The purified samples were finally freeze-dried. The changes in the chemical structure of dried fibril, furan-fibril and fibril cluster samples, as well as (MAL)4-PEG (10 kDa) were qualitatively analyzed using FT-IR (Spectrum 100, Perkin Elmer, Inc., USA). Samples were prepared by grinding the finely powdered samples with potassium bromide (KBr) and pressed into tablets. The spectrum was recorded over the wavenumber range of 4000-400 cm -1 .