Melamine driven supramolecular self-assembly of nucleobase derivatives in water

Water-soluble supramolecular polymers, especially made up of biomolecules, are ideally suited to build new biomaterials that can mimic or interact with dynamic, biological environments. Here, two derivatives from thymine (T), that is N-[2-(3,4-Dihydro-5-methyl-2,4-dioxo-1(2H)-pyrimidinyl)acetyl]-L-phenylalanine (T-phe) and N-(2-Aminoethyl)-3,4-dihydro-5-methyl-2,4-dioxo-1(2H)-pyrimidineacetamide (T-NH2) were synthesized. Then the optimal condition for self-assembly of T-phe and T-NH2 driven by melamine (M) was explored. It was observed that M/T kept at 1:3 with equivalent T-phe and T-NH2 under neutral environment resulted in long fibers (>1 m) with extremely high aspect ratios, which suggested that electrostatic and -stacking interactions could be effectively orchestrated by hydrogen bonds to direct the hierarchical assembly. Furthermore, hydrogels were spontaneously generated with a concentrated solution of T-phe, T-NH2, and M due to the fibril entanglement. Given its biomimetic nature and efficient self-assembly process, this newly developed supramolecular polymer stacked by tetrameric structures represented an innovative concept and pathway for novel bio-inspired materials. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 789-796