Synthesis of a novel amphiphilic polymer containing nucleobases in the self-organized nanospheres

A simple strategy to achieve molecular recognition in water is to make the polymers self-organized into nanospheres which could incorporate the functional groups containing hydrogen bonding sites into hydrophobic-lipophilic regions. A novel amphiphilic polymer, Poly(polyoxyethylene-600)-oxy-5-(6-(1-thymine)hexyl)) isophthaloyl (PPETHI), has been synthesized. The PPETHI polymer could self-organize into nanospheres in dilute aqueous solution, which were 150–300 nm in diameter as estimated by SEM. The isophthaloyl with side hexyl thymine of the polymer self-organized into hydrophobic regions and the PEG surrounded it. Molecular recognition between thymine in PPETHI polymer and adenine substrate has been studied by FT-IR. The FT-IR studies demonstrate that C 4 =O of thymine has recognized with N-H of adenine through complementary nucleobases. It shows that the typical characteristic band at 3,352 cm −1 of N-H stretching vibration of adenine shifted to 3,373 cm −1 and the band at 1,685 cm −1 of C 4 =O of thymine shifted to 1,680 cm −1 . To confirm the formation of hydrogen bonds, the N-H band at 3,373 cm −1 and C 4 =O band at 1,680 cm −1 have retrieved to 3,312 cm −1 and 1,685 cm −1 respectively upon heating to 115 °C or higher by means of variable temperature FT-IR. The formations of hydrogen-bonds between thymine in the polymer and adenine substrate in nanospheres were confirmed. It could enhance their interaction and loading capacity.