Adenosine-induced changes of the phase transition of poly(6-(acryloyloxymethyl)uracil) aqueous solution

Poly(6-(acryloyloxymethyl)uracil) (PAU) having uracil moieties as side chains was synthesized by ordinary radical polymerization to investigate its molecular discrimination for soluble nucleic acid bases in terms of phase transition changes of the polymer aqueous solution. PAU itself in distilled water formed a precipitate due to the polymer complexes at lower temperatures and changed drastically to become water-soluble above a characteristic transition temperature, showing an upper critical solution temperature (UCST). The phase transition behavior was shifted to lower temperatures with increasing concentrations of adenosine (Ado), which is the complementary nucleic acid base to uracil moiety. Ado might interact specifically with uracil moieties of the polymers, preventing the formation of the polymer complex at lower temperatures. Such changes were not observed in PAU aqueous solution containing guanosine (Guo). Additions of Ado and Guo exerted different effects to phase transition changes of the polymer. Moreover, addition of poly(adenylic acid) (Poly(A)) lowered remarkably the transition behavior of PAU solution as compared with Ado addition. It was conceivable that PAU and Poly(A) formed stable polymer complexes, assuming soluble states in even cold water. PAU changed its phase-transition temperature in response to species of the additive materials, demonstrating the specific molecular discrimination in aqueous milieu.