Hydrogen-bond-guided self-assembly of nucleotides on a receptor-array surface

The hydrogen-bond-guided self-assembly of 5'-ribonucleotides bearing adenine(A), cytosine (C), uracil (U), or guanine (G) bases from aqueous solution on a lipid-like surface decorated with synthetic bis(Zn(II)-cyclen) (cyclen=1,4,7,10-tetraazacyclodododecane) metal-complex receptor sites is described. The process was studied by using surface plasmon resonance spectroscopy. The data show that the mechanism of nucleotide binding to the 2D template is influenced by the chemistry of the bases and the pH value of the solution. In a neutral solution of pH 7.5, the process is cooperative and selective with respect to Watson-Crick pairs (A-U and C-G), which form stable double planes in accordance with the Chargaff rule. In a more acidic solution at pH 6.0, the interactions between complementary partners become non-cooperative and the surface also stabilizes mismatched and wobble pairs due to the pH-induced changes in the receptor coordination state. The results suggest that hydrogen bonding plays a key role in the self-assembly of complementary nucleotides at the lipid-like interface, and the cooperative character of the process stems from the ideal matching of the orientation and chemistry of all the interacting components with respect to each other in neutral solution.