Application of oligonucleotide as a template for the assembly of nucleoamphiphile bearing azobenzene at the air-water interface

In order to assemble amphiphilic adenine having azobenzene, C12AzoC5Ade (AzoAde), at the air-water interface based on the molecular recognition of DNA, we prepared aqueous linear oligothymidylic acids, dT(n) (n = 4, 6, 8, 10, 30), subphase as templates. Surface pressure-area (pi-A) isotherms and UV-Vis reflection absorption spectra of AzoAde were measured to investigate the effect of chain length of the oligothymidylic acid on the molecular recognition by forming a complementary A-T base pair. It was showed that AzoAde did not form a stable monolayer on the dT(4) subphase and remained monomeric state. While AzoAde provided expanded monolayers and formed J-aggregates of azobenzene moieties on the dTn (n > 4) subphases even at the low molecular density. We also investigated the molecular recognition of template oligonucleoticles by comparing dT(30) with dA(30), indicating that AzoAde had not a specific interaction with dA(30) at the air-water interface due to base mismatching. The AzoAde monolayer on the dA(30) subphase gave H-aggregate from monomeric state by compressing it. On the other hand, it remained J-aggregated state on dT(30) subphase regardless of compression. It was, therefore, suggested that the linear oligothymidylic acids, dT(n) (n > 4), acted as templates for assembling AzoAde at the air-water interface.