Self-assembly of biomolecules based on combinatorial molecular pairings

Combinatorial molecular pairing was applied to the pair of nicotinamide adenine dinucleotide (NAD), and cationic cyanine dyes. In water, the dye gives an absorption peak at 520 nm which is blue-shifted compared to that of monomeric dyes (577 nm, in methanol). Thus, the dye forms H-aggregates in water. Addition of NAD⁺ caused decrease in the absorption intensity at 520 nm, and a new absorption peak was appeared at 647 nm (J-band) with a strong fluorescence. TEM observations reveal the formation of nanowires with bundled dye/NAD ⁺ complexes (width; ca. 7 nm, length; several micrometers). On the other hand, such assemblies are not formed from the pair of dye/NADH. The amphiphilic organization of special molecular pairing demonstrated in this study would be widely applied to develop a new family of biomolecules-based supramolecular systems. We also envisage that control on assembly/disassembly of the biomolecules may lead to the regulation of protein functions.