Secondary Structure-Dependent Physicochemical Interaction of Oligonucleotides with Gold Nanorod and Photothermal Effect for Future Applications: A New Insight

We investigate the physicochemical interactions of gold nanorod (GNR) with single-stranded, double-stranded, and hairpin DNA structures to improve the biological compatibility as well as the therapeutic potential, including the photothermal effect of the conjugates. Studies have demonstrated that different DNA secondary structures, containing thiol group, have different patterns of physicochemical interaction. Conjugation efficiency of paired oligonucleotides are significantly higher than that of oligonucleotides with naked bases. Furthermore, hairpin-shaped DNA structures are most efficient in terms of conjugation and increased dispersion, with least interference on GNR near-infrared absorbance and photothermal effect. Our conjugation method can successfully exchange the overall coating of the GNR, attaching the maximum number of DNA molecules, thus far reported. Chemical mapping depicted uniform attachment of thiolated DNA molecules without any topological preference on the GNR surface. Hairpin DNA-coat...