Visible Light Responsive DNA Thermotropic Liquid Crystals Based on a Photothermal Effect of Gold Nanoparticles

Solvent free DNA–surfactant melts are receiving continuous attractions in recent years. Their physical properties could be regulated via changing the alkyl chain length of surfactants. As an ideal external stimulus, light has been used in the regulation of mechanical properties of DNA thermotropic liquid crystal (TLC) containing an azobenzene motif, while in this case, the UV light is the only effective excitation source. However, in comparison with visible light, UV light causes damage to DNA and has low tissue-penetration efficiency problem. In this work, a new type of DNA–didodecyldimethylammonium bromide (DNA–DDAB) TLCs fabricating with gold nanoparticles (AuNPs) was demonstrated. The visible light-induced photothermal effect of AuNPs could change the mechanical properties of AuNPs/DNA–DDAB TLCs, as shown by clearly boundary motion activity and viscoelasticity change. Furthermore, the ratio of AuNPs and charge stoichiometry of DNA:DDAB also affected photocurrent generation property of these DNA melts. The development of this visible light responsive DNA melt might facilitate the related studies in biomedicine and biomaterials.