||The structure of functional DNA was transformed dynamically, leading to a release of the cargo, thus achieving the specific delivery of siRNA or an anticancer drug, doxorubicin (DOX). Taking advantage of the intrinsic optical properties of Au nanoparticles, which depend on their size, a cytosine rich i-motif sequence was employed for intracellular pH-sensitive duplex dissociation and subsequent aggregation of the DNA-Au nanomachine, enabling anti-cancer drug release and photothermal ablation upon irradiation with infrared light. In this study, we also developed novel nitric oxide (NO) delivery system using catecholamine and diazeniumdiolates. Simple two-step reactions comprising catecholamine and diazeniumdiolates enable virtually any material surfaces to release NO with appreciable storage. The modified surfaces showed the antibacterial activity without cytotoxicity. We also prepared NO-scavenging hydrogel for alleviating inflammatory disease such as rheumatoid arthritis (RA).