NIR‐Responsive Gold Nanorod Capsules for Efficient Cargo Encapsulation and Release

ABSTRACT

Gold nanoparticle‐based vesicular nanostructures are attractive drug delivery platforms because of their tunable plasmonic properties; however, simultaneously achieving efficient cargo encapsulation, robust aqueous stability, and controllable near‐infrared (NIR)‐triggered release remains challenging. Herein, water‐dispersible and NIR‐responsive gold nanorod capsules (Au NrCs) are fabricated from mini‐gold nanorods (mini‐Au NRs) and small amphiphilic hexaethylene glycol (EG6) ligands via a solute‐induced phase separation strategy. Owing to their compact dimensions and tunable longitudinal localized surface plasmon resonance, the mini‐Au NRs enable assembly within sub‐200 nm nanocapsules while retaining NIR responsiveness. During capsule formation, nanoparticles and DNA cargoes are simultaneously encapsulated and concentrated within the capsules through liquid‐liquid phase separation, achieving approximately 90% DNA encapsulation efficiency and more than 1000‐fold enrichment. Furthermore, amino‐terminated EG6 ligands enable post‐assembly crosslinking of the Au NrCs with diepoxy‐polyethylene glycol, improving aqueous stability and dispersibility. The resulting Au NrCs exhibit efficient cargo release (>95% within a few minutes) under low‐power 810 nm NIR LED irradiation through capsule disassembly, highlighting the potential of plasmonic nanocapsules for externally controlled delivery under relatively mild NIR LED irradiation conditions. These results establish a plasmonic nanocarrier platform integrating concentration‐assisted cargo encapsulation, enhanced aqueous stability, and controllable NIR‐triggered release, providing a basis for future drug delivery applications.