Near‐Infrared II Plasmonic Au@Au–Ag Dot‐in‐Cubic Nanoframes for In Vivo Surface‐Enhanced Raman Spectroscopic Detection and Photoacoustic Imaging
Beibei Shan, Linhu Li, Yawen Zhao, Haitao Wang, Ming Li
Abstract
Abstract Near‐infrared II (NIR‐II) plasmonic noble‐metallic nanostructures are highly desirable for in vivo photodiagnostics because of their multiple functionalities and deep‐tissue optical imaging capability. Herein, a novel class of Au@Au–Ag dot‐in‐cubic nanoframes (DCFs) comprising a solid Au core and a Au–Ag alloy shell with a wall hole on each side face is reported, which exhibit remarkable plasmonic properties spectrally tunable beyond 1400 nm while maintaining a small size. The synthesis of Au@Au–Ag DCFs is principally based on the facet‐selective etching of Ag atoms and co‐deposition of Au and Ag atoms on the edges and corners of Au@Ag dot‐in‐cubes. The geometry (e.g., edge length and wall hole size) can be controllably tailored by simply varying the silver nitrate and chloroauric acid concentrations. Superior in vitro and in vivo NIR‐II photoacoustic imaging performances of Au@Au–Ag DCFs are demonstrated. Additionally, remarkable NIR‐II surface‐enhanced Raman spectroscopy (SERS) activity of Au@Au–Ag DCFs is evidenced with the maximum NIR‐II SERS enhancement occurring at a plasmon resonance wavelength blue‐shifting from the incident laser wavelength and an excellent effective detection depth. Finally, the potential of the developed Au@Au–Ag DCFs is highlighted for in vivo NIR‐II SERS detection of microtumors in animals.