To obtain depth profiles of surface-enhanced Raman scattering (SERS) information in living systems, a SERS-active needle was structured by acupuncture needles, gold nanoshells (GNSs), and polystyrene, which were used as carriers, SERS-active elements to be absorbed on the carriers, and coatings to protect the absorbed GNSs from being erased during insertion, respectively. The SERS-active needle is minimally invasive for entering and exiting the body. The interspaces between the GNSs became vessels to collect diffused fluids at different depths after a SERS-active needle was inserted into an agarose gel, and the SERS intensity profile on the SERS-active needle coincided with the concentration profile of Nile Blue A (NBA) in the gel. SERS detection in vitro avoided the signal attenuation in gels, and the SERS detection at different spots of the SERS-active needle provided a depth profile of the NBA molecule in the gel. In vivo experiments of NBA and 6-mercaptopurine confirmed that the SERS-active needle could collect fluids in living systems easily with minimal invasion and provide information about depth profiles of target molecules in tissues.
In this study, we present a new method to fabricate large-area two-dimensionally (2D) ordered gold nanobowl arrays based on 3D colloidal crystals by wet chemosynthesis, which combines the advantages of a very simple preparation and an applicability to "real" nanomaterials. By combination of in situ growth of gold nanoshell (GNSs) arrays based on three-dimensional (3D) colloidal silica crystals, a monolayer ordered reversed GNS array (2D ordered GNS array) was conveniently manufactured by an acrylic ester modified biaxial oriented polypropylene (BOPP). 2D ordered gold nanobowl array with adjustable periodic holes, good stability, reproducibility, and repeatability could be obtained when the silica core was etched by HF solution. The surface-enhanced Raman scattering (SERS) enhancement factor (EF) of this 2D ordered gold nanobowl array could reach 1.27 × 10(7), which shows high SERS enhancing activity and can be used as a universal SERS substrate.
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