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.

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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.

In this work, we have developed a novel SERS-based approach to detect hydrogen peroxide (H 2 O 2 ) scavenging activity by using gold nanoshell precursor nanocomposites (SiO 2 /GNPs) as nanoprobes. H 2 O 2 can reduce AuCl 4 À to Au 0 and enlarge the gold nanoparticles (GNPs) that attached on the surface of SiO 2 . As the concentration of H 2 O 2 increases, the surface coverage of resultant gold on silica cores increases accordingly until continuous gold nanoshells (GNSs) are formed. During the growth process, there is a strong correlation between the SERS-activity of the GNSs and the amount of H 2 O 2 that is used as reductant. When H 2 O 2 reaches 250 mM, the resultant GNSs show the highest SERS-activity. H 2 O 2 can be scavenged by antioxidants such as tannic acid and L-apple acid. Their H 2 O 2 scavenging activities were determined by restraining the H 2 O 2 -mediated (250 mM) growth of SiO 2 /GNPs. The decrease of the SERS-activity was proportional to the H 2 O 2 scavenging activity of the antioxidant. The results showed that tannic acid had a much higher H 2 O 2 scavenging activity than that of L-apple acid.

A novel method based on surface-enhanced Raman scattering (SERS) was developed to estimate the antioxidant activity of antioxidants by using self-assembled three-dimensionally (3D) ordered gold nanoparticles (GNPs) precursor composite (SiO(2)/GNPs) arrays as nanoprobes. H(2)O(2) could reduce AuCl(4)(-) to Au(0) which deposited onto the surface of the SiO(2)/GNPs arrays and enlarged the GNPs. As the concentration of H(2)O(2) increased, the surface coverage of the resultant gold on the silica cores increased accordingly until continuous gold nanoshells (GNSs) were formed. The change of the intensities of the SERS spectra correlated well with H(2)O(2) concentration which indicated that this SiO(2)/GNPs array was a potential SERS nanoprobe for H(2)O(2). The presence of antioxidant will prevent the growth of GNPs on the surface of the silica arrays from forming the structure which has strongest SERS-activity and the corresponding change in SERS intensity correlated well with the H(2)O(2) scavenging activity of the antioxidants. The H(2)O(2) scavenging activities of four plant-based antioxidants, tannic acid, citric acid, ferulic acid, and tartaric acid were studied. Our results showed the H(2)O(2) scavenging activities (SA(HP) values) of these four compounds were: tannic acid > ferulic acid > citric acid > tartaric acid.