A novel SERS sensor for adenine molecules is fabricated electrochemically using an ordered two-dimensional array of self-aligned silver nanoparticles encapsulated by alumina. Silver is electro-deposited on the interior surfaces at the bottom of nano-channels in a porous anodic aluminum oxide (AAO) film. After etching aluminum, the back-end alumina serves as a SERS substrate. SERS enhancement factor greater than 10(6) is measured by 532 nm illumination. It exhibits robust chemical stability and emits reproducible Raman signals from repetitive uses for eight weeks. The inexpensive mass production process makes this reliable, durable and sensitive plasmon based optical device promising for many applications.
We report on a polarized Raman study on mechanically cleaved single-layer graphene films. Under a specific orientation of scattering measurement, the width and position of the G peak change with the incident polarization direction, while the integrated intensity of that is unaltered. This phenomenon is explained by a proposed mode in which the peak is contributed by a mixture of un-, compressive-, and tensile-strained G sub-modes. The compression and tension are both uniaxial and approximately perpendicular to each other. They are undesigned and located in either separated or overlapped sub-areas within the probed local region. Compared to the unstrained wavenumber of 1580 cm(-1), compression induces a blue shift while tension causes a red one. The sub-modes correlated with the light polarization through different relationships split the G peak into three sub-ones. We develop a method to quantitatively analyze the positions, widths, intensities, and polarization dependences of sub-peaks. This analysis quantitatively reveals local strain, which changes with the detected area of a graphene film. The method presented here can be extended to detect the strain distribution in the film and thus is a promising technology for graphene characterization.
We report on strong plasmonic coupling from silver nanoparticles covered by hydrogen-terminated chemically vapor deposited single-layer graphene, and its effects on the detection and identification of adenine molecules through surface-enhanced Raman spectroscopy (SERS). The high resistivity of the graphene after subjecting to remote plasma hydrogenation allows plasmonic coupling induced strong local electromagnetic fields among the silver nanoparticles to penetrate the graphene, and thus enhances the SERS efficiency of adenine molecules adsorbed on the film. The graphene layer protects the nanoparticles from reactive and harsh environments and provides a chemically inert and biocompatible carbon surface for SERS applications.
Surgery is the most effective treatment for breast cancer patients. However, some patients developed recurrence and distant metastasis after surgery. Adjuvant therapy is considered for high-risk patients depending on several prognostic markers, and lymphovascular invasion has become one of such prognostic markers that help physicians to identify the risk for distant metastasis and recurrence. However, the mechanism of lymphovascular invasion in breast cancer remains unknown. This study aims to unveil the genes and pathways that may involve in lymphovascular invasion in breast cancer. In total, 108 breast cancer samples were collected during surgery and microarray analysis was performed. Significance analysis of the microarrays and limma package for R were used to examine differentially expressed genes between lymphovascular invasion-positive and lymphovascular invasion-negative cases. Network and pathway analyses were mapped using the Ingenuity Pathway Analysis and the Database for Annotation, Visualization and Integrated Discovery. In total, 86 differentially expressed genes, including 37 downregulated genes and 49 upregulated genes were identified in lymphovascular invasion-positive patients. Among these genes, TNFSF11, IL6ST, and EPAS1 play important roles in cytokine-receptor interaction, which is the most enriched pathway related to lymphovascular invasion. Moreover, the results also suggested that an imbalance between extracellular matrix components and tumor micro-environment could induce lymphovascular invasion. Our study evaluated the underlying mechanisms of lymphovascular invasion, which may further help to assess the risk of breast cancer progression and identify potential targets of adjuvant treatment.
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