Highly Efficient Construction of Silver Nanosphere Dimers on Poly(dimethylsiloxane) Sheets for Surface-Enhanced Raman Scattering

We reported a highly efficient and low-cost way to synthesize silver nanosphere dimers on a poly­(dimethylsiloxane) (PDMS) sheet by using a stepwise upright assembly method for the “hot spots” study of surface-enhanced Raman scattering (SERS). The first silver nanoparticle (NP) layer is almost entirely embedded in PDMS, and the second-layered silver NPs directionally position the tops of the embedded particles. The analysis of the localized electric field distributions of the silver nanosphere dimer presents that the strongest electric field coupling appears at the gap of two nanospheres when the incident angle is about 45° and its intensity achieves 400 times enhancement. The SERS enhancement activity on this novel substrate was determined, and the results showed that SERS intensities on nanodimers were much stronger than those on the silver NP monolayer due to the electromagnetic field coupling of upright NP-NP. By using this novel SERS substrate, the lowest detection concentration for 4-mercaptopyridine is 4.0 × 10^–14 M

Tunable Plasmons in Shallow Silver Nanowell Arrays for Directional Surface-Enhanced Raman Scattering

The purpose of this article is to improve the collection efficiency of surface-enhanced Raman scattering (SERS) further to increase SERS detection sensitivity in trace detection. To achieve this, a silver nanowell array substrate was designed based on its tunable propagating surface plasmons. This substrate supported directional surface plasmon coupling emission and could guide SERS to the vertical direction of the substrate. Silver nanoparticles were assembled on the shallow silver nanowell array to contribute localized surface plasmons for higher electromagnetic enhancement. Spatial SERS radiation patterns on the silver nanoparticle assembled nanowell array substrate were simulated by the finite-difference time-domain method and recorded by a self-made 3D angle-resolved Raman spectrometer. The results showed that SERS signals were strong and unidirectional in space. The half divergence angle of the SERS pattern was about 10°, which would facilitate SERS collection by using a conventional backscattering Raman spectrometer. This silver nanowell array is supposed to be an applicable configuration to many systems that require high collection efficiency like single-molecule SERS detection and tip-enhanced Raman spectroscopy

Additional file 1: of Association of APEX1 and OGG1 gene polymorphisms with breast cancer risk among Han women in the Gansu Province of China

A questionnaire survey of breast health. Questionnaire included participant's eating habits, living environment, lifestyle, smoking, physiological state, reproductive condition, past medical history and family history of cancer. (PDF 415 kb