Microchannel plate (MCP) functionalized with Ag nanorods as a high-porosity stable SERS-active membrane

Surface-enhanced Raman scattering (SERS) encountered in interstitial gaps between closely positioned metal nanostructures, hot spots, offers tremendous potential for molecular analysis at the trace or single-molecule level. SERS-active sites, hot spots, can be achieved at a higher density when metal nanostructures are configured on a three-dimensional (3D) platform than on a planar two-dimensional (2D) substrate. Yet, 3D platforms demonstrated thus far such as anodized alumina and microstructured fibers offer capillaries/pores either too narrow for the sample to be infused or may not be compatible with microfluidic integration due to their non-planar feature. Here, we introduce a 3D SERS-active platform based on a planar component that is readily available and presents densely packed highly aligned precision microchannels, the so-called microchannel plate (MCP). The microchannels, owing to their alignment biased at a small but precise angle (7 degrees) with respect to the plate surface normal and their reasonably large diameter (similar to 6 mu m) can be functionalized with Ag nanorods through shadowing-based deposition that requires no other template or lithography. The plate functionalized with Ag nanorods delivers an enhancement factor with values in the range of 10(6)-10(8) as verified with probing molecules 4-mercatobenzoic acid (4-MBA) and rhodamine-6G. (C) 2013 Elsevier B.V. All rights reserved.