Surface-enhanced Raman scattering (SERS): nanoimaging probes for biological analysis

Abstract

We have developed a surface enhanced Raman scattering (SERS) based nanoimaging probe capable of chemical imaging with nanometer scale spatial resolution. Using this SERS-nanoimaging probe it is possible to image individual chemical components within sub-cellular environments. The probe consists of a tapered coherent fiber optic imaging bundle that has been coated with a roughened layer of metal, providing a SERS active substrate. The fiber optic bundle is tapered using a specially programmed micropipette puller, allowing precise control over the probe tip's diameter, and thus the resolution of images. Tapered bundles having individual fiber elements ranging from 100-800 nanometers on the tapered end and 4 micrometers in diameter on the proximal end have been investigated. Through modification of the fibers' tapered tips, generation of nanoscale imaging with inherent image magnification and short pass filtering effects is possible. Following tapering of the fiber optic bundles, the fiber probes are spin-coated with alumina particles and coated with silver to provide a reproducible SERS active surface. Characterization of the response of these SERS nanoimaging probes has been evaluated using common SERS active chemical species (e.g., benzoic acid, brilliant cresyl blue, etc.) and application of these nanoimaging sensors to biological systems is discussed.