Development and Characterization of Surface Enhanced Raman Scattering (SERS) Nanoimaging Probes

Chemical imaging synergistically combines the chemical differentiation and identification; capabilities of spectroscopy with the spatial location and morphological information provided through imaging. Chemical imaging is a universally applicable means for characterizing complex; biological systems and samples using techniques ranging from basic microscopic imaging to the more advanced high-resolution techniques like near-field scanning optical microscopy (NSOM). Despite the current means by which chemical imaging is achieved, the development of a tool for chemical imaging on the nanoscale in a dynamic label-free manner has remained challenging. Such a visualization tool could potentially provide new insight and understanding into such extracellular events like lipid rafting. This work has resulted in the development, characterization, and optimization of surfaceenhanced; Raman scattering (SERS)-based imaging probes for the detection and imaging of biochemical species in real-time on the nanoscale. The nanoimaging probes synergistically combine the imaging capabilities of a tapered fiber optic bundle with chemical identification and; quantification using SERS-based spectroscopy. To fabricate the SERS nanoimaging probes, fiber optic bundles are first tapered, resulting in equi-diameter nanometer scale fiber elements. Following tapering, the fiber bundles are suspended in a solution of hydrofluoric acid (HF acid), which etches fiber element cores at a more rapid rate than surrounding cladding to create a uniformly roughened surface of cladding peaks across the fiber bundle. Raman signal enhancement across the probe surface is achieved by selectively depositing an array of metal islands onto the cladding peaks via vacuum evaporation. These SERS nanoimaging probes can; therefore be used to image biochemical species in a non-destructive, label-free manner i