High Fidelity Nano-Hole Enhanced Raman Spectroscopy.

Surface Enhanced Raman Spectroscopy (SERS) is a sensitive technique that can even detect single molecules. However, in many SERS applications, the strongly inhomogeneous distribution of intense local fields makes it very difficult for a quantitive assessment of the fidelity, or reproducibility of the signal, which limits the application of SERS. Herein we report the development of exceptionally high fidelity Hole-Enhanced Raman Spectroscopy (HERS) from ordered, two-dimensional hexagonal nanohole arrays.

Hole-enhanced Raman scattering.

Stokes and anti-Stokes non-resonant hole-enhanced Raman scattering (HERS) spectra with high signal-to-noise ratio (S/N) are reported for the first time for aqueous phase R6G molecules adsorbed onto random nanoholes in thin gold films. Compared to conventional surface-enhanced Raman scattering from nanometric gold colloid particles, HERS exhibits higher strength gain, exceptional reproducibility, simple and reliable substrate preparation, and excellent mechanical stability. By correlating the hole density with Raman scattering gain, we determined optimum HERS gain for 50 nm diameter holes at approximately 100 holes/microm(2).

Toward the detection of single virus particle in serum.

There is a grand challenge for the detection of target molecules at single molecule sensitivity in a bulk body fluid for the early diagnosis of diseases. We report our progress on tackling this challenge via the combination of fluorescence cross-correlation spectroscopy (FCCS) and micro fabricated devices toward highly sensitive detection of the dengue virus. We demonstrate that by using a dengue-specific antibody, we can probe the individual dengue virus in a nanomolar bulk solution by following the specific association of dengue antibody using FCCS.

Characterizing specific phage-protein interactions by fluorescence correlation spectroscopy.

The interactions of several affinity reagent displayed T7 and M13 phage particles with their corresponding target molecules were examined using Fluorescence Correlation Spectroscopy (FCS). Diffusion times, relative fractions of each component in the recognition reactions at the equilibrium state, and ultimately the dissociation constants were deduced from analyzing the fluorescence autocorrelation curves. Although the sample preparation and FCS characterization of icosahedral T7-related systems were relatively straight forward, procedures with filamentous M13-related systems were complicated by the physical size of M13 and its aggregate formation.