Structure enhancement factor relationships in single gold nanoantennas by surface-enhanced Raman excitation spectroscopy.

Determining the existence of any direct spectral relationship between the far-field scattering properties and the near-field Raman-enhancing properties of surface-enhanced Raman spectroscopy (SERS) substrates has been a challenging task with only a few significant results to date. Here, we prove that hot spot dominated systems show little dependence on the far-field scattering properties because of differences between near- and far-field localized surface plasmon resonance (LSPR) effects as well as excitation of new plasmon modes via a localized emitter. We directly probe the relationship between the near- and far-field light interactions using a correlated LSPR-transmission electron microscopy (TEM) surface-enhanced Raman excitation spectroscopy (SERES) technique.

Structure-activity relationships in gold nanoparticle dimers and trimers for surface-enhanced Raman spectroscopy.

Understanding the detailed relationship between nanoparticle structure and activity remains a significant challenge for the field of surface-enhanced Raman spectroscopy. To this end, the structural and optical properties of individual plasmonic nanoantennas comprised of Au nanoparticle assemblies that are coated with organic reporter molecules and encapsulated by a SiO(2) shell have been determined using correlated transmission electron microscopy (TEM), dark-field Rayleigh scattering microscopy, surface-enhanced Raman scattering (SERS) microscopy, and finite element method (FEM) calculations. The distribution of SERS enhancement factors (EFs) for a structurally and optically diverse set of nanoantennas is remarkably narrow.

Surface-enhanced Raman spectroscopy and homeland security: a perfect match?

This Nano Focus article reviews recent developments in surface-enhanced Raman spectroscopy (SERS) and its application to homeland security. It is based on invited talks given at the "Nanorods and Microparticles for Homeland Security" symposium, which was organized by one of the authors and presented at the 238th ACS National Meeting and Exhibition in Washington, DC. The three-day symposium included approximately 25 experts from academia, industry, and national laboratories and included both SERS and non-SERS approaches to detection of chemical and biological substances relevant to homeland security, as well as fundamental advances.

Multiplexed imaging of surface enhanced Raman scattering nanotags in living mice using noninvasive Raman spectroscopy.

Raman spectroscopy is a newly developed, noninvasive preclinical imaging technique that offers picomolar sensitivity and multiplexing capabilities to the field of molecular imaging. In this study, we demonstrate the ability of Raman spectroscopy to separate the spectral fingerprints of up to 10 different types of surface enhanced Raman scattering (SERS) nanoparticles in a living mouse after s.c.

Gold nanoparticle dimer plasmonics: finite element method calculations of the electromagnetic enhancement to surface-enhanced Raman spectroscopy.

Finite element method calculations were carried out to determine extinction spectra and the electromagnetic (EM) contributions to surface-enhanced Raman spectroscopy (SERS) for 90-nm Au nanoparticle dimers modeled after experimental nanotags. The calculations revealed that the EM properties depend significantly on the junction region, specifically the distance between the nanoparticles for spacings of less than 1 nm. For extinction spectra, spacings below 1 nm lead to maxima that are strongly red-shifted from the 600-nm plasmon maximum associated with an isolated nanoparticle.

Surface-enhanced Raman scattering tags for rapid and homogeneous detection of circulating tumor cells in the presence of human whole blood.

A novel, homogeneous SERS-based cell detection assay was developed for rapid and direct enumeration of circulating tumor cells in the presence of whole blood. Magnetic beads and SERS tags were respectively conjugated to EpCAM and her2 antibodies for the capture and detection of approximately 50 tumor cells/mL in the presence of whole blood in less than 1 h.

Nanomolecular histopathology for renal tumor classification.

Renal tumors are classified into histopathologic subtypes based on light microscopy. Classification is important because subtypes have distinct genetic abnormalities and clinical behavior, yet is difficult because many cases have heterogeneous morphology. Thus, several molecular assays have been developed for tumor classification.

Multiplexed SNP genotyping using nanobarcode particle technology.

Single-nucleotide polymorphisms (SNP) are the most common form of sequence variation in the human genome. Large-scale studies demand high-throughput SNP genotyping platforms. Here we demonstrate the potential of encoded nanowires for use in a particles-based universal array for high-throughput SNP genotyping.

Use of nanobarcodes particles in bioassays.

We have developed striped metal nanoparticles, Nanobarcodes particles, which can act as encoded substrates in multiplexed assays. These particles are metallic, encodeable, machine-readable, durable, submicron-sized tags. The power of this technology is that the particles are intrinsically encoded by virtue of the difference in reflectivity of adjacent metal stripes.

Encoded metal nanoparticle-based molecular beacons for multiplexed detection of DNA.

In this paper we describe a molecular beacon format assay in which encoded nanowire particles are used to achieve multiplexing. We demonstrate this principle with the detection of five viral pathogens; Hepatitis A virus, Hepatitis C virus, West Nile Virus, Human Immune Deficiency virus and Severe Acute Respiratory Syndrome virus. Oligonucleotides are designed complementary to a target sequence of interest containing a 3' universal fluorescence dye.

Nanoparticles for bioanalysis.

This review covers the emerging field of nanobiotechnology, in which nanoparticles are applied to the analysis of biomolecules. Nanoparticles can be used in a variety of bioanalytical formats, and this review discusses four classes of use. First, nanoparticles as quantitation tags, such as the optical detection of quantum dots and the electrochemical detection of metallic nanoparticles.

Particles for multiplexed analysis in solution: detection and identification of striped metallic particles using optical microscopy.

In this report, we present data demonstrating that cylindrical metallic particles, with various submicrometer striping patterns, may be readily distinguished in an optical microscope. Accurate particle identification is discussed relative to synthesis reproducibility and the limitations of optical microscopes. Results from a library of these particles, of which over 100 different striping patterns have been produced, are presented.