Analyzing the composition: Raman effect

NANOPLEX™ biomarker detection

These silica-coated, surface enhanced Raman scattering (SERS)-active metal nanoparticles allow robust, ultrasensitive, highly-multiplexed biomarker quantitation in any biological matrix, including whole blood.


http://www.oxonica.com/diagnostics/diagnostics_biodiagnostics.php

Raman scattering or the Raman effect is the inelastic scattering of a photon, discovered By Dr. Raman who received Noble in 1920 in recognition of its significance as a tool for analyzing the composition of liquids, gases, and solids.

When light is scattered from an atom or molecule, most photons are elastically scattered (Rayleigh scattering). The scattered photons have the same energy (frequency) and wavelength as the incident photons. However, a small fraction of the scattered light (approximately 1 in 10 million photons) is scattered by an excitation, with the scattered photons having a frequency different from, and usually lower than, the frequency of the incident photons. In a gas, Raman scattering can occur with a change in vibrational, rotational or electronic energy of a molecule. Chemists are concerned primarily with the vibrational Raman effect.

wikipedia.org

Glass-coated, analyte-tagged nanoparticles (GANs) are core-shell particles where a nanometer-scale Au or Ag core is functionalized with Raman active molecules and encapsulated in a glass shell. The glass shell provides the particle with mechanical and chemical stability. Specifically, the glass coating renders the particle amenable to use in many solvents without altering the Raman spectral response and makes agglomeration a nonfactor. The density and thickness of the glass shell are controllable through synthetic conditions; thus, the rate of diffusion through the silica network can be tuned and the metal cores kept sequestered from any exterior reaction. This will allow for the attachment of biomolecules to the glass shell without altering the Raman response. GANs can be identified by the Raman spectrum of the attached Raman tag, and two differently labeled samples are unambiguously identified. The scattering from the Raman tag is amplified through surface-enhanced Raman scattering. The narrow bandwidth (~20 cm-1) of the Raman peaks and fingerprint-like spectra will allow multiple Raman tags to be simultaneously evaluated with a single excitation source.


Mulvaney, 2003, A New Tagging System Based on Detection with Surface-Enhanced Raman Scattering;American Chemical Society





NANOPLEX™ No-wash Assay

NANOPLEX™ Direct is a homogeneous assay format rivalling conventional ELISAs while offering several advantages including

* Simple procedure using a one-step, no-wash assay format
* High sensitivity, on par with heterogeneous, amplified systems
* Leverages the performance of surface-enhanced Raman scattering (SERS)
* Near IR detection allows for data collection in whole blood, serum and plasma backgrounds
* Multiplexing capability of the technology allows for quantitation of multiple analytes in a single reaction
* Benchtop reader and proprietary software for data analysis






Procedure