New Plasmonic Sensing Technologies

Two new technologies based on plasmonic sensing have been unveiled that will expand the usefulness of surface plasmon resonance (SPR) in the fields of proteomics and genomics.

SPR is a phenomenon that occurs when light is reflected off thin metal films. A fraction of the light energy incident at a sharply defined angle can interact with the delocalized electrons in the metal film (plasmon), thus reducing the reflected light intensity. The rates of change of the SPR signal can be analyzed to yield apparent rate constants for the association and dissociation phases of the reaction.

The ratio of these values gives the apparent equilibrium constant (affinity). The size of the change in SPR signal is directly proportional to the mass being immobilized and can thus be interpreted crudely in terms of the stoichiometry of the interaction. Signals are easily obtained from submicrogram quantities of material. Since the SPR signal depends only on binding to the immobilized template, it is also possible to study binding events from molecules in extracts, i.e. it is not necessary to have highly purified components.

The new products are the NanoPlasmon Proteomics Array, which allows the user to inject molecules of interest in buffers of differing refractive index while maintaining signal-to-noise ratio and to select rapid changes in experimental temperature while simultaneously monitoring the resulting kinetic changes across an array of bound biomolecules; and real-time PCR (polymerase chain reaction), which can quantify the presence of a set of target polynucleotides within a sample without the use of fluorogenic probes. Both products are from Mobius Genomics (Exeter, UK).



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