Surface plasmons are surface electromagnetic waves that propagate in parallel along a metal/dielectric (or metal/vacuum) interface.

As the wave is on the boundary of the metal and the external medium (eg air or water), these oscillations are sensitive to changes in this boundary, including the adsorption of molecules to the metal surface.

You can choose from various models to describe the existence and properties of surface plasmons, but the easiest approach is to treat each material as a homogeneous continuum, described by a dielectric constant.

With the terms of this description for electronic surface plasmons to exist, the real part of the dielectric constant of the metal must be negative and its magnitude must be greater than that of the dielectric.

This condition is met in the IR-visible wavelength region for air/metal and water/metal interfaces (where the real dielectric constant of a metal is negative and that of air or water is positive).

Contact us

Contact Dr Amanda Nouwens for more information and bookings.

Applications

Primary use is in the quantitative measurement of intermolecular interactions, especially between proteins and other molecules.

In their simplest form, SPR reflectivity measurements can be used to detect DNA or proteins binding to a target by the changes in the adsorption of the target molecule to a metal surface.

The molecules are bound to a chemically modified chip. The chip may be coated with caboxymethyl groups (which will bind positively charged protein), streptavidin (binds biotinylated molecules), or NTA (for His-tagged proteins). Proteins, nucleic acids, carbohydrates and low molecular weight molecules may be attached to the surface.

SPR addresses questions including:

  • How specific is the binding between two molecules?
  • How much of a given molecule is present and capable of binding to another?
  • How fast is the binding?
  • How strong is the binding?

Related links

Visit the GE Healthcare website for more information about SPR and Biacore products.

Equipment and location

Equipment

  • Biacore 3000 Surface Plasmon Resonance Biosensor
  • BIA evaluation software for data analysis

Location

Molecular Biosciences Building (Building 76), Room 409

Sample requirements

SPR experiments need careful planning and interpretation. We recommend that you consult us when designing experiments.

Biacore

The Biacore uses microfluidics chips through which sub-microlitre volumes are passed. You'll need to supply buffers and reagents, including Biacore chips.

Typical anolyte concentrations required are 10ul/ml-250ul/ml, depending on affinity.

Ligand affinity is typically 2ug/ml-200ug/ml.

BIA evaluation

BIA evaluation software is available to analyse data.

Charges and considerations

Charges

  • School staff and students: free
  • Other UQ staff and students: $40/hour
  • Researchers from external non-profit organisations: $50/hour

Considerations

UQ users have priority of access.

You'll need to undertake the relevant building and other inductions before using equipment.