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Surface Plasmons Resonance:

SPR resonance is a sensitive probe for an assessment of the interfacial architecture.
The mass coverage, thickness and optical constants are measured with high precision. A time resolution in the sub-milliseconds regime and sub-monolayer sensitivity is achieved. S
PR is ideally suitable for the investigation of fast kinetic processes and has become a standard technique in the field of biosensing. SPR experiments are fairly simple and robust.

The main advantage of the SPR resonance is the localization of the electric field close to the interface. The plasmon is only sensitive to changes at the interface and the bulk has only little impact on the plasmon.
Unfortunately surface plasmons can only be formed in a couple of metals such as gold or silver.

The following review article can be recommended: 

Raether, Surface plasmons, Springer, Heidelberg
Homola et al. Surface plasmon resonance sensors:
Sensors and Actuators B 54 (1999), 3-15.

SPR biosensor chips:
Surface plasmons are a standard technique in the field of bio sensing. In order to excite a plasmon a very special geometry is required:
* Prism
* Index matching fluid
* Glass slide with gold of a thickness of about 44 nm
The surface of the gold is then chemically further functionalized. Typical surface modifications are thiol self assembly film of grafted hydrogels.
The sensor surface is the central part of the biosensor. It is here where the biomolecular interaction takes place and where the biochemical binding event is transduced into an opto-electronic signal. Therefore the quality of the sensor surface is a decisive element of the experiment. Utilizing SPR requires the technology to prepare thin gold samples and to further modify their surface chemistry.
However, not all of the potential customers or users of the Multiskop have the possibility to manufacture proper SPR sensors chips on their own.
For this reason we started a cooperation with:

XanTec Bioanalytics GmbH in Düsseldorf, Germany,
URL: www.xantec.com,
Phone: +49 (0)211 983980 47
Fax:   +49 (0)211 99364746
E-mail: info@xantec.com

XanTec manufactures SPR sensors for the Multiskop flow cell. A broad range of different surface modifications can be offered. The flyer shows the list of different surface modifications that are at present in the pipeline. The SPR sensor discs are of circular shape with 25 mm diameter and a thickness is 1 mm. The use of these SPR sensor discs require a special prism that can be supplied by Optrel.
A list with different surface modification is listed in the following PDF file. download PDF

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