ProteOn XPR36, User Manual

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Inside the Instrument
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M
ULTICHANNEL
M
ODULE
The multichannel module (MCM) is the centerpiece of the ProteOn XPR36
microfluidics system. The MCM has six parallel channels.
When pressed on
the sensor chip surface, the MCM forms a set of six flow channels. Ligand-
containing fluid flows through these channels during the immobilization step.
Analyte-containing fluid then flows through the channels in the second
(orthogonal) direction. These ligand and analyte sets create the 36-element
interaction array.
Optical Detection System
The ProteOn XPR36 system uses a synchronized angular scanning
illumination and array imaging detection system to detect the shift of the SPR
angle as the illumination angle passes through the critical angle. The optical
detection system illuminates the sensor chip at successive angles of
incidence. It generates an image of the light reflected at each incident angle
and segments the images into the regions of interest corresponding to the 36
interaction spots. This process generates 36 resonance curves. The complete
SPR curve of normalized reflected intensity versus the angle of illumination is
fitted and used to determine the shift of the SPR angle independently for each
of these points in an image of the chip surface.
In the acquired images, interspot regions (that is, regions of the chip surface
situated between areas of interest or measurement points), can be used to
correct for any noise arising from optical or mechanical sources (for example,
pressure variations and illumination variations). At the ligand immobilization
stage, interspots are chemically equivalent to measurement points. However,
at the analyte stage, interspots are true references, since the surface has not
been activated.