ChemoMetec NC-200 - Manual (Page 22)

2 Cell counting with the NucleoCounter NC-200
991-0203 Rev. 1.1 Sep. 2012 8
The cassettes to be used with NucleoCounter NC-200 are highly specialized devices, which
hold the key to several of the unique features of the NucleoCounter NC-200 concept. For
instance in the Via1-Cassette the fluorescent dyes AO (acridine orange) and DAPI (4',6-
diamidino-2-phenylindole) are immobilized inside the flow channels of the disposable
cassette. When the cassette has been loaded with approximately 60 µl of sample mixture,
the dyes are dissolved and mixed with the sample, staining the cells.
After being placed in the NucleoCounter NC-200, the stained mixture is automatically
transferred to the measurement chamber, where the fluorescent image is recorded. In a
cassette the measurement volume is as large as 1.4 µl.
After analysis the sample and dyes are contained inside the cassette, which can be safely
discarded. This offers a unique and safe sample handling and disposal.
As the Via1-Cassette (and all other cassettes) contains the entire flow system as well as
measurement chamber, neither cleaning nor maintenance of the NucleoCounter NC-200
instrument itself is needed.
2.2.2 Sample volume
During production, a calibration parameter for every cassette is found, which specifies the
precise depth or thickness of the measurement chamber of the device. The calibration
parameter is used by the instrument during analysis and the volume analyzed is
determined by multiplying the imaged area with the depth of the measurement area. The
imaged area is only dependent on the optics of the instrument. Therefore, the area is
constant and specific for each instrument.
The calibration parameter is printed on every single cassette as a dot code describing
actual thickness of the measurement chamber of the cassette.
2.2.3 Cassette handling
The image analysis method of the NucleoView NC-200 offers considerable stability, when
eliminating non-cellular objects from the image, including scratches and smears on the
cassette windows, and thus producing valid results even under extreme conditions. On the
other hand, the quality of the cell count is best assured by keeping the windows of the
cassette as clean as possible.
Caution! Be careful when attempting to wipe off the surface of the cassette, in an attempt
to remove any foreign object, since the plastic material of the cassette can be scratched.
In section 5.2 “Analysis with the cassettes” see how to place and remove the cassette.