ChemoMetec 900-0300, Руководство пользователя

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2 Introducing the NucleoCounter
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Figure 5 The NucleoCassette. The fluorescent dye, propidium iodide, is immobilized
in the first part of the flow system.
2.2.1 Loading the cassette
The NucleoCassette is loaded by gently pressing the white piston, which creates a
partial vacuum in the flow system. The tip of the NucleoCassette must be immersed
into a lyzate mixture when pressing the piston, resulting in lyzate being loaded into
the flow system. Approximately 50µl is loaded into the flow system.
2.2.2 Fluorescent dye
The fluorescent dye, propidium iodide, is immobilized in the first part of the flow
system. As the stabilized lyzate is loaded into the NucleoCassette, the immobilized
propidium iodide is dissolved immediately and mixed with the lyzate. Propidi um
iodide intercalates with DNA and forms a fluorescent stain, absorbing green light
and emitting red light, which is utilized for detection of stained cells. Furthermore
PI's ability to fluoresce is enhanced significantly upon binding to DNA thereby
substantially enhancing selectivity.
During the analysis the stained mixture is transported through the flow system,
where it is mixed with the propidium iodide, towards the chamber where the actual
cell counting is performed. The precise volume analyzed, is d etermined individually
for each cassette during analysis. This volume is approximately 1 µl, and thus the
volume analyzed is 10-20 times that of a conventional hemacytometer. After
analysis the NucleoCassette is disposed of as biological waste.
2.2.3 Sample volume
During production each cassette is marked with a dot code, which specify the
precise depth or thickness of the measurement chamber of the cassette. The dot
code is read and decoded in the instrument during analysis and the volume