
22
7.
Gate positive and negative fluorescent droplets to count relative numbers (Fig. 4.3). Please notice that the
“negative” population has a detectable fluorescent signal.
Fig. 4.3
.
Identify and gate positive and negative fluorescent population to count relative numbers and to sort.
Compare fraction of observed positive droplets to expected number using the online calculators at
samplix.com
Optional: Set up flow cytometry with Cell sorter control kit (Cat. No. CO10100)
To easily set up flow cytometry of dPCR droplets, use the Samplix Cell sorter control kit (Cat. No. CO10100).
1.
Make sure the 2x dPCR buffer
●
is diluted with molecular grade water to 1x. Mix well by vortexing 10 seconds
and inverting the tube at least 20 times.
2.
Stain the Control droplets
○
with Droplet dye
●
as follows:
Prepare flow cytometry buffer by adding 500 μl 1x dPCR-buffer to a flow cytometry tube
(tubes depend on flow cytometer instrument).
Spin down the vial of Droplet dye
●
1-2
minutes.
Add 5 μl Droplet dye
●
into the flow cytometry tube with dPCR buffer. Mix gently to dissolve
the dye in the dPCR-buffer.
Transfer 50 μl of Control droplets
○
to the prepared flow cytometry tube.
Leave at room temperature protected from light for 5 min to stain droplets
3.
Load tube on a flow cytometer and start analysis or sorting.
4.
Identify the dPCR droplets as described above (see Fig. 4.1).
5.
Identify positive and negative fluorescent droplets as described above (see Fig. 4.2). In the Cell sorter control
droplets, you can expect the fraction of positive droplets to be about 10-15% of the total observed dPCR
droplets.