Cell Size and Morphology

There is a simple rule we follow that helps govern nozzle selection based on cell size:

The cell size should not exceed one-fifth of the nozzle diameter

This rule helps ensure that stream stability can be maintained during the sort.  If larger particles are entering the stream, there is a deleterious effect on the droplet breakoff.  A drifting breakoff can disrupt the careful calibration of the droplet delay and lead to problems ranging from fanning of the side streams (desired sample ends up missing the tube) to changing of the breakoff (severely comprimises sample purity) to ultimately clogging the nozzle.

Morphology is a trickier subject due to the variation between cell types.  In general, the more the morphology deviates from an ideal spheroid shape, the more susceptible the cells become to shear induced damage.  We typically find that the greater the deviation from the ideal sphere, the larger the nozzle required by the instrument.  It is important that you communicate information relative to cell morphology prior to scheduling a sorting experiment.

questions or comments: asaluk@scripps.edu