Detecting 100 nanometer beads with the CytoSense

09.07.2015  by  George Dubelaar

Following our news item of November 2014 on the sensitivity of the CytoBuoy flow cytometers, we report the successful detection of 100 nm non-fluorescing polystyrene beads with the CytoSense.  They were well resolved from the background and noise using the sideward scatter channel on a standard CytoSense.

In the framework of our cooperation in the COAST-IMPACT project, we joined an experiment to test the flow cytometric detection of small microplastics particles by light scattering.  Several sizes of polystyrene beads were analysed on various flow cytometers by Selma van Staveren MSc, UMCU, Utrecht.

The aim was to see how well these small beads were detected using scattering only, sideward or forward.  The performance of the CytoSense was substantially better than three of the four other instruments tested (ForTessa, Gallios and Cytoflex) and slightly better than the FACSAria.

These results are particularly interesting for aquatic scientists who are interested in the smallest algae: prochlorococcus (400-600nm).  The fluorescence of these tiniest cells vanishes in the upper layers of the water column. The traditional way of flow cytometric detection by "red-fluorescence" gating yields large uncertainties in cell counts.

Because these dim cells have much stronger side scatter than the 100 nm beads detected by the CytoSense they cannot be overlooked anymore when using the new CytoSense.