The Biosorter from Union Biometrica is a large particle sorter capable of sorting bigger elements like spheroids and/or organoids. The Biosorter is able to deal with objects ranging from 20 to 1500 microns. The sample can be provided from a 50 ml conical tubes or alternatively from a plate thanks to the LP sampler module. It can sort samples to plates (from 6 to 384 wells) or tubes (1,5 to 15 ml). It is equiped with a 488 nm and a 561 nm laser. it can sort based on the axial length of the object (similar to FSC), its optical density/complexity (similar to SSC) and up to 3 fluorescences (filter sets availables : GFP, YFP, RFP, mCherry and equivalent fluorochromes).
The Biosorter operates at a lower pressure compared to conventional sorters and use gentle air stream diverter to sort events of interest. This is a viable alternative to manual isolation of large object such as cell clusters, seeds or small organisms.
It is located at the UNIL Biophore site. The machine was acquired in early 2021 and users can access it since April 2021.
Although the Biosorter system is based on traditional flow cytometry sorting principles (see above), it adapts some key aspects to be optimized for the handling of large particles.
In traditional flow cytometry, as the machine is installed, the stream of particles going through the flow cell has to be aligned with the path of the lasers to be able to gather the multiple parameters needed for the sort. This alignment and setup is performed by a trained technician and it could take hours. That is usually perform only during annual maintenance.
The initial limitation of large particle flow cytometry was the diversity of size the Biosorter would have to dealt with. Indeed, it would require different flow cell size to handle it. It would then be unrealistic to have a technician perform the adjustement between two sorts. Consequently, Union Biometrica found a way to produced a fixed assembly of the flow cell and pre align optics : The Fluidics and Optics Core Assemblies (FOCA) (see below).
That structure can easily be changed based on sample requirement even by casual users of the machine. Few cables have to be unplugged and the FOCA can be put in place and working in approximately 15 min. We have a FOCA-500 (40-300 um) and FOCA-1000 (200-700 um) available to our users.
The Biosorter operates at a very low pressure (1,5-2,5 PSI for FOCA-500, 0,2-0,3 PSI for FOCA-1000). As a consequence of the low pressure applied to the sample it limits the potential disruptive shear forces inherent to traditional sorting and should help encouraging viability.
Lastly, the sorting itself is done using a pneumatic mechanism located downstream of the flow cell. The sample is being pushed to the waste constantly and when an event or interest is detected, the air flow stops to let the particles drop in the collection device. There is no mechanical sorting or electrostatic charge involved.
These differences ensures that the Biosorter can perform high speed analysis and gentle sorting of large objects.
Examples of Applications
From the time of its instalment in the facility, we have already been able to try a diverse set of samples on this machine including :
- Seeds, Arabidopsis (Arabidopsis thaliana): RFP and/or GFP sorts on CRISP/Cas edited seeds. (Geldner Lab & Santiago Lab)
- Tumour pieces embed in alginate beads: Sort based on GFP signal of few tumour cells positive in order to keep the tumoral environment.(Brisken Lab)
- C. Elegans: WT or mCherry expressing worms (Ocampo Lab)
You can see below additional applications found in the litterature https://www.unionbio.com/publications/).
How to use the sorter ?
You can book a sort with us as you would for any other sorters. If you are planning on using the machine on a regular basis, it is possible to be trained to use it on your own for a cheaper price.
if you are interested in using the machine, please contact us to discuss the details !