an UV-C decontamination module for the sheath fluid of flow cytometers for germ-free cell sorting
The contamination of the sheath fluid of a cell sorter by germs inhibits the cultivation of the sorted cells. Such contamination can happen, for example, when the sheath fluid reservoir is opened for refilling or through contamination by compressed air that is required for cell sorter operation. For this reason, decontamination is usually accomplished by regular flushing the fluidics with sodium hypochlorite or ethanol. However, such cleaning procedures are time consuming and residues of cleaning reagents in the fluidics are toxic for the cells of interest.
The lethal effect of UV-C light is well known for inactivating microorganisms without the side effects of a chemical treatment. The antimicrobial effect of UV-C light is based on the absorption of photons in the wavelength range of 200 – 280 nm by the DNA, resulting in the formation of pyrimidine dimers which inhibit DNA replication and consequently block transcription to RNA. Multiple UV-C emitting LEDs combined in a flow-through reactor are very suitable for the decontamination of the sheath fluid of a cell sorter. The resulting UV-C dose of four LEDs enables the reduction of P. aeruginosa by log 5.