Liquid flourescent dye concentrate for flow cytometry evaluation of virus-size particles and related products and methods

A fluorescent stain product with multiple fluorogenic dyes for direct fluorescent staining of aqueous fluid samples containing biological materials with multiple fluorogenic dyes for flow cytometry evaluation of stained fluid samples for unassociated virus-size particles, the fluorescent stain product comprising:

• a liquid dye concentrate comprising a plurality of different fluorogenic dyes in a liquid medium, each different said fluorogenic dye having a different fluorescent emission signature for detection when bound to a said unassociated virus-size particle;
• and
• a sealed container containing the liquid dye concentrate;
• and wherein the liquid dye concentrate comprises at least one member selected from the group consisting of:
• (i) the liquid medium comprises a mixture including water and liquid phase organic material;
• (ii) disaccharide dissolved in the liquid medium;
• and
• (iii) a combination including both (i) and (ii).

A method for flow cytometry evaluation of biological material for unassociated virus-size particles, the method comprising:

• providing an aqueous preliminary fluid sample with biological material in an aqueous liquid for flow cytometry evaluation for unassociated virus-size particles;
• providing a liquid dye concentrate comprising a plurality of different fluorogenic dyes in a liquid medium, each different said fluorogenic dye having a different fluorescent emission signature for detection when bound to a said unassociated virus-size particle;
• preparing an aqueous stained fluid sample, comprising staining the preliminary fluid sample with liquid dye concentrate;
• subjecting the stained fluid sample to flow cytometry in a flow cytometer to detect and count occurrences of the unassociated virus-size particles stained with at least one of the fluorogenic dyes;
• and wherein the method comprises at least one member selected from the group consisting of:
• (i) the liquid medium comprising liquid phase organic material;
• (ii) the liquid dye concentrate comprising disaccharide dissolved in the liquid medium;
• (iii) the providing the liquid dye concentrate being in the absence of reconstituting the fluorogenic dyes from a dry form into the liquid medium;
• and
• (iv) combinations including two or more of any of (i)-(iii).

A stained fluid sample for flow cytometry evaluation for unassociated virus-size particles, the stained fluid sample comprising:

• an aqueous liquid medium;
• a biological material of interest for flow cytometry evaluation for the unassociated virus-size particles dispersed in the aqueous liquid medium;
• and
• a plurality of different fluorogenic dyes dispersed in the aqueous liquid medium, each said fluorogenic dye having a different fluorescent emission signature and each containing at least one aromatic group susceptible to pi stacking, the plurality of different fluorogenic dyes including at least a first fluorogenic dye with a first fluorescent emission signature and a second fluorogenic dye with a second fluorescent emission signature that is different than the first fluorescent emission signature;
• and wherein:
• the aqueous liquid medium comprises a liquid organic material at a concentration in a range of from 0.25 weight percent to 2 weight percent;
• and
• the stained fluid sample comprises a disaccharide dissolved in the aqueous liquid medium and the stained fluid sample comprises the disaccharide at a concentration in a range of from 0.1 weight percent to 3 weight percent.