Precision fluorescently dyed particles and methods of making and using same

A set of distinct populations of polymeric microspheres dyed with at least two fluorescent dyes, the set of distinct populations of polymeric microspheres being dyed using a method comprising:

• (a) preparing a series of solutions of mixed dyes, each solution having differing desired concentrations of at least two fluorescent dyes;
• and
• (b) contacting separate populations of dehydrated polymeric microspheres with the series of solutions to provide a set of distinct populations of polymeric microspheres, each of the distinct populations of polymeric microspheres having a different desired fluorescence intensity from the at least two fluorescent dyes.

A population of polymeric microspheres dyed with two or more fluorochromes, the population of polymeric microspheres being dyed using a method comprising:

• (a) combining at least two fluorochromes in a solvent mixture to provide a solution of mixed fluorochromes, the solvent mixture having the capacity to swell at least partially, but not dissolve, a plurality of polymeric microspheres brought into contact with the solution;
• (b) contacting a plurality of dehydrated polymeric microspheres with the solution for a period of time sufficient to provide uniform dying of substantially all of the members of the plurality of polymeric microspheres with the at least two fluorochromes,
• the at least two fluorochromes being selected such that, on isolation and excitation of the dyed population of polymeric microspheres, each fluorochrome emits a distinct signal having an intensity which is proportional to the amount of the fluorochrome in the dyed population of polymeric microspheres.

A set of distinct populations of polymeric microspheres dyed with at least two fluorochromes, the set of distinct populations of polymeric microspheres being dyed using a method comprising:

• (a) preparing a series of solutions of mixed fluorochromes, each solution having differing desired concentrations of at least two fluorochromes;
• and
• (b) contacting separate populations of dehydrated polymeric microspheres with the series of solutions to provide a set of distinct populations of polymeric microspheres, each of the distinct populations of polymeric microspheres having a different desired fluorescence intensity from the at least two fluorochromes.