a method of preparing polymeric particles with photographic couplers , such polymeric particles being useful in a microarray , the method comprising the steps of : preparing an organic composition by combining a photographic coupler and a high boiling organic solvent ; preparing a separate aqueous composition comprising polymeric particles with functionally active groups on their surfaces ; combining the organic composition of step with the aqueous composition of step , thereby effecting a loading of said photographic coupler and high boiling organic solvent into said polymeric particles ; and attaching biological probes to the functionally active groups on the surfaces of the loaded polymeric particles of step c ). polymeric particles made by the method is also disclosed .