Patent ID: 8722429

Claim:
A non-autofluorescent coated magnetic particle comprising: a porous magnetic polymer particle of a matrix polymer, said porous magnetic polymer particle having superparamagnetic crystals on a surface and within the pores thereof, wherein majority of the superparamagnetic crystals are within the pores in the porous magnetic polymer particle and wherein the porous magnetic polymer particle is essentially free of conjugated delocalised electron systems other than those found in benzene rings; and a coat formed of a coating polymer wherein the coating polymer is formed by the polymerization of coating monomers comprising at least one epoxide and wherein the coating monomers are essentially free of conjugated delocalised electron systems other than those found in benzene rings, wherein said coated magnetic particle has a coefficient of variation (CV) of less than 10%, wherein said coated magnetic particle is essentially non-autofluorescent, wherein the coated magnetic particle is essentially free of conjugated delocalised electron systems other than those found in benzene rings and having a level of autofluorescence corresponding to a difference in the Mean Grey Value (ΔMGV) at an excitation wavelength of 450±25 nm for an exposure time of 500 ms or 600 ms of less than 600.