Patent ID: 8008379

Claim:
A fluorescent polymer fine particle comprising: a polymer particle having a core-shell configuration comprising a hydrophobic core and a hydrophilic shell; and a fluorescent lanthanoid dye that is integrated with the polymer particle and comprises a fluorescent lanthanoid cation, wherein: a hydrophilic polymer which forms the hydrophilic shell comprises a polymerizable unit and at least one hydrophilic unit selected from the group consisting of a hydrophilic (meth)acrylamide unit and a hydrophilic vinyl amine unit, a volume-average particle size of the fluorescent polymer particle is in a range of 0.01 to 20 μm, and the fluorescent lanthanoid dye comprises a nitrogen-containing heterocyclic ligand represented by the following Formula (L-I): Formula (L-I) wherein each of A 21 , A 22 , and A 23 is the same as or different from each other and represents an atomic group represented by any one of the following Formulae (L-II) to (L-V), a hydroxyl group, an alkoxy group, an aryloxy group, an alkylamino group, a dialkylamino group, an arylamino group, or a diarylamino group; each of B 21 and B 22 independently represents a nitrogen atom or ═C(—R 30 )—; and R 30 represents a hydrogen atom or a substituent: wherein each of R 21 to R 29 independently represents a hydrogen atom or a substituent; R 27 and R 28 , R 28 and R 29 and/or R 27 and R 29 are optionally bonded with each other to form a ring; n represents an integer of 0, 1 or 2; G represents a substituted or unsubstituted carbon atom or a nitrogen atom; Q represents an atomic group which is used to form a 5-membered or 6-membered nitrogen-containing heterocyclic ring which optionally forms a condensed ring; Ar 21 represents an aromatic hydrocarbon ring or an aromatic heterocyclic ring; and # represents a site to be bonded with the nitrogen-containing heterocycle in the ligand represented by Formula (L-I).