Fluorescent particles

A water-dispersible fluorescent particle comprising:

• an internal hydrophobic region comprising a mixture of one or more first hydrophobic polymers and one or more second hydrophobic polymers, wherein the one or more first hydrophobic polymers is a fluorescent semiconducting polymer and has a first solubility parameter, wherein the one or more first hydrophobic polymers is a fluorene-based polymer or copolymer thereof, and the one or more second hydrophobic polymers is non-fluorescent and has a second solubility parameter, wherein the one or more second hydrophobic polymers is poly (styrene) or substituted poly (styrene), and wherein the first and second solubility parameters differ by less than 1 cal1/2 cm,−3/2;
• and
• an external region encapsulating the internal hydrophobic region, wherein the external region comprises one or more amphiphilic copolymers, wherein each of the one or more amphiphilic copolymers comprises at least one hydrophobic segment embedded in the internal hydrophobic region and at least one hydrophilic segment that renders the particle dispersible in water, wherein the at least one hydrophobic segment is not covalently bonded to the one or more first or second hydrophobic polymers,
• and the hydrophobic segment of the one or more amphiphilic copolymers comprises a monomer residue having a structure of the formula, —[Ar]n-, wherein Ar is an aryl or heteroaryl and is optionally substituted with one or more optionally substituted substituents selected from the group consisting of halogen, hydroxyl, C1-C12 alkyl, C2-C12 alkene, C2-C12 alkyne, C3-C12 cycloalkyl, C1-C12 haloalkyl, C1-C12 alkoxy, C2-C18 (hetero) aryloxy, and C2-C18 (hetero) arylamino.