Biocompatible Magnetic Conjugated Polymer Nanoparticles for Optical and Lifetime Imaging Applications in the Fir s t Biological Window

Conjugated polymers are organic semiconductors that can be used for fluorescence microscopy of living specimens. Here, we report the encapsulation of the bright-red-emitting conjugated polymer, poly[{9,9-dihexyl-2,7-bis(1-cyanovinylene)- fluorenylene}-alt-co-{2,5-bis(N,N '-diphenylamino)-1,4-phenyl-ene}] (CN-FO-DPD), and superparamagnetic iron oxide nano-particles (SPIONs) within poly(styrene-co-maleic anhydride) (PSMA) micelles. The resulting particles exhibited an emission peak at 657 nm, a fluorescence quantum yield of 21%, an average diameter of 65 nm, and a zeta potential of -30 mV. They are taken up by cells, and we describe their use in fluorescence microscopy of living Hela cells and zebrafish embryos and their associated cytotoxicity in HEK, HeLa, and HCE cells.