Aggregation-enhanced fluorescence in PEGylated phospholipid nanomicelles for in vivo imaging

We report polymeric nanomicelles doped with organic fluorophores (StCN, (Z)-2,3-bis[4-(N-4-(diphenylamino)styryl)phenyl]-acrylonitrile), which have the property of aggregation-enhanced fluorescence. The fluorescent nanomicelles have two unique features: (1) They give much brighter fluorescence emission than mono-fluorophores. (2) The nanomicelles with amphiphilic copolymers [e.g., phospholipids-PEG (polyethylene glycol)] make the encapsulated fluorophores more stable in various bio-environments and easy for further conjugation with bio-molecules. After chemical and optical characterization, these fluorescent nanomicelles are utilized as efficient optical probes for in vivo sentinel lymph node (SLN) mapping of mice. The StCN-encapsulated nanomicelles, as well as their bioconjugates with arginine-glycine-aspartic acid (RGD) peptides, are used to target subcutaneously xenografted tumors in mice, and in vivo fluorescence images demonstrate the potential to use PEGylated phospholipid nanomicelles with aggregation-enhanced fluorescence as bright nanoprobes for in vivo diagnosis of tumors.