Lipid‐PEG‐Folate Encapsulated Nanoparticles with Aggregation Induced Emission Characteristics: Cellular Uptake Mechanism and Two‐Photon Fluorescence Imaging

Folate functionalized nanoparticles (NPs) that contain fluorogens with aggregation-induced emission (AIE) characteristics are fabricated to show bright far-red/near-infrared fluorescence, a large two-photon absorption cross section and low cytotoxicity, which are internalized into MCF-7 cancer cells mainly through caveolae-mediated endocytosis. One-photon excited in vivo fluorescence imaging illustrates that these AIE NPs can accumulate in a tumor and two-photon excited ex vivo tumor tissue imaging reveals that they can be easily detected in the tumor mass at a depth of 400 μm. These studies indicate that AIE NPs are promising alternatives to conventional TPA probes for biological imaging.