Organic Nanoparticles with Aggregation-Induced Emission and Two-Photon Excitation for Fluorescence Imaging of Living Cells/Tissues

Aggregation-induced emission (AIE) nanoparticles (NPs) have been applied in bioimaging for cancer diagnosis due to high fluorescence efficiency. However, the poor cell permeability as well as autofluorescence of biological cells/tissues caused by ultraviolet (UV) irradiation is still the key problem of AIE luminophores for biological imaging. Here, we report green-emitting organic AIE luminophores for fluorescence imaging of living cells/tissues, which possess high fluorescence quantum yields and strong AIE under two-photon excitation with near-infrared light beyond 800 nm. These AIE luminophores can bind with bovine serum albumin (BSA) to form biocompatible BSA/AIE-NPs due to their terminal aldehyde groups providing specific anchor sites with the receptor groups in BSA. Furthermore, one/two-photon fluorescence bioimaging for Hela cancer cells has been successfully carried out with BSA/AIE-NPs as the fluorescent probe, and BSA/AIE-NPs show excellent stain properties with a fast permeability of only 5 min, high cellular uptakes, and strong fluorescence. The results demonstrate the great advantages of BSA/AIE-NPs in fast fluorescence biological imaging as well as further cancer diagnosis and therapy.