PEGylated chitosan nanoparticles with embedded bismuth sulfide for dual-wavelength fluorescent imaging and photothermal therapy

•PEGylated chitosan nanoparticles with embedded bismuth sulfide were facilely fabricated.•The nanoparticles could rapidly get into HepG2 cells in 30 min and light the cells with both green and red fluorescence.•The nanoparticles could efficiently kill HepG2 cells under the irradiation of 808 nm laser. It is of great significance to construct multifunctional nanosystems for simultaneous imaging and therapy of cancer cells. Herein, PEGylated chitosan nanoparticles with embedded bismuth sulfide were facilely fabricated via reverse-microemulsion method for fluorescent imaging and photothermal therapy of HepG2 cells. The obtained BSA-Bi2S3-CG-PEG nanospheres revealed dual-wavelength fluorescence, which were spectrally isolated from the bioautofluorescence. Moreover, they demonstrated remarkable photothermal conversion efficiency and stability. Importantly, these small BSA-Bi2S3-CG-PEG nanoparticles shown a zeta potential of + 42.3 mV, which could rapidly get into HepG2 cells and locate in the cytoplasm and nuclei of cells. Based on their excellent photothermal effect and high cellular uptake, BSA-Bi2S3-CG-PEG nanoparticles could efficiently kill HepG2 cells under an 808 nm laser irradiation. This construction strategy can be used for preparation of fluorescent chitosan nanoparticles with other therapeutic agents embedded, which would provide a versatile platform for dual-wavelength fluorescent imaging guided therapy of cancer.