Near-Infrared Frequency Upconversion Luminescence Bioimaging Based on Cyanine Nanomicelles

Upconversion optical imaging has great application prospects in biomedical imaging. However, research on molecular upconversion luminescence materials is very limited. In this study, a cyanine dye modified using polyethylene glycol is reported, which has frequency upconversion luminescence (FUCL) capability and can be applied for in vivo FUCL imaging after forming nanomicelles. The optical properties of PEGylated cyanine dye show that the light absorption property of cyanine does not be influenced and can still emit near-infrared fluorescence. However, under the condition that the illumination wavelength is larger than the maximal fluorescence wavelength, the FUCL of cyanine dye is generated at the same position as the down-converted luminescence. The nanomicelles exhibit good biocompatibility. When applied to in vivo imaging, the cyanine-based nanomicelles not only qualify for high-resolution subcutaneous blood vessel imaging but also exhibit good imaging ability for various organs and tumors. These results point out that cyanine-based nanomicelles with FUCL characteristics are expected to be further applied in the field of biomedicine, providing a basis for the construction of FUCL molecules.