Development Of Novel Near-Infrared Fluorophores,Synthesis,Spectral Test And Bioimaging Applications

Fluorescent dyes are widely used in biomedical studies,such as fluorescence detection,labeling,photodynamic therapy,and photothermal ablation.The wavelength of near infrared(NIR)light is longer than that of visible light,therefore Rayleigh scattering is effectively mitigated and tissue penetration depth is promoted.Besides,near infrared light is less photo toxic and better suited for photothermal abalation.Near infrared light can also help to avoid background signals when used for bioimaging,so the spectral range of 650-900 nm is called"NIR window".Development of near infrared fluorescent dyes can benefit the biomedical research.Currently,there are few bio compatible NIR dyes and they exhibit drawbacks for practical applications.For example,cyanine dyes have poor chemo-and photo-stability and the solubility of BODIPY dyes is typically insufficient.The emission wavelengths of current near infrared dyes are mainly in the range of 650-820 nm and rare dyes extend their wavelengths into 820-900 nm.Development of the near infrared dyes of this spectral region is significant to many fields including biomedical research.Our group made breakthrough in the design and synthesis of NIR dyes recently.The core structure of dibenzocarborhodamine was developed for the first time and the ECX series based on this core structure have an absorption peak at 880 nm.ECX has better chemical and optical properties than other dyes of this spectral region.ECX is biocompatible and successfully applied to cell imaging.This project is based on the above-mentioned work,to modify the novel core structure and synthesize a series of new NIR dyes ECY.Then spectroscopic studies were conducted to testify ECY's photophysical and chemical properties.Finally,ECY was linked to targeting moieties to recognize carcinoma cells and this tumor-targeting NIR dye was applied to in vivo imaging by fluorescence imaging and photoacoustic imaging,respectively.Through this study,we have demonstrated that ECY possesses excellent chemical and optical properties,as well as the potential as contrast agent.