Preparation And Properties Of Near-infrared Organic Photosensitizers

Near-infrared photosensitizers have attracted much attention because of their promising applications in photothermal therapy,photodynamic therapy,and bioimaging.In the field of near-infrared photosensitizers,near-infrared organic photosensitizers are being pushed forward because of their wide variety and structural flexibility.When NIR organic photosensitizers are excited by specific wavelengths of light,they produce some corresponding changes,such as state and color,which make NIR organic photosensitizers valuable in the fields of photothermal therapy,photodynamic therapy,and bioimaging.This thesis hopes to research and develop a series of NIR organic medical photosensitizers to further expand the field of NIR organic photosensitizers,thus providing a reference for the development of more materials with excellent properties.In this thesis,bithiophene Aza-boron-dipyrromethene(Aza-BODIPY)NIR photosensitizers(B7 and B8)were designed and synthesized,and selfassembled with mesoporous silica and Pluronic F127,respectively,to further enhance the application value of bithiophene Aza-BODIPY.The results showed that the bithiophene Aza-BODIPYs have the maximum characteristic absorption peak at 880 nm and the maximum emission peak at 980 nm,and have high molar extinction coefficients,which are red-shifted in wavelength compared with the conventional Aza-BODIPYs.On this basis,the photothermal,photodynamic,and photoacoustic properties of the bithiophene Aza-BODIPYs were tested under 808 nm NIR laser irradiation,and the results showed that both had high photothermal conversion efficiency and the ability to produce singlet oxygen as well as excellent photoacoustic properties in both the organic and aqueous phases.Further cytotoxicity experiments showed that B7 exhibited excellent effects in combined photothermal and photodynamic therapy and proved to be a promising organic medical photosensitizer in the near-infrared.In addition,we designed and synthesized DAE-P,an asymmetric diaryl ethylene based NIR photosensitizer.Using asymmetric diaryl ethylene as the parent,the terminus with aggregation-Induced emission(AIE)activity was introduced via a coupling condensation reaction,resulting in a molecule that is significantly red-shifted,with AIE photophysical behavior and fluorescence controllable NIR photosensitizer.The molecule exhibits sensitive photoisomerization ability,excellent temperature resistance,and fatigue resistance under alternating UV and NIR light irradiation.Meanwhile,we used Pluronic F127 for self-assembly with DAE-P to activate its photoisomerization ability in the water.The results show that DAE-P@F127can still undergo photochromism and modulation of its fluorescence in water,which promotes the development of NIR photosensitizers for fluorescent probe applications.