Synthesis And Phototheranostic Application Of D-A-D Photosensitizers Based On Benzotriazole

Combing diagnostic and therapeutic functions into a single nanoplatform is proved to be an effective and promising cancer treatment due to the specific and personalized features for various pathologies.The well-documented strategy was "all-in-one" strategy where multiple components with individual functions was integrated into one nanoplatform.However,it was limited by two types of lasers irradiations,low reproducibility,and complicated composition.To address the issues,developing a small organic molecule with one-for-all features was an ideal alternative of all-in-ones.The advantages of fluorescence imaging guided therapy are noninvasive,photo-controllable,and precise cancer treatment.To achieve all-round photo theranostic features involving fluorescence imaging(FL),photodynamic therapy(PDT),or photothermal therapy(PTT),the key point was to balance the radiative and non-radiative decay of excitation energy.The dissipated energy from radiative decay could be used as FL,and the nonradiative decay could be afford PDT or PTT.For fluorophores with D-A structural feature,strong electron donor-acceptor interactions allowed the molecule with reduced HOMO-LUMO energy gap and promoted intersystem crossing(ISC)process which favored long wavelength absorption/emission for NIR imaging and ROS generation for PDT.Moreover,introducing some twisted and propeller donor groups such as TPA or chemical decoration with long alkyl chains could render molecules with intramolecular motions in aggregates which were conductive to excitation energy dissipation as heat for PTT.Following these designing principles,we designed and synthesized two D-A-D molecules based on benzotriazole(acceptor moieties)for NIR imaging guided phototherapy.In Chapter 2,the photosensitizer 2Cz-BTZ had bright near-infrared emission and strong 1O2 generation ability.This work indicated that 2Cz-BTZ@F127 NPs had a great application prospect in near-infrared image-guided photodynamic therapy.The structure designed in Chapter 3 further enhanced the electron-supplying capacity based on Chapter 2 by introducing the rigid donor group triphenylamine(TPA)with aggregation-induced luminescence(AIE)properties.The photosensitizer molecule 2TPA-BTZ achieves the synergistic treatment of PDT and PTT guided by near-infrared fluorescence imaging.It is important to develop new highlyefficientphotosensitizers with synergistic function for enhanced optical therapy at present.