Metal-based Photosensitizers With Near-infrared Excitation For Cancer Phototherapy

In the recent years,phototherapy has received extensive attention as an emerging tumor treatment method from researchers.Photosensitizer is one of the key factors for phototherapy.Traditional photosensitizers have many drawbacks such as insufficant water solubility,poor stability,and narrow light absorption range.Donor-acceptor-donor（DAD）based organic photosensitizers exhibit good photostability and near-infrared light absorption,which can realize deep-tissue phototherapy.Using coordination to modify organic photosensitizer molecules into metal complexes can exert the heavy metal effect and enhance the photosensitizer’s non-radiative transition as well as intersystem crossing efficiency.The preparation of nano-based photosensitizers can exert the EPR effect to achieve the accumulation of drugs at the tumor site,significantly improving the efficacy of tumor treatment.1.Iridium（Ⅲ）complex-derived polymeric micelles with NIR excitation for tumor therapy.In this paper,DAD organic molecules were coordinated to the iridium（Ⅲ）complexes,and further react with N₃-PEG through click reaction to form IrNPs polymeric micelles.The nanoparticles are stable,and the particle size is about 100 nm.Moreover,IrNPs have an absorption peak at around 800 nm.An obvious emission peak at around 1050 nm can be observed with 830 nm excitation.The photodynamic and photothermal properties of IrNPs were evaluated with 808 nm laser irradiation.The results showed that IrNPs have excellent photodynamic properties and photothermal properties.In vitro anti-tumor activity experiments showed that IrNPs had almost no dark toxicity to A549 cells,and the IC₅₀ value was as low as 7μM upon 808 nm irradiation.2.Peptide-Tuned Self-Assembly of Ruthenium（Ⅱ）Photosensitizer for tumor therapy.In this paper,DAD organic molecules were coordinated to the ruthenium（Ⅱ）complexes,which were further used to form nanoparticle RuNPs with phenylalanine dipeptide.The nanoparticle was stable in the solution and the particle size was about 90 nm.After calculation,the drug loading rate of RuNPs is 45%,and the encapsulation rate is 90%.Under the excitation of 808 nm laser,RuNPs also have excellent photodynamic properties and photothermal properties.In vitro anti-tumor activity experiments showed that RuNPs had almost no dark toxicity to A549 cells,Whereas the IC₅₀value was as low as 4μM upon 808nm laser irradiation.