Combination Of Photothermal And Photodynamic Therapy For Tumors Using PPy-Te Copolymer Nanoparticles

In recent years,malignant tumors are still a major problem in today's world that threatens human health.The traditional treatment methods,mainly surgery,chemotherapy,radiotherapy,etc.,will cause some irreversible damage to the normal cells of the human body during the treatment.Compared to those,photothermal therapy?PPT?and photodynamic therapy?PDT?are playing important roles as novel types of treatment because of their noninvasively characters,slight side effect.Photothermal therapy uses a near infrared laser to illuminate the light absorber which generates heat to increase the temperature of the tumor site,thereby ablating the tumor cells.However,due to the uneven distribution of heat after laser irradiation,some tumors are not ablated,so a single photothermal therapy cannot achieve complete ablation of the tumor.PDT is the exposure of a photosensitizer to a laser of a specific wavelength to produce reactive oxygen species?ROS?with significant cytotoxicity,resulting in apoptosis or necrosis of cancer cells.However,the hypoxic environment of tumor cells causes insufficient ROS to produce,resulting in poor therapeutic effects.Therefore,combining photothermal therapy with photodynamic therapy produces a complementary effect that will enhance the effectiveness of cancer treatment.The research contents of this paper are as follows:Chapter 1:The present situation and traditional treatment methods of malignant tumors are described,the basic principles of photothermal therapy and photodynamic therapy for tumors are introduced,and some materials that can be used for photothermal therapy and photodynamic therapy are introduced.Chapter 2:The copolymer of pyrrole and tellurophene was synthesized,and the nanoparticles were obtained.The prepared PPy-Te nanoparticles have relatively small particle size and uniform distribution.In addition,the photothermal conversion rate and reactive oxygen production rate of different proportions of nanoparticles were tested.It was found that the photothermal conversion efficiency increased with the increase of pyrrole content in nanoparticles,while the reactive oxygen production rate increased with the increase of tellurophene content.It also shows that nanoparticles have good photothermal/photodynamic regulation.Chapter 3:In vitro cell survival experiments,4T1 cells died completely only when incubated with 92.3%nanoparticles under 808nm laser irradiation.In the presence of a single material,irradiated by an 808 nm laser alone,and without any treatment,4T1 cells can safely survive.Experiments on intracellular ROS production found that when DCFH-DA was used as an indicator of ¹O₂,only 92.3%PPy-Te nanoparticles irradiated by the 808 nm laser showed strong green fluorescence,while the other groups showed weak fluorescence.The difference in fluorescence intensity was sufficient to demonstrate that 92.3%PPy-Te nanoparticles produced singlet oxygen in 4T1 cells.Subcutaneous breast cancer tumor model was constructed using 4T1 cells,and the PTT/PDT effect of 92.3%PPy-Te nanoparticles in vivo was verified.The results showed that the tumors of three mice in the NPs+NIR group disappeared completely and the cure rate was 60%,while the tumors of the other two mice decreased significantly.The results showed that the nanoparticles had a good photothermal/photodynamic regulation effect and could inhibit the tumor.