Design And Performance Evaluation Of Photothermal Theranostic Agent Based On Bismuth Sulfide/Gold Nanocomposite

Cancer is one of the main killers that threaten human life and health.At present,early diagnosis and effective treatment of cancers are important means to reduce its mortality.In recent years,photothermal therapy for high temperature ablation of cancer cells by using near-infrared light has attracted widespread attention.This method has the ability to penetrate deep tissues and work on cancer cells,thereby killing cancer cells while protecting normal tissues from damage.The image-guided photothermal therapy can not only realize the precise positioning of the tumor,but also achieve the real-time monitoring of treatment effect.Therefore,design and construction of an efficient new photothermal nano-diagnosis and treatment platform has become a hot spot for scientists.Based on the above research background,this thesis designed and prepared two nanocomposites with different functions,and evaluated their photothermal treatment and fluorescence imaging performance.In addition,we analyzed the relationship between the preparation schemes and properties of the two nanocomposite materials.The main content is divided into the following three parts:1.By using bovine serum albumin?BSA?as a stabilizer and reducing agent,after introducing Bi³⁺and Au³⁺,the Au/Bi₂S₃ nanoflower composite material with high photothermal conversion efficiency was prepared in-situ.Next,the morphology,element distribution and solution stability of the nanocomposite were studied.The photothermal conversion performance of the Au/Bi₂S₃ nanoflower composite was investigated.The biocompatibility and the photothermal lethality of cells were explored with the assistance of MTT experiment and dead-live cell experiment.The results show that the nanocomposite material is expected to be used as a new nano platform for photothermal treatment of cancer.2.By using BSA as a stabilizer and reducing agent,bovine serum albumin?BSA?protected bismuth sulfide nanoparticles?Bi₂S₃ NPs?were prepared firstly,and then introduce Au³⁺into the system.By adjusting the concentration of Bi and Au,we successfully prepared the bismuth sulfide-gold nanocluster?Bi₂S₃-Au NC?composite material with fluorescent property.Next,the morphology,element distribution and solution stability of the nanocomposite were studied.The fluorescence performance and photothermal conversion performance of the nanocomposite were investigated,and the biocompatibility and photothermal lethality of the Bi₂S₃-Au NC composite at the cellular level was explored by using MTT experiment.The uptake ability of Hela cells to Bi₂S₃-Au NC composite material was evaluated by fluorescence performance.The results show that the nanocomposite material is expected to be used as a multifunctional nano diagnosis and treatment platform for fluorescent imaging guided photothermal treatment of cancers.3.Through analyzing the above two nanocomposite materials,we found that theconcentration ratio between BSA and ions(Bi³⁺,Au³⁺)has an important effect on the structure and morphology of nanomaterials.And Bi₂S₃-Au NC composite material with"dumbbell"morphology has stronger light-to-heat conversion performance.