Bismuth Sulfide Nanostructures:Preparation,Optical Properties Regulation And Their Application In Tumor Diagnosis And Treatment

Phototherapy as a new means of tumor treatment has been widely concerned by researchers.The research of multifunctional,stable and effective phototherapy agents is the key of phototherapy.Inspired by semiconductor catalyst,researchers use narrow band gap nanosemiconductors with good optical properties as therapeutic agents,simultaneously regulate their optical properties and improve their biocompatibility,so the phototherapy under the irradiation of near infrared band light source is realized.Bi-based semiconductor nanomaterials have been widely used in various fields such as radiotherapy,biosensors,heavy metal ion detectors,antibiotics,cancer combination therapy and biological imaging.Nanomaterials of Bi2S3 have excellent capabilities of CT imaging,photothermal therapy and radiotherapy,and their narrow semiconductor band gap enable them to be excited by near infrared light sources,therefore they are a promising phototherapy agent.However,Bi2S3 used in phototherapy has weak absorption of NIR-I and its photo-induced carriers recombine fast,which limits the further application of Bi2S3-based nanomaterials in the field of phototherapy.In this paper,we focus on the above problems,preparing bismuth sulfide nanomaterials with higher molar extinction coefficient and triplet-hetero-nanostructure of Bi2S3 by regulating the optical properties.The main research content of this paper is as follows:1.The band gap greatly affects the UV-visible spectral absorption of nanometer semiconductor drugs.The absorption of bismuth sulfide at 808 nm wavelength can be improved by proper regulation of the band gap,so as to improve the effect of phototherapy.By changing the experimental parameters to affect the particle size and the compact degree of polycrystalline aggregation,the band gap regulation of bismuth sulfide was realized.The basic characterization of Bi2S3 and vitro performance test showed that the bismuth sulfide prepared under optimized conditions had high molar extinction coefficient,and can extended carrier separation time to improve the performance of photodynamic therapy.In vivo experiments showed that the photothermal and photodynamic synergistic therapy of tumor could be achieved under the 808 nm laser irradiation,which could effectively inhibit tumor growth in tumor-bearing mice model.2.Heterostructure provides a solution to the problem of fast recombination of semiconductor photogenerated carriers.Therefore,it is an effective means to design reasonable heterostructure for Bi2S3 to integrate multiple therapeutic functions of Bi2S3-based nanomaterials.We synthesized homogeneous bismuth sulfide nanoparticles,and then dense gold particles were grown on their surface to form gold layer,finally,Bi2S3-Au was used as seeds to grow thin bismuth sulfide layer,and then similar-triplet-heterostructure of Bi2S3-Au-Bi2S3 was obtained.This nano-heterostructure has suitable size and good biocompatibility,and can be used as photosensitizer for photothermal and photodynamic therapy.The experiments showed that it had good photothermal and photodynamic properties,and had good killing effect on Hela tumor cells.