| Since 2015,two-dimensional nanomaterial antimonene has attracted much attention because of its graphene-like layered structure and some physical and optoelectronic properties superior to graphene.Antimonene nanomaterial presents many special physcichemical properties due to its high carrier mobility,tunable band gap,short out-of-plane atomic bond length and strong spin-orbit coupling effect,which are especially suitable for the fabrication of semiconductors,optoelectronic devices,plasma detection and ultrashort pulse generation.Photoacoustic imaging is a non-invasive imaging technology,which possess both the high resolution of optical imaging and the depth of ultrasonic imaging,promising in the field of biomedicine.Photoacoustic imaging contrast agents with excellent performance is one of the important factors to obtain high-resolution images.In this thesis,the optical properties of antimonene nanoflakes were studied,and its application as a novel photoacoustic imaging contrast agent for tumor-site imaging in vivo was explored.The main contents are as follows:(1)Preparation and characterization of antimonene nanoflakes.In this paper,we prepared the few-layer antimonene nanoflakes with the transverse size of 21±5 nm,longitudinal size of 52±3 nm and the thickness of 10～15nm(around 4～5 layers),the sample was prepared by cyclic-ultrasonic liquid phase exfoliation method in ice bath.Their morphology and properties were characterized by transmission electron microscope(TEM),atomic force microscope(AFM),X-ray diffractometer(XRD)and Raman spectroscopy.(2)Optical properties of antimonene nanoflakes.In this paper,the optical absorption spectrum of antimonene nanoflakes was detected by ultraviolet-visible spectrophotometer,its molar extinction coefficient at 808nm was calculated to be2.24×10~9.It is calculated that the photothermal conversion efficiency of antimonene nanoflakes is 42.36%,which is better than gold nanorods,graphene and other nanomaterials.The photoacoustic performances of antimonene nanoflakes were studied by MSOT photoacoustic system,and the photoacoustic performances of antimonene nanoflakes were systematically compared with other common photoacoustic imaging contrast agents(eg.gold nanorods,typical two-dimensional materials and indocyanine green).It was found that antimonene nanoflakes showed extraordinary photoacoustic performances compared with other contrast agents.In addition,this work also explores the factors influencing the photoacoustic performances of antimonene nanoflakes.Controlling a similar thickness,larger-sized antimonene nanoflakes produce stronger photoacoustic signals because of their lower interfacial thermal resistance.The photoluminescence properties of antimonene nanoflakes were also discussed.(3)Toxicity evaluation and surface modification of antimonene nanoflakes.In this work,cell proliferation assay(MTS method)was used to test the cytotoxicity of AMNFs on human embryonic kidney cells(293T)and breast cancer cells(T47D)after24 hours and 48 hours.The results showed that antimonene nanoflakes up to 200μg/ml co-cultivated with cells for 48 hours did not affect the physiological activity of cells,indicating that antimonene nanoflakes have good biocompatibility.The antimonene nanoflakes was modified with bovine serum albumin(BSA),and the protein loading of0.8μg BSA/μg AM was achieved.BSA modifying not only effectively reduces the aggregation of antimonene nanoflakes in solution,but also improves the biocompatibility of antimonene nanoflakes,making it more suitable for biomedical applications.What’s more,the photoacoustic performances of the antimonene nanoflakes is also developed.(4)photoacoustic imaging of tumor-site in vivo with antimonene nanoflakes.On account for the excellent photoacoustic performances of antimonene nanoflakes,its applications in biomedicine are explored in this paper.Firstly,the process of antimonene nanoflakes uptake by cells was explored based on the detectable strong photoacoustic signal.The photoacoustic signals of live cells(293T cells)were detected at different time points.The results show that the intensity of photoacoustic signals increased gradually from 1h to 4h,and then stared to decrease after 4h,indicating that the antimonene nanoflakes co-cultured with cells for 4 hours,antimonene nanoflakes internalizing maximum.7.4×10~4 cells equivalent to tissue with volume of 0.74 mm~3 co-cultured with antimonene nanoflakes for 0.5 hour could produce detectable photoacoustic signals.This means that antimonene nanoflakes are beneficial to the early diagnosis of small tumors.(5)And then,the tumor-baring mice models(breast cancer MCF-7)were imaging through MSOT photoacoustic imaging system with BSA-AMNFs as contrast agent.The results of long-term photoacoustic imaging of the tumor site for 48 hours showed that the antimonene nanoflakes could be rapidly accumulated in the tumor tissue,and the photoacoustic signal reached the peak at 1 hour after injection,there was still a strong signal 2 hours later,and the imaging quality was good.The imaging of the different organs of mice show that antimonene nanoflakes could be exerted through liver and kidney metabolism without residual side effects,so it is a very promising exogenous photoacoustic imaging contrast agent.(6)Antimonene quantum dots Preparation and drug delivery system design.In this paper,antimonene quantum dots with the size of 4～5nm were obtained by changing the preparation parameters,and based on the antimonene quantum dots,a photoresponsive nano-drug delivery system was designed and prepared.The sample was simply characterized by Transmission Electron Microscope,hoping to provide a new idea for nanomedicine to break through the obstacles of the complex tumor microenvironment.In summary,antimonene nanoflakes as a graphene-like two-dimensional material,excellent optical properties provide many potentials for its application in various fields.The photoacoustic performances of antimonene nanoflakes studied in this paper not only provide the possibility for early cancer diagnosis,but also pave the movement for photoacoustic imaging guided tumor elimination surgical. |
