Preparation,Characterization And Application Of Au Based Janus Nanomaterials

Janus nanomaterials are nanomaterials with asymmetric structure in composition,morphology and surface chemical properties.Compared with other nanomaterials,the nano materials have asymmetric structure,and the surface is very easy to be modified,and can be self-assembled to form more complex nanoparticles and so on.Thus,the performance of Janus particles is superior.It has wide application prospects and has become a research hotspot in the scientific research field.Gold as a precious metal,due to its unique surface optical effects,size effects,high specific surface area,surface plasmon effect and other characteristics,it has important applications in biology and catalysis.Therefore,Au is deposited on various substrates to form a new type of Janus material based on nanoscale gold.The composite nanomaterials have the functions and characteristics of nano gold and Janus materials,and are widely used in the field of biological and photocatalytic catalysis,which will be very meaningful.In view of the simple discussion above,in this paper,we choose the nano carbon ball?CNSs?and nano mesoporous silica?SiNPs?as the base material.The surface of Au is deposited by adsorption reduction method,and the composite nanomaterials with Janus structure are formed.The biological aspects of MCF-7 cells and the mouse model of breast cancer are discussed respectively.Related applications.In addition,Janus Au-TiO₂ composites were prepared on the basis of nano titanium dioxide?TiNPs?,and their photocatalytic properties were studied by rhodamine B.To this end,the following research is carried out:1.Preparation of Janus PG/CNSs based on surface of CNSs and its application in photothermal therapyIn this section,Janus PG/CNSs particles are prepared by depositing nano-Au in the CNSs through a simple adsorption-reduction method,which is not common in the synthesis methods of the previous Janus structural materials.In this structure,CNSs and Au can absorb near-infrared light at the same time,so that NIR absorption coefficient increases,thermal stability and photothermal conversion are more efficient.It can be used as an ideal material for cancer hyperthermia,which is also the reason why we try to design and build a new type of photothermal agent with Janus structure.At the same time,the formation of Au atoms is a spontaneous process driven by thermodynamics,and the tedious operation of traditional Au nanoparticles is discarded.The experiment mainly examined the photothermal therapeutic effects of PG/CNSs on cancer,and the results showed that:compared with common Au NRs,PG/CNSs have stronger absorption peaks in the near-infrared region?at 850 nm?and have higher photo-thermal conversion efficiency under near-infrared laser irradiation.Through related biological experiments,it was found that cells co-incubated with PG/CNSs were exposed to near-infrared laser irradiation for only 2 min,and MCF-7cells died over a large area.In addition,it was found that PG/CNSs had almost no toxicity to cells by MTT experiment.2.Synthesis of PAFS-YMSNs based on SiO₂ surface and its application in fluorescence imaging and cancer treatmentIn this chapter,a new type of silica nanoparticles?YMSNs?with hollow mesoporous structure?PAFS-YMSNs?is built in this chapter for reference to the preparation methods of the previous section of Janus.The fluorescence doped SiO₂nanoparticles and Au are encapsulated in mesoporous SiO₂ to form the yolk-shell structure.For this material,the formation of yolk shell structure is different from the reported synthetic methods,the doping of the internal SiO₂ layer FITC and the modification of the surface PEI have protective effect on it.The alkaline etching only acts on the external SiO₂,the internal SiO₂ is intact and prevents the leakage of FITC.Considering the function of the material,it integrates fluorescence imaging,photothermal therapy?PTT?and drug delivery,and realizes the diversification of material function and widens its application in biology.The experiments performed a series of characterizations of the materials,and investigated the drug release capabilities of the materials under different pH and light conditions.The effects of photothermal therapy in vivo and in vitro were analyzed through MCF-7 cells and mouse models with breast cancer.Fluorescent imaging conditions.The results showed that the size of PAFS-YMSNs was 200 nm,and with the shell thickness for 5 nm,and in addition,the size of the inner nano SiO₂ was 150 nm,the surface deposition Au patch size was 30-50 nm.The surface area of PAFS-YMSNs is up to 875 m²g^-1,with an aperture of about 2.2 and 4 nm,which makes it have a high DOX load?8.04 wt%?,and MCF-7 cell MTT experiment shows that PAFS-YMSNs has little toxicity to cells and has good biocompatibility.PAFS-YMSNs has near infrared absorption?720 nm?in the near infrared region.It is found that PAFS-YMSNs has good photothermal effect and can be used for the diagnosis and treatment of cancer by photothermal treatment and fluorescence imaging in vitro and in vivo.Meanwhile,the presence of FITC can track the location of tumor in vivo and facilitate the diagnosis of cancer.3.Preparation of Janus Au-TiO₂ based on TiO₂ surface and evaluation of its photocatalytic propertiesBased on the synthesis of Janus materials in the first two chapters,and in order to broaden the application of Janus nanomaterials in the field of catalysis,a new type of composite nanomaterial——Janus Au-TiO₂,which can be used for photodegradation of organic pollutants,is designed in this chapter with TiO₂ as the base material.It is characterized by a series of methods,and the photocatalytic performance of Janus Au-TiO₂ was investigated by RhB.Experimental results shows as following:Janus Au-TiO₂ was prepared by adsorption-reduction method with a particle size of approximately 120 nm and Au ranging in size from 20-50 nm.The aqueous solution has good dispersity,and after roasting,it is loose granular,and the TiO₂ powder in the material presents the anatase phase.The order of photodegradation of RhB was:Janus Au-TiO₂?ultraviolet light?>Janus Au-TiO₂?visible light?>TiNPs?ultraviolet light?;and its degradation rate is 8.76×10^-88 mol/L·min,1.17×10^-77 mol/L·min,2.04×10^-6mol/L·min,respectively.