Preparation Of Au,Au-Ag Nanostructures And Their Photothermal Effects

Au nanomaterials have a wide range of applications in the fields of analytic detection,catalysis,nano-devices and medical care because of their unique optical and catalytic properties.In particular,Au nanomaterials were expected to be an effective candidate for cancer therapy because of the heat effect induced by its LSPR property.Generally,LSPR peak of Au nanospheres is around 520 nm,which would be strongly absorbed and scattered by biological tissues,severely limiting their application in vivo.In order to improve the photothermal conversion efficiency of Au nanomaterials,Au nanoparticle assemblies have been designed to achieve near-infrared LSPR by employing the coupling of Au nanoparticles.Many studies have been reported that Au nanoparticle assemblies with near-infrared LSPR can effectively improve the photothermal conversion efficiency and have better effect in the treatment of tumors.Based on the above,this thesis will focus on the design of Au-based nanostructures,study their photothermal effect and its application in cancer therapy.The main contents are as follows:?1?Au nanoparticles and Au-CdSe mixed nanoparticles were assembled into Au and Au-CdSe nanoparticle assemblies,respectively,via a oil-in-water?O/W?microemulsion method involving Triton X-100 as the emulsifier and hexane solution containing nanoparticles as the oil phase.After the post-treatment of as-prepared Au nanoparticle assemblies in ammonium thiocyanate solution,spherical Au nanoparticle assemblies were transformed into bowl-like nanostructure.As-prepared nanoassembles may have potential applications in the field of photothermal therapy.?2?Au nanobowls were preliminarily explored in vitro photothermal experiments.Under optimized conditions,the photothermal conversion efficiency of Au nanobowls reached up to 41.7%.Also,the photothermal effects did not show noticeable change even after four cycles of heating and cooling at a higher power density of 2.5 W·cm^-2,exhibiting excellent chemical stability.When the concentration of Au nanobowls was lower than 0.2 mg·cm^-3,the cell survival rate was higher than 78%.After laser irradiation,the survival rate of HeLa cells is less than 20%,showing satisfactory performance for killing tumor cell.?3?AuAg nanocups were prepared by oriented etching of Ag cubes at water/air interface.In vitro photothermal experiment,when AuAg“nanocups”solution(0.2mg·cm^-3)was irradiated with 808 nm(1.5 W·cm^-2)laser,the temperature can reach49.7°C and no obvious change in the photothermal effects was observed after four cycles of heating and cooling processes at a higher power density of 3 W·cm^-2,exhibiting excellent chemical stability.At lower concentrations(0.1 mg·cm^-3),when irradiated with 808 nm,the survival rate of HeLa cells is higher than 20%.