Research On Optical Properties And The Photo-thermal Photo-acoustic Effects Of Gold Nanoparticles

The gold nanoparticles,which exhibit strong absorption and scattering properties under the laser irradiation around surface plasmon resonance(SPR)wavelength,is expected to be used in biomedical photothermal therapy and photoacoustic enhanced imaging.Besides,After incident light is strongly absorbed by gold nanoparticles,the temperature of the particles increases rapidly and heat transfer to the surrouding area induce photothermal and photoacoustic effects.This thesis mainly focuses on the optical properties of gold nanoparticles,the photothermal conversion and temperature changes of gold nanoparticles in biomimetic material,as well as photoacoustic phenomena produced by particle doping PDMS polymer films.Firstly,the optical properties of gold nanoparticles were st udied.The SPR peaks and amplitude strongly relate to the diameter of particle size and surrounding media.In this dissertation,the scattering and absorbing properties of different diameter gold nanoparticles in variety surrounding mediums were systematically researched using discrete dipole approximation method(DDA).When exposed to a pulsed laser whose energy beyond the threshold,a nuclear shell structure of bubble coated gold nanoparticles would be formed which induced by the evaporation of surrounding water after.Secondly,the application of gold nanoparticles in photothermal therapy was explored.Due to different damage threshold between cancer cells and normal cells under medium temperature varied,photothermal therapy can be realized based on photothermal effects.In this dissertation,different doping density o f gold nanoparticles into agar,which simulated as biological tissue,was carried out.The temperature rise curve of biomimetic tissue was measured under the irradiation of 532 nm continuous laser and its effects base on doping content and incident laser power density were investigated.Finally,the photoacoustic effect of gold nanoparticles doping into biomimetic tissue and organic polymer materials was researched.On the one hand,the photoacoustic effect of gold nanoparticles in biomimetic tissue was studied.The photoacoustic signal variety induced by different doping concentration and pulsed laser energy density were measured and analyzed.On the other hand,the photoacoustic signals of a new composite named polydimethylsiloxane(PDMS)with gold nanoparticles doping were investigated.The signal changes c aused by PDMS film thickness and laser energy density with gold nanoparticles doping were detected and analized.The measurement of photoacoustic signal changes caused by different laser energy density applied into gold nanoparticles doping PMDS coated on the tip face of optical fiber was carried out.All of these theoretical simulation and experimental results offered a great initial exploration of the photoacoustic effect caused by gold nanoparticles applied in biomedicine and optical fiber ultrasonic generator.