Master thesis defence by Yue He – University of Copenhagen

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Master thesis defence by Yue He

Title: Photothermal heating of agarose artificial tissue and brain tissue with gold nanoshells

Supervisor: Liselotte Jauffred, NBI, KU
Co-supervisor: Lene Broeng Oddershede, NBI, KU

Abstract: The heat generated by laser-irradiated nanoparticles could effectively kill the cancer cells and consequently cause the tumor degradation, this new way of treatment is normally termed as photo-thermal therapy. Gold nanoshell is one of the most promising candidate nanoparticle for the use of photo-thermal therapy and it has drawn a lot of attentions in recent years, owing to its tunable resonance frequency and excellent bio-compatibility. In this work, we used two important parameters to characterize the thermal behavior of our laser-irradiated material, including bulk AuNSs and brain tissue. One is the steady-state temperature, which is the highest possible temperature of the material under laser-irradiation and the other is the time-scale parameter, which characterizes the time for the temperature change. The steady state temperature of bulk AuNSs was proved to have a linear relation with the laser power, and it is also related to the AuNSs concentration. Then we showed that the heating feature of cerebrum brain tissue is dependent on the composition of white and gray matter. Next, in order to avoid the complex interactions  between brain matter and laser, and investigate the heat conduction in the brain tissue alone, a specially designed sample fabrication was invented, for this experiment, a synchronized temperature change between the heat source and the tissue was observed, before the laser-irradiated position reaches its steady-state, while once at the steady-state, a one-dimensional heat conduction model could be applied to explain the temperature profile of the brain tissue in the direction of heat conduction. Lastly, the enhancement of heating for the brain tissue injected with gold nanoshells was presented.