Master defense by Chano Birkelind – Niels Bohr Institute - University of Copenhagen

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Master defense by Chano Birkelind

Heat Induced Release of Cargo Molecules from Gold Nano Particles

The aim of this thesis is to develop a nano carrier system consisting of double stranded miRNA and spherical gold nanoparticles. Furthermore it is the aim of the project to construct a more stable nanocarrier system of double-stranded miRNA using the flixibility and unspecificity of poly-L-lysine carrier attached to the surface of colloidal gold nanospheres.

Gold nanoparticles are plasmonic, they absorb near infra-red light and release the absorbed energy as heat to the enviroment. By irradiating the GNP-miRNA complex by a 1064 nm laser, the miRNA was thermally released by melting the double-stranded miRNA or the miRNA-PLL complex. By exploiting the reflective nature of the gold nanospheres and fluorescently marking the anti-sense strand of the attached miRNA it is possible to detect the location of the coloidal gold nanospheres and the miRNA using a confocal microscope. It is possible to quantify the conjugation by comparing the overlap between the two signals. Loading and thermal release has been invistigated for particles of the diameter 60 nm, 80 nm, 100 nm and 200 nm. The initial experiments was done using TE buffer as it is preferable to PBS when working in a biophysiological environment and holds greater value with regard to future cell experiments.

During the initial experiments it became apparent that the grease chambers used had a devastating influence on the experiment when being subject to heating. Many of the difficulties with the early experiment can be credited to this grease contamination and it still remains unclear if it also had any influence at room temperature. Thus it was decided to shift the experiment to sterile grease-free chambers. Following this shift the experiment became functionally stable and results close to the theoreticla expectation and to the results reported by earlier experiments.

The PLL-assey shows great flexibility and both assays look promising for future experiments using controlled miRNA cargo delivery


Supervisor: Lene Odderhede