In this work, we investigate the minute circular dichroism effects of single nanoparticles.To this aim, we apply photothermal imaging with a polarization-modulated heating beam. This new technique,... Show moreIn this work, we investigate the minute circular dichroism effects of single nanoparticles.To this aim, we apply photothermal imaging with a polarization-modulated heating beam. This new technique, which we call photothermal circular dichroism microscopy, probes circular dichroism in an absorption measurement, unlike other techniques which usually probe the extinction. We also investigate in detail how to avoid measurement artefacts such as leakage of linear dichroism and residual intensity modulation.We then study the CD of formally achiral and wet-chemically synthesized chiral nanoparticles. We find that the achiral spherical-like particles, can exhibit considerable circular dichroism, some of them display almost as strong CD as specially designed chiral particles. Furthermore, we find that the control of handedness of the synthesized chiral particles is only limited and that, even from a geometric perspective, the relation between the 3D shape of these particles and their handedness is not straightforward.In the last chapter, we apply our method to magnetic samples which exhibit circular dichroism through their magnetization but not due to their shape. The excellent sensitivity of photothermal microscopy not only allows us to perform magnetic imaging of particles, but we also succeeded in obtaining magnetization curves of single particles and estimating their magnetization. Show less
The perfect anticancer drug would kill cancer cells without causing any harm to the surrounding healthy tissues. That ideal medicine is searched for in this thesis, in the form of a ruthenium... Show moreThe perfect anticancer drug would kill cancer cells without causing any harm to the surrounding healthy tissues. That ideal medicine is searched for in this thesis, in the form of a ruthenium coordination complex.Metal complexes are known to interact with DNA in several different modes, amongst which are coordination, intercalation of the aromatic part of the molecule between the DNA base-pairs and binding of the complex to one of the DNA grooves.Is there a correlation between the ruthenium–DNA interactions and the cytotoxicity of these complexes? Three ruthenium polypyridyl complexes (1a-c) were synthesized and characterized, which can coordinate to guanine. The structure-related 1e and 1f, as well as the dinuclear complex 1g, were also chosen for these studies. The interactions between each ruthenium complex and DNA were studied; the activities of the compounds in different cancer cells were tested.The results of these tests suggest that 1a-c and 1e coordinate to DNA, while 1g probably fits in the DNA groove. These complexes display moderate activity in some cancer cell lines. The inactive complex 1f can coordinate to guanine and bind to DNA via intercalation or groove-binding. 1f is the only one of the studied compounds that lacks an azo group, which suggests that this group is essential for cytotoxicity.The interactions between metal complexes and other biological molecules are also mentioned. Show less
