Electronic speckle pattern interferometry for cancer research

The determination of mechanical properties is a topic of on-going research and has over the years provided new insights regarding complex biochemical processes such as the cell cycle, the progression of diseases and even influenced new forms of therapeutically treatment. However, this field of biomechanical research strongly depends on the analysis of biological samples and their mechanical behavior under stress. In order to achieve reliable results, a high resolution measurement technology and a gentle stimulation method are needed to examine the samples as close as possible to their original condition. Therefore, the content of this work discusses the concept of a new potential technical approach, which introduces the electronic speckle pattern interferometry (ESPI) to this field of application. The ESPI is an optical laser based technique which is capable to determine deformations with a very high axial resolution. However, since this technique is commonly applied for the analyzation of macroscopic sample, additional modifications are required. Therefore, a first concept of such an adapted ESPI system is presented within this work as well as a modified experimental setup. This setup has been furthermore used to analyze the mechanical response of biological specimen in terms of a first proof of concept. As biological specimen adhesive HeLa cells have been cultured on silicon substrates and incubated with magnetic nanoparticles. These so called magnetites have been furthermore prepared with two different coatings in order to improve the uptake. After this preparation, the nanoparticles have been externally stimulated by applying an electromagnetic field, which in consequence caused a displacement of the cellular body. A variety of experiments have been carried out in order to validate the experimental setup as well as the applied method of excitation. Each experiment has been designed to focus on one specific process or preparation parameter such as the incubation time, the applied concentration of nanoparticles, the different coatings as well as the relative positioning of cell and electromagnet. Additionally the cellular behavior has been also analyzed regarding a prolonged excitation time as well as the repositioning of the cellular body during the relaxation. Based on the obtained results, this work also discusses possible modifications, which would improve the applied system. In conclusion, it has been possible to induce a displacement with the developed excitation technique as well as to determine this deformation with the presented ESPI setup. Accordingly, the proof of concept can be regarded as successful and therefore introduces the ESPI to the field of biomechanical research.