Ortsselektives, präzises Laserdrucken von Biomaterialien und Zellen

Aim of this thesis is to conceptualize a system for laser induced forward transfer (LIFT) either for high throughput (HTS) or for high content screening (HCS) applications. For the LIFT-system designated for HTS-microarray production a galvanometric scanner is used. This results in a fast process that allows the transfer of a large number of droplets in an easy manner. The reproducible transfers can be used to generate microarrays for different diagnostic purposes.Different Cells have to be arranged in a specific layout and stoichiometry for the fabrication of HCS-test systems. Hence a second LIFT-system is designed that allows the investigation of the transfer layer before the actual transfer takes place. Therefore single identified objects can be transferred onto a receiver substrate. This function is tested by transferring polystyrol particles. After single particle transfer their relative position within the droplet is analyzed depending on the laser fluence and the spatial beam shape. When a non-symmetric beam shape is used it can be seen that the particles are directed into a preferred direction. Biggest deviation from a defined position of the particles can be observed for low and high fluences. The highest position accuracy can be observed for medium range laser fluences. In regard to the influence of the beam shape a higher accuracy of tophat-like compared to donut or gaussian beam shape can be observed.The results from the particle transfers are applied to the transfer of individual cells. Single cells can be easily selected from matrigel or gelatin based transfer layers. But the cells are damaged with increasing laser fluence. When a different approach for the transfer layer is applied - a two-layered transfer layer of gelatin with cell culture medium - cell damage can be prevented. Cells can therefore be transferred in a highly defined manner and are arranged in arbitrary patterns

Ortsselektives, präzises Laserdrucken von Biomaterialien und Zellen

Aim of this thesis is to conceptualize a system for laser induced forward transfer (LIFT) either for high throughput (HTS) or for high content screening (HCS) applications. For the LIFT-system designated for HTS-microarray production a galvanometric scanner is used. This results in a fast process that allows the transfer of a large number of droplets in an easy manner. The reproducible transfers can be used to generate microarrays for different diagnostic purposes.Different Cells have to be arranged in a specific layout and stoichiometry for the fabrication of HCS-test systems. Hence a second LIFT-system is designed that allows the investigation of the transfer layer before the actual transfer takes place. Therefore single identified objects can be transferred onto a receiver substrate. This function is tested by transferring polystyrol particles. After single particle transfer their relative position within the droplet is analyzed depending on the laser fluence and the spatial beam shape. When a non-symmetric beam shape is used it can be seen that the particles are directed into a preferred direction. Biggest deviation from a defined position of the particles can be observed for low and high fluences. The highest position accuracy can be observed for medium range laser fluences. In regard to the influence of the beam shape a higher accuracy of tophat-like compared to donut or gaussian beam shape can be observed.The results from the particle transfers are applied to the transfer of individual cells. Single cells can be easily selected from matrigel or gelatin based transfer layers. But the cells are damaged with increasing laser fluence. When a different approach for the transfer layer is applied - a two-layered transfer layer of gelatin with cell culture medium - cell damage can be prevented. Cells can therefore be transferred in a highly defined manner and are arranged in arbitrary patterns

Laser tool for single cell transfer

Many structures in living organisms show a high complexity. One example is the stem cell niche, where different cell types interact in a highly defined manner. Such structures need a building technology, which enables a highly defined and reproducible positioning of the cell types of interest. Laser Induced Forward Transfer (LIFT) however enables us to achieve a very good cell transfer even on a single cell resolution. As a test system for cell transfer polystyrene particles with a diameter of 10 μm and a cell-like density were used. Single particles embedded in MatrigelTM are reproducibly deposited onto a receiver in a pre-set pattern. Cell transfer is performed thereafter with mouse fibro-blast 3T3 cells. Results are comparable to particle transfer experiments. Viability of these cells is tested with Life/Dead staining after three hours and six days. Further, proliferation of the cell line is observed after six days of cell incubation