Browsing by Subject "ohutsuolen solumallit"

The aim of this thesis was to investigate the potential of label-free CARS microscopy as a new method for chemically-specific imaging of live cells and particle-cell interactions in a drug delivery context. Cells used to mimic the intestinal epithelium, Caco-2 cells and HT-29 cells and nano-/ microcrystal particle interactions with macrophages were studied. More information about drug absorption from intestinal and particle cell interactions are needed, since many novel drugs lack properties needed for good bioavailability. It would be beneficial if these events could be visualized without labels. CARS microscopy was found to be well suited to imaging live Caco-2 and HT-29 cells that were grown on PTFE Transwell inserts. CARS microscopy revealed lipid droplets inside these cells. The size of lipid droplets increased in Caco-2 cells a lot during a three week period so that at the end a large part of the inner part of the cell was filled with lipid droplets. It was also observed that Caco-2 cells and HT-29 cells can grow on top of each other on Transwell inserts and not just as a monolayer. These two facts could cause variations in drug absorption studies based on Caco-2 cell monolayers. CARS microscopy was able to detect nanocrystals as small as about 500 nm with label-free, molecular-specific CARS microscope inside RAW 264.7 macrophages after incubation of 120 min. This observation was important, since nanocrystal drug formulations are gaining interest in the field of pharmacy. Nanocrystals can be used in parenteral drug formulations as well as in oral dosage forms. In suspensions, nanocrystals can be used to cause long lasting drug release. Nanocrystals can be also used to enhance poor bioavailability of drugs. Whether these nanocrystals are used in parenteral formulations or in oral drug formulations it is evident that imaging techniques are needed to image interactions between these nanocrystals and cells. CARS microscopy could be one of those techniques, since it is suitable for live cell imaging and it can be used to image nanocrystals that are not labeled. The results in this thesis suggest that CARS microscopy could be used as fast imaging technique for nanocrystal particle cell interactions. Overall, CARS microscopy is a relatively new imaging method that shows much promise as a label-free chemically specific imaging technique for imaging cells and cell-particle interactions in a drug delivery context. As the technique becomes more widely available and undergoes some technical developments, it will become much more widespread imaging method in the future.