The complex structure of skin represents an effective barrier against external environmental factors, as for example,
different chemical and biochemical compounds, yeast, bacterial and viral infections. However, this impermeability
prevents efficient transdermal drug delivery which limits the number of drugs that are able to penetrate the skin
efficiently. Current trends in drug application through skin focus on the design and use of nanocarriers for transport of
active compounds. The transport systems applied so far have several drawbacks, as they often have low payload, high
toxicity, a limited variability of inclusion molecules, or long degradation times. The aim of these current studies is to
investigate novel topical drug delivery systems, e.g. nanocarriers based on cyclic oligosaccharides - cyclodextrins (CD)
or iron (III)-based metal-organic frameworks (MOF). Earlier studies on cell cultures imply that these drug nanocarriers
show promising characteristics compared to other drug delivery systems.
In our studies, we use two-photon microscopy to investigate the ability of the nanocarriers to deliver compounds through
ex-vivo skin samples. Using near infrared light for excitation in the so called optical window of skin allows deep-tissue
visualization of drug distribution and localization. In addition, it is possible to employ two-photon based fluorescence
correlation spectroscopy for quantitative analysis of drug distribution and concentrations in different cell layers.