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The femtosecond laser multiphoton tomograph DermaInspect as well as high NA two-photon GRIN microendoscopes
for in vivo tomography of human skin have been used to detect malignant melanoma as well as to study the diffusion and
intradermal accumulation of topically applied cosmetical and pharmaceutical components. So far, more than 500 patients
and volunteers in Europe, Australia, and Asia have been investigated with this unique tomograph.
Near infrared 80 MHz picojoule femtosecond laser pulses were employed to excite endogenous fluorophores such as
NAD(P)H, flavoproteins, melanin, and elastin as well as fluorescent components of a variety of ointments via a twophoton
excitation process. In addition, collagen has been imaged by second harmonic generation. Using a two-PMT
detection system, the ratio of elastin to collagen was determined during optical sectioning. A high submicron spatial
resolution and 50 picosecond temporal resolution was achieved using galvoscan mirrors and piezodriven focusing optics
as well as a time-correlated single photon counting module with a fast microchannel plate detector and fast
photomultipliers. Individual intratissue cells, mitochondria, melanosomes, and the morphology of the nuclei as well as
extracellular matrix elements could be clearly visualized due to molecular imaging and the calculation of fluorescence
lifetime images. Nanoparticles and intratissue drugs have been detected non-invasively, in situ and over a period of up to
3 months. In addition, hydration effects and UV effects were studied by monitoring modifications of cellular morphology
and autofluorescence. The system was used to observe the diffusion through the stratum corneum and the accumulation
and release of functionalized nanoparticles along hair shafts and epidermal ridges. The DermaInspect been also
employed to gain information on skin age and wound healing in patients with ulcers. Novel developments include a
galvo/piezo-scan driven flexible articulated arm as well as a piezoscan-driven flexible high-NA GRIN microendoscope
with photonic crystal fiber.
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