Daria K. Tuchina, Alexey N. Bashkatov, Elina A. Genina, Valery V. Tuchin Department of Optics and Biophotonics of Saratov State University, Saratov, Russia Saratov Fall Meeting 2012

For the last two decades the optical method as a tool for clinical functional imaging of physiological conditions, cancer diagnostics and therapies is of great interest due to its unique informative features, simplicity, safety and low cost in contrast to conventional X-ray computed tomography, magnetic resonance imaging and ultrasound. However, the main limitations of the optical imaging techniques are connected with strong light scattering in tissue. Optical clearing is perspective technique for solution of the problem. However, in spite of numerous investigations, optical clearing of skin tissue has not be studied in detail. Goal of the study is to investigate of optical clearing of skin by PEG-300 Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Twelve samples of intact rat skin were used in the in vitro experiments. Before experiments hairs and hypodermic fatty layer were removed. The area of the samples was about 10 × 20 mm. Collimated transmittance spectra of the skin samples were measured by USB4000-Vis-NIR spectrometer (Ocean Optics, USA) concurrently with administration of PEG-300 in the spectral range nm. All measurements were performed at room temperature (about 20°C). Refractive index of PEG-300 was measured as Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Dynamic of collimated transmittance of the rat skin sample placed in PEG-300 Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Spectra of collimated transmittance of the rat skin sample placed in PEG-300 measured at different time intervals concurrently with administration of PEG-300 Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

The time dependence of attenuation coefficient during optical clearing of the rat skin sample placed in PEG-300 Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Spectra of light attenuation coefficient during optical clearing of the rat skin sample placed in PEG-300 measured at different time intervals Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Degree of optical clearing of skin tissue was estimated as: µ t (t=0) is attenuation coefficient at t = 0 µ t (t) is the time-dependent attenuation coefficient Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

The equation was used to calculate parameter A, which characterizes maximum of degree of optical clearing of skin tissue, and parameter τ, which characterizes time of optical clearing of skin tissue: The solution of the problem is minimization of the target function: N t is the number of time points obtained at registration of the time dependence of collimated transmittance, µ t is experimental values of the time-dependent attenuation coefficient Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

A0.381 τ, min8.691 Saratov State University Department of Optics and Biophotonics Saratov Fall Meeting 2012

Acknowledgements Saratov Fall Meeting 2012 Saratov State University Department of Optics and Biophotonics Grants # and КО of Russian Foundation of Basis Research Russian Federation governmental contacts , , , and 14.B Grant # Network of Excellence for Biophotonics (PHOTONICS4LIFE) of the Seventh Framework Programme of Commission of the European Communities