V. V. Tuchin

Optical Properties of the Subcutaneous Adipose Tissue in the Spectral Range 400-2500 nm

The optical characteristics of subcutaneous adipose tissue are studied in the wavelength range 400–2500 nm. The experiments are conducted in vitro using a Cary 2415 spectrophotometer. Based on the measured diffuse reflectance and total transmittance spectra, the spectra of the absorption and transport scattering coefficients are calculated in terms of the inverse adding-doubling method.

In vivo investigation of the immersion-liquid-induced human skin clearing dynamics

The results of an in vivo investigation of human skin clearing caused by the immersion-liquid-induced matching of the refractive indices are reported for the first time. It was established that subcutaneous injections of a glucose solution produce a significant long-term suppression of the light scattering in the skin dermis, which is an important factor ensuring an increase in efficacy of the optical tomography, photodynamic therapy, and photodestruction of deep objects.

Immersion clearing of human blood in the visible and near-infrared spectral regions

The possibility of the immersion clearing of human blood in the visible and near-IR spectral regions is considered and theoretically substantiated. On the basis of the model presented, the spectral behavior of the scattering and absorption characteristics of blood upon its immersion clearing by glucose is analyzed.

Optical properties of human sclera in spectral range 370-2500 nm

Optical characteristics of human sclera are experimentally studied. Experiments are performed in vitro on a Cary-2415 spectrophotometer in the spectral range 370–2500 nm. Based on the measured diffuse reflection and total transmission spectra, the absorption and transport scattering coefficient spectra are calculated by the inverse adding-doubling method.

Finger tissue model and blood perfused skin tissue phantom

Measurements of optical properties of fingernail and underlying tissues using OCT are presented. Review and measurements of Raman spectra of tissue and phantom compounds were done. Updating of modeling algorithm for scattering coefficient calculation on the basis of integrating sphere measurements accounting for particle size-distribution was also done. The adequate fingernail and underlying tissue optical model at 830 nm was evaluation. Tissue phantoms potentially suitable for calibration of Raman instrumentation for glucose sensing were designed and tested on the basis of epoxy resin, TiO2-nanoparticles and micron-sized silica particles with the capillary net-work.

Optical clearing of skin under action of glycerol: Ex vivo and in vivo investigations

The behavior of optical parameters of the skin of a laboratory rat under the action of an aqueous solution of glycerol is studied ex vivo and in vivo. It is found that the collimated transmission coefficient of ex vivo skin samples increases by a factor of 20–40-fold depending on the wavelength in the studied spectral range, and the diffuse reflection coefficient of skin in vivo decreases on the average by 16%. The results presented can be useful for many methods of laser therapy and optical diagnostics of skin diseases and localization of subcutaneous neoplasms.

Spectral characteristics of indocyanine Green upon its interaction with biological tissues

The changes in the absorption spectra of solutions of Indocyanine Green are studied in relation to the nature and composition of the solvent and the dye concentration. The reflection spectra from selected areas of human skin stained with different solutions of Indocyanine Green are studied in vivo upon successive stripping of stained surface epidermal layers. The reflection spectra from human hairs stained in vitro with an alcohol solution of Indocyanine Green are measured. It is shown that the shift of the absorption band maximum of Indocyanine Green determined by the interaction of the dye with epidermal or hair keratin does not depend on the solvent composition or the depth of location of the stained layer.

Optical properties of mucous membrane in the spectral range 350-2000 nm

The optical characteristics of the mucous membrane from the human maxillary sinus are studied experimentally. The experiments were carried out in vitro in the spectral range 350–2000 nm. On the basis of the measured total transmittance and diffuse reflectance spectra, the absorption and transport scattering coefficients are calculated in the entire range in terms of the inverse adding-doubling method.

Optical anisotropy of a biological tissue under conditions of immersion clearing and without them

The optical anisotropy of a biological tissue is studied under conditions of immersion clearing of the tissue and without them. It is shown that the rate of immersion clearing of a biological tissue depends on its type and is determined by the rate of diffusion of immersion liquids into the sample. The parameters that characterize the rate of diffusion of an immersion liquid into a biological tissue are determined. The types of anisotropy of different samples of biological tissues are found. Based on the Müller matrix formalism, a model for calculating the spectrum of collimated polarized transmission of a biological tissue is constructed. Comparison of calculated and experimental transmission spectra of biological tissues showed their good quantitative coincidence.

Application of gold nanoparticles to X-ray diagnostics and photothermal therapy of cancer

We describe applications of colloidal gold nanoparticles and silica/gold nanoshells to photothermal therapy and X-ray diagnostics of cancer exemplified by spontaneous tumor of cats and dog. It is shown that the contrast of X-ray images of a cat mammalian tumor can be increased significantly by injection of 3-5-nm gold nanoparticles. We also present preliminary results of a complex approach to treatment a dog mouth cavity melanoma by using immunotherapy together with laser photothermolysis enhanced with silica/gold nanoshells.