Objective: to study the dynamics of the state of autografts of skin and allodermal protectors on a wound using multimodal optical monitoring. Material and methods. A burn wound was simulated in rats (n = 16), 20% of the wound area was covered with skin autografts. The allodermal protector of 0.35 mm thick was applied over the autografts. Studied in vivo the state of the grafts for 10 days: saturation - according to diffuse optical spectroscopy (DOS); perfusion - according to laser Doppler flowmetry (LDF); microstructure - according to optical coherence tomography (OCT). Results. Multimodal monitoring of blood circulation, metabolism and microstructure of skin grafts on a burn wound showed that changes in auto- and allografts occur asynchronously. In the tissues of the autograft, blood saturation directly correlated with the restoration of perfusion (Spearman's coefficient = 0.795); in the allograft, the correlation between perfusion and saturation was weakly inverse (-0.179). Those differences were confirmed by OCT data and histological analysis: allografts lost their normal microstructure simultaneously with a rapid decrease of the blood saturation, despite the preservation of perfusion parameters.
In the current paper we present preliminary data demonstrating therapeutic efficiency of local laser hyperthermia of
mouse tumors with gold nanoparticles. Measuring the tumor temperatures both superficial and inner by means of
standard NIR-thermograph and original acoustic thermometer correspondingly we show that the gold nanoparticles
increase thermal sensitivity of tumor tissue. Transmission electron microscopy and histopathology of the tumor tissue
indicated that the mechanism of apoptotic death of tumor cells is triggered following the laser treatment. 5 days after the
treatment tumor growth inhibition was 104 %.
KEYWORDS: Nanoparticles, Skin, Gold, Optical coherence tomography, Monte Carlo methods, Particles, Scattering, In vivo imaging, Coherence imaging, Titanium dioxide
The effect of silica/gold nanoshells and titanium dioxide nanoparticles on the optical properties of skin is studied. By implementing in vivo measurements and Monte Carlo simulations, we analyze the efficiency of using these nanoparticles as contrasting agents for optical coherence tomography (OCT) imaging of skin. In vivo measurements are performed on pig skin, where nanoparticle suspension drops have been applied. The identification of skin layers is performed by comparison with corresponding histology images. Experimental results exhibit an increase in contrast of the obtained OCT images after a single nanoparticles application. Multiple applications do not lead to increase in the obtained contrast. To interpret the obtained experimental OCT images of skin and understand the mechanisms of contrasting, a set of Monte Carlo calculations is performed. The results of the simulations exhibit good qualitative agreement with the experimental images, and prove that the contrasting originates from the nanoparticles added, while the contrast of inclusion originates from the absence of nanoparticles within it and their presence in the surrounding area.
KEYWORDS: Optical coherence tomography, Skin, Gold, Monte Carlo methods, In vivo imaging, Nanoparticles, Optical properties, Scattering, Tissue optics, Computer simulations
We have investigated the effect of application of gold nanoshells with a 150 nm silica core size and 25 nm thick gold
coating on optical properties of skin. We have analyzed the possibility of using these particles as a contrasting agent for
optical coherence tomography (OCT). A set of Monte Carlo calculations was performed in order to simulate the images
of skin before and after application of the nanoshells for a skin model close to that in vivo. We investigated the
mechanisms of boundary contrasting between tissue layers with different optical properties in the presence of gold
nanoshells on two-layer agar gel phantom. Gold nanoshells were also applied on the skin surface in vivo. Gold-silica
nanoshells caused an increase in the intensity of OCT signal, brightness of the superficial part of the dermis, contrast
between dermis layers and contrast of hair follicles and glands in the OCT image. The contrasting effects of the gold
nanoshells lasted up to 24 hours of observation.
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