For many years, photobiomodulation in cancer patients has been used empirically, based on the positive clinical experience. When using PBM for the prevention and treatment of early radiation toxicity, exposure can occur directly in the area of the tumor site. For that reason, the data is need about a potential influence of low-intensity red light as on the normal as well on the tumor cells exposed to ionizing radiation. The aim of the work was to study the effects of photobiomodulation (PBM) in the red spectrum (640 nm) with fluences from 3 mJ/cm2 to 2 J/cm2 in combination with ionizing radiation at doses of 2–6 Gy against human BJ-5ta-hTERT cells – postnatal fibroblasts. The cells were exposed to low-intensity red light before or after their exposure to IR, the viability of the cells was determined by MTT-test 24 hours after the last exposure. The effects of PBM depend on the fluence of PBM, the dose of IR and the sequence of the actions of these physical factors on cells. The adaptive effect of PBM was observed only for high fluences – 1 and 2 J/cm2 when exposed to PBM and subsequent irradiation of IR. At the same time, the stimulating effect of PBM was observed only for low fluences from 3 to 300 mJ/cm2 under IR irradiation and subsequent (after 1 hour) exposure to PBM. These data should be taken into account when using PBM for the correction of adverse events of radiation therapy in a clinic.
One of the promising approaches to the treatment of injured tissue is the application of bioengineering techniques based on the introduction of cells into the damage area. An application of cells alone does not provide a complete replacement of the tissue defect. Therefore, scaffolds are used allowing organization of the cells into a structure, which is capable of the total reproduction of the damaged tissue integrity. Great number of factors, which influence the cell behavior and tissue formation at the injury site when using scaffolds are known. Here, we analyzed the effect of structural heterogeneity of scaffolds on cellular behavior and metabolism. All scaffolds were obtained by two-photon polymerization technic. It was found that colonization of heterogeneous scaffolds was insignificant less than homogeneous ones. However, there were not dead cells on heterogeneous matrix. We found that the level of free and bound NAD(P)H for the cells on the heterogeneous and homogeneous scaffolds was differ. This can indicate a different contribution of glycolysis and oxidative phosphorylation intensity in stem cells seeded on two types of scaffolds.
Results of development and experimental verification of a bench-top system for synthesis of highly porous polymer matrices are presented. Synthesis of the matrices is based on the initial plasticization of a raw polymer material provided using a subcritical/supercritical fluidic agent with the follow-up foaming of the plasticized polymer due to gradual depressurization of a working volume of the high-pressure reactor. The design of the reactor makes it possible to provide the quasi-real-time optical control of the polymer foaming using various optical probes (e.g., the small-angle diffuse transmittance measurements at various wavelengths, the multi-speckle diffusing wave spectroscopy, the polarimetric measurements using a transmitted light, the direct imaging of a foamed volume in the trans-illumination mode, etc.). The optical control is carried out through a set of sapphire glass windows symmetrically located around the working volume of the reactor. A precise control of the pressure and temperature in the working volume is synchronized with the optical probing of the foamed volume. Bench-top tests of the developed system were carried out using two extreme foaming modes: the quasi-adiabatic foaming under the condition of fast depressurization of the working volume, and the quasiisothermal foaming provided with the extremely slow depressurization and the constant temperature in the working volume. In the experiments, a granular polylactide from the PURACORB Inc. was used as the raw polymer material and carbon dioxide was applied as the plasticizing/foaming agent. The results of pilot foaming experiments for these extreme modes of polylactide foaming are presented.
We demonstrate a novel approach of femtosecond laser pulse spectral-temporal control under filamentation in a wide range of pressures from 5 bar up to supercritical state. We showed that laser-induced processes such as supercontinuum generation and pulse self-compression could be tuned both by pressure and by energy adjustment due to the nonlinear refractive index alteration via pressure change. Thanks to the high pressure-controlled nonlinearity, a broadband (from 250 to 2500nm) supercontinuum with total efficiency more than 50% of energy can be generated in supercritical Xe and CO2. It was also demonstrated that the femtosecond laser pulse can be compressed in Xe in the femtosecond monofilamentation mode by 3.5 times with efficiency as high as 60%.
Light field intensity distribution in three-dimensional polylactide scaffolds after irradiation with low-intensity light from one side of the samples has been determined in the visible and near-infrared regions of the spectrum. Two different types of scaffolds manufactured by the methods of supercritical fluid foaming and surface selective laser sintering have been investigated. The problem is solved by numerical calculation according to the Monte Carlo method involving experimentally obtained information about effective optical parameters of the scaffold material. Information about intensity distribution of the incident light in the matrix volume is needed to assess the radiation level for the scaffold cells after photobiostimulation. It has been shown that the formation of the light field in case of strongly scattering media, such as polylactide scaffolds, is determined by anisotropy g and the scattering coefficient μs.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.