Search results for "ionizing"

Ionizing radiation synthesis of multifunctional nanogels for biomedical applications

Nanogels (NGs) are nanosized three-dimensional networks of crosslinked hydrophilic polymers. Their tunable chemical structure, physico-chemical properties and potential biocompatibility make them interesting substrates for the synthesis of “nanodevices” with therapeutic and/or diagnostic functions. In this PhD project, NGs were synthesized through pulsed e-beam irradiation of Poly-N-(Vinyl-Pyrrolidone) (PVP) aqueous solutions. The manufacturing process is fast and straightforward; it does not require the employment of organic solvents, surfactants, initiators or catalyst and guarantees high yields of the desired product. In dilute aqueous polymer solutions, ionizing radiation is mainly abso…

Jauni viedie materiāli no multifāzu polimēru kompozīcijām, to fizikāli-mehānisko, deformatīvo un struktūras īpašību izmaiņas jonizējošā starojuma un …

2014

Promocijas darbā pētītas poliolefīnu – multifāzu kompozīcijas ar elastomēriem un šķērssaistīšanās promotoriem. Izvērtēta radiācijķīmiskās modificēšanas un lielas indukcijas magnētiskā lauka (B = 1,0-1,7 T) ietekme uz pētīto kompozītsistēmu stiprības-deformācijas, struktūras īpašībām, kā arī novērtēta magnētiskā lauka un jonizējošā starojuma mijiedarbības ietekme uz poliolefīnu makromolekulu šķērssaistīšanās efektivitāti. Iegūtas jaunas teorētiskas un praktiskas atziņas par radiācijķīmiski modificētu poliolefīnu multifāzu kompozīciju ekspluatācijas īpašībām, kas ļāva radīt jaunus uz polipropilēna bāzētus termonosēdmateriālus.

Portrait of inflammatory response to ionizing radiation treatment

2015

Ionizing radiation (IR) activates both pro-and anti-proliferative signal pathways producing an imbalance in cell fate decision. IR is able to regulate several genes and factors involved in cell-cycle progression, survival and/or cell death, DNA repair and inflammation modulating an intracellular radiation-dependent response. Radiation therapy can modulate anti-tumour immune responses, modifying tumour and its microenvironment. In this review, we report how IR could stimulate inflammatory factors to affect cell fate via multiple pathways, describing their roles on gene expression regulation, fibrosis and invasive processes. Understanding the complex relationship between IR, inflammation and …

Radiation effects on optical frequency domain reflectometry fiber-based sensor

2015

International audience; We investigate the radiation effects on germanosilicate optical fiber acting as the sensing element of optical frequency domain reflectometry devices. Thanks to a new setup permitting to control temperature during irradiation, we evaluate the changes induced by 10 keV x rays on their Rayleigh response up to 1 MGy in a temperature range from −40°C up to 75°C. Irradiation at fixed temperature points out that its measure is reliable during both irradiation and the recovery process. Mixed temperature and radiation measurements show that changing irradiation temperature leads to an error in distributed measurements that depends on the calibration procedure. These results …

Effects of gamma-irradiation on trehalose–hydroxyethylcellulose microspheres loaded with vancomycin

2003

Ionizing radiation can be used as a drug sterilization technique, provided that the drug itself is not modified and that no toxic products are produced; moreover, if the irradiated product is a drug delivery system, the drug release characteristics must not be significantly altered by radiation. The aim of this work was to study the effects of sterilization by ionizing radiation on hydroxyethylcellulose/trehalose spherical micromatrices, containing the antibiotic vancomycin. Our experimental results showed that gamma-rays did not alter the chromophore groups of vancomycin (UV measurements), and did not modify the kinetic behavior of drug release from microspheres. Moreover, no significant c…

Multifunctional nanogels from e-beam irradiation of PVP aqueous solutions, only

2017

Nanogels (NGs) are 3D networks of crosslinked hydrophilic polymers with nanoscalar dimensions. Due to their structure and physico-chemical properties, they are a promising nanomaterial platform for site-specific drug delivery and diagnostic nanodevices.

New insights on the mechanism of PVP nanogels radiation synthesis

2017

In this work, the H2O2 build-up for several system compositions and irradiation conditions was investigated, by using the Ghormley triiodide method. Interestingly, the application of the method has revealed the occurrence of two concurrent reactions, the expected one responsible for the I3 - production (by reaction with the H2O2 formed upon irradiation) and one that is responsible for I3 - consumption. Both the concentrations of I3 - -forming and I3 - -consuming species are dose-dependent and polymer concentration-dependent. The kinetic study of the two reactions and some further experiments carried out with model molecules will be described. We believe that the results of this study can of…

Concentration-Dependent Protection by Ethanol Extract ofPropolis against &#947

2011

[EN] Radioprotection with natural products may be relevant to the mitigation of ionizing radiation-induced damage in mammalian systems; in this sense, propolis extracts have shown effects such as antioxidant, antitumoral, anti-inflammatory, and immunostimulant. We report for the first time a cytogenetic study to evaluate the radioprotective effect, in vitro, of propolis against radiation-induced chromosomal damage. Lymphocytes were cultured with increasing concentrations of ethanol extract of propolis (EEP), including 20, 40, 120, 250, 500, 750, 1000, and 2000 ¿g mL-1 and then exposed to 2 Gy ¿-rays. A significant and concentration-dependent decrease is observed in the frequency of chromoso…

Radiation-Engineered Functional Nanoparticles in Aqueous Systems.

2015

Controlled synthesis of nanoscalar and nanostructured materials enables the development of novel functional materials with fine-tuned optical, mechanical, electronic, magnetic, conductive and catalytic properties that are of use in numerous applications. These materials have also found their potential use in medicine as vehicles for drug delivery, in diagnostics or in combinations thereof. In principle, nanoparticles can be divided into two broad categories, organic and inorganic nanoparticles. For both types of nanoparticles there are numerous possible synthetic routes. Considering the large difference in nature of these materials and the elementary reactions involved in the synthetic rout…

A comparison of the transcriptome of Drosophila melanogaster in response to entomopathogenic fungus, ionizing radiation, starvation and cold shock

2015

Background The molecular mechanisms that determine the organism's response to a variety of doses and modalities of stress factors are not well understood. Results We studied effects of ionizing radiation (144, 360 and 864 Gy), entomopathogenic fungus (10 and 100 CFU), starvation (16 h), and cold shock (+4, 0 and -4°C) on an organism's viability indicators (survival and locomotor activity) and transcriptome changes in the Drosophila melanogaster model. All stress factors but cold shock resulted in a decrease of lifespan proportional to the dose of treatment. However, stress-factors affected locomotor activity without correlation with lifespan. Our data revealed both significant similarities …