Modeling Cell Reactions to Ionizing Radiation: From a Lesion to a Cancer

This article focuses on the analytic modeling of responses of cells in the body to ionizing radiation. The related mechanisms are consecutively taken into account and discussed. A model of the dose- and time-dependent adaptive response is considered for 2 exposure categories: acute and protracted. In case of the latter exposure, we demonstrate that the response plateaus are expected under the modelling assumptions made. The expected total number of cancer cells as a function of time turns out to be perfectly described by the Gompertz function. The transition from a collection of cancer cells into a tumor is discussed at length. Special emphasis is put on the fact that characterizing the growth of a tumor (ie, the increasing mass and volume), the use of differential equations cannot properly capture the key dynamics—formation of the tumor must exhibit properties of the phase transition, including self-organization and even self-organized criticality. As an example, a manageable percolation-type phase transition approach is used to address this problem. Nevertheless, general theory of tumor emergence is difficult to work out mathematically because experimental observations are limited to the relatively large tumors. Hence, determination of the conditions around the critical point is uncertain

Single cell temperature probed by Eu 3 doped TiO2 nanoparticles luminescence

Abstract Temperature is a critical parameter in biology, affecting the speed of reactions that occur in living systems. Nevertheless, measuring temperature with subcellular resolution (micrometric scale) and reliability remains a challenge to overcome. In this perspective, luminescence nanothermometry is a non‐contact technique which aims to measure temperature with a sub‐micrometric spatial resolution through the use of nanomaterials whose luminescence is affected solely by changes in temperature. Here, TiO2 nanoparticles doped with Eu+3 ions (Eu+3‐TiO2) are used for sensing temperature differences within single living cells. XRD, XPS, SEM, TEM and NEXAFS analysis allow the determination of the physicochemical characteristics of the Eu+3‐TiO2 nanoparticles and, the variation of the luminescence intensity of the Eu+3‐TiO2 nanoparticles with their temperature is investigated. The successful internalization of Eu+3‐TiO2 nanoparticles in different types of cells is observed. The luminescence of nanoparticles internalized in L929 fibroblast cells is measured when the system is heated in a biological relevant temperature range. Making use of an appropriate calibration curve the temperature variation inside the cells is determined with sensitivity of 0.5 K per 1% of luminosity change when heated

Phosphorous-Based Titania Nanoparticles for the Photocatalytic Abatement of VOCs

In this work, different TiO2-based systems were synthesized. Specifically, phosphorous was considered as nonmetal dopant into TiO2 structure of the photocatalysts. The doped samples were herein labeled as TiO2-P0.6, TiO2-P0.7, and TiO2-P3, where 0.6, 0.7, and 3 indicate the average atomic phosphorus content into each sample. The physico-chemical properties of the samples were investigated by complementary techniques, including XRD, N2 physisorption at −196 °C, FESEM, EDX, XPS, and (DR)UV-Vis spectroscopies. Then, the samples were tested for the total oxidation of ethylene under two different sources: UVB (wavelength = 312 nm, intensity = 12 W m−2) and UVA (wavelength = 365 nm, intensity = 8 W m−2). The results under UVB source have shown that the most promising catalyst is TiO2-P3 (TOF = 7.5 μmol h−1 g−1, TOS = 160 min) and a positive reactivity trend was observed: the higher the P-content, the higher the reactivity. On the other hand, under the UVA source, the most promising catalyst is TiO2-P0.6 (TOF = 21.3 μmol h−1 g−1, TOS = 160 min). In fact, the samples with higher P-contents decrease their performances at longer TOS, likely due to the surface deposition of carbon-like molecules