Polymer-grafted gold nanoparticles for cancer treatment: synthesis and evaluation of their radiosensitizing properties

International audienceToday, even though treatments have much improved, cancer is still a leading cause of death in the world, being responsible for 1 death out of 6. Radiotherapy is widely used for tumor treatment, but suffers from side effects due to the irradiation of healthy surrounding tissues. Another issue is the radioresistance developed by some tumor cells, which implies to increase the involved doses. The challenge remains to deliver curative doses to tumor tissues while sparing sound ones. Hence the use of tumor-located radiosensitizers is a promising way to improve the efficacy of radiotherapy. High-Z materials have been known for several decades to amplify the damaging effects of both photon and ion radiations. Various nanoparticles have already been developed to take advantage of this property: gold, platinum and gadolinium are amongst the most investigated elements. A well-controlled synthesis is key to obtain stable and scalable nano-objects. Here, various polymers were grafted onto metallic nanoparticles to improve stability and biocompatibility and to facilitate subsequent functionalization. Advanced methods of characterization attested both robustness and reproducibility of the synthesis procedure. Moreover, promising results were obtained regarding the radioenhancing properties of these hybrid nanocompounds. Therefore, special attention has been given to the underlying mechanisms of the assessed radiosensitization, since they are not fully understood yet. Synthesis of polymer-grafted gold nanoparticles was performed through an in situ method, via the reduction of gold salts in the presence of polymeric ligands mainly prepared using controlled radical polymerization. The resulting nano-objects were fully characterized by thermogravimetric analysis, inductively coupled plasma mass spectrometry (ICP-MS), transmission electronic microscopy and small-angle x-ray and neutron scattering. Interactions between our nanocompounds and biological systems were studied in order to better understand the mechanisms at play. At the cellular scale, three aspects were examined for each type of nanoparticles: cellular uptake, cytotoxicity and radiosensitizing properties, through ICP-MS measurements, cell proliferation assays and clonogenic assays respectively. All irradiations were performed while keeping the delivered doses to low values (under 30 Gy) that are typical of clinic reality. Different types of radiations were tested, in order to compare their effects and their synergy with the nanocompounds. The synthesized nano-objects have shown great potential to enhance radiation cancer treatment. Their stability and controlled surface chemistry have allowed to develop multiple strategies in order to optimize their radiosensitizing effect and in vitro behavior

Well dispersed fractal aggregates as filler in polymer-silica nanocomposites: long range effects in rheology

We are presenting a new method of processing polystyrene-silica nanocomposites, which results in a very well-defined dispersion of small primary aggregates (assembly of 15 nanoparticles of 10 nm diameter) in the matrix. The process is based on a high boiling point solvent, in which the nanoparticles are well dispersed, and controlled evaporation. The filler's fine network structure is determined over a wide range of sizes, using a combination of Small Angle Neutron Scattering (SANS) and Transmission Electronic Microscopy (TEM). The mechanical response of the nanocomposite material is investigated both for small (ARES oscillatory shear and Dynamical Mechanical Analysis) and large deformations (uniaxial traction), as a function of the concentration of the particles. We can investigate the structure-property correlations for the two main reinforcement effects: the filler network contribution, and a filler-polymer matrix effect. Above a silica volume fraction threshold, we see a divergence of the modulus correlated to the build up of a connected network. Below the threshold, we obtain a new additional elastic contribution of much longer terminal time than the matrix. Since aggregates are separated by at least 60 nm, this new filler-matrix contribution cannot be described solely with the concept of glassy layer (2nm)

Evolution of DNA methylome from precancerous lesions to invasive lung adenocarcinomas

The evolution of DNA methylome and methylation intra-tumor heterogeneity (ITH) during early carcinogenesis of lung adenocarcinoma has not been systematically studied. We perform reduced representation bisulfite sequencing of invasive lung adenocarcinoma and its precursors, atypical adenomatous hyperplasia, adenocarcinoma in situ and minimally invasive adenocarcinoma. We observe gradual increase of methylation aberrations and significantly higher level of methylation ITH in later-stage lesions. The phylogenetic patterns inferred from methylation aberrations resemble those based on somatic mutations suggesting parallel methylation and genetic evolution. De-convolution reveal higher ratio of T regulatory cells (Tregs) versus CD8 + T cells in later-stage diseases, implying progressive immunosuppression with neoplastic progression. Furthermore, increased global hypomethylation is associated with higher mutation burden, copy number variation burden and AI burden as well as higher Treg/CD8 ratio, highlighting the potential impact of methylation on chromosomal instability, mutagenesis and tumor immune microenvironment during early carcinogenesis of lung adenocarcinomas

Integrating precision cancer medicine into healthcare—policy, practice, and research challenges

Abstract Precision medicine (PM) can be defined as a predictive, preventive, personalized, and participatory healthcare service delivery model. Recent developments in molecular biology and information technology make PM a reality today through the use of massive amounts of genetic, ‘omics’, clinical, environmental, and lifestyle data. With cancer being one of the most prominent public health threats in developed countries, both the research community and governments have been investing significant time, money, and efforts in precision cancer medicine (PCM). Although PCM research is extremely promising, a number of hurdles still remain on the road to an optimal integration of standardized and evidence-based use of PCM in healthcare systems. Indeed, PCM raises a number of technical, organizational, ethical, legal, social, and economic challenges that have to be taken into account in the development of an appropriate health policy framework. Here, we highlight some of the more salient issues regarding the standards needed for integration of PCM into healthcare systems, and we identify fields where more research is needed before policy can be implemented. Key challenges include, but are not limited to, the creation of new standards for the collection, analysis, and sharing of samples and data from cancer patients, and the creation of new clinical trial designs with renewed endpoints. We believe that these issues need to be addressed as a matter of priority by public health policymakers in the coming years for a better integration of PCM into healthcare

Adsorption of toluene and toluene–water vapor mixture on almond shell based activated carbons

The aim of work is to study the adsorption of a common volatile organic compound such as toluene using activated carbons prepared by chemical activation with phosphoric acid of a lignocellulosic precursor, almond shell, under different conditions. The Impregnation ratio, temperature and time of activation were modified to obtain activated carbons with different characteristics. Regarding the characteristics of the activated carbons, the effects of porous structure and surface chemistry on the toluene adsorption capacity from toluene isotherms have been analysed. Results show that the control of properties of the activated carbons, particularly porous structure, highly dependent on the preparation conditions, plays a decisive role on the toluene adsorption capacity of the activated carbons. Concerning the experiments of toluene adsorption conducted in dynamic mode, activated carbons prepared at low temperatures of activation show higher breakthrough times than those obtained for activated carbons prepared at higher activation temperatures. The amount of toluene adsorbed in presence of water vapor in the gas stream lead to a decrease ranging from 33 to 46 % except for carbons prepared at higher temperatures activated that show only a slight decrease in the amount of toluene adsorbed. Activated carbons can be regenerated with soft heat treatment showing a slight decrease in the adsorption capacity. The high toluene adsorption capacities as well as the high breakthrough times obtained in presence of water vapor make these activated carbons suitable for commercial applicationsSpanish Ministry of Environment (contracts 439/2006/3-11.2 and B030/2007/2-11.2)Peer reviewe

Proceso para la obtención de tamices moleculares de carbón

La presente invención describe un proceso en el que un precursor de carbón adecuado, como por ejemplo fibras de carbón, fibras de carbón activadas, carbones activos etc. se someten a un calentamiento en un horno microondas en condiciones de temperaturas elevadas y atmósfera inerte. Las particulares características de este calentamiento en microondas producen cambios en la textura porosa de los precursores en forma tal que los transforma en materiales que pueden ser denominados tamices moleculares de carbón. Los tamices moleculares así obtenidos presentan una selectividad para la separación de mezclas O2/N2, CO2/CH4, comparable a la de otros tamices moleculares de carbón obtenidos mediante otros métodos más complejos y costosos que el aquí descrito.Peer reviewe

Erratum to ‘Dissolution of LnYSiAlO glass (Ln=La or Ce) in aqueous media. I. Influence of the pH on hydrolysis mechanisms and kinetics'

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