In silico before in vivo: How to predict the heating efficiency of magnetic nanoparticles within the intracellular space

This work aims to demonstrate the need for in silico design via numerical simulation to produce optimal Fe 3 O 4 -based magnetic nanoparticles (MNPs) for magnetic hyperthermia by minimizing the impact of intracellular environments on heating efficiency. By including the relevant magnetic parameters, such as magnetic anisotropy and dipolar interactions, into a numerical model, the heating efficiency of as prepared colloids was preserved in the intracellular environment, providing the largest in vitro specific power absorption (SPA) values yet reported. Dipolar interactions due to intracellular agglomeration, which are included in the simulated SPA, were found to be the main cause of changes in the magnetic relaxation dynamics of MNPs under in vitro conditions. These results pave the way for the magnetism-based design of MNPs that can retain their heating efficiency in vivo, thereby improving the outcome of clinical hyperthermia experiments

Magnetic hyperthermia experiments with magnetic nanoparticles in clarified butter oil and paraffin: A thermodynamic analysis

In specific power absorption models for magnetic fluid hyperthermia (MFH) experiments, the magnetic relaxation time of nanoparticles (NPs) is known to be a fundamental descriptor of the heating mechanisms. The relaxation time is mainly determined by the interplay between the magnetic properties of NPs and the rheological properties of NPs’ environment. Although the role of magnetism in MFH has been extensively studied, the thermal properties of the NP medium and their changes during MFH experiments have been underrated so far. Herein, we show that ZnxFe3-xO4 NPs dispersed through different media with phase transition in the temperature range of experiment as clarified butter oil (CBO) and paraffin. These systems show nonlinear behavior of the heating rate within the temperature range of MFH experiments. For CBO, a fast increase at ~306 K is associated with changes in the viscosity (¿(T)) and specific heat (cp(T)) of the medium at its melting temperature. This increment in the heating rate takes place around 318 K for paraffin. The magnetic and morphological characterization of NPs together with the observed agglomeration of NPs above 306 and 318 K for CBO and paraffin, respectively, indicate that the fast increase in MFH curves could not be associated with the change in the magnetic relaxation mechanism, with Neél relaxation being dominant. In fact, successive experimental runs performed up to temperatures below and above the CBO and paraffin melting points resulted in different MFH curves due to agglomeration of NPs driven by magnetic field inhomogeneity during the experiments. Our results highlight the relevance of the thermodynamic properties of the system NP-medium for an accurate measurement of the heating efficiency for in vitro and in vivo environments, where the thermal properties are largely variable within the temperature window of MFH experiments

Adjusting the Neel relaxation time of Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles for optimal heat generation in magnetic hyperthermia

In this work it is shown a precise way to optimize the heat generation in high viscosity magnetic colloids, by adjusting the Neel relaxation time in core/shell bimagnetic nanoparticles, for magnetic fluid hyperthermia (MFH) applications. To pursue this goal, Fe3O4/ZnxCo1-xFe2O4 core/shell nanoparticles were synthesized with 8.5 nm mean core diameter, encapsulated in a shell of similar to 1.1 nm of thickness, where the Zn atomic ratio (Zn/(Zn + Co) at%) changes from 33 to 68 at%. The magnetic measurements are consistent with a rigid interface coupling between the core and shell phases, where the effective magnetic anisotropy systematically decreases when the Zn concentration increases, without a significant change of the saturation magnetization. Experiments of MFH of 0.1 wt% of these particles dispersed in water, in Dulbecco modified Eagles minimal essential medium, and a high viscosity butter oil, result in a large specific loss power (SLP), up to 150 W g(-1), when the experiments are performed at 571 kHz and 200 Oe. The SLP was optimized adjusting the shell composition, showing a maximum for intermediate Zn concentration. This study shows a way to maximize the heat generation in viscous media like cytosol, for those biomedical applications that require smaller particle sizes

Role of age and comorbidities in mortality of patients with infective endocarditis

Purpose: The aim of this study was to analyse the characteristics of patients with IE in three groups of age and to assess the ability of age and the Charlson Comorbidity Index (CCI) to predict mortality. Methods: Prospective cohort study of all patients with IE included in the GAMES Spanish database between 2008 and 2015. Patients were stratified into three age groups:<65 years, 65 to 80 years, and = 80 years.The area under the receiver-operating characteristic (AUROC) curve was calculated to quantify the diagnostic accuracy of the CCI to predict mortality risk. Results: A total of 3120 patients with IE (1327 < 65 years;1291 65-80 years;502 = 80 years) were enrolled.Fever and heart failure were the most common presentations of IE, with no differences among age groups.Patients =80 years who underwent surgery were significantly lower compared with other age groups (14.3%, 65 years; 20.5%, 65-79 years; 31.3%, =80 years). In-hospital mortality was lower in the <65-year group (20.3%, <65 years;30.1%, 65-79 years;34.7%, =80 years;p < 0.001) as well as 1-year mortality (3.2%, <65 years; 5.5%, 65-80 years;7.6%, =80 years; p = 0.003).Independent predictors of mortality were age = 80 years (hazard ratio [HR]:2.78;95% confidence interval [CI]:2.32–3.34), CCI = 3 (HR:1.62; 95% CI:1.39–1.88), and non-performed surgery (HR:1.64;95% CI:11.16–1.58).When the three age groups were compared, the AUROC curve for CCI was significantly larger for patients aged <65 years(p < 0.001) for both in-hospital and 1-year mortality. Conclusion: There were no differences in the clinical presentation of IE between the groups. Age = 80 years, high comorbidity (measured by CCI), and non-performance of surgery were independent predictors of mortality in patients with IE.CCI could help to identify those patients with IE and surgical indication who present a lower risk of in-hospital and 1-year mortality after surgery, especially in the <65-year group

Solar Energy Based Water Potabilization: Low-cost Technologies For Isolated Regions Of Latin America And The Caribbean

Low-cost technologies, based on the use of solar energy, are proposed in the framework of the OAS/AE/141/2001 project to provide safe drinking water in isolated rural populations of Latin America and the Caribbean, with scarce hydric and economical resources. The offered technologies are Solar Disinfection in Individual Units (SODIS-DSAUI), Arsenic Removal by Solar Oxidation (SORAS-RAOS) and Solar Heterogeneous Photocatalysis with Titanium Dioxide (HP). It was found that DSAUI can be applied in all cases for disinfection, although HP can treat simultaneously bacterial and chemical contamination. RAOS is efficient in synthetic samples but the applicability to real waters is very dependent on the water matrix. All results are described and discussed together with actions to impulse the application by disseminating the methods and educating the population.428742879Litter, M.I., Mansilla, H., (2001) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/aguapura/default.htm, Solar water disinfection in rural communities of Latin America, Project OEA/AE141. ISBN 987 43 6942 6, La PlataNavntoft, C., Dawidowski, L., Paladini, A., Blesa, M.A., Assessment of a simple UV radiation model for applications in photocatalytic systems in Argentina (2004) 12th SolarPACES Int. Symp., , Oaxaca, Mexico, OctoberWegelin, M., (2000) EAWAG News, 48. , 11-12, SeptemberWater & Sanitation in Developing Countries, , http:/www.sodis.ch, EAWAG-SANDECBlesa, M.A., Eliminación de contaminantes por fotocatálisis heterogénea (2001) CYTED VIII-G Network, , http://www.cnea.gov.ar/xxi/ambiental/CYTED/default.htm, Digital Grafic, La PlataHug, S., (2000) EAWAG News, 49. , 18-20, DecemberWegelin, M., Gechter, D., Hug, S., Mahmud, A., Motaleb, A., http://www.sandec.ch/WaterTreatment/Documents/SORAS.pdfLitter, M.I., (2002) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/aguapura/default.htm, Prospect of rural communities of Latin America for the application of low-cost technologies for water potabilization, Project OEA/AE141, La PlataIbáñez, J.A., Litter, M.I., Pizarro, R.A., (2003) J. Photochem. Photobiol. A: Chem., 157, p. 81Litter, M.I., Mansilla, H.D., (2003) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/aguapura/default.htm, Sunlight assisted arsenic removal in rural communities of Latin America, Project OEA/AE141, La PlataLitter, M.I., Jiménez González, A., (2004) Digital Grafic, , http://www.cnea.gov.ar/xxi/ambiental/agua-pura/default.htm, Advances in low-cost solar technologies for disinfection, decontamination and arsenic removal in waters of rural communities of Latin America (HP and RAOS methods), Project OEA/AE141, La PlataGarcía, M.G., D'hiriart, J., Giulitti, J., Lin, H., Custo, G., Del Hidalgo, M.V., Litter, M.I., Blesa, M.A., Solar light induced removal of arsenic from contaminated groundwater: The interplay of solar energy and chemical variables (2004) Solar Energy, 77, p. 60