Inorganic multifunctional nanostructures based on iron oxide

Tesis Doctoral inédita leída en la Universidad Autónoma de Madrid, Facultad de Ciencias, Departamento de Física Aplicada. Fecha de lectura: 31-03-2017Esta tesis tiene embargado el acceso al texto completo hasta el 30-09-2018Los sistemas coloidales constituidos por nanopartículas magnéticas constituyen en la actualidad uno de los sistemas más estudiados debido a su gran potencial en el campo de la biotecnología. El presente trabajo estudia comparativamente la síntesis y la caracterización química, estructural y magnética tanto de nanopartículas de tamaños menores de 15 nm obtenidas por la técnica estándar de coprecipitación, como de nanocristales magnéticos de óxido de hierro de mayor tamaño (30-100 nm) obtenidos por precipitación oxidante (capítulos 2-4). Además, debido a la necesidad de aportar nuevas funcionalidades a las partículas para ampliar su campo de aplicación, se han sintetizado nuevos nanocristales bimetálicos adaptando la precipitación oxidante a este fin (capítulo 5). Las muestras con mejores características se han dispersado y recubierto con diferentes moléculas para obtener suspensiones coloidales estables. Estas moléculas, además, presentan grupos terminales activos lo que permitiría una funcionalización posterior de las partículas con biomoléculas que proporcionen características especiales (capítulo 6). Por último, debido a las propiedades que presentan las nanopartículas magnéticas relacionadas con el tratamiento y diagnóstico del cáncer, las muestras seleccionadas y estabilizadas se han evaluado para su utilización en tratamientos de hipertermia magnética y como agentes de contraste para resonancia magnética de imagen. También se han llevado a cabo estudios preliminares de toxicidad que han consistido en el análisis de la interacción de las nanopartículas con el medio celular y con diferentes líneas celulares (capítulo7)

Safety assessment of chronic oral exposure to iron oxide nanoparticles

Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.Peer Reviewe

Doped-iron oxide nanocrystals synthesized by one-step aqueous route for multi-imaging purposes

New doped inorganic nanocrystals (NC) consisting on iron oxide and other metal integrated into the structure have been synthesized in one-step by adapting the oxidant precipitation synthesis route for magnetite. Different metals have been chosen to confer extra and unique properties to the resulting magnetic hetero-nanostructure: Co and Gd for enhancing transversal and longitudinal relaxivities for magnetic resonance imaging and Bi and Au for achieving X-ray absorption for computed tomography imaging. Apart of that, gold optical properties are interesting for photothermal therapy and iron oxides for magnetic hyperthermia. All metals have been incorporated into the magnetite structure in different ways during the synthesis: by forming a solid solution, by modifying the surface of the NCs, or by co-crystallization with the magnetite. The nanostructure formed in each case depends on the ionic radius of the secondary metal ion and the solubility of its hydroxide that control the co-precipitation in the initial steps of the reaction. Magnetic properties and imaging capabilities of the hetero-nanostructures have been analyzed as a function of the element distribution. Due to the synergistic combination of the different element properties, these magnetic hetero-nanostructures have great potential for biomedical applications

Synthesis of a theranostic platform based on fibrous silica nanoparticles for the enhanced treatment of triple-negative breast cancer promoted by a combination of chemotherapeutic agents.

A new series of theranostic silica materials based on fibrous silica particles acting as nanocarriers of two different cytotoxic agents, namely, chlorambucil and an organotin metallodrug have been prepared and structurally characterized. Besides the combined therapeutic activity, these platforms have been decorated with a targeting molecule (folic acid, to selectively target triple negative breast cancer) and a molecular imaging agent (Alexa Fluor 647, to enable their tracking both in vitro and in vivo). The in vitro behaviour of the multifunctional silica systems showed a synergistic activity of the two chemotherapeutic agents in the form of an enhanced cytotoxicity against MDA-MB-231 cells (triple negative breast cancer) as well as by a higher cell migration inhibition. Subsequently, the in vivo applicability of the siliceous nanotheranostics was successfully assessed by observing with in vivo optical imaging techniques a selective tumour accumulation (targeting ability), a marked inhibition of tumour growth paired to a marked antiangiogenic ability after 13 days of systemic administration, thus, confirming the enhanced theranostic activity. The systemic nanotoxicity was also evaluated by analyzing specific biochemical markers. The results showed a positive effect in form of reduced cytotoxicity when both chemotherapeutics are administered in combination thanks to the fibrous silica nanoparticles. Overall, our results confirm the promising applicability of these novel silica-based nanoplatforms as advanced drug-delivery systems for the synergistic theranosis of triple negative breast cancer.We would like to thank the funding of the Ministerio de Ciencia e Innovación of Spain (former Ministerio de Ciencia Innovación y Universidades of Spain) and FEDER, Una manera de hacer Europa for the grant number RTI2018-094322-B-I00. We would also like to thank Comunidad de Madrid for the predoctoral grant PEJD-2017-PRE/BMD3512 (I.M.-P.). M.M, Y.L.M., and M.F. are grateful to the Comunidad Autónoma de Madrid and FEDER for the I + D collaborative Programme in Biomedicine NIETO-CM (Project reference B2017-BMD3731). M.F. and K.O.P. thank the Comunidad Autonoma ´ de Madrid for research project No. 2017-T1/BIO-4992 (“Atraccion ´ de Talento” Action) cofunded by Universidad Complutense de Madrid. M.F is grateful to Instituto de Salud Carlos III (ISCIII) for project No DTS20/00109 (AES-ISCIII). M. M., M.F. and L.L.C would also like to thank Comunidad de Madrid for the predoctoral grant IND2020/BIO-17523. M.F. and K.O.P. acknowledge the support of Microscopy & Dynamic Imaging Unit of CNIC, Madrid, Spain. The Unit is part of the ReDiB-ICTS and has the support of FEDER, “Una manera de hacer Europa.” The CNIC is supported by the Instituto de Salud Carlos III (ISCIII), the Ministerio de Ciencia e Innovacion ´ (MCIN) and the Pro CNIC Foundation, and is a Severo Ochoa Center of Excellence (grant CEX2020-001041-S funded by MICIN/AEI/10.13039/ 501100011033).S

Fine Control of In Vivo Magnetic Hyperthermia Using Iron Oxide Nanoparticles with Different Coatings and Degree of Aggregation

Cancer; Magnetic hyperthermia; NanoparticlesCáncer; Hipertermia magnética; NanopartículasCàncer; Hipertèrmia magnètica; NanopartículesThe clinical implementation of magnetic hyperthermia has experienced little progress since the first clinical trial was completed in 2005. Some of the hurdles to overcome are the reliable production of magnetic nanoparticles with controlled properties and the control of the temperature at the target tissue in vivo. Here, forty samples of iron oxide superparamagnetic nanoparticles were prepared by similar methods and thoroughly characterized in terms of size, aggregation degree, and heating response. Selected samples were intratumorally administered in animals with subcutaneous xenografts of human pancreatic cancer. In vivo experiments showed that it is possible to control the rise in temperature by modulating the field intensity during in vivo magnetic hyperthermia protocols. The procedure does not require sophisticated materials and it can be easily implemented by researchers or practitioners working in magnetic hyperthermia therapies.This research was funded by European Commission H2020 programme (NoCanTher project, grant agreement no. 685795), the Ministerio de Ciencia e Innovación (PID2019-106301RB-I00), Comunidad de Madrid (Consejería de Educación e Investigación, NANOMAGCOST-CM, ref. P2018/NMT-4321), COST actions MyWave (CA17115) and Nano2Clinic (CA17140). MICINN “Redes de Investigación” (RED2018-102626-T). IMDEA Nanociencia acknowledges support from the ‘Severo Ochoa’ Programme for Centres of Excellence in R&D (MINECO, CEX2020-001039-S)

Combining Ag and γ-Fe2O3 properties to produce effective antibacterial nanocomposites

The antibacterial activity of hybrid γ-Fe2O3/Ag nanocomposites against the bacterial pathogens E. coli (Gram-negative) and S. aureus (Gram-positive) has been studied. Silver is a well-known bactericidal agent and γ-Fe2O3 nanoparticles release heat when they are exposed to alternating magnetic fields. The combination of both properties to fight infections has not been previously explored. The nanocomposites were synthesized through reduction of silver nitrate in the presence of pre-synthesized superparamagnetic γ-Fe2O3 nanoparticles. Changing systematically the ratio of γ-Fe2O3 and silver precursor and the temperature of the reaction allowed obtaining superparamagnetic nanocomposites with different Ag contents and particle sizes. The antibacterial activity of the samples was tested, and the minimum inhibitory concentrations and minimum bactericidal concentrations of the nanocomposites were determined to compare the microbicidal activity of the samples. It was found that it is related with the release of silver ions from the nanocomposites. Finally, we studied the combination of the bactericidal effect of silver and magnetic hyperthermia finding a synergetic effect between them when plates containing E. coli or S. aureus bacteria with γ-Fe2O3/Ag nanocomposites were subjected to an alternating magnetic field. This effect is related with an increase in the release of silver ions due to that heat dissipation.This work has been partially funded by the Spanish Ministry of Economy and Competitiveness (projects SAF2017-87305-R and MAT2015-71806-R), the Madrid Regional Government (NANOMAGCOST-CM P2018/NMT-4321) and the European Commission’s H2020 program (NoCanTher project, grant agreement No. 685795)

Counterion and solvent effects on the size of magnetite nanocrystals obtained by oxidative precipitation

We present the effect of the counterions and the proportion of ethanol in the preparation of uniform magnetite nanocrystals by oxidative precipitation. In this work we compared the materials produced using iron(II) chloride, bromide and sulfate, sodium and potassium nitrates and hydroxides in water and ethanol 25%–water solution. The process was followed by chemical analysis of the remaining iron(II), and the variation of the pH. The magnetite nanoparticles were characterized by X-ray powder diffraction, transmission electron microscopy and specific surface area. Although the final product was always magnetite nanocrystals, the morphology and particle size distributions depended significantly on the nature of the counterions and the ethanol content. The morphologies observed ranged between cubic and octahedral depending on the size. Particle sizes were correlated with the Hofmeister scale that reflects the influence of the cosmotropic or caotropic character of the counterions in water or in water/ethanol mixtures. The Hofmeister effect accounts for the competition that occurs between the counterions and the magnetite precursors for the water molecules. The main conclusion is that cosmotropic counterions in the presence of ethanol favor the nucleation of magnetite and generate smaller nanocrystals. Nanoparticle size variations are greater than 50%, which is extremely relevant to their magnetic properties and therefore to their biomedical applications.This work was partially supported by grant No. MAT2014-52069-R from the Spanish Ministry of Economy and Competitiveness and the NanoMag project from the European Commission Framework Program 7 under grant agreement No. 604448. Lucía Gutiérrez acknowledges financial support from the Ramón y Cajal subprogram (RYC-2014-15512).Peer reviewe

Different cell responses induced by exposure to maghemite nanoparticles

Recent advances in nanotechnology have permitted the development of a wide repertoire of inorganic magnetic nanoparticles (NPs) with extensive promise for biomedical applications. Despite this remarkable potential, many questions still arise concerning the biocompatible nature of NPs when in contact with biological systems. Herein, we have investigated how controlled changes in the physicochemical properties of iron oxide NPs at their surface (i.e., surface charge and hydrodynamic size) affect, first, their interaction with cell media components and, subsequently, cell responses to NP exposure. For that purpose, we have prepared iron oxide NPs with three different coatings (i.e., dimercaptosuccinic acid-DMSA, (3-aminopropyl)triethoxysilane-APS and dextran) and explored the response of two different cell types, murine L929 fibroblasts and human Saos-2 osteoblasts, to their exposure. Interestingly, different cell responses were found depending on the NP concentration, surface charge and cell type. In this sense, neutral NPs, as those coated with dextran, induced negligible cell damage, as their cellular internalization was significantly reduced. In contrast, surface-charged NPs (i.e., those coated with DMSA and APS) caused significant cellular changes in viability, morphology and cell cycle under certain culture conditions, as a result of a more active cellular internalization. These results also revealed a particular cellular ability to detect and remember the original physicochemical properties of the NPs, despite the formation of a protein corona when incubated in culture media. Overall, conclusions from these studies are of crucial interest for future biomedical applications of iron oxide NPs. © 2013 The Royal Society of Chemistry.Peer Reviewe

Safety assessment of chronic oral exposure to iron oxide nanoparticles

Iron oxide nanoparticles with engineered physical and biochemical properties are finding a rapidly increasing number of biomedical applications. However, a wide variety of safety concerns, especially those related to oral exposure, still need to be addressed for iron oxide nanoparticles in order to reach clinical practice. Here, we report on the effects of chronic oral exposure to low doses of γ-Fe2O3 nanoparticles in growing chickens. Animal observation, weight, and diet intake reveal no adverse signs, symptoms, or mortality. No nanoparticle accumulation was observed in liver, spleen, and duodenum, with feces as the main excretion route. Liver iron level and duodenal villi morphology reflect the bioavailability of the iron released from the partial transformation of γ-Fe2O3 nanoparticles in the acid gastric environment. Duodenal gene expression studies related to the absorption of iron from γ-Fe2O3 nanoparticles indicate the enhancement of a ferric over ferrous pathway supporting the role of mucins. Our findings reveal that oral administration of iron oxide nanoparticles is a safe route for drug delivery at low nanoparticle doses.Peer Reviewe