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Ferroptosis, a form of iron-dependent, lipid peroxidation-driven cell death, has been extensively investigated in recent years, and several studies have suggested that the ferroptosis-inducing properties of iron-containing nanomaterials could be harnessed for cancer treatment. Here we evaluated the potential cytotoxicity of iron oxide nanoparticles, with and without cobalt functionalization (Fe2O3 and Fe2O3@Co-PEG), using an established, ferroptosis-sensitive fibrosarcoma cell line (HT1080) and a normal fibroblast cell line (BJ). In addition, we evaluated poly (ethylene glycol) (PEG)-poly(lactic-co-glycolic acid) (PLGA)-coated iron oxide nanoparticles (Fe3O4-PEG-PLGA). Our results showed that all the nanoparticles tested were essentially non-cytotoxic at concentrations up to 100 μg/mL. However, when the cells were exposed to higher concentrations (200–400 μg/mL), cell death with features of ferroptosis was observed, and this was more pronounced for the Co-functionalized nanoparticles. Furthermore, evidence was provided that the cell death triggered by the nanoparticles was autophagy-dependent. Taken together, the exposure to high concentrations of polymer-coated iron oxide nanoparticles triggers ferroptosis in susceptible human cancer cells.

Enzymes are selective, specific, efficient, and more sustainable catalysts than their chemical counterparts. From an industrial perspective, multienzymatic systems to produce chemical compounds are particularly attractive since they comply with most green production principles including the minimization of wastes and their ecological footprints. However, the number of industrial processes based on the use of enzymes as catalysts remains limited. Indeed, incompatibility issues of enzymes with respect to reaction conditions or cross-reactivity are still challenging aspects that make one-pot enzyme cascade reactions hard to perform. The urgent need for more sustainable industrial processes has made different research fields, not accustomed to working together, join efforts to develop innovative technologies that could be key enabling to overcome these challenges. Among these technologies are those that seek to synergistically integrate the specific recognition and unique catalytic properties of enzymes with the size-dependent unique properties of nanoparticles. However, rather than giving a complete overview of the use of nanomaterials in biocatalysts, here it will be discussed the feasibility of triggering magnetic nanoparticles (MNPs) into hotspots by remote nanoactuation for the thermal modulation of discrete enzyme molecules activity with minimal collateral heating., The possibility of heating discrete and defined local regions within a sample offers the potential to introduce a game-changing breakthrough in industrial biocatalysis by achieving coordinated enzyme function and thus concurrent multienzyme reactions. Therefore, not only the principles behind the activation of MNPs as hotspots, but also those examples that report the selective control of enzyme activity by magnetic heating, together with the foreseen challenges for the transfer of this technology to the industry, will be discussed.

Magnetic nanoparticles (MNPs) are widely used for immobilizing complex biomolecules such as proteins due to their high loading capacity, biocompatibility, and easy magnetic harvesting. However, there is not a universal solution to achieve the oriented immobilization of the protein of interest. One common strategy involves the selective binding of poly-histidine-tagged (His-tag) proteins to divalent transition metal centers (TM2+) chelated by organic molecules like nitrilotriacetic acid (NTA). This article describes an innovative procedure to functionalize MNPs by simply growing of a thin layer of TM2+ hydroxides on the MNP surface, which increases the number of coordination centers and enhances the surface interaction with the protein surface. The immobilization yields of two sets of MNPs coated with Co2+, Ni2+ and Cu2+ hydroxides were compared to the conventional coating using the same inorganic cores but coated and functionalized with NTA-TM2+ moieties. It is shown that the one-step Co coated MNPs showed the highest selectivity and specificity towards His-tags. Thus, this coating not only reduce the functionalization steps to drive an oriented protein binding but also achieve an increment of immobilization yields over 1.5-fold respect to NTA-Co2+ analogous for his-tagged proteins with different 3D complexity while preserving similar or even higher enzymatic activity.

Oriented and covalent immobilization of proteins on magnetic nanoparticles (MNPs) is particularly challenging as it requires both the functionality of the protein and the colloidal stability of the MNPs to be preserved. Here, we describe a simple, straightforward, and efficient strategy for MNP functionalization with proteins using metal affinity binding. Our method involves a single-step process where MNPs are functionalized using a preformed, ready-to-use nitrilotriacetic acid-divalent metal cation (NTA-M2+) complex and polyethylene glycol (PEG) molecules. As a proof-of-concept, we demonstrate the oriented immobilization of a recombinant cadherin fragment engineered with a hexahistidine tag (6His-tag) onto the MNPs. Our developed methodology is simple and direct, enabling the oriented bioconjugation of His-tagged cadherins to MNPs while preserving protein functionality and the colloidal stability of the MNPs, and could be extended to other proteins expressing a polyhistidine tag. When compared to the traditional method where NTA is first conjugated to the MNPs and afterward free metal ions are added to form the complex, this novel strategy results in a higher functionalization efficiency while avoiding MNP aggregation. Additionally, our method allows for covalent bonding of the cadherin fragments to the MNP surface while preserving functionality, making it highly versatile. Finally, our strategy not only ensures the correct orientation of the protein fragments on the MNPs but also allows for the precise control of their density. This feature enables the selective targeting of E-cadherin-expressing cells only when MNPs are decorated with a high density of cadherin fragments.

The present invention relates to a process to carry out two or more enzymatic reactions in a reaction medium, wherein the process comprises providing a system comprising at least two substantially homogeneous and colloidal populations of magnetic nanoparticles (MNPs) and applying one or more external alternating magnetic field to produce the simultaneous or sequential activation of the enzymes functionalized on the surface of each population of MNPs so that the enzymatic reactions can be thermally activated.

[EN] The present invention relates to a process to carry out two or more enzymatic reactions in a reaction medium, wherein the process comprises providing a system comprising at least two substantially homogeneous and colloidal populations of magnetic nanoparticles (MNPs) and applying one or more external alternating magnetic field to produce the simultaneous or sequential activation of the enzymes functionalized on the surface of each population of MNPs so that the enzymatic reactions can be thermally activated., [FR] La présente invention concerne un procédé pour effectuer deux ou plusieurs réactions enzymatiques dans un milieu réactionnel, le procédé comprenant la fourniture d'un système comprenant au moins deux populations sensiblement homogènes et colloïdales de nanoparticules magnétiques (MNPs) et l'application d'un ou plusieurs champs magnétiques alternatifs externes pour produire l'activation simultanée ou séquentielle des enzymes fonctionnalisées sur la surface de chaque population de MNPs de telle sorte que les réactions enzymatiques peuvent être activées thermiquement.

[EN] Tuning the magnetic properties of nanoparticles is a strategic goal to use them in the most effective way to perform specific functions in the nanomedicine field. We report a systematic study carried out on a set of samples obtained by mixing together iron oxide nanoparticles with different shape: elongated with aspect ratio ~5.2 and mean volume of the order of 103 nm3 (excluding the silica coating) and spherical with mean volume one order of magnitude larger. These structural features of the nanoparticles together with their aggregation state determine the magnetic anisotropy and the magnetic relaxation processes. In particular, the spherical nanoparticles turn out to be more stable against superparamagnetic relaxation. Mixing the nanoparticles in different proportions allows to modulate the magnetic response of the samples. The two populations of nanoparticles magnetically influence each other through a mean field mechanism, which depends crucially on temperature and rules the hysteretic magnetic properties and their thermal evolution. This magnetic phenomenology has a direct impact on the ability of the mixed samples to generate heat under an alternating magnetic field, a key function in view of nanomedicine applications. Under proper testing conditions, the heating efficiency of the mixed samples is larger compared to that obtained as the sum of those of the parent nanoparticles. This occurs thanks to the mean field produced by the magnetically blocked spherical nanoparticles that stabilizes the thermally fluctuating moments of the elongated ones, which therefore contribute more effectively to the heat production. This journal is

RESEARCHER ID M-9921-2014 (Isabel Izquierdo Barba) ORCID 0000-0002-4139-4646 (Isabel Izquierdo Barba) RESEARCHER ID K-4773-2015 (Blanca González Ortiz) ORCID 0000-0002-0493-6071 (Blanca González Ortiz) RESEARCHER ID M-3378-2014 (María Vallet Regí) ORCID 0000-0002-6104-4889 (María Vallet Regí), Nowadays, there is an ever-increasing interest in the development of systems able to guide and influence cell activities for bone regeneration. In this context, we have explored for the first time the combination of type-I collagen and superparamagnetic iron oxide nanoparticles (SPIONs) to design magnetic and biocompatible electrospun scaffolds. For this purpose, SPIONs with a size of 12 nm were obtained by thermal decomposition and transferred to an aqueous medium via ligand exchange with dimercaptosuccinic acid (DMSA). The SPIONs were subsequently incorporated into type-I collagen solutions to prove the processability of the resulting hybrid formulation by means of electrospinning. The optimized method led to the fabrication of nanostructured scaffolds composed of randomly oriented collagen fibers ranging between 100 and 200 nm, where SPIONs resulted distributed and embedded into the collagen fibers. The SPIONs-containing electrospun structures proved to preserve the magnetic properties of the nanoparticles alone, making these matrices excellent candidates to explore the magnetic stimuli for biomedical applications. Furthermore, the biological assessment of these collagen scaffolds confirmed high viability, adhesion, and proliferation of both preosteoblastic MC3T3-E1 cells and human bone marrow-derived mesenchymal stem cells (hBM-MSCs)., Europea. Horizonte 2020, Depto. de Química en Ciencias Farmacéuticas, Fac. de Farmacia, TRUE, pub

Tuning the fundamental properties of iron oxide magnetic nanoparticles (MNPs) according to the required biomedical application is an unsolved challenge, as the MNPs’ properties are affected by their composition, their size, the synthesis process, and so on. In this work, we studied the effect of zinc and manganese doping on the magnetic and structural properties of MNPs synthesized by the microwave-assisted polyol process, using diethylene glycol (DEG) and tetraethylene glycol (TEG) as polyols. The detailed morpho-structural and magnetic characterization showed a correspondence between the higher amounts of Mn and smaller crystal sizes of the MNPs. Such size reduction was compensated by an increase in the global magnetic moment so that it resulted in an increase of the saturation magnetization. Saturation magnetization MS values up to 91.5 emu/g and NMR transverse relaxivities r2 of 294 s−1mM−1 were obtained for Zn and Mn- doped ferrites having diameters around 10 nm, whereas Zn ferrites with diameters around 15 nm reached values of MS∼ 97.2 emu/g and of r2∼ 467 s−1mM−1, respectively. Both kinds of nanoparticles were synthesized by a simple, reproducible, and more sustainable method that makes them very interesting for diagnostic applications as MRI contrast agents.

Background Coronaviruses usually cause mild respiratory disease in humans but as seen recently, some human coronaviruses can cause more severe diseases, such as the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), the global spread of which has resulted in the ongoing coronavirus pandemic. Results In this study we analyzed the potential of using iron oxide nanoparticles (IONPs) coated with biocompatible molecules like dimercaptosuccinic acid (DMSA), 3-aminopropyl triethoxysilane (APS) or carboxydextran (FeraSpin™ R), as well as iron oxyhydroxide nanoparticles (IOHNPs) coated with sucrose (Venofer®), or iron salts (ferric ammonium citrate -FAC), to treat and/or prevent SARS-CoV-2 infection. At non-cytotoxic doses, IONPs and IOHNPs impaired virus replication and transcription, and the production of infectious viruses in vitro, either when the cells were treated prior to or after infection, although with different efficiencies. Moreover, our data suggest that SARS-CoV-2 infection affects the expression of genes involved in cellular iron metabolism. Furthermore, the treatment of cells with IONPs and IOHNPs affects oxidative stress and iron metabolism to different extents, likely influencing virus replication and production. Interestingly, some of the nanoparticles used in this work have already been approved for their use in humans as anti-anemic treatments, such as the IOHNP Venofer®, and as contrast agents for magnetic resonance imaging in small animals like mice, such as the FeraSpin™ R IONP. Conclusions Therefore, our results suggest that IONPs and IOHNPs may be repurposed to be used as prophylactic or therapeutic treatments in order to combat SARS-CoV-2 infection.

The Pechini method has been used as a synthetic route for obtaining self-assembling magnetic and plasmonic nanoparticles in hybrid silica nanostructures. This manuscript evaluates the influence of shaking conditions, reaction time, and pH on the size and morphology of the nanostructures produced. The characterization of the nanomaterials was carried out by transmission electron microscopy (TEM) to evaluate the coating and size of the nanomaterials, Fourier-transform infrared spectroscopy (FT-IR) transmission spectra to evaluate the presence of the different coatings, and thermogravimetric analysis (TGA) curves to determine the amount of coating. The results obtained show that the best conditions to obtain core–satellite nanostructures with homogeneous silica shells and controlled sizes (<200 nm) include the use of slightly alkaline media, the ultrasound activation of silica condensation, and reaction times of around 2 h. These findings represent an important framework to establish a new general approach for the click chemistry assembling of inorganic nanostructures., Ministerio de Ciencia e Innovación (España), Fac. de Medicina, TRUE, pub

It is well known that magnetic nanoparticles (MNPs) absorb magnetic energy when exposed to an alternating magnetic field (AMF) and therefore dissipate heat in their local environment. So far, the heat dissipated by the MNPs has been widely used in biomedicine for cancer treatment and drug delivery. The FET-OPEN project HOTZYMES proposes instead to exploit this property for the biotechnological production of pharmaceuticals and bio-commodities, by conjugating thermophilic enzymes on the MNPs surface in order to selectively tune their activity by triggering this highly localized magnetic heating while maintaining the reaction media at low temperature., To this aim superparamagnetic iron oxide nanoparticles coated with different organic shells (dimercaptusuccinic acid, DMSA; polyacrylic acid, PAA) have been selected due to their good colloidal stability, high density of functionalizable chemical groups (-COOH) and a good combination of different heating efficiencies. They have been further functionalized with NTA-Cu2+, a chelating agent commonly used in protein purification by metal affinity interaction. Herein, we demonstrate that we can selectively bind a His-tag variant of the superfolded GFP protein, thanks to the high affinity of the immobilized copper to the 6xhistidine tag genetically fused to the protein. Furthermore, using the same strategy, we were able to bind the tetrameric recombinant His-tag variant of the B. stearothermophilus alcohol dehydrogenase (ADH) with also high specificity. Additionally, we demonstrate that the application of an AMF to the selected protein@MNPs derivatives can lead to the generation of different temperature gradients on the MNPs surface by studying both the GFP fluorescence (that strongly depends on temperature), and the effect of the triggered local heating on ADH activity. These first results suggest the feasibility of tuning remotely protein properties by combining their coupling to MNPs with the application of alternating magnetic fields.

The histidine tag (His-tag) is one of the most used affinity-tag for protein purification due to its small size and versatility. Agarose and sepharose beads containing nitriloacetic acid (NTA) transition metal derivatives are widely used for the purification of His-tagged proteins, thanks to their high affinity to the His-tag genetically fused to the protein of interest [1]. The same chemistry can be used to conjugate enzymes to magnetic nanoparticles (MNPs) with the aim of tuning their activity by magnetic heating [2, 3]. Within the frame of the FET-OPEN project HOTZYMES (https://www.hotzymes.eu), different MNPs have been synthetized and coated with polyacrylic acid and dimercaptosuccinic acid, and then were further functionalized with NTA-Cu2+ as His-tag chelating agent. Different proteins were expressed as His-tag variants and immobilized on the MNPs, including monomeric (superfolded GFP), dimeric (C. violaceum transaminase, CvTA; C. uda cellobiose phosphorylase, CuCbP), and tetrameric (B. stearothermophilus alcohol dehydrogenase, ADH) variants. While for the monomeric protein selected as model no difficulties in the bioconjugation processes were observed, when using dimeric or tetrameric enzymes the aggregation of the MNPs occurs very easily due to crosslinking between the nanoparticles. This colloidal destabilization of the MNPs is favored due to its high surface area and the presence of several tags per enzyme molecule. To avoid this situation, different strategies have been developed: saturation of the binding site of the nanoparticles, presence of a small percentage of imidazole in reaction, changes in the incubation conditions (pH, ionic strength, …). First positive results confirm that by playing with different factors it is possible to conjugate different His-tagged enzymes to very different MNPs in terms of size, shape, surface area, and colloidal stability. Actually, it is possible to avoid protein and MNPs aggregation while obtaining good activity yiel

The contactless heating capacity of magnetic nanoparticles (MNPs) has been exploited in fields such as hyperthermia cancer therapy, catalysis, and enzymatic thermal regulation. Herein, we propose an advanced technology to generate multiple local temperatures in a single-pot reactor by exploiting the unique nanoheating features of iron oxide MNPs exposed to alternating magnetic fields (AMFs). The heating power of the MNPs depends on their magnetic features but also on the intensity and frequency conditions of the AMF. Using a mixture of diluted colloids of MNPs we were able to generate a multi-hot-spot reactor in which each population of MNPs can be selectively activated by adjusting the AMF conditions. The maximum temperature reached at the surface of each MNP was registered using independent fluorescent thermometers that mimic the molecular link between enzymes and MNPs. This technology paves the path for the implementation of a selective regulation of multienzymatic reactions.

[EN] In this study, we evaluate the magnetic properties and cytotoxic effect of magnetic nanoparticles (MNPs) based on magnetite and Mn, Co and Ni ferrites, obtained by electrochemical synthesis. These nanoparticles have almost spherical shape and an mode size of 9±1 nm. The electrochemical synthesis produces a single crystallographic phase with a spinel-like structure in all cases. Magnetization saturation at room temperature varies with the composition of the ferrites from M S (Fe3O4) > M S (MnFe2O4) > M S (CoFe2O4) > M S (NiFe2O4). Ferrite MNPs present low magnetic remanence indicating a superparamagnetic-like response at room temperature. However, the different values of magnetic anisotropy and size produce variations in the values of coercivity and susceptibility of the ferrite MNPs. The cytotoxicity of the different ferrites was evaluated by internalizing MNP in HeLa cancer cells. Although magnetite and Mn ferrite present low toxicity for all the concentrations studied, significant cytotoxic effect were observed when incubating the cells with high concentration of Co and Ni ferrites.

©2019 American Scientific Publishers The authors thank MINECO (Spain) for financial support under project MAT2015-67557-C2-2-P and MAT2015-67557-C2-1-P. Jesus Garcia Ovejero thanks to the MINECO for the FPI scholarship., In this study, we evaluate the magnetic properties and cytotoxic effect of magnetic nanoparticles (MNPs) based on magnetite and Mn, Co and Ni ferrites, obtained by electrochemical synthesis. These nanoparticles have almost spherical shape and an mode size of 9 +/- 1 nm. The electrochemical synthesis produces a single crystallographic phase with a spinel-like structure in all cases. Magnetization saturation at room temperature varies with the composition of the ferrites from M_S (Fe_3O_4) > M_S (MnFe_2O_4) > M_S (CoFe_2O_4) > M_S (NiFe_2O_4). Ferrite MNPs present low magnetic remanence indicating a superparamagnetic-like response at room temperature. However, the different values of magnetic anisotropy and size produce variations in the values of coercivity and susceptibility of the ferrite MNPs. The cytotoxicity of the different ferrites was evaluated by internalizing MNP in HeLa cancer cells. Although magnetite and Mn ferrite present low toxicity for all the concentrations studied, significant cytotoxic effect were observed when incubating the cells with high concentration of Co and Ni ferrites., Ministerio de Economia y Competitividad (MINECO), Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

In this paper Co/CoO thick layers (hundreds of nanometers) of different porosity and oxidation degree were prepared in a magnetron sputtering deposition process by tailoring the DC sputtering power, as well as the process gas and target composition. The control of the synthesis parameters allowed the nanostructuration of the films with a singular distribution of closed pores and a controlled amount of CoO. We observed an exchange bias field of 2.8 KOe for porous Co/CoO composites, similar to Co/CoO bilayers but for coatings thicker than 300 nm. Besides, it was observed that the coating presents bistable magnetic features when cooled under zero field conditions as a result of the unusual exchange coupling.

© The Royal Society of Chemistry. The authors would like to thank the Dr. Ueslen Silva and Prof. Daniel Jaque for their help with the initial test of these systems. This work was supported by the Spanish Ministry of Science and Innovation: MAT2015-67557-C2-2-P and MAT2015-67557-C2-2-P. Financial support from COST Action TD1402 RADIOMAG for a STSM at LPCNO, Tolouse, is also acknowledged., The present manuscript reports the use of hybrid magneto-plasmonic nanoparticles (HMPNPs) based on iron oxide nanoparticles and Au nanorods as colloidal nanoheaters. The individual synthesis of the magnetic and plasmonic components allowed optimizing their features for heating Performance separately, before they were hybridized. Besides, a detailed characterization and finite element simulations were carried out to explain the interaction effects observed between the phases of the HMPNPs. The study also analyzed the heating power of these nanostructures when they were excited with infrared light and AC magnetic fields, and compared this with the heating power of their plasmonic and magnetic components. In the latter case, the AC magnetization curves revealed that the magnetic dipolar interactions increase the amount of heat released by the hybrid nanostructures., Ministerio de Ciencia e Innovación (MICINN), COST Action, ERC Advanced Grant, Depto. de Física de Materiales, Fac. de Ciencias Físicas, TRUE, pub

Iron oxide nanoparticles have found an increasing number of biomedical applications as sensing or trapping platforms and therapeutic and/or diagnostic agents. Most of these applications are based on their magnetic properties, which may vary depending on the nanoparticle aggregation state and/or concentration. In this work, we assess the effect of the inter- and intra-aggregate magnetic dipolar interactions on the heat dissipation power and AC hysteresis loops upon increasing the nanoparticle concentration and the hydrodynamic aggregate size. We observe different effects produced by inter- (long distance) and intra-aggregate (short distance) interactions, resulting in magnetizing and demagnetizing effects, respectively. Consequently, the heat dissipation power under alternating magnetic fields strongly reflects such different interacting phenomena. The intra-aggregate interaction results were successfully modeled by numerical simulations. A better understanding of magnetic dipolar interactions is mandatory for achieving a reliable magnetic hyperthermia response when nanoparticles are located into biological matrices.

FePt nanoparticles (NPs) and colloidal nanoparticle clusters (CNCs) have been synthesized by the reduction of platinum acetylacetonate (Pt(acac)) combined with thermal decomposition of iron pentacarbonyl (Fe(CO)) and compared to pure Pt NPs and CNCs for the catalytic activity of the oxygen reduction (ORR). The formation of NPs and CNCs has been carried out controlling injection temperature of the precursors and the surfactants during the synthesis. The size of the NPs and the CNCs formed is around 3 and 38 nm, respectively. High electrocatalytic performance of the FePt CNCs in comparison with that of nanoparticles and nanocluster of platinum has been obtained for the reduction reaction (ORR) in basic medium. The ORR is carried out by a four-electron charge transfer. The increase in the activity of the CNC structures formed by FePt nanoparticles can be attributed to the alloy formation that produces surface and electronic changes of the Pt atoms and to the structure of the CNCs obtained.

(Fe, Ni, CoFe) @ Au core-shell magnetic nanowires have been synthesized by optimized two-step potentiostatic electrodeposition inside self-assembled nanopores of anodic aluminium templates. The optimal electrochemical parameters (e.g., potential) have been firstly determined for the growth of continuous Au nanotubes at the inner wall of pores. Then, a magnetic core was synthesized inside the Au shells under suitable electrochemical conditions for a wide spectrum of single elements and alloy compositions (e.g., Fe, Ni and CoFe alloy). Novel opportunities offered by such nanowires are discussed particularly, the magnetic behavior of (Fe, Ni, CoFe) @ Au core-shell nanowires was tested and compared with that of bare nanowires. These core-shell nanowires can be released from the template thereby opening novel opportunities for biofunctionalization of individual nanowires.