Iron Oxide Core Research Articles

PEGlatyon-SPION surface functionalization with folic acid for magnetic hyperthermia applications

Superparamagnetic iron oxide nanoparticles (SPION) are of great interest for application in magnetic fluid hyperthermia (MFH) due to their heat generation capability in an external alternating magnetic field, besides biocompatibility, and surface properties. MFH has emerged as a promisor therapeutic approach for cancer treatment and is based in controlled heating tumor tissue through the accumulation of SPIONs within cancer cells. This work describes a new route for the preparation of folate-conjugated PEGylated SPIONs, which involves the attachment of such molecules at the surface through polycondensation reactions, without the need for coupling agents or prior modification on the species involved. The size of iron oxide cores obtained by transmission electron microscopy was about 12 nm. The conjugation of folate onto SPIONs was confirmed by FTIR spectroscopy. The folate conjugated nanoparticles were colloidal stable in PBS, presenting a hydrodynamic diameter of 109 ± 1 nm and PDI 0.148. The obtained folate-targeted PEGylated SPIONs showed superparamagnetic behavior with a saturation magnetization of 73.1 emu·g−1 at 300 K. Their specific absorption rate (SAR) ranged from 32.8 to 15.0 W g−1 in an alternating magnetic field of 10–16 kA m−1 and frequency of 420–203 kHz. The heat generated was sufficient to raise the sample temperature to the therapeutic range used in MFH establishing this system as promising candidates for use in MFH treatment.

Nonlinear elastic aspects of multi-component iron oxide core-shell nanowires by means of atom probe tomography, analytical microscopy, and nonlinear mechanics.

One-dimensional objects as nanowires have been proven to be building blocks in novel applications due to their unique functionalities. In the realm of magnetic materials, iron-oxides form an important class by providing potential solutions in catalysis, magnetic devices, drug delivery, or in the field of sensors. The accurate composition and spatial structure analysis are crucial to describe the mechanical aspects and optimize strategies for the design of multi-component NWs. Atom probe tomography offers a unique analytic characterization tool to map the (re-)distribution of the constituents leading to a deeper insight into NW growth, thermally-assisted kinetics, and related mechanisms. As NW-based devices critically rely on the mechanical properties of NWs, the appropriate mechanical modeling with the resulting material constants is also highly demanded and can open novel ways to potential applications. Here, we report a compositional and structural study of quasi-ceramic one-dimensional objects: α-Fe ⊕ α-FeOOH(goethite) ⊕ Pt and α-Fe ⊕ α-Fe3O4(magnetite) ⊕ Pt core–shell NWs. We provide a theoretical model for the elastic behavior with terms accounting for the geometrical and mechanical nonlinearity, prior and subsequent to thermal treatment. The as-deposited system with a homogeneous distribution of the constituents demonstrates strikingly different structural and elastic features than that of after annealing, as observed by applying atom probe tomography, energy-dispersive spectroscopy, analytic electron microscopy, and a micromanipulator nanoprobe system. During annealing at a temperature of 350 °C for 20 h, (i) compositional partitioning between phases (α-Fe, α-Fe3O4 and in a minority of α-Fe2O3) in diffusional solid–solid phase transformations takes place, (ii) a distinct newly-formed shell formation develops, (iii) the degree of crystallinity increases and (iv) nanosized precipitation of evolving phases is detected leading to a considerable change in the description of the elastic material properties. The as-deposited nanowires already exhibit a significantly large maximum strain (1–8%) and stress (3–13 GPa) in moderately large bending tests, which become even more enhanced after the annealing treatment resulting at a maximum of about 2.5–10.5% and 6–18 GPa, respectively. As a constitutive parameter, the strain-dependent stretch modulus undoubtedly represents changes in the material properties as the deformation progresses.

Continuously manufactured single-core iron oxide nanoparticles for cancer theranostics as valuable contribution in translational research.

Micromixer technology was used to manufacture magnetic single core iron oxide nanoparticles that combine imaging as well as therapeutic functions. In a continuous, scalable and highly controllable manner, synthesis with biocompatible educts via an aqueous synthesis route was performed. Size control by varying relevant process parameters e.g. temperature was confirmed by transmission electron microscopy measurements of experimental series demonstrating the exceptional size control and homogeneity. Furthermore, analytical centrifugation evidenced the stably dispersed state of the single core nanoparticles in aqueous media. Size controlled production of single-core iron oxide nanoparticles was used to design optimized nanoparticles with a core diameter of about 30 nm, showing high signal amplitudes in Magnetic Particle Imaging (MPI) as a promising MPI tracer material. Moreover, therapeutic potential of these particles in magnetic fluid hyperthermia was evaluated and specific absorption rates (SAR values) up to 1 kW per g(Fe) were obtained, which exceed the comparable SAR value of Resovist® by more than a factor of three. Relaxometry measurements clearly confirmed the capacity of these single-core magnetic nanoparticles to generate significant T2-weighted magnetic resonance imaging (MRI) contrast that potentially allows multimodal imaging for monitoring the particles in vivo in a theranostic application scenario. Finally, first cell viability and apoptosis tests on endothelial cells did not show any cytotoxicity certifying a good biocompatibility of the iron oxide nanoparticles. This microtechnological approach provides reproducible, scalable single core iron oxide nanoparticles as highly performing tracers for MPI diagnosis as well as efficient heat generators for hyperthermia therapy. These preliminary results contribute to translational research in image guided cancer therapy – a further step from basic research to future medicine.

Zero valent iron core-iron oxide shell nanoparticles as small magnetic particle imaging tracers.

Nanoparticle tracers with small sizes and large magnetization are critical for biomedical imaging and especially for magnetic particle imaging (MPI). Small size is important for accessing future intracellular and neurological in vivo applications Here, we show <15 nm nanoparticles made of zero valent iron cores, iron oxide shells and coated with a strongly binding brush co-polymer are effective MPI tracers. The small nanoparticle cores create a hydrodynamic diameter that is half of the state-of-the-art iron oxide tracers while the strongly magnetic zero valent iron maintains similar MPI signal magnitude and resolution.

Fe2O3-GaSb Synthesis as coaxial Nanowires for Optical Applications

A theoretical study shows the effect of the Gallium antimonide (GaSb) shell on several visual properties of the Iron (III) oxide (ferric oxide) Fe2O3 core as a nanowire using the Mie-Lorentz Scattering theory. The thickness of GaSb shell was fixed at around 20 nm with Fe2O3 core diameter of 20 nm. The study indicated that the nanowires of the Iron (III) oxide core have transmittance approximately 95% in the visible spectrum. Absorbance and low absorption coefficient in the Infrared (IR) are observed. Electronic transitions of the allowed direct type by the coaxial nanowire and reducing in the energy gap after adding the shell around the Fe2O3 to energy gap about 1.7 eV are also seen.

Silver-coated magnetic nanocomposites induce growth inhibition and protein changes in foodborne bacteria

Cytotoxicity concerns of nanoparticles on animal or human bodies have led to the design of iron oxide core nanocomposites, coated with elemental silver to allow their magnetic removal from bio-mixtures. Although the antimicrobial effect of silver is well-described, the effects of nanoparticles derived from silver on microorganisms remain unfolded. Here, we characterized a customized magnetic silver nanocomposite (Ag-MNP) and evaluated its effects on bacterial growth and protein changes. The Ag-MNP displayed both longitudinal and round shapes under High-Resolution Transmission Electron Microscopy imaging, while the Energy Dispersive X-ray Spectroscopy and X-ray diffraction analysis confirmed the presence of Ag, Fe3O4 (Magnetite) and FeO2 (Goethite). Optical density, bioluminescence imaging, and Colony Forming Unit assessments revealed that the presence of Ag-MNP induced strong dose-dependent bacteria (Escherichia coli O157:H7, Salmonella enterica serovar Typhimurium and S. Anatum) growth inhibition. The TEM imaging showed penetration and infiltration of bacteria by Ag-MNP, leading to membrane degeneration and vacuole formation. The presence of Ag-MNP led to fifteen up-regulated and nine down-regulated proteins (P < 0.05) that are involved in cell membrane synthesis, inhibition of protein synthesis, interference with DNA synthesis, and energy metabolism inhibition. This study provides insights to develop alternative antimicrobials to treat foodborne pathogens with antibiotic resistance avoidance.

Selective and rapid extraction of piroxicam from water and plasma samples using magnetic imprinted polymeric nanosorbent: Synthesis, characterization and application

Here, a selective nano-sized magnetic sorbent based on iron oxide (Fe3O4) core and molecular imprinted polymer (MIP) shell was synthesized and used as a selective sorbent for separation of piroxicam (PIX) from aqueous media. The magnetic MIP functionalized with NH2 group (Fe3O4@SiO2@NH2) was prepared by a surface imprinting approach. The characterization of the MMIP sorbent was carried out by scanning electron microscopy (SEM), infrared spectroscopy (FT-IR), X-ray diffraction (XRD), vibrating sample magnetometer (VSM), Brumauer-Emmett-Teller (BET) and Barrett–Joyner–Halenda (BJH) analyses. The results indicated that the magnetic sorbent were as microspherical nanoparticles with the average size of 50 nm, with well water-dispersibility and easily magnetically separation. The influence of the variables on PIX recovery including initial pH of sample solution, volume and concentration of the eluent, ultrasonic time, ionic strength, and the amount of MMIP were studied and optimized. The linear range (LR), relative standard deviation (RSD) and limit of detection (LOD = 3Sb/m) for determination of PIX were found to be 0.01–10.0 mg L−1, 2.56 % and 5.0 ng mL−1, respectively. The used Fe3O4@SiO2@NH2-MMIP sorbent can be regenerated with 2 ml of pure methanol, without any significant decrease in its adsorption affinity. The results demonstrated an enhanced affinity for the as-prepared MMIP toward the PIX compared to non-imprinted polymer.

Microstructure and chemical stability analysis of magnetic core coated with SILICA and functionalized with silane OTS

Aiming to develop hydrophobic magnetic nanoparticles that are resistant to aqueous acid mediums, the synthesis, characterization, and chemical stability analysis of a magnetite/maghemite magnetic core covered with silica and functionalized with silane OTS (NANO + SILICA + OTS) were investigated. The synthesis of the magnetic core was performed by the alkaline coprecipitation method. The coat, obtained by the sol-gel method, using TEOS silane, aims to protect the magnetic core when exposed to acidic environments. The OTS silane was used as modifier for the silica surface and provides hydrophobicity to the synthesized material; as a result, such nanoparticles are capable of being dispersed in an organic liquid. The obtained results revealed that the nanoparticles have a diameter size of approximately 10 nm, a high surface area, and a superparamagnetic behavior. The coating of the nanoparticles with silica gave the iron oxide core greater protection against oxidation and attack from acid environments. And NANO + SILICA + OTS concentrations of 20 g/L and 30 g/L in the organic fluid demonstrated that iron release from the nanoparticles to the aqueous phase was lower than 0.6% of the total iron mass, even after 24-h contact in an aqueous medium with an acidity of 2 mol/L. The obtained nanoparticles are suitable for applications, even in severe acid environments.

Aquatic toxicity of iron-oxide-doped microplastics to Chlorella pyrenoidosa and Daphnia magna

Novel metal-oxide-doped microplastic particles (MMPs) have become emerging particulate plastics. The toxicity of MMPs in the aquatic environment remains unknown yet. In this study, toxicological effects of a representative MMP (iron-oxide core) with the nominal diameter of 1 μm and two different surface functional groups, amine-modified (MPS (Fe)–NH2) and carboxyl-modified (MPS (Fe)–COOH) polystyrene, were investigated by toxicity testing using Chlorella pyrenoidosa and Daphnia magna. The aquatic toxicity of two microplastic particles (MPS-NH2 and MPS-COOH) with the same particle size and surface modification in the absence of iron-oxide core was also observed and compared. Results show that the toxicity of MPS (Fe)–NH2 to the studied organisms (in terms of median effective concentration) was greater than the MPS (Fe)–COOH and non-iron-oxide-doped microplastic particles. Moreover, the MMPs mainly contributed to the toxicity rather than their dissolved fraction. The accumulation (based on total Fe) of MPS (Fe)–NH2 in C. pyrenoidosa was higher than the MPS (Fe)–COOH at low effect concentrations. The observations by optical microscopy indicated that the MPS (Fe)–NH2 was heavily adsorbed on the surface and distributed over the antennae, carapace, and apical spine of D. magna body whereas the MPS (Fe)–COOH was mainly accumulated inside the digestive tract of the daphnia. Furthermore, the analysis of intracellular reactive oxygen species level and antioxidant capacity confirmed that the intensities of the toxic effects cannot be linked to oxidative stress induced by the particles in the algae and daphnids. This work provides valuable insights into the ecological effects of MMPs, which is helpful for the quantitative assessment of food chain transfer of microplastics.

MPI Phantom Study with A High-Performing Multicore Tracer Made by Coprecipitation.

Magnetic particle imaging (MPI) is a new imaging technique that detects the spatial distribution of magnetic nanoparticles (MNP) with the option of high temporal resolution. MPI relies on particular MNP as tracers with tailored characteristics for improvement of sensitivity and image resolution. For this reason, we developed optimized multicore particles (MCP 3) made by coprecipitation via synthesis of green rust and subsequent oxidation to iron oxide cores consisting of a magnetite/maghemite mixed phase. MCP 3 shows high saturation magnetization close to that of bulk maghemite and provides excellent magnetic particle spectroscopy properties which are superior to Resovist® and any other up to now published MPI tracers made by coprecipitation. To evaluate the MPI characteristics of MCP 3 two kinds of tube phantoms were prepared and investigated to assess sensitivity, spatial resolution, artifact severity, and selectivity. Resovist® was used as standard of comparison. For image reconstruction, the regularization factor was optimized, and the resulting images were investigated in terms of quantifying of volumes and iron content. Our results demonstrate the superiority of MCP 3 over Resovist® for all investigated MPI characteristics and suggest that MCP 3 is promising for future experimental in vivo studies.

Fe3O4@C particles synthesized with iron‐containing water treatment residuals and its potential for methylene blue removal

AbstractBACKGROUNDIron (Fe)‐containing groundwater treatment residual is a kind of waste from groundwater treatment plants, showing good potential to be reused. Attention has been paid to Fe‐based magnetic water treatment materials for their easy magnetic separation, and in the meantime, kinds of adsorbents were developed to address the severe global dyes pollution.RESULTSBlack magnetic material was obtained with using the iron‐containing wastes as iron source without adding other iron chemical reagents by hydrothermal reaction. The X‐ray diffraction (XRD), X‐ray photoelectron spectroscopy (XPS) and Fourier‐transform infrared (FTIR) results show that the product is comprised of crystalline iron(II,III) oxide (Fe3O4) core and amorphous carbon shell (Fe3O4@C), and the core‐shell structure can also been seen clearly in transmission electron microscopy (TEM) images. Vibrating sample magnetometer (VSM) result shows its saturation magnetization is 33.56 emu/g. This sample's sorption experiments for methylene blue (MB) removal were conducted, and the experiment results indicated that this sample could be used in a wide range of pH (5–12) and the adsorption might be a complex chemical diffusion process consisting of boundary layer effect due to kinetic modeling fitting analysis. The maximum sorption amount of MB was 16.33 and 19.13 mg/g, respectively at 298 K and 308 K. This sample after five regeneration cycles still had 72.1% MB removal rate.CONCLUSIONThe Fe3O4@C particles with good magnetism were synthesized successfully with Fe‐containing water treatment residuals, water treatment waste sludge, via a one‐step hydrothermal reaction, which could be of reasonable analogy for treating other Fe‐containing industrial waste. Furthermore, this sample could be used as adsorbent for MB molecules removal from dyed water with good reusability and easy magnetic separation. © 2019 Society of Chemical Industry

Magnetic Manganese Oxide Sweetgum-Ball Nanospheres with Large Mesopores Regulate Tumor Microenvironments for Enhanced Tumor Nanotheranostics.

An important objective of cancer nanomedicine is to improve the delivery efficacy of functional agents to solid tumors for effective cancer imaging and therapy. Stimulus-responsive nanoplatforms can target and regulate the tumor microenvironment (TME) for the optimization of cancer theranostics. Here, we developed magnetic manganese oxide sweetgum-ball nanospheres (MMOSs) with large mesopores as tools for improved cancer theranostics. MMOSs contain magnetic iron oxide nanoparticles and mesoporous manganese oxide (MnO2) nanosheets, which are assembled into gumball-like structures on magnetic iron oxides. The large mesopores of MMOSs are suited for cargo loading with chlorin e6 (Ce6) and doxorubicin (DOX), thus producing so-called CD@MMOSs. The core of magnetic iron oxides could achieve magnetic targeting of tumors under a magnetic field (0.25 mT), and the targeted CD@MMOSs may decompose under TME conditions, thereby releasing loaded cargo molecules and reacting with endogenous hydrogen peroxide (H2O2) to generate oxygen (O2) and manganese (II) ions (Mn2+). Investigation in vivo in tumor-bearing mice models showed that the CD@MMOS nanoplatforms achieved TME-responsive cargo release, which might be applied in chemotherapy and photodynamic therapy. A remarkable in vivo synergy of diagnostic and therapeutic functionalities was achieved by the decomposition of CD@MMOSs and coadministration with chemo-photodynamic therapy of tumors using the magnetic targeting mechanism. Thus, the result of this study demonstrates the feasibility of smart nanotheranostics to achieve tumor-specific enhanced combination therapy.

Protein Binding Effects of Dopamine Coated Titanium Dioxide Shell Nanoparticles

Non-targeted nanoparticles are capable of entering cells, passing through different subcellular compartments and accumulating on their surface a protein corona that changes over time. In this study, we used metal oxide nanoparticles with iron-oxide core covered with titanium dioxide shell (Fe3O4@TiO2), with a single layer of covalently bound dopamine covering the nanoparticle surface. Mixing nanoparticles with cellular protein isolates showed that these nanoparticles can form complexes with numerous cellular proteins. The addition of non-toxic quantities of nano-particles to HeLa cell culture resulted in their non-specific uptake and accumulation of protein corona on nanoparticle surface. TfRC, Hsp90 and PARP were followed as representative protein components of nanoparticle corona; each protein bound to nanoparticles with different affinity. The presence of nanoparticles in cells also mildly modulated gene expression on the level of mRNA. In conclusion, cells exposed to non-targeted nanoparticles show subtle but numerous changes that are consistent from one experiment to another.

Treatment of glioblastoma using multicomponent silica nanoparticles.

Glioblastomas (GBMs) remain highly lethal. This partially stems from the presence of brain tumor initiating cells (BTICs), a highly plastic cellular subpopulation that is resistant to current therapies. In addition to resistance, the blood-brain barrier limits the penetration of most drugs into GBMs. To effectively deliver a BTIC-specific inhibitor to brain tumors, we developed a multicomponent nanoparticle, termed Fe@MSN, which contains a mesoporous silica shell and an iron oxide core. Fibronectin-targeting ligands directed the nanoparticle to the near-perivascular areas of GBM. After Fe@MSN particles deposited in the tumor, an external low-power radiofrequency (RF) field triggered rapid drug release due to mechanical tumbling of the particle resulting in penetration of high amounts of drug across the blood-brain tumor interface and widespread drug delivery into the GBM. We loaded the nanoparticle with the drug 1400W, which is a potent inhibitor of the inducible nitric oxide synthase (iNOS). It has been shown that iNOS is preferentially expressed in BTICs and is required for their maintenance. Using the 1400W-loaded Fe@MSN and RF-triggered release, in vivo studies indicated that the treatment disrupted the BTIC population in hypoxic niches, suppressed tumor growth and significantly increased survival in BTIC-derived GBM xenografts.

Improving Longitudinal Transversal Relaxation Of Gadolinium Chelate Using Silica Coating Magnetite Nanoparticles.

Introduction and objectivePrecisely and sensitively diagnosing diseases especially early and accurate tumor diagnosis in clinical magnetic resonance (MR) scanner is a highly demanding but challenging task. Gadolinium (Gd) chelate is the most common T1 magnetic resonance imaging (MRI) contrast agent at present. However, traditional Gd-chelates are suffering from low relaxivity, which hampers its application in clinical diagnosis. Currently, the development of nano-sized Gd based T1 contrast agent, such as incorporating gadolinium chelate into nanocarriers, is an attractive and feasible strategy to enhance the T1 contrast capacity of Gd chelate. The objective of this study is to improve the T1 contrast ability of Gd-chelate by synthesizing nanoparticles (NPs) for accurate and early diagnosis in clinical diseases.MethodsReverse microemulsion method was used to coat iron oxide (IO) with tunable silica shell and form cores of NPs IO@SiO2 at step one, then Gd-chelate was loaded on the surface of silica-coated iron oxide NPs. Finally, Gd-based silica coating magnetite NPs IO@SiO2-DTPA-Gd was developed and tested the ability to detect tumor cells on the cellular and in vivo level.ResultsThe r1 value of IO@SiO2-DTPA-Gd NPs with the silica shell thickness of 12 nm was about 33.6 mM−1s−1, which was approximately 6 times higher than Gd-DTPA, and based on its high T1 contrast ability, IO@SiO2-DTPA-Gd NPs could effectively detect tumor cells on the cellular and in vivo level.ConclusionOur findings revealed the improvement of T1 relaxation was not only because of the increase of molecular tumbling time caused by the IO@SiO2 nanocarrier but also the generated magnetic field caused by the IO core. This nanostructure with high T1 contrast ability may open a new approach to construct high-performance T1 contrast agent.

Synthesis and characterization of molecularly imprinted magnetite nanomaterials as a novel adsorbent for the removal of heavy metals from aqueous solution

For simultaneous water purification from both inorganic and organic pollutants, a novel multifunctional hybrid nanoadsorbent has been produced. Molecularly imprinted (MI) magnetic submicron-particles with iron oxide core and silica shell (Fe3O4/SiO2) were used as a substrate for immobilization of different functions. The activity towards heavy metals was provided via attachment of ethylene diamine tetra acetate (EDTA) silica-coated magnetite nanomaterials; then their use in the immobilization of MI magnetite nanomaterials (Fe3O4/SiO2/Thermo sensitive/EDTA-CS) to the silica surface with subsequent chemical grafting of ethylene diamine tetra acetate (EDTA) on which coupling occurred via an chitosan bonding. XRD spectra revealed the cubic spinel nature of nanoparticles with an average particle size 20nm and have phase stability besides. In addition to this, monodispersity of the nanoparticles was confirmed due to the size distribution of the particles. The EDX study also established the elemental ratio of EDTA functionalized silica coated magnetite nanoparticles (Fe3O4/SiO2/Thermosensitive/EDTA-CS). FT-IR spectral analysis revealed that the successful grafting of –COOH functional groups from EDTA on the surface of silica coated magnetite nanoparticles. Magnetic properties are found to be super paramagnetic at room temperature analyzed by VSM. The functionalization of EDTA on the surface of silica coated magnetite nanoparticles provides –COOH group and –NH2 group to be bonded with heavy metals from contaminated water by physicochemical interactions (physisorption and chemisorption). The effects of the adsorption process were studied with these parameters such as pH, contact time, adsorbent dose, temperature, and initial concentration (heavy metals). The Langmuir, Freundlich and Temkin adsorption isotherm models were applied to describe equilibrium data. The desorption study, as well as its reusability and recyclability, were accessible that indicates magnetite nanocomposites succeeding adequately.

Fabrication and evaluation of novel quercetin-conjugated Fe3O4-β-cyclodextrin nanoparticles for potential use in epilepsy disorder.

BackgroundDespite the numerous pharmacological activities of quercetin, its biomedical application has been hampered, because of poor water solubility and low oral bioavailability. In the present study, we fabricated a novel form of quercetin-conjugated Fe3O4–β-cyclodextrin (βCD) nanoparticles (NPs), and the effect of these prepared NPs was evaluated in a chronic model of epilepsy.MethodsQuercetin-loaded NPs were prepared using an iron oxide core coated with βCD and pluronic F68 polymer. The chronic model of epilepsy was developed by intraperitoneal injection of pentylenetetrazole (PTZ) at dose of 36.5 mg/kg every second day. Quercetin or its nanoformulation at doses of 25 or 50 mg/kg were administered intraperitoneally 10 days before PTZ injections and their applications continued 1 hour before each PTZ injection. Immunostaining was performed to evaluate the neuronal density and astrocyte activation of hippocampi.ResultsOur data showed successful fabrication of quercetin onto Fe3O4–βCD NPs. In comparison to free quercetin, quercetin NPs markedly reduced seizure behavior, neuronal loss, and astrocyte activation in a PTZ-induced kindling model.ConclusionOverall, quercetin–Fe3O4–βCD NPs might be regarded as an ideal therapeutic approach in epilepsy disorder.

Doxorubicin-Loaded Thermoresponsive Superparamagnetic Nanocarriers for Controlled Drug Delivery and Magnetic Hyperthermia Applications.

This study reports on the development of thermoresponsive core/shell magnetic nanoparticles (MNPs) based on an iron oxide core and a thermoresponsive copolymer shell composed of 2-(2-methoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol)methacrylate (OEGMA) moieties. These smart nano-objects combine the magnetic properties of the core and the drug carrier properties of the polymeric shell. Loading the anticancer drug doxorubicin (DOX) in the thermoresponsive MNPs via supramolecular interactions provides advanced features to the delivery of DOX with spatial and temporal controls. The so coated iron oxide MNPs exhibit superparamagnetic behavior with a saturation magnetization of around 30 emu g-1. Drug release experiments confirmed that only a small amount of DOX was released at room temperature, while almost 100% drug release was achieved after 52 h at 42 °C with Fe3-δO4@P(MEO2MA60OEGMA40), which grafted polymer chains displaying a low critical solution temperature of 41 °C. Moreover, the MNPs exhibit magnetic hyperthermia properties as shown by specific absorption rate measurements. Finally, the cytotoxicity of the core/shell MNPs toward human ovary cancer SKOV-3 cells was tested. The results showed that the polymer-capped MNPs exhibited almost no toxicity at concentrations up to 12 μg mL-1, whereas when loaded with DOX, an increase in cytotoxicity and a decrease of SKOV-3 cell viability were observed. From these results, we conclude that these smart superparamagnetic nanocarriers with stealth properties are able to deliver drugs to tumor and are promising for applications in multimodal cancer therapy.

Magnetic Particle Imaging: Current Applications in Biomedical Research.

Magnetic particle imaging (MPI) is a new imaging modality with the potential for high-resolution imaging while retaining the noninvasive nature of other current modalities such as magnetic resonance imaging (MRI) and positron emission tomography (PET). It is able to track location and quantities of special superparamagnetic iron oxide nanoparticles without tracing any background signal. MPI utilizes the unique, intrinsic aspects of the nanoparticles: how they react in the presence of the magnetic field, and the subsequent turning off of the field. The current group of nanoparticles that are used in MPI are usually commercially available for MRI. Special MPI tracers are in development by many groups that utilize an iron-oxide core encompassed by various coatings. These tracers would solve the current obstacles by altering the size and material of the nanoparticles to what is required by MPI. In this review, the theory behind and the development of these tracers are discussed. In addition, applications such as cell tracking, oncology imaging, neuroimaging, and vascular imaging, among others, stemming from the implementation of MPI into the standard are discussed. Level of Evidence: 5 Technical Efficacy Stage: 3 J. Magn. Reson. Imaging 2020;51:1659-1668.

Fluorescent and magnetic stellate mesoporous silica for bimodal imaging and magnetic hyperthermia

There is currently a crucial need of innovative multifunctional nanoparticles combining, in one formulation, imaging and therapy capacities allowing thus an accurate diagnosis and a therapy monitored by imaging. Multimodal imaging will ensure to speed up diagnosis, and to increase its sensitivity, reliability and specificity for a better management of the disease. Combined with a therapeutic action, it will also enable to treat the disease in a specific personalized manner in feedback mode. The mastered design of such bioprobes as well as the demonstration of their efficiency are still challenges to face in nanomedicine. In this work, novel fluorescent and magnetic core–shell nanocomposites have been designed to ensure, in one nanoformulation, bimodal fluorescence and MRI imaging coupled with therapy by magnetic hyperthermia. They consist in the coating of a magnetic iron oxide (IO) core (ca.18nm diameter to ensure magnetic hyperthermia) by an original large pore stellate mesoporous silica (STMS) shell to produce uniform and mono-core magnetic core–shell nanocomposites denoted IO@STMS NPs. To confer fluorescence properties, CdSe/ZnS quantum dots (QDs) NPs were grafted inside the large pores of the IO@STMS nanocomposites. To provide biocompatibility and opsonization-resistance, a tightly-bound human serum albumin (HSA) coating is added around the nanocomposite using an original IBAM-based strategy. Cellular toxicity and non-specific cell–nanomaterial interactions allowed to determine a concentration range for safe application of these NPs. Cellular endosomes containing spontaneously-uptaken NPs displayed strong and photostable QD fluorescence signals while magnetic relaxivity measurements confirm their suitability as contrast agent for MRI. HeLa cell-uptaken NPs exposed to a magnetic field of 100kHz and 357Gauss (or 28.5kAm−1) display an outstanding 65% cell death at a very low iron concentration (1.25μgFemL−1), challenging current magnetic hyperthermia nanosystems. Furthermore, at the particularly demanding conditions of clinical use with low frequency and amplitude field (100kHz, 117Gauss or 9.3kAm−1), magnetic hyperthermia combined with the delivery of a chemotherapeutic drug, doxorubicin, allowed 46% cell death, which neither the drug nor the NPs alone yielded, evidencing thus the synergistic effect of this combined treatment.