Effect of ultrasmall superparamagnetic iron oxide nanoparticles (Ferumoxtran-10) on human monocyte-macrophages in vitro

Protein-Free Hapten-Carbon Nanotube Constructs Induce the Secondary Immune Response

Carbon nanotubes are novel technological tools with multiple applications. The interaction between such nanoparticles and living organisms is nowadays a matter of keen research by academic and private institutions. In this study, carbon nanotube constructs were investigated as delivery vehicles for immunostimulation and induction of the secondary immune response to a small organic molecule, namely, a hapten. Two types of nanoconstructs were prepared: on one hand, carbon nanotubes carrying a protein bioconjugate of a hapten covalently linked to the carbon surface, and on the other hand, covalent carbon nanotube constructs of the same model chemical compound without the carrier protein. Nanotube vehicles carrying a hapten-protein bioconjugate were demonstrated to stimulate the immune system and to induce a strong primary immune response against the hapten with as low as 0.1 μg of the model chemical. The influence of the different elements of those nanoconstructs over the immune response was investigated to better understand the molecular mechanisms that are involved. As expected, the presence of the carrier protein was shown to be necessary in order to trigger the immune response. Interestingly, we found that a remarkable secondary immune response to the model organic compound occurred in the absence of a carrier protein. Additionally, a satisfactory adjuvant effect of carbon nanotubes was observed and a potent immune response was elicited without employing an oil-based adjuvant.

Iron oxide nanoparticles and induced autophagy in human monocytes

Superparamagnetic iron oxide nanoparticles have been widely used in biomedical applications, but understanding of their interactions with the biological immune system is relatively limited. This work is focused on dextran-coated iron oxide nanoparticles and their induced autophagy in human monocytes. We found that these nanoparticles can be taken up by human monocytes, followed by localization within vesicles or free in cytoplasm. Autophagosome formation was observed with increased expression of LC3II protein, the specific marker of autophagy. The autophagy substrate p62 was degraded in a dose-dependent manner, and autophagy was blocked by autophagy (or lysosome) inhibitors alone or along with iron oxide nanoparticles, indicating that autophagosome accumulation was mainly due to autophagy induction, rather than blockade of autophagy flux. Interestingly, iron oxide nanoparticles increased the viability of human monocytes, but the mechanism was not clear. We further found that inhibition of autophagy mostly attenuated the survival of cells, with acceleration of the inflammation induced by these nanoparticles. Taken together, autophagic activation in human monocytes may play a protective role against the cytotoxicity of iron oxide nanoparticles.

The effect of core and lanthanide ion dopants in sodium fluoride-based nanocrystals on phagocytic activity of human blood leukocytes

Sodium fluoride-based β-NaLnF4 nanoparticles (NPs) doped with lanthanide ions are promising materials for application as luminescent markers in bio-imaging. In this work, the effect of NPs doped with yttrium (Y), gadolinium (Gd), europium (Eu), thulium (Tm), ytterbium (Yb) and terbium (Tb) ions on phagocytic activity of monocytes and granulocytes and the respiratory burst was examined. The surface functionalization of <10-nm NPs was performed according to our variation of patent pending ligand exchange method that resulted in meso-2,3-dimercaptosuccinic acid (DMSA) molecules on their surface. Y-core-based NCs were doped with Eu ions, which enabled them to be excited with UV light wavelengths. Cultures of human peripheral blood (n = 8) were in vitro treated with five different concentrations of eight NPs for 24 h. In summary, neither type of nanoparticles is found toxic with respect to conducted test; however, some cause toxic effects (they have statistically significant deviations compared to reference) in some selected doses tested. Both core types of NPs (Y-core and Gd-core) impaired the phagocytic activity of monocytes the strongest, having minimal or none whatsoever influence on granulocytes and respiratory burst of phagocytic cells. The lowest toxicity was observed in Gd-core, Yb, Tm dopants and near-infrared nanoparticles. Clear dose-dependent effect of NPs on phagocytic activity of leukocytes and respiratory burst of cells was observed for limited number of samples.

Toxicity of antimony, copper, cobalt, manganese, titanium and zinc oxide nanoparticles for the alveolar and intestinal epithelial barrier cells in vitro

Heavy metals are found naturally on Earth and exposure to them in the living environment is increasing as a consequence of human activity. The toxicity of six different metal oxide nanoparticles (NP) at different points in time was compared using resazurin assay. After incubating Caco2 and A549 cells with 100 μg/mL of Sb₂O₃, Mn₃O₄ and TiO₂ nanoparticles (NPs) for 24 h no toxic effects were observed while Co₃O₄ and ZnO NPs had moderate effects and CuO NPs were toxic below 100 μg/mL (24 h EC₂₅ = 11 for A549 and 71 μg/mL for Caco2). The long-term monitoring (up to 9 days) of cells to NPs revealed that the toxic effects of Mn₃O₄ and Sb₂O₃ NPs remarkably increased over time. The 9 day EC₅₀ values for Sb₂O₃ NPs were 22 and 48 μg/mL for A549 and Caco2 cells; and for Mn₃O₄ NPs were 47 and 29 μg/mL for A549 and Caco2 cells, respectively. In general, the sensitivity of the cell lines in the resazurin assay was comparable. Trans epithelial electrical resistance (TEER) measurements were performed for both cell types exposed to Co₃O₄, Sb₂O₃ and CuO NPs. In TEER assay, the Caco2 cells were more susceptible to the toxic effects of these NPs than A549 cells, where the most toxic NPs were the Sb₂O₃ NPs: the permeability of the Caco2 cell layer exposed to 10 μg/mL Sb₂O₃ NPs already increased after 24 h of exposure.

Functionalized porous silica&maghemite core-shell nanoparticles for applications in medicine: design, synthesis, and immunotoxicity

AIM

To determine cytotoxicity and effect of silica-coated magnetic nanoparticles (MNPs) on immune response, in particular lymphocyte proliferative activity, phagocytic activity, and leukocyte respiratory burst and in vitro production of interleukin-6 (IL-6) and 8 (IL-8), interferon-gamma (IFN-γ), tumor necrosis factor-alpha (TNF-α), and granulocyte macrophage colony stimulating factor (GM-CSF).

METHODS

Maghemite was prepared by coprecipitation of iron salts with ammonia, oxidation with NaOCl and modified by tetramethyl orthosilicate and aminosilanes. Particles were characterized by transmission electron microscopy (TEM), dynamic light scattering (DLS), Fourier-transform infrared (FTIR), and X-ray photoelectron spectroscopy (XPS). Cytotoxicity and lymphocyte proliferative activity were assessed using [3H]-thymidine incorporation into DNA of proliferating human peripheral blood cells. Phagocytic activity and leukocyte respiratory burst were measured by flow cytometry; cytokine levels in cell supernatants were determined by ELISA.

RESULTS

γ-Fe2O3&SiO2-NH2 MNPs were 13 nm in size. According to TEM, they were localized in the cell cytoplasm and extracellular space. Neither cytotoxic effect nor significant differences in T-lymphocyte and T-dependent B-cell proliferative response were found at particle concentrations 0.12-75 μg/cm2 after 24, 48, and 72 h incubation. Significantly increased production of IL-6 and 8, and GM-CSF cytokines was observed in the cells treated with 3, 15, and 75 µg of particles/cm2 for 48 h and stimulated with pokeweed mitogen (PHA). No significant changes in TNF-α and IFN-γ production were observed. MNPs did not affect phagocytic activity of monocytes and granulocytes when added to cells for 24 and 48 h. Phagocytic respiratory burst was significantly enhanced in the cultures exposed to 75 µg MNPs/cm2 for 48 h.

CONCLUSIONS

The cytotoxicity and in vitro immunotoxicity were found to be minimal in the newly developed porous core-shell γ-Fe2O3&SiO2-NH2 magnetic nanoparticles.

Casp3/7-Instructed Intracellular Aggregation of Fe3O4 Nanoparticles Enhances T2 MR Imaging of Tumor Apoptosis

Large magnetic nanoparticles or aggregates are advantageous in their magnetic resonance properties over ultrasmall superparamagnetic iron oxide (USPIO) nanoparticles (NPs), but the former are cleared faster from the blood pool. Therefore, the "smart" strategy of intracellular aggregation of USPIO NPs is required for enhanced T2-weighted MR imaging. Herein, employing an enzyme-instructed condensation reaction, we rationally designed a small molecule Ac-Asp-Glu-Val-Asp-Cys(StBu)-Lys-CBT (1) to covalently modify USPIO NPs to prepare monodispersive Fe3O4@1 NPs. In vitro results showed that Fe3O4@1 NPs could be subjected to caspase 3 (Casp3)-instructed aggregation. T2 phantom MR imaging showed that the transverse molar relaxivity (r2) of Fe3O4@1 NPs with Casp3 or apoptotic HepG2 cells was significantly larger than those of control groups. In vivo tumor MR imaging results indicated that Fe3O4@1 NPs could be specifically applied for enhanced T2 MR imaging of tumor apoptosis. We propose that the enzyme-instructed intracellular aggregation of Fe3O4 NPs could be a novel strategy for the design of "smart" probes for efficient T2 MR imaging of in vivo biomarkers.

Physiological function and inflamed-brain migration of mouse monocyte-derived macrophages following cellular uptake of superparamagnetic iron oxide nanoparticles-Implication of macrophage-based drug delivery into the central nervous system

This study was designed to use superparamagnetic iron oxide nanoparticles (SPIONs) as evaluating tools to study monocyte-derived macrophages (MDM)-mediated delivery of small molecular agents into the diseased brains. MDM were tested with different-configured SPIONs at selected concentrations for their impacts on carrier cells' physiological and migratory properties, which were found to depend largely on particle size, coating, and treatment concentrations. SHP30, a SPION of 30-nm core size with oleic acids plus amphiphilic polymer coating, was identified to have high cellular uptake efficiency and cause little cytotoxic effects on MDM. At lower incubation dose (25μg/mL), few alteration was observed in carrier cells' physiological and in vivo migratory functions, as tested in a lipopolysaccharide-induced acute neuroinflammation mouse model. Nevertheless, significant increase in monocyte-to-macrophage differentiation, and decrease in in vivo carrier MDM inflamed-brain homing ability were found in groups treated with a higher dose of SHP30at 100μg/mL. Overall, our results have identified MDM treatment at 25μg/mL SHP30 resulted in little functional changes, provided valuable parameters for using SPIONs as evaluating tools to study MDM-mediated therapeutics carriage and delivery, and supported the concepts of using monocytes-macrophages as cellular vehicles to transport small molecular agents to the brain.

Antioxidant Activity/Capacity Measurement. 3. Reactive Oxygen and Nitrogen Species (ROS/RNS) Scavenging Assays, Oxidative Stress Biomarkers, and Chromatographic/Chemometric Assays

There are many studies in which the antioxidant potential of different foods have been analyzed. However, there are still conflicting results and lack of information as a result of unstandardized assay techniques and differences between the principles of the methods applied. The measurement of antioxidant activity, especially in the case of mixtures, multifunctional or complex multiphase systems, cannot be evaluated satisfactorily using a simple antioxidant test due to the many variables influencing the results. In the literature, there are many antioxidant assays that are used to measure the total antioxidant activity/capacity of food materials. In this review, reactive oxygen and nitrogen species (ROS/RNS) scavenging assays are evaluated with respect to their mechanism, advantages, disadvantages, and potential use in food systems. On the other hand, in vivo antioxidant activity (AOA) assays including oxidative stress biomarkers and cellular-based assays are covered within the scope of this review. Finally, chromatographic and chemometric assays are reviewed, focusing on their benefits especially with respect to their time saving, cost-effective, and sensitive nature.

Use of ultrasmall superparamagnetic iron oxide particles for imaging carotid atherosclerosis

Based on the results of histopathological studies, inflammation within atherosclerotic tissue is now widely accepted as a key determinant of the disease process. Conventional imaging methods can highlight the location and degree of luminal stenosis but not the inflammatory activity of the plaque. Iron oxide-based MRI contrast media particularly ultrasmall supermagnetic particles of iron oxide have shown potential in assessing atheromatous plaque inflammation and in determining efficacy of antiatherosclerosis pharmacological treatments. In this paper, we review current data on the use of ultrasmall superparamagnetic iron oxides in atherosclerosis imaging with focus on ferumoxtran-10 and ferumoxytol. The basic chemistry, pharmacokinetics and dynamics, potential applications, limitations and future perspectives of these contrast media nanoparticles are discussed.

Value of phagocyte function screening for immunotoxicity of nanoparticles in vivo

Nanoparticles (NPs) present in the environment and in consumer products can cause immunotoxic effects. The immune system is very complex, and in vivo studies are the gold standard for evaluation. Due to the increased amount of NPs that are being developed, cellular screening assays to decrease the amount of NPs that have to be tested in vivo are highly needed. Effects on the unspecific immune system, such as effects on phagocytes, might be suitable for screening for immunotoxicity because these cells mediate unspecific and specific immune responses. They are present at epithelial barriers, in the blood, and in almost all organs. This review summarizes the effects of carbon, metal, and metal oxide NPs used in consumer and medical applications (gold, silver, titanium dioxide, silica dioxide, zinc oxide, and carbon nanotubes) and polystyrene NPs on the immune system. Effects in animal exposures through different routes are compared to the effects on isolated phagocytes. In addition, general problems in the testing of NPs, such as unknown exposure doses, as well as interference with assays are mentioned. NPs appear to induce a specific immunotoxic pattern consisting of the induction of inflammation in normal animals and aggravation of pathologies in disease models. The evaluation of particle action on several phagocyte functions in vitro may provide an indication on the potency of the particles to induce immunotoxicity in vivo. In combination with information on realistic exposure levels, in vitro studies on phagocytes may provide useful information on the health risks of NPs.

Effects of PVA coated nanoparticles on human immune cells

Nanotechnology provides new opportunities in human medicine, mainly for diagnostic and therapeutic purposes. The autoimmune disease rheumatoid arthritis (RA) is often diagnosed after irreversible joint structural damage has occurred. There is an urgent need for a very early diagnosis of RA, which can be achieved by more sensitive imaging methods. Superparamagnetic iron oxide nanoparticles (SPION) are already used in medicine and therefore represent a promising tool for early diagnosis of RA. The focus of our work was to investigate any potentially negative effects resulting from the interactions of newly developed amino-functionalized amino-polyvinyl alcohol coated (a-PVA) SPION (a-PVA-SPION), that are used for imaging, with human immune cells. We analyzed the influence of a-PVA-SPION with regard to cell survival and cell activation in human whole blood in general, and in human monocytes and macrophages representative of professional phagocytes, using flow cytometry, multiplex suspension array, and transmission electron microscopy. We found no effect of a-PVA-SPION on the viability of human immune cells, but cytokine secretion was affected. We further demonstrated that the percentage of viable macrophages increased on exposure to a-PVA-SPION. This effect was even stronger when a-PVA-SPION were added very early in the differentiation process. Additionally, transmission electron microscopy analysis revealed that both monocytes and macrophages are able to endocytose a-PVA-SPION. Our findings demonstrate an interaction between human immune cells and a-PVA-SPION which needs to be taken into account when considering the use of a-PVA-SPION in human medicine.

MRI using ultrasmall superparamagnetic particles of iron oxide in patients under surveillance for abdominal aortic aneurysms to predict rupture or surgical repair: MRI for abdominal aortic aneurysms to predict rupture or surgery-the MA(3)RS study

Introduction

Population screening for abdominal aortic aneurysms (AAA) halves the associated mortality and has led to the establishment of national screening programmes. Prediction of aneurysm growth and rupture is challenging and currently relies on serial diameter measurements with ultrasound. Recently, a novel MRI-based technique using ultrasmall superparamagnetic particles of iron oxide (USPIO) has demonstrated considerable promise as a method of identifying aneurysm inflammation and expansion.

Methods and analysis

The MA³RS study is a prospective observational multicentre cohort study of 350 patients with AAA in three centres across Scotland. All participants will undergo MRI with USPIO and aneurysm expansion will be measured over 2 years with CT in addition to standard clinical ultrasound surveillance. The relationship between mural USPIO uptake and subsequent clinical outcomes, including expansion, rupture and repair, will be evaluated and used to determine whether the technique augments standard risk prediction markers. To ensure adequate sensitivity to answer the primary question, we need to observe 130 events (composite of rupture or repair) with an estimated event rate of 41% over 2 years of follow-up. The MA³RS study is currently recruiting and expects to report in 2017.

Discussion

This is the first study to evaluate the use of USPIO-enhanced MRI to provide additional information to aid risk prediction models in patients with AAA. If successful, this study will lay the foundation for a large randomised controlled trial targeted at applying this technique to determine clinical management.

Trial registration number

Current Controlled Trials: ISRCTN76413758.

Nanopharmaceuticals (part 2): products in the pipeline

In part I of this review we assessed nanoscience-related definitions as applied to pharmaceuticals and we discussed all 43 currently approved drug formulations, which are widely publicized as nanopharmaceuticals or nanomedicines. In continuation, here we review the currently ongoing clinical trials within the broad field of nanomedicine. Confining the definition of nanopharmaceuticals to therapeutic formulations, in which the unique physicochemical properties expressed in the nanosize range, when man-made, play the pivotal therapeutic role, we found an apparently low number of trials, which reflects neither the massive investments made in the field of nanomedicine nor the general hype associated with the term "nano." Moreover, after an extensive search for information through clinical trials, we found only two clinical trials with materials that show unique nano-based properties, ie, properties that are displayed neither on the atomic nor on the bulk material level.

Size dependent biodistribution and toxicokinetics of iron oxide magnetic nanoparticles in mice

In spite of the immense benefits from iron oxide magnetic nanoparticles (IOMNs), there is scanty information regarding their metabolic activities and toxicity in vivo. In this study, we investigated the size dependent in vivo biodistribution, toxicokinetics, and toxicity and gene expression changes of various sizes of carboxyl coated IOMNs (diameters of 10, 20, 30, and 40 nm). Our findings demonstrated that the various sizes of IOMNs accumulated primarily in the liver and spleen on the first day post-injection. Interestingly, size dependent biodistribution and transport were observed: the smallest IOMNs (10 nm) showed the highest uptake by the liver, whereas the largest IOMNs (40 nm) showed the highest uptake by the spleen. Moreover, the IOMNs with the smallest size (10 nm) were cleared faster from the liver and kidneys, but more readily entered the brain and the uterus. IOMNs with the largest size (40 nm) accumulated more readily but were easily eliminated in the spleen. However, the level of iron in the heart decreased in all IOMN exposed groups. In addition, blood biochemistry, hematological analyses and histological examination demonstrated that there was no apparent acute toxicity caused by IOMNs in mice. However, smaller IOMNs (10 nm and 20 nm) more effectively changed the expression level of sensitive genes related to oxidant stress, iron transport, metabolic process, apoptosis, and others.

In vitro toxicity evaluation of ultra-small MFe2O4 (M = Fe, Mn, Co) nanoparticles using A549 cells

As ferrite nanoparticles (MFe₂O₄) have been widely used in biomedical field, their safety evaluation has been paid great attention both in vitro and in vivo.

Nano magnetite supported metal ions as robust, efficient and recyclable catalysts for green synthesis of propargylamines and 1,4-disubstituted 1,2,3-triazoles in water

Superparamagnetic supported metals complex catalysts have been synthesized and applied for the synthesis of propargylamines and 1,2,3-triazoles.

Dextran coated bismuth-iron oxide nanohybrid contrast agents for computed tomography and magnetic resonance imaging

Bismuth nanoparticles have been proposed as a novel CT contrast agent, however few syntheses of biocompatible bismuth nanoparticles have been achieved. We herein report the synthesis of composite bismuth-iron oxide nanoparticles (BION) that are based on a clinically approved, dextran-coated iron oxide formulation; the particles have the advantage of acting as contrast agents for both CT and MRI. BION were synthesized and characterized using various analytical methods. BION CT phantom images revealed that the X-ray attenuation of the different formulations was dependent upon the amount of bismuth present in the nanoparticle, while T2-weighted MRI contrast decreased with increasing bismuth content. No cytotoxicity was observed in Hep G2 and BJ5ta cells after 24 hours incubation with BION. The above properties, as well as the yield of synthesis and bismuth inclusion efficiency, led us to select the Bi-30 formulation for in vivo experiments, performed in mice using a micro-CT and a 9.4 T MRI system. X-ray contrast was observed in the heart and blood vessels over a 2 hour period, indicating that Bi-30 has a prolonged circulation half-life. Considerable signal loss in T2-weighted MR images was observed in the liver compared to pre-injection scans. Evaluation of the biodistribution of Bi-30 revealed that bismuth is excreted via the urine, with significant concentrations found in the kidneys and urine. In vitro experiments confirmed the degradability of Bi-30. In summary, dextran coated BION are biocompatible, biodegradable, possess strong X-ray attenuation properties and also can be used as T2-weighted MR contrast agents.

Ferumoxytol administration does not alter infarct volume or the inflammatory response to stroke in mice

Ferumoxytol is an ultrasmall superparamagnetic iron oxide (USPIO) nanoparticle that is FDA-approved as an intravenous iron replacement therapy for the treatment of iron deficiency anemia in patients with chronic kidney disease. Ferumoxytol has also been used as a contrast agent for cerebral blood volume mapping by magnetic resonance imaging (MRI), which suggests it could be used for imaging hemodynamic abnormalities after stroke. However, circulating macrophages can internalize USPIOs, and recent data indicate that the accumulation of iron in macrophages can lead them to adopt the M1 pro-inflammatory phenotype. Therefore, the uptake of intravenously administered iron particles by circulating macrophages that home to the stroke core could potentially alter the inflammatory response to stroke. To test this possibility in vivo we administered a dose of ferumoxytol previously used to obtain cerebral blood volume maps in healthy humans by steady-state susceptibility contrast (SSC) MRI to BALB/cJ mice 48h after stroke and examined cytokine levels, microglial/macrophage activation, and lesion volume in the brain 5 days later. Treatment with ferumoxytol did not lead to any differences in these parameters. These data indicate that the use of ferumoxytol as a contrast agent for brain imaging after stroke does not alter the inflammatory response to stroke in mice, and is therefore unlikely to do so in human subjects.

Biological impact of superparamagnetic iron oxide nanoparticles for magnetic particle imaging of head and neck cancer cells

Background

As a tomographic imaging technology, magnetic particle imaging (MPI) allows high spatial resolution and sensitivity, and the possibility to create real-time images by determining the spatial distribution of magnetic particles. To ensure a prospective biosafe application of UL-D (University of Luebeck-Dextran coated superparamagnetic nanoparticles), we evaluated the biocompatibility of superparamagnetic iron oxide nanoparticles (SPIONs), their impact on biological properties, and their cellular uptake using head and neck squamous cancer cells (HNSCCs).

Methods

SPIONs that met specific MPI requirements were synthesized as tracers. Labeling and uptake efficiency were analyzed by hematoxylin and eosin staining and magnetic particle spectrometry. Flow cytometry, 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assays, and real-time cell analyzer assays were used to investigate apoptosis, proliferation, and the cytokine response of SPION-labeled cells. The production of reactive oxygen species (ROS) was determined using a fluorescent dye. Experimental results were compared to the contrast agent Resovist^®, a standard agent used in MPI.

Results

UL-D nanoparticles and Resovist particles were taken up in vitro by HNSCCs via unspecific phagocytosis followed by cytosolic accumulation. To evaluate toxicity, flow cytometry analysis was performed; results showed that dose- and time-dependent administration of Resovist induced apoptosis whereas cell viability of UL-D-labeled cells was not altered. We observed decreased cell proliferation in response to increased SPION concentrations. An intracellular production of ROS could not be detected, suggesting that the particles did not cause oxidative stress. Tumor necrosis factor alpha (TNF-α) and interleukins IL-6, IL-8, and IL-1β were measured to distinguish inflammatory responses. Only the primary tumor cell line labeled with >0.5 mM Resovist showed a significant increase in IL-1β secretion.

Conclusion

Our data suggest that UL-D SPIONs are a promising tracer material for use in innovative tumor cell analysis in MPI.

Immunomodulation of nanoparticles in nanomedicine applications

Nanoparticles (NPs) have promising applications in medicine. Immune system is an important protective system to defend organisms from non-self matters. NPs interact with the immune system and modulate its function, leading to immunosuppression or immunostimulation. These modulating effects may bring benefits or danger. Compositions, sizes, and surface chemistry, and so forth, affect these immunomodulations. Here we give an overview of the relationship between the physicochemical properties of NPs, which are candidates to be applied in medicine, and their immunomodulation properties.

Evidence of redox-active iron formation following aggregation of ferrihydrite and the Alzheimer's disease peptide β-amyloid

Recent work has demonstrated increased levels of redox-active iron biominerals in Alzheimer's disease (AD) tissue. However, the origin, nature, and role of iron in AD pathology remains unclear. Using X-ray absorption, X-ray microspectroscopy, and electron microscopy techniques, we examined interactions between the AD peptide β-amyloid (Aβ) and ferrihydrite, which is the ferric form taken when iron is stored in humans. We report that Aβ is capable of reducing ferrihydrite to a pure iron(II) mineral where antiferromagnetically ordered Fe(2+) cations occupy two nonequivalent crystal symmetry sites. Examination of these iron(II) phases following air exposure revealed a material consistent with the iron(II)-rich mineral magnetite. These results demonstrate the capability of Aβ to induce the redox-active biominerals reported in AD tissue from natural iron precursors. Such interactions between Aβ and ferrihydrite shed light upon the processes of AD pathogenesis, while providing potential targets for future therapies.

Interaction of polyacrylic acid coated and non-coated iron oxide nanoparticles with human neutrophils

Iron oxide nanoparticles (ION), with different coatings and sizes, have attracted extensive interest in the last years to be applied in drug delivery, cancer therapy and as contrast agents in imagiologic techniques such as magnetic resonance imaging. However, the safety of these nanoparticles is still not completely established, particularly to host defense systems that are usually recruited for their clearance from the body. In this paper, given the importance of neutrophils in the immune response of the organism to nanoparticles, the effect of polyacrylic acid (PAA)-coated and non-coated ION on human neutrophils was evaluated in vitro, namely their capacity to activate the oxidative burst and to modify their lifespan. The obtained results showed that the studied PAA-coated and non-coated ION triggered neutrophils' oxidative burst in a NADPH oxidase dependent manner, and that PAA-coated ION increased - while non-coated ION prevented - apoptotic signaling and apoptosis. These effects may have important clinical implications in biomedical applications of ION.

Biodistribution of newly synthesized PHEA-based polymer-coated SPION in Sprague Dawley rats as magnetic resonance contrast agent

Objectives

The purpose of this study was to observe the pharmacokinetic behavior of newly synthesized biocompatible polymers based on polyhydroxyethylaspartamide (PHEA) to be used to coat an iron oxide core to make superparamagnetic iron oxide nanoparticles (SPION).

Materials and methods

The isotopes [¹⁴C] and [⁵⁹Fe] were used to label the polymer backbone (CLS) and iron oxide core (FLS), respectively. In addition, unradiolabeled cold superparamagnetic iron oxide nanoparticles (SPION/ULS) were synthesized to characterize particle size by dynamic light scattering, morphology by transmission electron microscopy, and in vivo magnetic resonance imaging (MRI). CLS and FLS were used separately to investigate the behavior of both the synthesized polymer and [Fe] in Sprague Dawley (SD) rats, respectively. Because radioactivity of the isotopes was different by β for CLS and γ for FLS, synthesis of the samples had to be separately prepared.

Results

The mean particle size of the ULS was 66.1 nm, and the biodistribution of CLS concentrations in various organs, in rank order of magnitude, was liver > kidney > small intestine > other. The biodistribution of FLS concentrations was liver > spleen > lung > other. These rank orders show that synthesized SPION mainly accumulates in the liver. The differences in the distribution were caused by the SPION metabolism. Radiolabeled polymer was metabolized by the kidney and excreted mainly in the urine; [⁵⁹Fe] was recycled for erythrocyte production in the spleen and excreted mainly in the feces. The MR image of the liver after intravenous injection demonstrated that [Fe] effectively accumulated in the liver and exhibited high-contrast enhancement on T2-weighted images.

Conclusion

This newly synthesized, polymer-coated SPION appears to be a promising candidate for use as a liver-targeted, biocompatible iron oxide MR imaging agent.

The effect of particle agglomeration on the formation of a surface-connected compartment induced by hydroxyapatite nanoparticles in human monocyte-derived macrophages

Agglomeration dramatically affects many aspects of nanoparticle–cell interactions. Here we show that hydroxyapatite nanoparticles formed large agglomerates in biological medium resulting in extensive particle uptake and dose-dependent cytotoxicity in human macrophages. Particle citration and/or the addition of the dispersant Darvan 7 dramatically reduced mean agglomerate sizes, the amount of particle uptake and concomitantly cytotoxicity. More surprisingly, agglomeration governed the mode of particle uptake. Agglomerates were sequestered within an extensive, interconnected membrane labyrinth open to the extracellular space. In spite of not being truly intracellular, imaging studies suggest particle degradation occurred within this surface-connected compartment (SCC). Agglomerate dispersion prevented the SCC from forming, but did not completely inhibit nanoparticle uptake by other mechanisms. The results of this study could be relevant to understanding particle–cell interactions during developmental mineral deposition, in ectopic calcification in disease, and during application of hydroxyapatite nanoparticle vectors in biomedicine.

Superparamagnetic iron oxide nanoparticles (SPIONs)-loaded Trojan microparticles for targeted aerosol delivery to the lung

Targeted aerosol delivery to specific regions of the lung may improve therapeutic efficiency and minimise unwanted side effects. Targeted delivery could potentially be achieved with porous microparticles loaded with superparamagnetic iron oxide nanoparticles (SPIONs)-in combination with a target-directed magnetic gradient field. The aim of this study was to formulate and evaluate the aerodynamic properties of SPIONs-loaded Trojan microparticles after delivery from a dry powder inhaler. Microparticles made of SPIONs, PEG and hydroxypropyl-β-cyclodextrin (HPβCD) were formulated by spray drying and characterised by various physicochemical methods. Aerodynamic properties were evaluated using a next generation cascade impactor (NGI), with or without a magnet positioned at stage 2. Mixing appropriate proportions of SPIONs, PEG and HPβCD allowed Trojan microparticle to be formulated. These particles had a median geometric diameter of 2.8±0.3μm and were shown to be sensitive to the magnetic field induced by a magnet having a maximum energy product of 413.8kJ/m(3). However, these particles, characterised by a mass median aerodynamic diameter (MMAD) of 10.2±2.0μm, were considered to be not inhalable. The poor aerodynamic properties resulted from aggregation of the particles. The addition of (NH4)2CO3 and magnesium stearate (MgST) to the formulation improved the aerodynamic properties of the Trojan particles and resulted in a MMAD of 2.2±0.8μm. In the presence of a magnetic field on stage 2 of the NGI, the amount of particles deposited at this stage increased 4-fold from 4.8±0.7% to 19.5±3.3%. These Trojan particles appeared highly sensitive to the magnetic field and their deposition on most of the stages of the NGI was changed in the presence compared to the absence of the magnet. If loaded with a pharmaceutical active ingredient, these particles may be useful for treating localised lung disease such as cancer nodules or bacterial infectious foci.

Induction heating studies of dextran coated MgFe2O4 nanoparticles for magnetic hyperthermia

MgFe(2)O(4) nanoparticles with sizes around 20 nm have been prepared by a combustion method and functionalized with dextran for their possible applications in magnetic particle hyperthermia. The induction heating study of these nanoparticles at different magnetic field amplitudes, from 6.7 kA m(-1) to 26.7 kA m(-1), showed self-heating temperature rise up to 50.25 °C and 73.32 °C (at 5 mg mL(-1) and 10 mg mL(-1) concentrations in water respectively) which was primarily thought to be due to hysteresis losses activated by an AC magnetic field. The dextran coated nanoparticles showed a maximum specific absorption rate (SAR) of about 85.57 W g(-1) at 26.7 kA m(-1) (265 kHz). Dextran coated nanoparticles at concentrations below 1.8 mg mL(-1) exhibit good viability above 86% on mice fibroblast L929 cells. The results suggest that combustion synthesized MgFe(2)O(4) nanoparticles coated with dextran can be used as potential heating agents in magnetic particle hyperthermia. Uncoated and dextran coated samples were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FTIR), thermogravimetric-differential thermal analysis (TG-DTA) and zeta potential-DLS studies.

Chemical design of biocompatible iron oxide nanoparticles for medical applications

Iron oxide nanoparticles are one of the most versatile and safe nanomaterials used in medicine. Recent progress in nanochemistry enables fine control of the size, crystallinity, uniformity, and surface properties of iron oxide nanoparticles. In this review, the synthesis of chemically designed biocompatible iron oxide nanoparticles with improved quality and reduced toxicity is discussed for use in diverse biomedical applications.

Applications and potential toxicity of magnetic iron oxide nanoparticles

Owing to their unique physical and chemical properties, magnetic iron oxide nanoparticles have become a powerful platform in many diverse aspects of biomedicine, including magnetic resonance imaging, drug and gene delivery, biological sensing, and hyperthermia. However, the biomedical applications of magnetic iron oxide nanoparticles arouse serious concerns about their pharmacokinetics, metabolism, and toxicity. In this review, the updated research on the biomedical applications and potential toxicity of magnetic iron oxide nanoparticles is summarized. Much more effort is required to develop magnetic iron oxide nanoparticles with improved biocompatible surface engineering to achieve minimal toxicity, for various applications in biomedicine.

The cytotoxicity evaluation of magnetic iron oxide nanoparticles on human aortic endothelial cells

One major obstacle for successful application of nanoparticles in medicine is its potential nanotoxicity on the environment and human health. In this study, we evaluated the cytotoxicity effect of dimercaptosuccinic acid-coated iron oxide (DMSA-Fe2O3) using cultured human aortic endothelial cells (HAECs). Our results showed that DMSA-Fe2O3 in the culture medium could be absorbed into HAECs, and dispersed in the cytoplasm. The cytotoxicity effect of DMSA-Fe2O3 on HAECs was dose-dependent, and the concentrations no more than 0.02 mg/ml had little toxic effect which were revealed by tetrazolium dye assay. Meanwhile, the cell injury biomarker, lactate dehydrogenase, was not significantly higher than that from control cells (without DMSA-Fe2O3). However, the endocrine function for endothelin-1 and prostacyclin I-2, as well as the urea transporter function, was altered even without obvious evidence of cell injury in this context. We also showed by real-time PCR analysis that DMSA-Fe2O3 exposure resulted in differential effects on the expressions of pro- and anti-apoptosis genes of HAECs. Meanwhile, it was noted that DMSA-Fe2O3 exposure could activate the expression of genes related to oxidative stress and adhesion molecules, which suggested that inflammatory response might be evoked. Moreover, we demonstrated by in vitro endothelial tube formation that even a small amount of DMSA-Fe2O3 (0.01 and 0.02 mg/ml) could inhibit angiogenesis by the HAECs. Altogether, these results indicate that DMSA-Fe2O3 have some cytotoxicity that may cause side effects on normal endothelial cells.

Magnetic resonance imaging of mouse islet grafts labeled with novel chitosan-coated superparamagnetic iron oxide nanoparticles

OBJECT

To better understand the fate of islet isografts and allografts, we utilized a magnetic resonance (MR) imaging technique to monitor mouse islets labeled with a novel MR contrast agent, chitosan-coated superparamagnetic iron oxide (CSPIO) nanoparticles.

MATERIALS AND METHODS

After being incubated with and without CSPIO (10 µg/ml), C57BL/6 mouse islets were examined under transmission electron microscope (TEM) and their insulin secretion was measured. Cytotoxicity was examined in α (αTC1) and β (NIT-1 and βTC) cell lines as well as islets. C57BL/6 mice were used as donors and inbred C57BL/6 and Balb/c mice were used as recipients of islet transplantation. Three hundred islets were transplanted under the left kidney capsule of each mouse and then MR was performed in the recipients periodically. At the end of study, the islet graft was removed for histology and TEM studies.

RESULTS

After incubation of mouse islets with CSPIO (10 µg/mL), TEM showed CSPIO in endocytotic vesicles of α- and β-cells at 8 h. Incubation with CSPIO did not affect insulin secretion from islets and death rates of αTC1, NIT-1 and βTC cell lines as well as islets. After syngeneic and allogeneic transplantation, grafts of CSPIO-labeled islets were visualized on MR scans as persistent hypointense areas. At 8 weeks after syngeneic transplantation and 31 days after allogeneic transplantation, histology of CSPIO-labeled islet grafts showed colocalized insulin and iron staining in the same areas but the size of allografts decreased with time. TEM with elementary iron mapping demonstrated CSPIO distributed in the cytoplasm of islet cells, which maintained intact ultrastructure.

CONCLUSION

Our results indicate that after syngeneic and allogeneic transplantation, islets labeled with CSPIO nanoparticles can be effectively and safely imaged by MR.

Pulsed magnetic field improves the transport of iron oxide nanoparticles through cell barriers

Understanding how a magnetic field affects the interaction of magnetic nanoparticles (MNPs) with cells is fundamental to any potential downstream applications of MNPs as gene and drug delivery vehicles. Here, we present a quantitative analysis of how a pulsed magnetic field influences the manner in which MNPs interact with and penetrate across a cell monolayer. Relative to a constant magnetic field, the rate of MNP uptake and transport across cell monolayers was enhanced by a pulsed magnetic field. MNP transport across cells was significantly inhibited at low temperature under both constant and pulsed magnetic field conditions, consistent with an active mechanism (i.e., endocytosis) mediating MNP transport. Microscopic observations and biochemical analysis indicated that, in a constant magnetic field, transport of MNPs across the cells was inhibited due to the formation of large (>2 μm) magnetically induced MNP aggregates, which exceeded the size of endocytic vesicles. Thus, a pulsed magnetic field enhances the cellular uptake and transport of MNPs across cell barriers relative to a constant magnetic field by promoting accumulation while minimizing magnetically induced MNP aggregation at the cell surface.

Ex vivo magnetic resonance imaging of transplanted hepatocytes in a rat model of acute liver failure

Hepatocyte transplantation is being evaluated as an alternative to liver transplantation. However, the fate of hepatocytes after transplantation is not well defined. The aims of the study were to improve hepatocyte labeling in vitro using superparamagnetic iron oxide nanoparticles (SPIOs) and to perform in vivo experiments on tracking labeled cells by magnetic resonance imaging (MRI). Human and rat hepatocytes were labeled in vitro for 16 h with clinically approved SPIOs (12.5 µg Fe/ml) and protamine sulfate (3 µg/ml) as a transfection agent. Increased cellular iron uptake was obtained, and cell viability and function were shown not to be affected by labeling. Labeled cells (2,000/µl) could be detected on T2-weighted images in vitro using a 7T MR scanner. In a rat model of acute liver failure (ALF), female recipients received intrasplenic transplantation of 2 × 10(7) male rat hepatocytes 28-30 h after intraperitoneal injection of d-galactosamine (1.2 g/kg). There were four groups (n = 4 each): vehicle injection, injection of freshly isolated cells labeled with CM-DiI, injection of cultured cells labeled with CM-DiI, and injection of cultured cells labeled with both SPIOs and CM-DiI. Ex vivo T2*-weighted gradient-echo images at 7T MRI were acquired at day 7 post-ALF induction. Six days after transplantation, SPIOs were detected in the rat liver as a decrease in the MRI signal intensity in the surviving animals. Histologically, most of the SPIOs were located in Kupffer cells, indicating clearance of labeled hepatocytes. Furthermore, labeled cells could not be detected in the liver by the fluorescent dye or by PCR for the Y-chromosome (Sry-2 gene). In conclusion, optimum conditions to label human hepatocytes with SPIOs were established and did not affect cell viability or metabolic function and were sufficient for in vitro MRI detection. However, the clearance of hepatocytes after transplantation limits the value of MRI for assessing long-term hepatocyte engraftment.

Nanoparticles and their potential for application in bone

Biomaterials are commonly applied in regenerative therapy and tissue engineering in bone, and have been substantially refined in recent years. Thereby, research approaches focus more and more on nanoparticles, which have great potential for a variety of applications. Generally, nanoparticles interact distinctively with bone cells and tissue, depending on their composition, size, and shape. Therefore, detailed analyses of nanoparticle effects on cellular functions have been performed to select the most suitable candidates for supporting bone regeneration. This review will highlight potential nanoparticle applications in bone, focusing on cell labeling as well as drug and gene delivery. Labeling, eg, of mesenchymal stem cells, which display exceptional regenerative potential, makes monitoring and evaluation of cell therapy approaches possible. By including bioactive molecules in nanoparticles, locally and temporally controlled support of tissue regeneration is feasible, eg, to directly influence osteoblast differentiation or excessive osteoclast behavior. In addition, the delivery of genetic material with nanoparticulate carriers offers the possibility of overcoming certain disadvantages of standard protein delivery approaches, such as aggregation in the bloodstream during systemic therapy. Moreover, nanoparticles are already clinically applied in cancer treatment. Thus, corresponding efforts could lead to new therapeutic strategies to improve bone regeneration or to treat bone disorders.

Biological evaluation of Fe₃O₄-poly(L-lactide)-poly(ethylene glycol)-poly(L-lactide) magnetic microspheres prepared in supercritical CO₂

The biocompatibility of Fe₃O₄-poly(L-lactide)-poly(ethylene glycol)-poly(L-lactide) magnetic microspheres (Fe₃O₄-PLLA-PEG-PLLA MMPs) prepared in a process of suspension-enhanced dispersion by supercritical CO₂ (SpEDS) was evaluated at various levels: cellular, molecular, and integrated. At the cellular level, the investigations of cytotoxicity and intracellular reactive oxygen species (ROS) generation indicate that the polymer-coated MMPs (2.0 mg/mL) had a higher toxicity than uncoated Fe₃O₄ nanoparticles, which led to about 20% loss of cell viability and an increase (0.2 fold) in ROS generation; the differences were not statistically significant (p > 0.05). However, an opposite phenomenon was observed in tests of hemolysis, which showed that the MMPs displayed the weakest hemolytic activity, namely only about 6% at the highest concentration (20 mg/mL). This phenomenon reveals that polymer-coated MMPs created less toxicity in red blood cells than uncoated Fe₃O₄ nanoparticles. At the molecular level, the MMPs were shown to be less genotoxic than Fe₃O₄ nanoparticles by measuring the micronucleus (MN) frequency in CHO-K1 cells. Furthermore, the mRNA expression of pro-inflammatory cytokines demonstrates that polymer-coated MMPs elicited a less intense secretion of pro-inflammatory cytokines than uncoated Fe₃O₄ nanoparticles. Acute toxicity tests of MMPs show quite a low toxicity, with an LD₅₀ > 1575.00 mg/kg. The evidence of low toxicity presented in the results indicates that the Fe₃O₄-PLLA-PEG-PLLA MMPs from the SpEDS process have great potential for use in biomedical applications.