Toxicity assessment of silica coated iron oxide nanoparticles and biocompatibility improvement by surface engineering

Magnetically Tuning Tether Mobility of Integrin Ligand Regulates Adhesion, Spreading, and Differentiation of Stem Cells

Cells sense and respond to the surrounding microenvironment through binding of membranous integrin to ligands such as the Arg-Gly-Asp (RGD) peptide. Previous studies show that the RGD tether properties on substrate influence cell adhesion and spreading, but few studies have reported strategies to control the tether mobility of RGD on substrate via a physical and noncontact approach. Herein, we demonstrate a novel strategy to tune the tether mobility of RGD on substrate via magnetic force. We conjugate a monolayer of RGD-bearing magnetic nanoparticles (MNPs) on a glass substrate via the flexible and coiled poly(ethylene glycol) linker of large molecular weight (PEG, average MW: 2000), and this increases the RGD tether mobility, which can be significantly reduced by applying magnetic attraction on MNPs. Our data show that high RGD tether mobility delays the early adhesion and spreading of human mesenchymal stem cells (hMSCs), leading to compromised osteogenic differentiation at later stage. In contrast, hMSCs cultured on substrate with restricted RGD tether mobility, achieved either via a shorter PEG linker (MW: 200) or magnetic force, show significantly better adhesion, spreading, and osteogenic differentiation. The control utilizing RGD-bearing nonmagnetic nanoparticles shows no such enhancing effect of magnetic field on cellular events, further supporting our conjecture of magnetic tuning of RGD tether mobility. We hypothesize that high tether mobility of RGD entails additional time and effort by the cells to fully develop traction force and mechanical feedback, thereby delaying the maturation of FAs and activation of subsequent mechanotransduction signaling. Our staining results of vinculin, a critical component of FAs, and Yes-associated protein (YAP), an important mechanosensitive transcriptional factor, support our hypothesis. We believe that our work not only sheds light on the impact of dynamic presentation of cell adhesive ligands on cellular behaviors, which should be taken into consideration for designing novel biomaterials, but also formulate an effective noncontact strategy that enables further investigation on the mechanobiological mechanisms underlying such cellular responses.

Strategies to reduce the intracellular effects of iron oxide nanoparticle degradation

Mesenchymal stem cells (MSCs) have a significant self-renewal capacity and can differentiate into a variety of cell types. Cell labeling is crucial as it is difficult to detect cell fate after transplantation in vivo. MSCs labeled with iron oxide nanoparticles (IONPs), which can be tracked by MRI, have tremendous potential in regenerative medicine and oncological research. As a part of nanoparticle, the iron oxide core is a key aspect that can exhibit adverse or beneficial effects on MSCs labeled for tracking. Some IONPs exhibit adverse effects, such as cytotoxicity and apoptosis, while other IONPs exhibit beneficial functions that can promote both MSC proliferation and homing efficiency. This review reveals the cytotoxic mechanisms and potential functions of the iron oxide core of IONPs in cell labeling as well as strategies for minimizing the intracellular effects of IONPs.

Earthicle: The Design of a Conceptually New Type of Particle

The conception and the steps made in the design of a conceptually new type of composite particle, so-called "earthicle", are being described. This particle is meant to roughly mimic the layered structure of the Earth, having zerovalent iron core, silicate mantle, and a thin carbonaceous crust resembling the biosphere and its geological remnants. Particles are made in a stable colloidal form in an aqueous medium, involving chemical precipitation and pyrolysis of citric acid in the solution. The effects of various synthesis parameters were studied, including borohydride and oleate concentrations, APTES/TEOS molar ratio, chemical nature of the carbon precursors, and others. XRD analysis confirmed the predominantly zerovalent iron composition of the core, amorphous silica and crystalline iron silicate/silicide composition of the mesolayer, and the carbonaceous, amorphous graphitic composition of the surface coating. The atomically thin carbon shell was also detected as a distinct shoulder on the broad n-π* absorption resonance and the peak at ∼300 nm, a signature of sp² hybridized electronic orbitals and the result of the interband π-π* transition characteristic of graphitic structures. The irregularity of the shape of generally round Fe⁰ particles has caused the uniformity of the silica shell to be directly proportional to the particle size. The size of the earthicles ranged from 60 to 500 nm depending on the ionic concentration of the precursors and additives. Silica layer effectively prevented the aggregation of the iron core and increased the biocompatibility of the particles. The point of zero charge first increased from the acidic to the neutral range after coating Fe⁰ core with the APTES-functionalized, aminated silica shell and then restored its low value after depositing the carboxylated carbonic crust in a charge-reversal process designed to facilitate the formation of core-multishell structures. Tested on K7M2 osteosarcoma cell line and primary kidney and lung fibroblasts, cytotoxicity was cell-line dependent; however, the trend assessed in both planar and 3D cell culture with respect to the three types of particles, Fe⁰, Fe/SiO₂, and Fe/SiO₂/C, was general and independent of the cell line. Thus, the pronounced toxicity of Fe⁰ alone became neutralized after the silica layer was coated around Fe⁰. The further addition of the carbonic layer reduced the viability as compared to Fe/SiO₂, albeit in a statistically significant manner only for K7M2 cell line when compared against the untreated control. Cell response also varied depending on the formulation: while some formulations exhibited lethal effects on kidney fibroblasts, were harmless to lung fibroblasts, and boosted the proliferation of K7M2 osteosarcoma cells, other formulations exhibited the opposite behavior despite being similar in terms of their core/double-shell structure. Compared across three different cancerous cell lines, K7M2 osteosarcoma and U87 and E297 glioblastoma, a similar cell-line dependency in response was observed, yet the viability reduction was consistent for all Fe/SiO₂/C particles, ranging from 80% to 85% of the untreated control. Carbon surface layer, albeit of graphitic structural nature, was of a markedly more viable character than that of nanosized graphene oxide. The viability of lung fibroblasts incubated with Fe/SiO₂/C particles was reduced in the presence of the alternating magnetic field of 312.75 A/m and 1 MHz, while the viability reduction caused by Fe/SiO₂/C particles in kidney fibroblasts and K7M2 cells was converted from statistically insignificant to significant, suggesting that the composite particles could be used for hyperthermia treatments, although their properties should be optimized for a more intense effect. A single-cell immunofluorescent analysis of the interaction of primary kidney fibroblasts and K7M2 osteosarcoma cells with Fe/SiO₂/C particles demonstrated that the cell uptake and perinuclear localization may be responsible for the necrotic effects. This analysis also showed that composite Fe/SiO₂/C particles may have the ability to cause the rupture of the cancer cell nucleus while having a harmless effect on the primary cells. Such a promising and selective anticancer activity will be investigated in more detail in future studies.

Immobilization of tyrosinase on polyacrylonitrile beads: biodegradation of phenol from aqueous solution and the relevant cytotoxicity assessment

An economical and stabilized immobilized-enzyme method was developed for the removal of phenol in wastewater.

Hollow mesoporous silica nanosphere-supported FePt nanoparticles for potential theranostic applications

A nanocomposite comprising FePt nanoparticles and hollow mesoporous silica nanospheres has been fabricated for MRI, NIR photothermal therapy and combined chemo-/thermotherapy.

Cytotoxicity and oxidative stress responses of silica-coated iron oxide nanoparticles in CHSE-214 cells

The present study aimed at investigating cytotoxicity and oxidative stress induced by silica-coated iron oxide nanoparticles functionalized with dithiocarbamate (Fe₃O₄ NPs) in Chinook salmon cells (CHSE-214) derived from Oncorhynchus tshawytscha embryos. A significant reduction in cell viability was evident in response to Fe₃O₄ NPs as revealed by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay after 24 h of exposure. Out of the tested concentrations (10, 20, and 30 μg/ml), the highest concentration has shown significant decrease in the viability of cells after 24 h of exposure. Alterations in the morphology of CHSE-214 cells was also evident at 10 μg/ml concentration of Fe₃O₄ NPs after 24 h. Fe₃O₄ NPs elicited a significant dose-dependent reduction in total glutathione content (TGSH), catalase (CAT), glutathione reductase (GR) with a concomitant increase in lipid peroxidation (LPO), and protein carbonyl (PC) at highest concentration (30 μg/ml) after 24 h of exposure. In conclusion, our data demonstrated that Fe₃O₄ NPs have potential to induce cytotoxicity in CHSE-214 cells, which is likely to be mediated through reactive oxygen species generation and oxidative stress.

Cellular uptake, genotoxicity and cytotoxicity of cobalt ferrite magnetic nanoparticles in human breast cells

Magnetic nanoparticles (MNPs) have been increasingly used for many years as MRI agents and for gene delivery and hyperthermia therapy, although there have been conflicting results on their safety. In this study, cobalt ferrite magnetic nanoparticles (CoFe-MNPs) were prepared by the co-precipitation method and their surfaces were modified with silica by the sol-gel method. The particle and hydrodynamic sizes, morphology and crystal structure of the bare and silica-coated CoFe-MNPs were evaluated by transmission electron microscopy (TEM), dynamic light scattering (DLS), X-ray diffraction spectroscopy (XRD) and Fourier transform infrared spectroscopy (FTIR). The size of the bare CoFe-MNPs was in the range 8-20 nm and they were homogeneously coated with 3-4 nm silica shells. The bare and silica-coated CoFe-MNPs were agglomerated at physiological pH. However, the sizes of the agglomerates were below 200 nm both in water and complete medium. The cytotoxic and genotoxic potentials of the bare and silica-coated CoFe-MNPs were evaluated in a metastatic breast cancer cell line, MDA-MB-231, as well as a noncancerous mammary epithelial cell line, MCF-10A, by using XTT cytotoxicity, single-cell gel electrophoresis (comet), and cytokinesis-blocked (CB) micronucleus (CBMN) assays. Characterization studies with TEM, inductively coupled plasma optical emission spectroscopy (ICP-OES) and Prussian blue staining indicated that the CoFe-MNPs were internalized into the cells by energy-dependent endocytosis. The highest amount of uptake was observed in the cancer cells and the uptake of the silica-coated CoFe-MNPs was higher than that of the bare ones in both cell lines. The bare CoFe-MNPs showed higher levels of both cytotoxicity and genotoxicity than the silica-coated CoFe-MNPs. Moreover, the cancer cells seemed to be more susceptible to the CoFe-MNPs' toxicity compared to the noncancerous cells. There was a concentration and time-dependent increase in DNA damage and the micronucleus (MN) frequency, which was statistically significant starting with the lowest concentration of bare CoFe-MNPs (p < 0.05), while no significance was observed below the concentration of 250 μg mL-1 for the silica-coated MNPs. Also, the extent of both DNA damage and MN frequency was much higher in the cancer cells compared to the noncancerous cells. According to our results, the silica coating ameliorated both the cytotoxicity and genotoxicity as well the internalization of the CoFe-MNPs.

Toxicity and mutagenicity of low-metallic automotive brake pad materials

Organic friction materials are standardly used in brakes of small planes, railroad vehicles, trucks and passenger cars. The growing transportation sector requires a better understanding of the negative impact related to the release of potentially hazardous materials into the environment. This includes brakes which can release enormous quantities of wear particulates. This paper addresses in vitro detection of toxic and mutagenic potency of one model and two commercially available low-metallic automotive brake pads used in passenger cars sold in the EU market. The model pad made in the laboratory was also subjected to a standardized brake dynamometer test and the generated non-airborne wear particles were also investigated. Qualitative "organic composition" was determined by GC/MS screening of dichloromethane extracts. Acute toxicity and mutagenicity of four investigated sample types were assessed in vitro by bioluminescence assay using marine bacteria Vibrio fischeri and by two bacterial bioassays i) Ames test on Salmonella typhimurium His(-) and ii) SOS Chromotest using Escherichia coli PQ37 strain. Screening of organic composition revealed a high variety of organic compounds present in the initial brake pads and also in the generated non-airborne wear debris. Several detected compounds are classified by IARC as possibly carcinogenic to humans, e. g. benzene derivatives. Acute toxicity bioassay revealed a response of bacterial cells after exposure to all samples used. Phenolic resin and wear debris were found to be acutely toxic; however in term of mutagenicity the response was negative. All non-friction exposed brake pad samples (a model pad and two commercial pad samples) were mutagenic with metabolic activation in vitro.

Magnetic Core-Shell Silica Nanoparticles with Large Radial Mesopores for siRNA Delivery

A novel type of magnetic core-shell silica nanoparticles is developed for small interfering RNA (siRNA) delivery. These nanoparticles are fabricated by coating super-paramagnetic magnetite nanocrystal clusters with radial large-pore mesoporous silica. The amine functionalized nanoparticles have small particle sizes around 150 nm, large radial mesopores of 12 nm, large surface area of 411 m(2) g(-1) , high pore volume of 1.13 cm(3) g(-1) and magnetization of 25 emu g(-1) . Thus, these nanoparticles possess both high loading capacity of siRNA (2 wt%) and strong magnetic response under an external magnetic field. An acid-liable coating composed of tannic acid can further protect the siRNA loaded in these nanoparticles. The coating also increases the dispersion stability of the siRNA-loaded carrier and can serve as a pH-responsive releasing switch. Using the magnetic silica nanoparticles with tannic acid coating as carriers, functional siRNA has been successfully delivered into the cytoplasm of human osteosarcoma cancer cells in vitro. The delivery is significantly enhanced with the aid of the external magnetic field.

Fe3 O4 nanoparticle redox system modulation via cell-cycle progression and gene expression in human mesenchymal stem cells

The use of engineered nanoparticles (NPs) across multiple fields and applications has rapidly increased over the last decade owing to their unusual properties. However, there is an increased need in understanding their toxicological effect on human health. Particularly, iron oxide (Fe3 O4 ) have been used in various sectors, including biomedical, food, and agriculture, but the current understanding of their impact on human health is inadequate. In this investigation, we assessed the toxic effect of Fe3 O4 NPs on human mesenchymal stem cells (hMSCs) adopting cell viability, cellular morphological changes, mitochondrial transmembrane potential, and cell-cycle progression assessment methodologies. Furthermore, the expression of oxidative stress, cell death, and cell-cycle regulatory genes was assessed using quantitative polymerase chain reaction. The Fe3 O4 NPs induced cytotoxicity and nuclear morphological changes in hMSCs by dose and time exposure. Cell-cycle analysis indicated that Fe3 O4 NPs altered the cell-cycle progression through a decrease in the proportion of cells in the G0 -G1 phase. The hMSC mitochondrial membrane potential loss increased with an increase in the concentration of Fe3 O4 NPs exposure. The observed expression levels of the CYP1A, TNF3, TNFSF10, E2F1, and CCNC genes were significantly upregulated in hMSCs in response to Fe3 O4 NPs exposure. Our findings suggest that Fe3 O4 NPs caused metabolic stress through altered cell cycle, oxidative stress, and cell death regulatory gene expression in hMSCs. The results of this investigation revealed that Fe3 O4 NPs exhibited moderate toxicity on hMSCs and that Fe3 O4 NPs may have biomedical applications at low concentrations. © 2014 Wiley Periodicals, Inc. Environ Toxicol 31: 901-912, 2016.

Oxidative removal of phenol by HRP-immobilized beads and its environmental toxicology assessment

Horseradish peroxidase shows potential biological and environmental applications on the removal of phenolic compounds. In the present study, the HRP-immobilized beads were synthesized to detect the efficiency of the removal of phenol at optimum pH and H2O2 concentration. Comparative in vitro cytotoxicity of phenol/treated solutions were evaluated in HeLa, HepG2 and mcf-7 cells by using MTT method along with flow cytometry study for cell viability and cell cycle distributions. The results showed that the toxicity of phenol solutions were greatly reduced after treated by HRP-immobilized beads, and phenol could lead to deactivate of cells in the S phase and preventing them from going into the G2/M checkpoint. In addition, molecular docking study showed that phenol was a valid inhibitor for the cyclin E in the cell cycle and cell metabolism. Thereby, we established a suitable strategy with promising application for efficient harmless removal of phenol, which significantly decreased the cytotoxic impacts of phenol.

Silica-coated magnetic nanoparticles impair proteasome activity and increase the formation of cytoplasmic inclusion bodies in vitro

The potential toxicity of nanoparticles, particularly to neurons, is a major concern. In this study, we assessed the cytotoxicity of silica-coated magnetic nanoparticles containing rhodamine B isothiocyanate dye (MNPs@SiO₂(RITC)) in HEK293 cells, SH-SY5Y cells, and rat primary cortical and dopaminergic neurons. In cells treated with 1.0 μg/μl MNPs@SiO₂(RITC), the expression of several genes related to the proteasome pathway was altered, and proteasome activity was significantly reduced, compared with control and with 0.1 μg/μl MNPs@SiO₂(RITC)-treated cells. Due to the reduction of proteasome activity, formation of cytoplasmic inclusions increased significantly in HEK293 cells over-expressing the α–synuclein interacting protein synphilin-1 as well as in primary cortical and dopaminergic neurons. Primary neurons, particularly dopaminergic neurons, were more vulnerable to MNPs@SiO₂(RITC) than SH-SY5Y cells. Cellular polyamines, which are associated with protein aggregation, were significantly altered in SH-SY5Y cells treated with MNPs@SiO₂(RITC). These findings highlight the mechanisms of neurotoxicity incurred by nanoparticles.

Direct stimulation of human fibroblasts by nCeO2 in vitro is attenuated with an amorphous silica coating

Background

Nano-scaled cerium oxide (nCeO₂) is used in a variety of applications, including use as a fuel additive, catalyst, and polishing agent, yet potential adverse health effects associated with nCeO₂ exposure remain incompletely understood. Given the increasing utility and demand for engineered nanomaterials (ENMs) such as nCeO₂, “safety-by-design” approaches are currently being sought, meaning that the physicochemical properties (e.g., size and surface chemistry) of the ENMs are altered in an effort to maximize functionality while minimizing potential toxicity. In vivo studies have shown in a rat model that inhaled nCeO₂ deposited deep in the lung and induced fibrosis. However, little is known about how the physicochemical properties of nCeO_2, or the coating of the particles with a material such as amorphous silica (aSiO₂), may affect the bio-activity of these particles. Thus, we hypothesized that the physicochemical properties of nCeO₂ may explain its potential to induce fibrogenesis, and that a nano-thin aSiO₂ coating on nCeO₂ may counteract that effect.

Results

Primary normal human lung fibroblasts were treated at occupationally relevant doses with nCeO₂ that was either left uncoated or was coated with aSiO₂ (amsCeO₂). Subsequently, fibroblasts were analyzed for known hallmarks of fibrogenesis, including cell proliferation and collagen production, as well as the formation of fibroblastic nodules. The results of this study are consistent with this hypothesis, as we found that nCeO₂ directly induced significant production of collagen I and increased cell proliferation in vitro, while amsCeO₂ did not. Furthermore, treatment of fibroblasts with nCeO₂, but not amsCeO₂, significantly induced the formation of fibroblastic nodules, a clear indicator of fibrogenicity. Such in vitro data is consistent with recent in vivo observations using the same nCeO₂ nanoparticles and relevant doses. This effect appeared to be mediated through TGFβ signaling since chemical inhibition of the TGFβ receptor abolished these responses.

Conclusions

These results indicate that differences in the physicochemical properties of nCeO₂ may alter the fibrogenicity of this material, thus highlighting the potential benefits of “safety-by-design” strategies. In addition, this study provides an efficient in vitro method for testing the fibrogenicity of ENMs that strongly correlates with in vivo findings.

Platinum nanozymes recover cellular ROS homeostasis in an oxidative stress-mediated disease model

In recent years, the use of nanomaterials as biomimetic enzymes has attracted great interest. In this work, we show the potential of biocompatible platinum nanoparticles (Pt NPs) as antioxidant nanozymes, which combine abundant cellular internalization and efficient scavenging activity of cellular reactive oxygen species (ROS), thus simultaneously integrating the functions of nanocarriers and antioxidant drugs. Careful toxicity assessment and intracellular tracking of Pt NPs proved their cytocompatibility and high cellular uptake, with compartmentalization within the endo/lysosomal vesicles. We have demonstrated that Pt NPs possess strong and broad antioxidant properties, acting as superoxide dismutase, catalase, and peroxidase enzymes, with similar or even superior performance than natural enzymes, along with higher adaptability to the changes in environmental conditions. We then exploited their potent activity as radical scavenging materials in a cellular model of an oxidative stress-related disorder, namely human Cerebral Cavernous Malformation (CCM) disease, which is associated with a significant increase in intracellular ROS levels. Noteworthily, we found that Pt nanozymes can efficiently reduce ROS levels, completely restoring the cellular physiological homeostasis.

In vitro toxicity evaluation of silica-coated iron oxide nanoparticles in human SHSY5Y neuronal cells

Iron oxide nanoparticles (ION) have been widely used in biomedical applications, for both diagnosis and therapy, due to their unique magnetic properties. They are intensively explored in neuromedicine mostly because of their ability to cross the blood brain barrier. Hence, their potential harmful effects on neuronal cells need to be carefully assessed. The objective of this study was to evaluate the toxicity of silica-coated ION (S-ION) (10-200 μg ml-1) on human neuronal SHSY5Y cells. Alterations in the cell cycle, cell death by apoptosis or necrosis, and membrane integrity were assessed as cytotoxicity parameters. Genotoxicity was determined by a γH2AX assay, a micronucleus (MN) test, and a comet assay. Complementarily, possible effects on DNA damage repair were also analysed by means of a DNA repair competence assay. All analyses were performed in complete and serum-free cell culture media. Iron ion release from the nanoparticles was notable only in complete medium. Despite being effectively internalized by the neuronal cells, S-ION presented in general low cytotoxicity; positive results were only obtained in some assays at the highest concentrations and/or the longest exposure time tested (24 h). Genotoxicity evaluations in serum-free medium were negative for all conditions assayed; in complete medium, dose and time-dependent increase in DNA damage not related to the production of double strand breaks or chromosome loss (according to the results of the γH2AX assay and MN test), was obtained. The presence of serum slightly influenced the behaviour of S-ION; further studies to investigate the formation of a protein corona and its role in nanoparticle toxicity are necessary.

Multifunctional FePt–Au heterodimers: promising nanotheranostic agents for dual-modality MR/CT imaging diagnosis and in situ cancer therapy

We report the synthesis of multifunctional FePt–Au hybrid nanoparticles via a simple hydrothermal approach and their potential application in cancer dual-modality MR/CT imaging diagnosis and simultaneous in situ therapy.

Nanoparticle-assisted optical tethering of endosomes reveals the cooperative function of dyneins in retrograde axonal transport

Dynein-dependent transport of organelles from the axon terminals to the cell bodies is essential to the survival and function of neurons. However, quantitative knowledge of dyneins on axonal organelles and their collective function during this long-distance transport is lacking because current technologies to do such measurements are not applicable to neurons. Here, we report a new method termed nanoparticle-assisted optical tethering of endosomes (NOTE) that made it possible to study the cooperative mechanics of dyneins on retrograde axonal endosomes in live neurons. In this method, the opposing force from an elastic tether causes the endosomes to gradually stall under load and detach with a recoil velocity proportional to the dynein forces. These recoil velocities reveal that the axonal endosomes, despite their small size, can recruit up to 7 dyneins that function as independent mechanical units stochastically sharing load, which is vital for robust retrograde axonal transport. This study shows that NOTE, which relies on controlled generation of reactive oxygen species, is a viable method to manipulate small cellular cargos that are beyond the reach of current technology.

Magnetic nanoparticles and nanocomposites for remote controlled therapies

This review highlights the state-of-the-art in the application of magnetic nanoparticles (MNPs) and their composites for remote controlled therapies. Novel macro- to nano-scale systems that utilize remote controlled drug release due to actuation of MNPs by static or alternating magnetic fields and magnetic field guidance of MNPs for drug delivery applications are summarized. Recent advances in controlled energy release for thermal therapy and nanoscale energy therapy are addressed as well. Additionally, studies that utilize MNP-based thermal therapy in combination with other treatments such as chemotherapy or radiation to enhance the efficacy of the conventional treatment are discussed.

In Vitro/In Vivo Toxicity Evaluation and Quantification of Iron Oxide Nanoparticles

Increasing biomedical applications of iron oxide nanoparticles (IONPs) in academic and commercial settings have alarmed the scientific community about the safety and assessment of toxicity profiles of IONPs. The great amount of diversity found in the cytotoxic measurements of IONPs points toward the necessity of careful characterization and quantification of IONPs. The present document discusses the major developments related to in vitro and in vivo toxicity assessment of IONPs and its relationship with the physicochemical parameters of IONPs. Major discussion is included on the current spectrophotometric and imaging based techniques used for quantifying, and studying the clearance and biodistribution of IONPs. Several invasive and non-invasive quantification techniques along with the pitfalls are discussed in detail. Finally, critical guidelines are provided to optimize the design of IONPs to minimize the toxicity.

Protective Effects of Bovine Serum Albumin on Superparamagnetic Iron Oxide Nanoparticles Evaluated in the Nematode Caenorhabditis elegans

Nanomaterials give rise to unique biological reactivity that needs to be thoroughly investigated. The quest for enhanced magnetic nanomaterials of different shapes, magnetic properties, or surface coatings continues for applications in drug delivery, targeting therapies, biosensing, and magnetic separation. In this context, the use of simple in vivo models, such as Caenorhabditis elegans, to biologically evaluate nanoparticles is currently in increasing demand as it offers low-cost and information-rich experiments. In this work, we evaluated how surface modification (citrate- and protein-coated) of superparamagnetic iron oxide nanoparticles (C-SPIONs and BSA-SPIONs, respectively) induces changes in their toxicological profile and biodistribution using the animal model C. elegans and combining techniques from materials science and biochemistry. The acute toxicity and nanoparticle distribution were assessed in two populations of worms (adults and larvae) treated with both types of SPIONs. After 24 h treatment, nanoparticles were localized in the alimentary system of C. elegans; acute toxicity was stronger in adults and larvae exposed to C-SPIONs rather than BSA-SPIONs. Adult uptake was similar for both SPION types, whereas uptake in larvae was dependent on the surface coating, being higher for BSA-SPIONs. Nanoparticle size was evaluated upon excretion, and a slight size decrease was found. Interestingly, all results indicate the protective effects of the BSA to prevent degradation of the nanoparticles and decrease acute toxicity to the worms, especially at high concentrations. We argue that this relevant information on the chemistry and toxicity of SPIONs in vivo could not be gathered using more classical in vitro approaches such as cell culture assays, thus endorsing the potential of C. elegans to assess nanomaterials at early stages of their synthetic formulations.

The role of ROS generation from magnetic nanoparticles in an alternating magnetic field on cytotoxicity

Monosaccharide coated iron oxide nanoparticles were developed to selectively target colon cancer cell lines for magnetically mediated energy delivery therapy. The nanoparticles were prepared using a coupling reaction to attach the glucose functional group to the iron oxide core, and functionality was confirmed with physicochemical characterization techniques. The targeted nanoparticles were internalized into CT26 cells at a greater extent than non-targeted nanoparticles, and the nanoparticles were shown to be localized within lysosomes. Cells with internalized nanoparticles were exposed to an AMF to determine the potential to delivery therapy. Cellular ROS generation and apoptotic cell death was enhanced with field exposure. The nanoparticle coatings inhibit the Fenton-like surface generation of ROS suggesting a thermal or mechanical effect is more likely the source of the intracellular effect, unless the nanoparticle coating is unstable in the cellular environment.

STATEMENT OF SIGNIFICANCE

This is the first study to assess glucose coated MNPs for the delivery of MagMED therapy. With exposure of an AMF, the glucose-coated nanoparticles displayed a significant increase in cellular ROS and apoptotic cell death with no measurable increase in media temperature. To determine the mechanism of toxicity, we investigated the surface generation of ROS through Fenton-like chemistry. The coated systems displayed negligible ROS generation compared to uncoated nanoparticles. These observations suggest the cellular ROS measured is attributed to a thermal or mechanical effect of the internalized nanoparticles. In summary, this manuscript reports on some new insights as to the mechanism of MagMED therapies, which are of high interest to the biomaterials and cancer nanomedicine fields.

Mutagenic Effects of Iron Oxide Nanoparticles on Biological Cells

In recent years, there has been an increased interest in the design and use of iron oxide materials with nanoscale dimensions for magnetic, catalytic, biomedical, and electronic applications. The increased manufacture and use of iron oxide nanoparticles (IONPs) in consumer products as well as industrial processes is expected to lead to the unintentional release of IONPs into the environment. The impact of IONPs on the environment and on biological species is not well understood but remains a concern due to the increased chemical reactivity of nanoparticles relative to their bulk counterparts. This review article describes the impact of IONPs on cellular genetic components. The mutagenic impact of IONPs may damage an organism's ability to develop or reproduce. To date, there has been experimental evidence of IONPs having mutagenic interactions on human cell lines including lymphoblastoids, fibroblasts, microvascular endothelial cells, bone marrow cells, lung epithelial cells, alveolar type II like epithelial cells, bronchial fibroblasts, skin epithelial cells, hepatocytes, cerebral endothelial cells, fibrosarcoma cells, breast carcinoma cells, lung carcinoma cells, and cervix carcinoma cells. Other cell lines including the Chinese hamster ovary cells, mouse fibroblast cells, murine fibroblast cells, Mytilus galloprovincialis sperm cells, mice lung cells, murine alveolar macrophages, mice hepatic and renal tissue cells, and vero cells have also shown mutagenic effects upon exposure to IONPs. We further show the influence of IONPs on microorganisms in the presence and absence of dissolved organic carbon. The results shed light on the OPEN ACCESS Int. J. Mol. Sci. 2015, 16 23483 transformations IONPs undergo in the environment and the nature of the potential mutagenic impact on biological cells.

Effect of superparamagnetic iron oxide nanoparticles on fluidity and phase transition of phosphatidylcholine liposomal membranes

Superparamagnetic iron oxide nanoparticles (SPIONs) with multifunctional properties have shown great promise in theranostics. The aim of our work was to compare the effects of SPIONs on the fluidity and phase transition of the liposomal membranes prepared with zwitterionic phosphatidylcholine lipids. In order to study if the surface modification of SPIONs has any influence on these membrane properties, we have used four types of differently functionalized SPIONs, such as: plain SPIONs (primary size was shown to bê11 nm), silica-coated SPIONs, SPIONs coated with silica and functionalized with positively charged amino groups or negatively charged carboxyl groups (the primary size of all the surface-modified SPIONs was ~20 nm). Small unilamellar vesicles prepared with 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine lipids and multilamellar vesicles prepared with 1,2-dipalmitoyl-sn-glycero-3-phosphocholine lipids were encapsulated or incubated with the plain and surface-modified SPIONs to determine the fluidity and phase transition temperature of the bilayer lipids, respectively. Fluorescent anisotropy and differential scanning calorimetric measurements of the liposomes that were either encapsulated or incubated with the suspension of SPIONs did not show a significant difference in the lipid ordering and fluidity; though the encapsulated SPIONs showed a slightly increased effect on the fluidity of the model membranes in comparison with the incubated SPIONs. This indicates the low potential of the SPIONs to interact with the nontargeted cell membranes, which is a desirable factor for in vivo applications.

Silicon-based quantum dots induce inflammation in human lung cells and disrupt extracellular matrix homeostasis

Quantum dots (QDs) are nanocrystalline semiconductor materials that have been tested for biological applications such as cancer therapy, cellular imaging and drug delivery, despite the serious lack of information of their effects on mammalian cells. The present study aimed to evaluate the potential of Si/SiO2 QDs to induce an inflammatory response in MRC-5 human lung fibroblasts. Cells were exposed to different concentrations of Si/SiO2 QDs (25-200 μg·mL(-1)) for 24, 48, 72 and 96 h. The results obtained showed that uptake of QDs was dependent on biocorona formation and the stability of nanoparticles in various biological media (minimum essential medium without or with 10% fetal bovine serum). The cell membrane damage indicated by the increase in lactate dehydrogenase release after exposure to QDs was dose- and time-dependent. The level of lysosomes increased proportionally with the concentration of QDs, whereas an accumulation of autophagosomes was also observed. Cellular morphology was affected, as shown by the disruption of actin filaments. The enhanced release of nitric oxide and the increase in interleukin-6 and interleukin-8 protein expression suggested that nanoparticles triggered an inflammatory response in MRC-5 cells. QDs decreased the protein expression and enzymatic activity of matrix metalloproteinase (MMP)-2 and MMP-9 and also MMP-1 caseinase activity, whereas the protein levels of MMP-1 and tissue inhibitor of metalloproteinase-1 increased. The present study reveals for the first time that silicon-based QDs are able to generate inflammation in lung cells and cause an imbalance in extracellular matrix turnover through a differential regulation of MMPs and tissue inhibitor of metalloproteinase-1 protein expression.

In vitro cytotoxic evaluation of MgO nanoparticles and their effect on the expression of ROS genes

Water-dispersible MgO nanoparticles were tested to investigate their cytotoxic effects on oxidative stress gene expression. In this in vitro study, genes related to reactive oxygen species (ROS), glutathione S-transferase (GST) and catalase, were quantified using real-time polymerase chain reactions (molecular level) and molecular beacon technologies (cellular level). The monodispersed MgO nanoparticles, 20 nm in size, were used to treat human cancer cell lines (liver cancer epithelial cells) at different concentrations (25, 75 and 150 µg/mL) and incubation times (24, 48 and 72 h). Both the genetic and cellular cytotoxic screening methods produced consistent results, showing that GST and catalase ROS gene expression was maximized at 150 µg/mL nanoparticle treatment with 48 h incubation. However, the genotoxic effect of MgO nanoparticles was not significant compared with control experiments, which indicates its significant potential applications in nanomedicine as a diagnostic and therapeutic tool.

Magnetic nanoparticle-supported lipid bilayers for drug delivery

Magnetic nanoparticle-supported lipid bilayers (SLBs) constructed around core-shell Fe3O4-SiO2 nanoparticles (SNPs) were prepared and evaluated as potential drug carriers. We describe how an oxime ether lipid can be mixed with SNPs to produce lipid-particle assemblies with highly positive ζ potential. To demonstrate the potential of the resultant cationic SLBs, the particles were loaded with either the anticancer drug doxorubicin or an amphiphilic analogue, prepared to facilitate integration into the supported lipid bilayer, and then examined in studies against MCF-7 breast cancer cells. The assemblies were rapidly internalized and exhibited higher toxicity than treatments with doxorubicin alone. The magnetic SLBs were also shown to increase the efficacy of unmodified doxorubicin.

Accelerated generation of free radicals by iron oxide nanoparticles in the presence of an alternating magnetic field

The surfaces of iron oxide nanoparticles are capable of catalytically generating reactive oxygen species (ROS) through the Fenton and Haber-Weiss reactions. Fenton chemistry has been shown to be temperature dependent with an increase in activity up to 40 °C and then a decrease above this temperature as the hydrogen peroxide degrades into oxygen and water which limits the reaction. When exposed to an alternating magnetic field (AMF), iron oxide nanoparticles absorb the energy from the magnetic field and convert it into heat. In this study, we observed an increase in the degradation of methylene blue when a suspension of magnetite nanoparticles (Fe3O4) was exposed to an AMF indicating there was an increase in the ROS generation in response to the AMF. The increase in ROS generation compared to the Arrhenius prediction was both time and concentration dependent; in which we observed a decrease in ROS enhancement with increased time of exposure and concentration. We postulate that the decrease is due to agglomeration in the presence of the field. As the nanoparticles agglomerate, there is a decrease in surface area per mass limiting the reaction rate.

Effects of iron oxide nanoparticles: cytotoxicity, genotoxicity, developmental toxicity, and neurotoxicity

Iron oxide nanoparticles (ION) with superparamagnetic properties hold great promise for use in various biomedical applications; specific examples include use as contrast agents for magnetic resonance imaging, in targeted drug delivery, and for induced hyperthermia cancer treatments. Increasing potential applications raise concerns over their potential effects on human health. Nevertheless, very little is currently known about the toxicity associated with exposure to these nanoparticles at different levels of biological organization. This article provides an overview of recent studies evaluating ION cytotoxicity, genotoxicity, developmental toxicity and neurotoxicity. Although the results of these studies are sometimes controversial, they generally indicate that surface coatings and particle size seem to be crucial for the observed ION-induced effects, as they are critical determinants of cellular responses and intensity of effects, and influence potential mechanisms of toxicity. The studies also suggest that some ION are safe for certain biomedical applications, while other uses need to be considered more carefully. Overall, the available studies provide insufficient evidence to fully assess the potential risks for human health related to ION exposure. Additional research in this area is required including studies on potential long-term effects.

Reduced astrocyte viability at physiological temperatures from magnetically activated iron oxide nanoparticles

Superparamagnetic iron oxide nanoparticles (SPIONs) can generate heat when subjected to an alternating magnetic field (AMF). In the European Union, SPIONs actuated by AMF are used in hyperthermia treatment of glioblastoma multiforme, an aggressive form of brain cancer. Current data from clinical trials suggest that this therapy improves patient life expectancy, but their effect on healthy brain cells is virtually unknown. Thus, a viability study involving SPIONs subjected to an AMF was carried out on healthy cortical rat astrocytes, the most abundant cell type in the mammalian brain. The cells were cultured with aminosilane- or starch-coated SPIONs with or without application of an AMF. Significant cell death (p < 0.05) was observed only when SPIONs were added to astrocyte cultures and subjected to an AMF. Unexpectedly, the decrease in astrocyte viability was observed at physiological temperatures (34-40 °C) with AMF. A further decrease in astrocyte viability was found only when bulk temperatures exceeded 45 °C. To discern differences in the astrocyte structure when astrocytes were cultured with particles with or without AMF, scanning electron microscopy (SEM) was performed. SEM images revealed a change in the structure of the astrocyte cell membrane only when astrocytes were cultured with SPIONs and actuated with an AMF. This study is the first to report that astrocyte death occurs at physiological temperatures in the presence of magnetic particles and AMF, suggesting that other mechanisms are responsible for inducing astrocyte death in addition to heat.

In vitro toxicity assessment of chitosan oligosaccharide coated iron oxide nanoparticles

Iron oxide nanoparticles (INPs) have potential biological, biomedical and environmental applications. These applications require surface modification of the iron oxide nanoparticles, which makes it non-toxic, biocompatible, stable and non-agglomerative in natural and biological surroundings. In the present study, iron oxide nanoparticles (INPs) and chitosan oligosaccharide coated iron oxide nanoparticles (CSO-INPs) were synthesized to evaluate the effect of surface coating on the stability and toxicity of nanoparticles. Comparative in vitro cytotoxicity of nanoparticles was evaluated in HeLa (human cervix carcinoma), A549 (human lung carcinoma) and Hek293 (human embryonic kidney) cells by using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay along with flow cytometry study for cell viability, membrane integrity, mitochondrial membrane potential (MMP) and reactive oxygen species (ROS) production. Morphological alteration in nanoparticles treated cells was analyzed by Acridine orange/ethidium bromide double staining and electron microscopy. Synthesized nanoparticles were found to be spherical in shape, well dispersed and stable at various pH values, making them suitable for biomedical and environmental applications. The present study also indicates that the chitosan oligosaccharide coating on iron oxide nanoparticles results in the decrease in cellular damage and moderate ROS production, thereby, significantly decreasing the cytotoxic impact of bare iron oxide nanoparticles.

Transport across the cell-membrane dictates nanoparticle fate and toxicity: a new paradigm in nanotoxicology

The toxicity of metallic nanoparticles (MNPs) has been fully ascertained, but the mechanisms underlying their cytotoxicity remain still largely unclear. Here we demonstrate that the cytotoxicity of MNPs is strictly reliant on the pathway of cellular internalization. In particular, if otherwise toxic gold, silver, and iron oxide NPs are forced through the cell membrane bypassing any form of active mechanism (e.g., endocytosis), no significant cytotoxic effect is registered. Pneumatically driven NPs across the cell membrane show a different distribution within the cytosol compared to NPs entering the cell by active endocytosis. Specifically, they exhibit free random Brownian motions within the cytosol and do not accumulate in lysosomes. Results suggest that intracellular accumulation of metallic nanoparticles into endo-lysosomal compartments is the leading cause of nanotoxicity, due to consequent nanoparticle degradation and in situ release of metal ions.

Design of multifunctional FePt/GO nanocomposites for targeting, dual-modal imaging diagnostic and in situ therapeutic potential theranostic platform

In this work, highly monodispersed chemically disordered face centered cubic (fcc) FePt nanoparticles (NPs) were assembled on graphene oxide (GO) surface to form FePt/GO nanocomposites via a simple polyol protocol.