Oleic Acid-coated Iron Oxide Nanoparticles Research Articles

Influence of oleic acid coating on the magnetic susceptibility and Fenton reaction-mediated ROS generation by the iron oxide nanoparticles

Fenton reaction-mediated reactive oxygen species (ROS) generation by the iron oxide nanoparticles (IONPs) is responsible for its antibacterial activity. In general, IONPs are surface-coated to facilitate stability, control over size, biocompatibility, solubility, etc. We hypothesize that the extent of surface coating onto the IONPs might affect Fenton reaction-mediated ROS generation, which would eventually impact its antibacterial activity. In the present study, IONPs were prepared using the co-precipitation method, and different weights of oleic acid (OA) were loaded onto the IONPs. Pristine IONPs and oleic acid-coated iron oxide nanoparticles (OA-IONPs) were characterized using Fourier transform-infrared spectroscopy, dynamic light scattering, transmission electron microscopy, X-ray diffraction, vibrating sample magnetometry, goniometer, and thermogravimetric analysis. We found that magnetic susceptibilities of the IONPs were significantly enhanced with an increase in OA loading on the IONPs. The antibacterial study showed that the percentage inhibition was inversely related to the extent of oleic acid coating on the IONPs. The dependency of ROS generation on the extent of surface coating over IONPs was demonstrated using the 2’,7’-dichlorodihydrofluorescein diacetate (DCFDA) assay. Although pristine IONPs showed the least ROS generation, they exhibited maximum percentage inhibition of bacteria. This might be due to mechanical damage to the bacterial cells because of their crystalline nature. In vitro biocompatibility study conducted on L929 fibroblast cell lines indicated that all the nanoparticle preparations were cytocompatible. This study concluded that the extent of surface coating influences the Fenton reaction-mediated ROS generation and also the magnetic susceptibilities of the IONPs.

Iron oxide nanoparticle-stabilized Pickering emulsion-templated porous scaffolds loaded with polyunsaturated fatty acids (PUFAs) for bone tissue engineering.

Dietary intake of ω-3-polyunsaturated fatty acids (PUFAs) can significantly improve the expression levels of alkaline phosphatase (ALP) and osteocalcin. However, PUFAs are hydrophobic and highly sensitive to temperature, oxygen concentration, pH, and ionic strength. Hence, it is challenging to use PUFAs as bioactive compounds for bone tissue engineering. Here, we encapsulated PUFAs in liposomes to improve their stability. The hydrodynamic size of the PUFA-loaded liposomes was found to be 121.3 ± 35 nm. GC-MS analysis showed that the encapsulation efficiency of the PUFAs was 19.9 ± 3.4%. These PUFA-loaded liposomes were loaded into porous scaffolds that were prepared by polymerizing glycidyl methacrylate and trimethylolpropane triacrylate monomers using the Pickering emulsion polymerization technique. Oleic acid-coated iron oxide nanoparticles were used as the stabilizing agent to prepare these acrylate-based scaffolds containing PUFA-loaded liposomes (P-Lipo-IO(GMA-TMPTA)). SEM micrographs confirmed the porous nature of the scaffolds and the presence of well-adhered liposomes. An in vitro cytotoxicity study conducted using MG63 cells confirmed that these scaffolds showed desirable cytocompatibility. Cell adhesion study showed a well-spread morphology, indicating firm adhesion of the cells. The alizarin red staining of P-Lipo-IO(GMA-TMPTA) scaffolds showed 3- and 2-fold higher calcium deposition compared to the control on days 7 and 14, respectively. ALP activity was also 2-fold higher than that of the control on day 14. RT-PCR analysis of cells exposed to P-Lipo-IO(GMA-TMPTA) scaffolds showed significantly higher expression of osteogenic markers compared to the control. An antibacterial study conducted on Staphylococcus aureus showed a higher percentage inhibition and reactive oxygen species generation in samples treated with P-Lipo-IO(GMA-TMPTA) scaffolds. These desirable biological properties indicate that the developed scaffolds are suitable for bone tissue engineering.

Understand the Fe3C nanocrystalline grown on rGO and its performance for oxygen reduction reaction

Transition metal carbide catalysts are the alternative products of traditional noble metal Pt/C in oxygen reduction reaction (ORR). Oleic acid-coated iron oxide nanoparticles (F3O4@OA) was prepared by pyrolysis, assembled with reduced graphene oxide (rGO), and carbonized at 800 °C to obtain N doped iron carbide nanoparticles supported rGO (N–Fe3C/rGO). The particle size of nanocrystals increases significantly with the graphene loading risen can be seen in the transmission electron microscope (TEM) image which roughly distributed around 40 nm. The linear scanning voltammetry (LSV) curve shows the material has an ORR performance equivalent to Pt/C in alkaline media.

Evaluating physical changes of iron oxide nanoparticles due to surface modification with oleic acid

The physical characterization of a colloidal system of superficially modified magnetic nanoparticles (MNPs) is presented. The system consists of oleic acid-coated iron oxide nanoparticles (OAMNP) suspended in water. A structural analysis is carried out by using standard physical techniques to determine the diameter and shape of the MNPs and also the width of the coating shell. The colloidal stability and the polydispersity index of this ferrofluid are determined by using Zeta potential measurements. Additionally, the magnetic characterization is conducted by obtaining the DC magnetization loops, and the blocking temperatures are determined according to the ZFC–FC protocol. Finally, the values of power absorption density P of the ferrofluid are estimated by using a magneto-calorimetric procedure in a wide range of magnetic field amplitude H and frequency f. The experimental results exhibit spherical-like shape of OAMNP with (20 ± 4) nm in diameter. Due to the use of coating process, the parameters of the magnetization loops and the blocking temperatures are significantly modified. Hence, while the uncoated MNPs show a blocking state of the magnetization, the OAMNP are superparamagnetic above room temperature (300 K). Furthermore, the reached dependence P versus f and P versus H of the ferrofluid with coated MNPs are clearly fitted to linear and quadratic correlations, respectively, showing their accordance with the linear response theory.

Core-Shell-Heterostructured Magnetic-Plasmonic Nanoassemblies with Highly Retained Magnetic-Plasmonic Activities for Ultrasensitive Bioanalysis in Complex Matrix.

Herein, a facile self‐assembly strategy for coassembling oleic acid‐coated iron oxide nanoparticles (OC‐IONPs) with oleylamine‐coated gold nanoparticles (OA‐AuNPs) to form colloidal magnetic–plasmonic nanoassemblies (MPNAs) is reported. The resultant MPNAs exhibit a typical core–shell heterostructure comprising aggregated OA‐AuNPs as a plasmonic core surrounded by an assembled magnetic shell of OC‐IONPs. Owing to the high loading of OA‐AuNPs and reasonable spatial distribution of OC‐IONPs, the resultant MPNAs exhibit highly retained magnetic–plasmonic activities simultaneously. Using the intrinsic dual functionality of MPNAs as a magnetic separator and a plasmonic signal transducer, it is demonstrated that the assembled MPNAs can achieve the simultaneous magnetic manipulation and optical detection on the lateral flow immunoassay platform after surface functionalization with recognition molecules. In conclusion, the core–shell‐heterostructured MPNAs can serve as a nanoanalytical platform for the separation and concentration of target compounds from complex biological samples using magnetic properties and simultaneous optical sensing using plasmonic properties.

Evaluation of cytotoxicity and genotoxicity induced by oleic acid-coated iron oxide nanoparticles in human astrocytes.

Iron oxide nanoparticles (ION) are gaining importance as diagnostic and therapeutic tool of central nervous system diseases. Although oleic acid-coated ION (O-ION) have been described as stable and biocompatible, their potential neurotoxicity was scarcely evaluated in human nervous cells so far. The primary aim of this work was to assess the molecular and cellular effects of O-ION on human astrocytes (A172 cells) under different experimental conditions. An extensive set of cyto- and genotoxicity tests was carried out, including lactate dehydrogenase release assay, cell cycle alterations, and cell death production, as well as comet assay, γH2AX assay, and micronucleus (MN) test, considering also iron ion release capacity and alterations in DNA repair ability. Results showed a moderate cytotoxicity related to cell cycle arrest and cell death promotion, regardless of serum presence. O-ION induced genotoxic effects, namely primary DNA damage, as detected by the comet assay and H2AX phosphorylation, but A172 cells were able to repair this particular damage because no chromosome alterations were found (confirmed by MN test results). Accordingly, no effects on the DNA repair ability were observed. The presence of serum proteins did not influence O-ION toxicity. Iron ions released from the O-ION surface seemed not to be responsible for the cytotoxic and genotoxic effects observed. Environ. Mol. Mutagen. 2019. © 2019 Wiley Periodicals, Inc.

Injectable, Magnetically Orienting Electrospun Fiber Conduits for Neuron Guidance.

Magnetic electrospun fibers are of interest for minimally invasive biomaterial applications that also strive to provide cell guidance. Magnetic electrospun fibers can be injected and then magnetically positioned in situ, and the aligned fiber scaffolds provide consistent topographical guidance to cells. In this study, magnetically responsive aligned poly-l-lactic acid electrospun fiber scaffolds were developed and tested for neural applications. Incorporating oleic acid-coated iron oxide nanoparticles significantly increased neurite outgrowth, reduced the fiber alignment, and increased the surface nanotopography of the electrospun fibers. After verifying neuron viability on two-dimensional scaffolds, the system was tested as an injectable three-dimensional scaffold. Small conduits of aligned magnetic fibers were easily injected in a collagen or fibrinogen hydrogel solution and repositioned using an external magnetic field. The aligned magnetic fibers provided internal directional guidance to neurites within a three-dimensional collagen or fibrin model hydrogel, supplemented with Matrigel. Neurites growing from dorsal root ganglion explants extended 1.4-3× farther on the aligned fibers compared with neurites extending in the hydrogel alone. Overall, these results show that magnetic electrospun fiber scaffolds can be injected and manipulated with a magnetic field in situ to provide directional guidance to neurons inside an injectable hydrogel. Most importantly, this injectable guidance system increased both neurite alignment and neurite length within the hydrogel scaffold.

Neurotoxicity assessment of oleic acid-coated iron oxide nanoparticles in SH-SY5Y cells

Iron oxide nanoparticles (ION) awaken a particular interest for biomedical applications due to their unique physicochemical properties, especially superparamagnetism, and ability to cross the blood-brain barrier. ION surface can be coated to improve their properties and facilitate functionalization. Still, coating may affect toxicity. The aim of this work was to evaluate the possible effects of oleic acid-coated ION (O-ION) on human neuronal cells (SH-SY5Y). A set of assays was conducted in complete and serum-free culture media for 3 and 24 h to assess O-ION cytotoxic effects – cell membrane disruption, cell cycle alteration and cell death induction –, and genotoxic effects – primary DNA damage, H2AX phosphorylation and micronuclei induction –, considering also DNA repair competence and iron ion release. Results obtained show that O-ION exhibit a moderate cytotoxicity related to cell membrane impairment, cell cycle disruption and cell death induction, especially notable in serum-free medium. Iron ion release was only observed in complete medium, indicating that cytotoxicity observed was not related to the presence of ions in the medium. However, O-ION genotoxic effects were limited to the induction of primary DNA damage, not related to double strand breaks, and this damage did not become fixed in cells in most conditions. Alterations in repair ability (DNA repair competence assay) were observed when cells where treated with O-ION before or during the challenge with H2O2, but not during the repair period. Further investigation is needed to clarify the possible role of oxidative stress and protein corona on observed O-ION toxicity.

Comet assay assessment of oleic acid-coated magnetite nanoparticles on human SHSY5Y neuronal cells

Event Abstract Back to Event Comet assay assessment of oleic acid-coated magnetite nanoparticles on human SHSY5Y neuronal cells Joao P. Teixeira1*, Blanca Laffon2, Gözde Kiliç2, Natalia Fernández-Bertólez2, Carla Costa1, Solange Costa1, Eduardo Passaro2 and Vanessa Valdiglesias2 1 National Institute of Health, Environmental Health Department, Portugal 2 Universidade da Coruña, Spain Superparamagnetic iron oxide nanoparticles (ION) have a wide range of potential applications. Among them, the most important uses in biology and medicine are as contrast agents in magnetic resonance imaging, as carriers for drug delivery or transfection and as therapeutic agents in cancer therapy by magnetic field-mediated hyperthermia. For all these applications, ION must be introduced in the human body and come into contact with cells and tissues, so it is imperative to know the potential risks associated to this exposure. Nevertheless, although ION biocompatibility has been reported to be high, there is a lack of information regarding their genotoxic potential, especially on the nervous system. Thus, the main objective of this work was to examine possible genotoxic effects of ION (crystalline phase magnetite, covered by oleic acid) on human SHSY5Y neuronal cells by the standard alkaline comet assay, along with its OGG1 enzyme modified version to analyse oxidative DNA damage. Previously we evaluated the possible interference of the ION with the comet assay methodology and with OGG1 enzyme activity. ION were dispersed both in complete and serum-free cell culture media, and cells were exposed to four concentrations in the range 10-200 µg/ml for 3 and 24 h. Results obtained showed increases in DNA damage, both primary and oxidative, after treatment with oleic acid-coated ION, even though the highest concentrations were found to interfere with OGG1 enzyme activity in incomplete cell culture medium. The results of this study encourage the need for checking the suitability of comet assay when used for testing genotoxicity of nanomaterials. Further investigations are required to assess the ability of ION to induce oxidative stress, and to elucidate the specific mechanism involved in primary DNA damage induced by these ION. Acknowledgements Acknowledgements: Research funded by grants from ERA‐SIINN/0001/2013-FCT, Xunta de Galicia (EM 2012/079), and MODENA project (COST Action TD1204). G. Kiliç was supported by a fellowship from the University of A Coruña. Keywords: Comet Assay, DNA Damage, Magnetite Nanoparticles, Neurotoxicity, Oxidative damage Conference: ICAW 2015 - 11th International Comet Assay Workshop, Antwerpen, Belgium, 1 Sep - 4 Sep, 2015. Presentation Type: Poster Discussion Topic: Genotoxicity testing of chemicals and nanomaterials Citation: Teixeira JP, Laffon B, Kiliç G, Fernández-Bertólez N, Costa C, Costa S, Passaro E and Valdiglesias V (2015). Comet assay assessment of oleic acid-coated magnetite nanoparticles on human SHSY5Y neuronal cells. Front. Genet. Conference Abstract: ICAW 2015 - 11th International Comet Assay Workshop. doi: 10.3389/conf.fgene.2015.01.00026 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 02 Jun 2015; Published Online: 23 Jun 2015. * Correspondence: Dr. Joao P Teixeira, National Institute of Health, Environmental Health Department, Porto, 4000-055, Portugal, jpft12@gmail.com Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Joao P Teixeira Blanca Laffon Gözde Kiliç Natalia Fernández-Bertólez Carla Costa Solange Costa Eduardo Passaro Vanessa Valdiglesias Google Joao P Teixeira Blanca Laffon Gözde Kiliç Natalia Fernández-Bertólez Carla Costa Solange Costa Eduardo Passaro Vanessa Valdiglesias Google Scholar Joao P Teixeira Blanca Laffon Gözde Kiliç Natalia Fernández-Bertólez Carla Costa Solange Costa Eduardo Passaro Vanessa Valdiglesias PubMed Joao P Teixeira Blanca Laffon Gözde Kiliç Natalia Fernández-Bertólez Carla Costa Solange Costa Eduardo Passaro Vanessa Valdiglesias Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Stress reaction of kidney epithelial cells to inorganic solid-core nanoparticles

A route of accumulation and elimination of therapeutic engineered nanoparticles (NPs) may be the kidney. Therefore, the interactions of different solid-core inorganic NPs (titanium-, silica-, and iron oxide-based NPs) were studied in vitro with the MDCK and LLC-PK epithelial cells as representative cells of the renal epithelia. Following cell exposure to the NPs, observations include cytotoxicity for oleic acid-coated iron oxide NPs, the production of reactive oxygen species for titanium dioxide NPs, and cell depletion of thiols for uncoated iron oxide NPs, whereas for silica NPs an apparent rapid and short-lived increase of thiol levels in both cell lines was observed. Following cell exposure to metallic NPs, the expression of the tranferrin receptor/CD71 was decreased in both cells by iron oxide NPs, but only in MDCK cells by titanium dioxide NPs. The tight association, then subsequent release of NPs by MDCK and LLC-PK kidney epithelial cells, showed that following exposure to the NPs, only MDCK cells could release iron oxide NPs, whereas both cells released titanium dioxide NPs. No transfer of any solid-core NPs across the cell layers was observed.

Preparation of magnetic polymer microspheres with reactive epoxide functional groups for direct immobilization of antibody

Monodisperse magnetic polymer microspheres with epoxide functional groups have been developed through ex situ swelling and diffusion process. Poly(glycidyl methacrylate-co-divinyl benzene) (poly(GMA-co-DVB)) microspheres were prepared by cross-linking precipitation polymerization of GMA and DVB monomers without the use of surfactants and stabilizers. The microspheres were subsequently swollen in chloroform in the presence of oleic acid-coated iron oxide nanoparticles (IOs). The size of poly(GMA-co-DVB) microspheres can be controlled by varying the concentration of DVB cross-linker. Based on FTIR, XRD, and vibrating sample magnetometer (VSM) analysis, IOs were successfully entrapped in poly(GMA-co-DVB) microspheres. For a constant IO feed, increase in DVB content resulted in the decrease in the IO loading. It was found that the reactive epoxide functional groups of the microsphere's surface can covalently conjugate with monoclonal antibody, specific to CD4 molecules expressed on CD4+ lymphocytes, which was confirmed from flow cytometry. Thus, these microspheres are promising to be used in various biomedical applications including diagnosis, and monitoring of human diseases.

Improved functionalization of oleic acid-coated iron oxide nanoparticles for biomedical applications

Superparamagnetic iron oxide nanoparticles can provide multiple benefits for biomedical applications in aqueous environments such as magnetic separation or magnetic resonance imaging. To increase the colloidal stability and allow subsequent reactions, the introduction of hydrophilic functional groups onto the particles’ surface is essential. During this process, the original coating is exchanged by preferably covalently bonded ligands such as trialkoxysilanes. The duration of the silane exchange reaction, which commonly takes more than 24 h, is an important drawback for this approach. In this paper, we present a novel method, which introduces ultrasonication as an energy source to dramatically accelerate this process, resulting in high-quality water-dispersible nanoparticles around 10 nm in size. To prove the generic character, different functional groups were introduced on the surface including polyethylene glycol chains, carboxylic acid, amine, and thiol groups. Their colloidal stability in various aqueous buffer solutions as well as human plasma and serum was investigated to allow implementation in biomedical and sensing applications.Electronic supplementary materialThe online version of this article (doi:10.1007/s11051-012-1100-5) contains supplementary material, which is available to authorized users.

Induction of oxidative stress, lysosome activation and autophagy by nanoparticles in human brain-derived endothelial cells

Different types of NPs (nanoparticles) are currently under development for diagnostic and therapeutic applications in the biomedical field, yet our knowledge about their possible effects and fate in living cells is still limited. In the present study, we examined the cellular response of human brain-derived endothelial cells to NPs of different size and structure: uncoated and oleic acid-coated iron oxide NPs (8-9 nm core), fluorescent 25 and 50 nm silica NPs, TiO2 NPs (21 nm mean core diameter) and PLGA [poly(lactic-co-glycolic acid)]-PEO [poly(ethylene oxide)] polymeric NPs (150 nm). We evaluated their uptake by the cells, and their localization, generation of oxidative stress and DNA-damaging effects in exposed cells. We show that NPs are internalized by human brain-derived endothelial cells; however, the extent of their intracellular uptake is dependent on the characteristics of the NPs. After their uptake by human brain-derived endothelial cells NPs are transported into the lysosomes of these cells, where they enhance the activation of lysosomal proteases. In brain-derived endothelial cells, NPs induce the production of an oxidative stress after exposure to iron oxide and TiO2 NPs, which is correlated with an increase in DNA strand breaks and defensive mechanisms that ultimately induce an autophagy process in the cells.