In vitro and in vivo experiments with iron oxide nanoparticles functionalized with DEXTRAN or polyethylene glycol for medical applications: magnetic targeting

Multifunctional Iron Oxide Nanoparticles as Promising Magnetic Biomaterials in Drug Delivery: A Review

A wide range of applications using functionalized magnetic nanoparticles (MNPs) in biomedical applications, such as in biomedicine as well as in biotechnology, have been extensively expanding over the last years. Their potential is tremendous in delivery and targeting systems due to their advantages in biosubstance binding. By applying magnetic materials-based biomaterials to different organic polymers, highly advanced multifunctional bio-composites with high specificity, efficiency, and optimal bioavailability are designed and implemented in various bio-applications. In modern drug delivery, the importance of a successful therapy depends on the proper targeting of loaded bioactive components to specific sites in the body. MNPs are nanocarrier-based systems that are magnetically guided to specific regions using an external magnetic field. Therefore, MNPs are an excellent tool for different biomedical applications, in the form of imaging agents, sensors, drug delivery targets/vehicles, and diagnostic tools in managing disease therapy. A great contribution was made to improve engineering skills in surgical diagnosis, therapy, and treatment, while the advantages and applicability of MNPs have opened up a large scope of studies. This review highlights MNPs and their synthesis strategies, followed by surface functionalization techniques, which makes them promising magnetic biomaterials in biomedicine, with special emphasis on drug delivery. Mechanism of the delivery system with key factors affecting the drug delivery efficiency using MNPs are discussed, considering their toxicity and limitations as well.

Polypropylene sulphide coating on magnetic nanoparticles as a novel platform for excellent biocompatible, stimuli-responsive smart magnetic nanocarriers for cancer therapeutics

Magnetic nanoparticle (MNP) delivery systems are promising for targeted drug delivery, imaging, and chemo-hyperthermia of cancer; however, their uses remain limited primarily due to their toxicity associated with reactive oxygen species (ROS) generation, targeted delivery, and biodegradation. Attempts employing polymer coatings to minimize the toxicity, along with other challenges, have had limited success. We designed a novel yet generic 'one-for-all' polypropylene sulphide (PPS) coated magnetic nano-delivery system (80 ± 15 nm) as a multi-faceted approach for significant biocompatibility improvement, loading of multiple drugs, ROS-responsive delivery, and combined chemo-hyperthermia therapy for biomedical applications. Three distinct MNP systems (15 ± 1 nm) were fabricated, coated with PPS polymer, and investigated to validate our hypothesis and design. Simultaneous degradation of MNPs and PPS coatings with ROS-scavenging characteristics boosted the biocompatibility of MNPs 2-3 times towards non-cancerous fibroblasts (NIH3T3) and human epithelial cells (HEK293). In an alternating magnetic field, PPS-MNPs (MnFe) had the strongest heating characteristics (SAR value of 240 W g^-1). PPS-MNP drug-loaded NPs were efficiently internalised into cells and released 80% of the drugs under tumor microenvironment-mimicking (pH 5-7, ROS) conditions, and demonstrated effective chemo-hyperthermia (45 °C) application for breast cancer cells with 95% cell death in combined treatment vs. 55% and 30% cell death in only hyperthermia and chemotherapy respectively.

The effect of size, shape, coating and functionalization on nuclear relaxation properties in iron oxide core-shell nanoparticles: a brief review of the situation

In this perspective article, we present a short selection of some of the most significant case studies on magnetic nanoparticles for potential applications in nanomedicine, mainly magnetic resonance. For almost 10 years, our research activity focused on the comprehension of the physical mechanisms on the basis of the nuclear relaxation of magnetic nanoparticles in the presence of magnetic fields; taking advantage of the insights gathered over this time span, we report on the dependence of the relaxation behaviour on the chemico-physical properties of magnetic nanoparticles and discuss them in full detail. In particular, a critical review is carried out on the correlations between their efficiency as contrast agents in magnetic resonance imaging and the magnetic core of magnetic nanoparticles (mainly iron oxides), their size and shape, and the coating and solvent used for making them biocompatible and well dispersible in physiological media. Finally, the heuristic model proposed by Roch and coworkers is presented, as it was extensively adopted to describe most of the experimental data sets. The large amount of data analyzed allowed us to highlight both the advantages and limitations of the model.

Influence of PEG Chain Length of Functionalized Magnetic Nanoparticles on the Cytocompatibility and Immune Competence of Primary Murine Macrophages and Dendritic Cells

A major drawback of nanoparticles (NPs) for biomedical applications is their preferential phagocytosis in immune cells, which can be avoided by surface modifications like PEGylation. Nevertheless, examinations of different polyethylene glycol (PEG) chain lengths on the competence of immune cells as well as possible immunotoxic effects are still sparse. Therefore, primary murine macrophages and dendritic cells were generated and incubated with magnetic nanoporous silica nanoparticles (MNPSNPs) modified with different mPEG chains (2 kDa, 5 kDa, and 10 kDa). Cytotoxicity, cytokine release, and the formation of reactive oxygen species (ROS) were determined. Immune competence of both cell types was examined and uptake of MNPSNPs into macrophages was visualized. Concentrations up to 150 µg/mL MNPSNPs showed no effects on the metabolic activity or immune competence of both cell types. However, ROS significantly increased in macrophages incubated with larger PEG chains, while the concentration of cytokines (TNF-α and IL-6) did not indicate a proinflammatory process. Investigations on the uptake of MNPSNPs revealed no differences in the onset of internalization and the intensity of intracellular fluorescence. The study gives no indication for an immunotoxic effect of PEGylated MNPSNPs. Nevertheless, there is still a need for optimization regarding their internalization to ensure an efficient drug delivery.

Synthesis and Characterization of a Biocompatible Nanoplatform Based on Silica-Embedded SPIONs Functionalized with Polydopamine

Superparamagnetic iron oxide nanoparticles (SPIONs) have gained increasing interest in nanomedicine, but most of those that have entered the clinical trials have been withdrawn due to toxicity concerns. Therefore, there is an urgent need to design low-risk and biocompatible SPION formulations. In this work, we present an original safe-by-design nanoplatform made of silica nanoparticles loaded with SPIONs and decorated with polydopamine (SPIONs@SiO2-PDA) and the study of its biocompatibility performance by an ad hoc thorough in vitro to in vivo nanotoxicological methodology. The results indicate that the SPIONs@SiO₂-PDA have excellent colloidal stability in serum-supplemented culture media, even after long-term (24 h) exposure, showing no cytotoxic or genotoxic effects in vitro and ex vivo. Physiological responses, evaluated in vivo using Caenorhabditis elegans as the animal model, showed no impact on fertility and embryonic viability, induction of an oxidative stress response, and a mild impact on animal locomotion. These tests indicate that the synergistic combination of the silica matrix and PDA coating we developed effectively protects the SPIONs, providing enhanced colloidal stability and excellent biocompatibility.

Formulation, Optimization and Evaluation of Cytarabine-Loaded Iron Oxide Nanoparticles: From In Vitro to In Vivo Evaluation of Anticancer Activity

Innovative drug delivery systems based on iron oxide nanoparticles (INPs) has generated a lot of interest worldwide and have prime biomedical benefits in anticancer therapy. There are still issues reported regarding the stability, absorption, and toxicity of iron oxide nanoparticles (INPs) when administered due to its rapid surface oxidation and agglomeration with blood proteins. To solve this problem, we have synthesized trehalose-coated stabilized iron oxide nanoparticles (TINPs) by a co-precipitation technique. The surface coating of INPs with trehalose helps to improve the stability, prevents protein binding, and increase absorption uptake inside the body. Developed TINPs was then loaded with anticancer drug cytarabine by chemical crosslinking encapsulation method using suitable solvent. Engineered cytarabine-loaded trehalose-coated stabilized iron oxide nanoparticles (CY-TINPs) were optimized for particle size, zeta potential (-13.03 mV), and solid-state characterization such as differential scanning calorimetry (DSC), X-ray powder diffraction (XRD), and transmission electron microscope (TEM) studies. The particle size of 50 nm was achieved for developed CY-TINPs. The developed CY-TINPs was further evaluated for in vitro cell line investigations which confirmed potential cytotoxic activity. Developed CY-TINPs show remarkable enhancement in in vivo pharmacokinetic parameters Cmax as 425.26 ± 2.11 and AUC0-72 as 11,546.64 ± 139.82 as compared to pure drug. Compared to traditional drug delivery, the CY-TINPs formulation can effectively delay release, improve bioavailability, and boost cytotoxic activity against tumors.

Vascular Repair by Grafting Based on Magnetic Nanoparticles

Magnetic nanoparticles (MNPs) have attracted much attention in the past few decades because of their unique magnetic responsiveness. Especially in the diagnosis and treatment of diseases, they are mostly involved in non-invasive ways and have achieved good results. The magnetic responsiveness of MNPs is strictly controlled by the size, crystallinity, uniformity, and surface properties of the synthesized particles. In this review, we summarized the classification of MNPs and their application in vascular repair. MNPs mainly use their unique magnetic properties to participate in vascular repair, including magnetic stimulation, magnetic drive, magnetic resonance imaging, magnetic hyperthermia, magnetic assembly scaffolds, and magnetic targeted drug delivery, which can significantly affect scaffold performance, cell behavior, factor secretion, drug release, etc. Although there are still challenges in the large-scale clinical application of MNPs, its good non-invasive way to participate in vascular repair and the establishment of a continuous detection process is still the future development direction.

Magnetic particle imaging: tracer development and the biomedical applications of a radiation-free, sensitive, and quantitative imaging modality

Magnetic particle imaging (MPI) is an emerging tracer-based modality that enables real-time three-dimensional imaging of the non-linear magnetisation produced by superparamagnetic iron oxide nanoparticles (SPIONs), in the presence of an external oscillating magnetic field. As a technique, it produces highly sensitive radiation-free tomographic images with absolute quantitation. Coupled with a high contrast, as well as zero signal attenuation at-depth, there are essentially no limitations to where that can be imaged within the body. These characteristics enable various biomedical applications of clinical interest. In the opening sections of this review, the principles of image generation are introduced, along with a detailed comparison of the fundamental properties of this technique with other common imaging modalities. The main feature is a presentation on the up-to-date literature for the development of SPIONs tailored for improved imaging performance, and developments in the current and promising biomedical applications of this emerging technique, with a specific focus on theranostics, cell tracking and perfusion imaging. Finally, we will discuss recent progress in the clinical translation of MPI. As signal detection in MPI is almost entirely dependent on the properties of the SPION employed, this work emphasises the importance of tailoring the synthetic process to produce SPIONs demonstrating specific properties and how this impacts imaging in particular applications and MPI's overall performance.

Charge-Modulated Synthesis of Highly Stable Iron Oxide Nanoparticles for In Vitro and In Vivo Toxicity Evaluation

The surface charge of iron oxide nanoparticles (IONPs) plays a critical role in the interactions between nanoparticles and biological components, which significantly affects their toxicity in vitro and in vivo. In this study, we synthesized three differently charged IONPs (negative, neutral, and positive) based on catechol-derived dopamine, polyethylene glycol, carboxylic acid, and amine groups, via reversible addition-fragmentation chain transfer-mediated polymerization (RAFT polymerization) and ligand exchange. The zeta potentials of the negative, neutral, and positive IONPs were -39, -0.6, and +32 mV, respectively, and all three IONPs showed long-term colloidal stability for three months in an aqueous solution without agglomeration. The cytotoxicity of the IONPs was studied by analyzing cell viability and morphological alteration in three human cell lines, A549, Huh-7, and SH-SY5Y. Neither IONP caused significant cellular damage in any of the three cell lines. Furthermore, the IONPs showed no acute toxicity in BALB/c mice, in hematological and histological analyses. These results indicate that our charged IONPs, having high colloidal stability and biocompatibility, are viable for bio-applications.

Imaging Constructs: The Rise of Iron Oxide Nanoparticles

Over the last decade, an important challenge in nanomedicine imaging has been the work to design multifunctional agents that can be detected by single and/or multimodal techniques. Among the broad spectrum of nanoscale materials being investigated for imaging use, iron oxide nanoparticles have gained significant attention due to their intrinsic magnetic properties, low toxicity, large magnetic moments, superparamagnetic behaviour and large surface area-the latter being a particular advantage in its conjunction with specific moieties, dye molecules, and imaging probes. Tracers-based nanoparticles are promising candidates, since they combine synergistic advantages for non-invasive, highly sensitive, high-resolution, and quantitative imaging on different modalities. This study represents an overview of current advancements in magnetic materials with clinical potential that will hopefully provide an effective system for diagnosis in the near future. Further exploration is still needed to reveal their potential as promising candidates from simple functionalization of metal oxide nanomaterials up to medical imaging.

In vitro cytotoxicity of co-exposure to superparamagnetic iron oxide and solid lipid nanoparticles

Increased production and use of different types of nanoparticles (NPs) in the last decades has led to increased environmental release of these NPs with potential detrimental effects on both the environment and public health. Information is scarce in the literature on the cytotoxic effect of co-exposure to many NPs as this concern is relatively recent. Thus, in this study, we hypothesized scenarios of cell's co-exposure to two kinds of NPs, solid lipid nanoparticles (SLNs) and superparamagnetic iron oxide nanoparticles (SPIONs), to assess the potential cytotoxicity of exposure to NPs combination. Cytotoxicity of SPIONs, SLNs, and their 1:1 mixture (MIX) in six tumor and six non-tumor cell lines was investigated. The mechanisms underlining the induced cytotoxicity were studied through cell cycle analysis, detection of reactive oxygen species (ROS), and alterations in mitochondrial membrane potential (ΔΨM). Double staining with acridine orange and ethidium bromide was also used to confirm cell morphology alterations. The results showed that SPIONs induced low cytotoxicity compared to SLNs. However, the mixture of SPIONs and SLNs showed synergistic, antagonistic, and additive effects based on distinct tests such as viability assay, ROS generation, ΔΨM, and DNA damage, depending on the cell line. Apoptosis triggered by ROS and disturbances in ΔΨM are the most probable related mechanisms of action. As was postulated, there is possible cytotoxic interaction between the two kinds of NPs.

Investigation of magnetically driven passage of magnetic nanoparticles through eye tissues for magnetic drug targeting

This paper elucidates the feasibility of magnetic drug targeting to the eye by using magnetic nanoparticles (MNPs) to which pharmaceutical drugs can be linked. Numerical simulations revealed that a magnetic field gradient of 20 T m^-1 seems to be promising for dragging magnetic multicore nanoparticles of about 50 nm into the eye. Thus, a targeting magnet system made of superconducting magnets with a magnetic field gradient at the eye of about 20 T m^-1 was simulated. For the proof-of-concept tissue experiments presented here the required magnetic field gradient of 20 T m^-1 was realized by a permanent magnet array. MNPs with an optimized multicore structure were selected for this application by evaluating their stability against agglomeration of MNPs with different coatings in water for injections, physiological sodium chloride solution and biological media such as artificial tear fluid. From these investigations, starch turned out to be the most promising coating material because of its stability in saline fluids due to its steric stabilization mechanism. To evaluate the passage of MNPs through the sclera and cornea of the eye tissues of domestic pigs (Sus scrofa domesticus), a three-dimensionally printed setup consisting of two chambers (reservoir and target chamber) separated by the eye tissue was developed. With the permanent magnet array emulating the magnetic field gradient of the superconducting setup, experiments on magnetically driven transport of the MNPs from the reservoir chamber into the target chamber via the tissue were performed. The resulting concentration of MNPs in the target chamber was determined by means of quantitative magnetic particle spectroscopy. It was found that none of the tested particles passed the cornea, but starch-coated particles could pass the sclera at a rate of about 5 ng mm^-2 within 24 h. These results open the door for future magnetic drug targeting to the eye.

Immobilization of alcohol dehydrogenase from Saccharomyces cerevisiae onto carboxymethyl dextran-coated magnetic nanoparticles: a novel route for biocatalyst improvement via epoxy activation

A novel method is described for the immobilization of alcohol dehydrogenase (ADH) from Saccharomyces cerevisiae onto carboxymethyl dextran (CMD) coated magnetic nanoparticles (CMD-MNPs) activated with epoxy groups, using epichlorohydrin (EClH). EClH was used as an activating agent to bind ADH molecules on the surface of CMD-MNPs. Optimal immobilization conditions (activating agent concentration, temperature, rotation speed, medium pH, immobilization time and enzyme concentration) were set to obtain the highest expressed activity of the immobilized enzyme. ADH that was immobilized onto epoxy-activated CMD-MNPs (ADH-CMD-MNPs) maintained 90% of the expressed activity. Thermal stability of ADH-CMD-MNPS after 24 h at 20 °C and 40 °C yielded 79% and 80% of initial activity, respectively, while soluble enzyme activity was only 19% at 20 °C and the enzyme was non-active at 40 °C. Expressed activity of ADH-CMD-MNPs after 21 days of storage at 4 °C was 75%. Kinetic parameters (K_M, v_max) of soluble and immobilized ADH were determined, resulting in 125 mM and 1.2 µmol/min for soluble ADH, and in 73 mM and 4.7 µmol/min for immobilized ADH.

Superparamagnetic Iron Oxide Nanoparticles Carrying Chemotherapeutics Improve Drug Efficacy in Monolayer and Spheroid Cell Culture by Enabling Active Accumulation

Cytotoxic and cytostatic chemotherapeutics act by attacking rapidly dividing tumor cells, predominantly affecting malignant tissue and to a certain degree preserving healthy cells. Nonetheless, severe side effects are caused as quickly proliferating healthy cells such as hematopoietic precursors and mucous membranes are impaired as well. This limits the administered dose and eventually allows tumor cells to escape treatment. In order to increase intratumoral drug concentration and simultaneously reduce systemic side effects, nanoparticles have come into focus as drug carriers. The functionalization of superparamagnetic iron oxide nanoparticles (SPIONs) with chemotherapeutics such as mitoxantrone (MTO) enables targeted drug transport by using magnetic forces. Here, we investigate SPIONs consisting of individual iron oxide cores of 10 nm in diameter and a total hydrodynamic diameter of 53 ± 0.8 nm as a transporting system for MTO. Comparing the killing efficacy in monolayer cell culture and multicellular tumor spheroids of HT-29 cells, we show that spheroids tolerate considerably higher doses of nanoparticle-loaded MTO. Therefore, dose predictions from conventional monolayer cell cultures are often misleading for in vivo applications. This was true for both soluble and nanoparticle-bound MTO. Using flow chambers mimicking in vivo blood flow, we furthermore demonstrate that SPIONs can magnetically accumulate MTO. We conclude that SPIONs can function as an effective delivery platform to increase local drug concentrations, thereby potentially overcoming chemotherapy resistance of cells.

Applications of superparamagnetic iron oxide nanoparticles in drug and therapeutic delivery, and biotechnological advancements

Superparamagnetic iron oxide nanoparticles (SPIONs) have unique properties with regard to biological and medical applications. SPIONs have been used in clinical settings although their safety of use remains unclear due to the great differences in their structure and in intra- and inter-patient absorption and response. This review addresses potential applications of SPIONs in vitro (formulations), ex vivo (in biological cells and tissues) and in vivo (preclinical animal models), as well as potential biomedical applications in the context of drug targeting, disease treatment and therapeutic efficacy, and safety studies.

Endocytic trafficking of polymeric clustered superparamagnetic iron oxide nanoparticles in mesenchymal stem cells

The technology of directing nanoparticles to specific locations in the body continues to be an area of great interest in a myriad of research fields. In the present study, we have developed nanoparticles and a method that allows the nanoparticles to move to specific sites by simultaneously utilizing the homing ability and magnetism of stem cells. Polymeric clustered SPIO (PCS) nanoparticles are composed of a superparamagnetic iron oxide nanoparticle (SPION) cluster core coated with poly lactic-co-glycolic acid (PLGA) and labeled with the fluorescent dye Cy5.5 for tracking. PCS is designed to be internalized by stem cells via endocytosis and then moved to the desired subcellular location through magnetism. Here, we investigated the interactions between SPIONs and mesenchymal stem cells (MSCs), including their absorption mechanism and subcellular localization. Exposure to the nanoparticles at 40 μg/mL for over 96 h did not affect cell survival or differentiation. We used a variety of endocytosis inhibitors and identified the potential cellular internalization pathway of SPIONs to be clathrin-mediated endocytosis. Antibodies to organelles were used to accumulate lysosomes through early and late endosomes. PCS at 40 μg/mL was internalized and stored without significant deleterious effects on stem cells, indicating that MSCs can act as an effective nanoparticle carrier. These findings also demonstrate the successful localization of the novel particles using magnetic attraction.

Novel Polymeric Micelles-Coated Magnetic Nanoparticles for In Vivo Bioimaging of Liver: Toxicological Profile and Contrast Enhancement

Magnetic nanoparticles are intensively studied for magnetic resonance imaging (MRI) as contrast agents but yet there remained some gaps regarding their toxicity potential and clinical implications of their biodistribution in organs. This study presents the effects induced by magnetite nanoparticles encapsulated in polymeric micelles (MNP-DSPE-PEG) on biochemical markers, metabolic functions, and MRI signal in CD1 mice liver. Three groups of animals, one control and the other ones injected with a suspension of five, respectively, 15 mg Fe/kg bw nanoparticles, were monitored up to 14 days. The results indicated the presence of MNP-DSPE-PEG in the liver in the first two days of the experiment. The most significant biochemical changes also occurred in the first 3 days after exposure when the most severe histological changes were observed. The change of the MRI signal intensity on the T2-weighted images and increased transverse relaxation rates R2 in the liver were observed after the first minutes from the nanoparticle administration. The study shows that the alterations of biomarkers level resulting from exposure to MNP-DSPE-PEG are restored in time in mice liver. This was associated with a significant contrast on T2-weighted images and made us conclude that these nanoparticles might be potential candidates for use as a contrast agent in liver medical imaging.

Engineered iron oxide nanoparticles to improve regenerative effects of mesenchymal stem cells

Abstract

Mesenchymal stem cells (MSCs) based therapies are a major field of regenerative medicine. However, the success of MSC therapy relies on the efficiency of its delivery and retention, differentiation, and secreting paracrine factors at the target sites. Recent studies show that superparamagnetic iron oxide nanoparticles (SPIONs) modulate the regenerative effects of MSCs. After interacting with the cell membrane of MSCs, SPIONs can enter the cells via the endocytic pathway. The physicochemical properties of nanoparticles, including size, surface charge (zeta-potential), and surface ligand, influence their interactions with MSC, such as cellular uptake, cytotoxicity, homing factors, and regenerative related factors (VEGF, TGF-β1). Therefore, in-depth knowledge of the physicochemical properties of SPIONs might be a promising lead in regenerative and anti-inflammation research using SPIONs mediated MSCs. In this review, recent research on SPIONs with MSCs and the various designs of SPIONs are examined and summarized.

Graphic abstract

A graphical abstract describes important parameters in the design of superparamagnetic iron oxide nanoparticles, affecting mesenchymal stem cells. These physicochemical properties are closely related to the mesenchymal stem cells to achieve improved cellular responses such as homing factors and cell uptake.

Biodistribution, biocompatibility and targeted accumulation of magnetic nanoporous silica nanoparticles as drug carrier in orthopedics

BACKGROUND

In orthopedics, the treatment of implant-associated infections represents a high challenge. Especially, potent antibacterial effects at implant surfaces can only be achieved by the use of high doses of antibiotics, and still often fail. Drug-loaded magnetic nanoparticles are very promising for local selective therapy, enabling lower systemic antibiotic doses and reducing adverse side effects. The idea of the following study was the local accumulation of such nanoparticles by an externally applied magnetic field combined with a magnetizable implant. The examination of the biodistribution of the nanoparticles, their effective accumulation at the implant and possible adverse side effects were the focus. In a BALB/c mouse model (n = 50) ferritic steel 1.4521 and Ti90Al6V4 (control) implants were inserted subcutaneously at the hindlimbs. Afterwards, magnetic nanoporous silica nanoparticles (MNPSNPs), modified with rhodamine B isothiocyanate and polyethylene glycol-silane (PEG), were administered intravenously. Directly/1/7/21/42 day(s) after subsequent application of a magnetic field gradient produced by an electromagnet, the nanoparticle biodistribution was evaluated by smear samples, histology and multiphoton microscopy of organs. Additionally, a pathohistological examination was performed. Accumulation on and around implants was evaluated by droplet samples and histology.

RESULTS

Clinical and histological examinations showed no MNPSNP-associated changes in mice at all investigated time points. Although PEGylated, MNPSNPs were mainly trapped in lung, liver, and spleen. Over time, they showed two distributional patterns: early significant drops in blood, lung, and kidney and slow decreases in liver and spleen. The accumulation of MNPSNPs on the magnetizable implant and in its area was very low with no significant differences towards the control.

CONCLUSION

Despite massive nanoparticle capture by the mononuclear phagocyte system, no significant pathomorphological alterations were found in affected organs. This shows good biocompatibility of MNPSNPs after intravenous administration. The organ uptake led to insufficient availability of MNPSNPs in the implant region. For that reason, among others, the nanoparticles did not achieve targeted accumulation in the desired way, manifesting future research need. However, with different conditions and dimensions in humans and further modifications of the nanoparticles, this principle should enable reaching magnetizable implant surfaces at any time in any body region for a therapeutic reason.

In vitro exploration of the synergistic effect of alternating magnetic field mediated thermo–chemotherapy with doxorubicin loaded dual pH- and thermo-responsive magnetic nanocomposite carriers

Nanoparticle induced hyperthermia has been considered as a promising approach for cancer treatment for decades.

Magnetic Graphene Oxide Nanocarrier for Targeted Delivery of Cisplatin: A Perspective for Glioblastoma Treatment

Selective vectorization of Cisplatin (CisPt) to Glioblastoma U87 cells was exploited by the fabrication of a hybrid nanocarrier composed of magnetic γ-Fe2O3 nanoparticles and nanographene oxide (NGO). The magnetic component, obtained by annealing magnetite Fe3O4 and characterized by XRD measurements, was combined with NGO sheets prepared via a modified Hummer's method. The morphological and thermogravimetric analysis proved the effective binding of γ-Fe2O3 nanoparticles onto NGO layers. The magnetization measured under magnetic fields up to 7 Tesla at room temperature revealed superparamagnetic-like behavior with a maximum value of MS = 15 emu/g and coercivity HC ≈ 0 Oe within experimental error. The nanohybrid was found to possess high affinity towards CisPt, and a rather slow fractional release profile of 80% after 250 h. Negligible toxicity was observed for empty nanoparticles, while the retainment of CisPt anticancer activity upon loading into the carrier was observed, together with the possibility to spatially control the drug delivery at a target site.

Genetic, reproductive and oxidative damage in mice triggered by co-exposure of nanoparticles: From a hypothetical scenario to a real concern

Humans are potentially exposed to multiple nanoparticles kinds through nanotechnology-based consumer products. There is insufficient data on the in vivo toxicity of nanotechnology products, as well as no data on the possible toxicity, including genotoxicity and reproductive toxicity of co-exposure to different kind of nanoparticles. In this work, solid lipid nanoparticles (SLNs) and superparamagnetic iron oxide nanoparticles (SPIONs) were selected for evaluation of a hypothetical condition of in vivo co-exposure. Genotoxicity of SPIONs and SLNs was performed separately and in 1:1 mixture in mice. Bone marrow micronucleus assay, sperm morphology test, and sperm count were carried out. Also, the serum ALT and AST activities; and hematological parameters of the treated mice were analyzed. The results showed a significant increase (p < 0.05) in micronucleated polychromatic erythrocytes (MNPCE) and nuclear abnormalities (NA) in SPIONs, SLNs and their mixture treated mice. The mixture induced the highest frequency of MNPCE and NA. A similar result was observed in the sperm morphology test, with the mixture inducing the highest sperm abnormalities, followed by SLNs and the least by SPIONs. Significant alteration to RDW, MCHC, MCV, GRAN, and platelets, as well as increased activities of serum AST were observed in the mice treated with a mixture of the two kinds of nanoparticles. Calculation of interaction factor showed a possible synergistic effect between SPIONs and SLNs in MNPCE, NA and sperm morphology studied. Even as a hypothetical scenario of co-exposure to SLNs and SPIONs, this study showed, for the first time, that co-exposure to SPIONs and SLNs is more genotoxic to somatic and germ cells than their individual exposure.

Controlling the dominant magnetic relaxation mechanisms for magnetic hyperthermia in bimagnetic core-shell nanoparticles

We report a simple and effective way to control the heat generation of a magnetic colloid under alternate magnetic fields by changing the shell composition of bimagnetic core-shell Fe3O4/ZnxCo1-xFe2O4 nanoparticles. The core-shell structure constitutes a magnetically-coupled biphase system, with an effective anisotropy that can be tuned by the substitution of Co2+ by Zn2+ ions in the shell. Magnetic hyperthermia experiments of nanoparticles dispersed in hexane and butter oil showed that the magnetic relaxation is dominated by Brown relaxation mechanism in samples with higher anisotropy (i.e., larger concentration of Co within the shell) yielding high specific power absorption values in low viscosity media as hexane. Increasing the Zn concentration of the shell, diminishes the magnetic anisotropy, which results in a change to a Néel relaxation that dominates the process when the nanoparticles are dispersed in a high-viscosity medium. We demonstrate that tuning the Zn contents at the shell of these exchange-coupled core/shell nanoparticles provides a way to control the magnetic anisotropy without loss of saturation magnetization. This ability is an essential prerequisite for most biomedical applications, where high viscosities and capturing mechanisms are present.

Human adipose-derived stem cells loaded with drug-coated magnetic nanoparticles for in-vitro tumor cells targeting

Magnetic nanoparticles (MNPs) functionalized with different therapeutics delivered by mesenchymal stem cells represent a promising approach to improve the typical drug delivery methods. This innovative method, based on the "Trojan horse" principle, faces however important challenges related to the viability of the MNPs-loaded cells and drug stability. In the present study we report about an in vitro model of adipose-derived stem cells (ADSCs) loaded with palmitate-coated MNPs (MNPsPA) as antitumor drug carriers targeting a 3D tissue-like osteosarcoma cells. Cell viability, MNPsPA-drug loading capacity, cell speed, drug release rate, magnetization and zeta potential were determined and analysed. The results revealed that ADSCs loaded with MNPsPA-drug complexes retained their viability at relatively high drug concentrations (up to 1.22 pg antitumor drug/cell for 100% cell viability) and displayed higher speed compared to the targeted tumor cells in vitro. The magnetization of the sterilized MNPsPA complexes was 67 emu/g within a magnetic field corresponding to induction values of clinical MRI devices. ADSCs payload was around 9 pg magnetic material/cell, with an uptake rate of 6.25 fg magnetic material/min/cell. The presented model is a proof-of-concept platform for stem cells-mediated MNPs-drug delivery to solid tumors that could be further correlated with MRI tracking and magnetic hyperthermia for theranostic applications.

Iron oxide nanoparticles: Diagnostic, therapeutic and theranostic applications

Many different iron oxide nanoparticles have been evaluated over the years, for a wide variety of biomedical applications. We here summarize the synthesis, surface functionalization and characterization of iron oxide nanoparticles, as well as their (pre-) clinical use in diagnostic, therapeutic and theranostic settings. Diagnostic applications include liver, lymph node, inflammation and vascular imaging, employing mostly magnetic resonance imaging but recently also magnetic particle imaging. Therapeutic applications encompass iron supplementation in anemia and advanced cancer treatments, such as modulation of macrophage polarization, magnetic fluid hyperthermia and magnetic drug targeting. Because of their properties, iron oxide nanoparticles are particularly useful for theranostic purposes. Examples of such setups, in which diagnosis and therapy are intimately combined and in which iron oxide nanoparticles are used, are image-guided drug delivery, image-guided and microbubble-mediated opening of the blood-brain barrier, and theranostic tissue engineering. Together, these directions highlight the versatility and the broad applicability of iron oxide nanoparticles, and indicate the integration in future medical practice of multiple iron oxide nanoparticle-based materials.

Graphene Oxide Functional Nanohybrids with Magnetic Nanoparticles for Improved Vectorization of Doxorubicin to Neuroblastoma Cells

With the aim to obtain a site-specific doxorubicin (DOX) delivery in neuroblastoma SH-SY5Y cells, we designed an hybrid nanocarrier combining graphene oxide (GO) and magnetic iron oxide nanoparticles (MNPs), acting as core elements, and a curcumin⁻human serum albumin conjugate as functional coating. The nanohybrid, synthesized by redox reaction between the MNPs@GO system and albumin bioconjugate, consisted of MNPs@GO nanosheets homogeneously coated by the bioconjugate as verified by SEM investigations. Drug release experiments showed a pH-responsive behavior with higher release amounts in acidic (45% at pH 5.0) vs. neutral (28% at pH 7.4) environments. Cell internalization studies proved the presence of nanohybrid inside SH-SY5Y cytoplasm. The improved efficacy obtained in viability assays is given by the synergy of functional coating and MNPs constituting the nanohybrids: while curcumin moieties were able to keep low DOX cytotoxicity levels (at concentrations of 0.44⁻0.88 µM), the presence of MNPs allowed remote actuation on the nanohybrid by a magnetic field, increasing the dose delivered at the target site.

Effective delivery of hydrophobic drugs to breast and liver cancer cells using a hybrid inorganic nanocarrier: A detailed investigation using cytotoxicity assays, fluorescence imaging and flow cytometry

This study was focused on developing a drug carrier system composed of a polymer containing hydroxyapatite (HAp) shell and a magnetic core of iron oxide nanoparticles. Doxorubicin and/or curcumin were loaded into the carrier via a simple diffusion deposition approach, with encapsulation efficiencies (EE) for curcumin and doxorubicin of 93.03 ± 0.3% and 97.37 ± 0.12% respectively. The co-loading of curcumin and doxorubicin led to a total EE of 76.02 ± 0.48%. Release studies were carried out at pH 7.4 and 5.3, and revealed a greater extent of release at pH 5.3, showing the formulations to have potential applications in tumor microenvironments. Cytotoxicity assays, fluorescence imaging and flow cytometry demonstrated that the formulations could effectively inhibit the growth of MCF-7 (breast) and HEpG2 (liver) cancer cells, being more potent than the free drug molecules both in terms of dose and duration of action. Additionally, hemolysis tests and cytotoxicity evaluations determined the drug-loaded carriers to be non-toxic towards non-cancerous cells. These formulations thus have great potential in the development of new cancer therapeutics.

Systematic magnetic fluid hyperthermia studies of carboxyl functionalized hydrophilic superparamagnetic iron oxide nanoparticles based ferrofluids

We have systematically studied heating efficiencies (via specific absorption rate-SAR/intrinsic loss power-ILP) of carboxyl (terephthalic acid-TA) functionalized hydrophilic SPIONs based ferrofluids (with good biocompatibility/high magnetization) and influence of following key factors in magnetic fluid hyperthermia (MFH): (i) alternating magnetic fields (AMFs - H)/frequencies (f) - chosen below/above Hergt's biological safety limit, (ii) concentrations (0.5-8 mg/ml) and (iii) dispersion media (water, a cell-culture medium and triethylene glycol (TEG)) for in vitro cancer therapy. In calorimetric MFH, aqueous ferrofluids have displayed excellent time-dependent temperature rise for the applied AMFs, which resulted in high SAR ranging from 23.4 to 160.7 W/g_Fe, attributed to the enhanced magnetic responses via π-conjugations of short-chained TA molecules on the surface of SPIONs_. Moreover, ILP values up-to 2.5 nHm²/kg (higher than the best commercial ferrofluids) are attained for the aqueous ferrofluids when excited below the recommended safety limit. Besides, the SPIONs dispersed in high viscous TEG have exhibited the highest SAR value (178.8 W/g_Fe) and reached therapeutic temperatures at faster rates for the lowest concentration due to prominent Neel relaxations. Moreover, these SPIONs have higher killing efficiency towards MCF-7 cancer cells in in vitro studies. Thus, the TA-based ferrofluids have great potential for in vivo/clinical MFH cancer therapies.

A physiologically based pharmacokinetic model to predict the superparamagnetic iron oxide nanoparticles (SPIONs) accumulation in vivo

Superparamagnetic iron oxide nanoparticles (SPIONs) have been identified as a promising material for biomedical applications. These include as contrast agents for medical imaging, drug delivery and/or cancer cell treatment. The nanotoxicological profile of SPIONs has been investigated in different studies and the distribution of SPIONs in the human body has not been fully characterized. The aim of this study was to develop a physiologically-based pharmacokinetic (PBPK) model to predict the pharmacokinetics of SPIONs. The distribution and accumulation of SPIONs in organs were simulated taking into consideration their penetration through capillary walls and their active uptake by specialized macrophages in the liver, spleen and lungs. To estimate the kinetics of SPION uptake, a novel experimental approach using primary macrophages was developed. The murine PBPK model was validated against in vivo pharmacokinetic data, and accurately described accumulation in liver, spleen and lungs. After validation of the murine model, a similar PBPK approach was developed to simulate the distribution of SPIONs in humans. These data demonstrate the utility of PBPK modeling for estimating biodistribution of inorganic nanoparticles and represents an initial platform to provide computational prediction of nanoparticle pharmacokinetics.

Influence of chitosan coating on magnetic nanoparticles in endothelial cells and acute tissue biodistribution

Chitosan coating on magnetic nanoparticles (MNPs) was studied on biological systems as a first step toward the application in the biomedical field as drug-targeted nanosystems. Composition of MNPs consists of magnetite functionalized with oleic acid and coated with the biopolymer chitosan or glutaraldehyde-cross-linked chitosan. The influence of the biopolymeric coating has been evaluated by in vitro and in vivo assays on the effects of these MNPs on rat aortic endothelial cells (ECs) viability and on the random tissue distribution in mice. Results were correlated with the physicochemical properties of the nanoparticles. Nitric oxide (NO) production by ECs was determined, considering that endothelial NO represents one of the major markers of ECs function. Cell viability was studied by MTT assay. Different doses of the MNPs (1, 10 and 100 μg/mL) were assayed, revealing that MNPs coated with non-cross-linked chitosan for 6 and 24 h did not affect neither NO production nor cell viability. However, a significant decrease in cell viability was observed after 36 h treatment with the highest dose of this nanocarrier. It was also revealed that the presence and dose of glutaraldehyde in the MNPs structureimpact on the cytotoxicity. The study of the acute tissue distribution was performed acutely in mice after 24 h of an intraperitoneal injection of the MNPs and sub acutely, after 28 days of weekly administration. Both formulations greatly avoided the initial clearance by the reticuloendothelial system (RES) in liver. Biological properties found for N1 and N2 in the performed assays reveal that chitosan coating improves biocompatibility of MNPs turning these magnetic nanosystems as promising devices for targeted drug delivery.

An affinity triggered MRI nanoprobe for pH-dependent cell labeling

The pH-sensitive affinity pair composed by neutravidin and iminobiotin was used to develop a multilayered Magnetic Resonance Imaging (MRI) nanoprobe responsive to the acidic pH of tumor microenvironment.

Facile synthesis of novel hydrophilic and carboxyl-amine functionalized superparamagnetic iron oxide nanoparticles for biomedical applications

We report a one-step facile synthesis of novel water-soluble and functionalized SPIONs, which could be promising candidates for cancer theranostics.

Effects of Iron-Oxide Nanoparticle Surface Chemistry on Uptake Kinetics and Cytotoxicity in CHO-K1 Cells

Superparamagnetic iron-oxide nanoparticles (SPIONs) show great promise for multiple applications in biomedicine. While a number of studies have examined their safety profile, the toxicity of these particles on reproductive organs remains uncertain. The goal of this study was to evaluate the cytotoxicity of starch-coated, aminated, and PEGylated SPIONs on a cell line derived from Chinese Hamster ovaries (CHO-K1 cells). We evaluated the effect of particle diameter (50 and 100 nm) and polyethylene glycol (PEG) chain length (2k, 5k and 20k Da) on the cytotoxicity of SPIONs by investigating cell viability using the tetrazolium dye 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) and sulforhodamine B (SRB) assays. The kinetics and extent of SPION uptake by CHO-K1 cells was also studied, as well as the resulting generation of intracellular reactive oxygen species (ROS). Cell toxicity profiles of SPIONs correlated strongly with their cellular uptake kinetics, which was strongly dependent on surface properties of the particles. PEGylation caused a decrease in both uptake and cytotoxicity compared to aminated SPIONs. Interestingly, 2k Da PEG-modifed SPIONs displayed the lowest cellular uptake and cytotoxicity among all studied particles. These results emphasize the importance of surface coatings when engineering nanoparticles for biomedical applications.

In vivo delivery, pharmacokinetics, biodistribution and toxicity of iron oxide nanoparticles

Iron oxide nanoparticles (IONPs) have been extensively used during the last two decades, either as effective bio-imaging contrast agents or as carriers of biomolecules such as drugs, nucleic acids and peptides for controlled delivery to specific organs and tissues. Most of these novel applications require elaborate tuning of the physiochemical and surface properties of the IONPs. As new IONPs designs are envisioned, synergistic consideration of the body's innate biological barriers against the administered nanoparticles and the short and long-term side effects of the IONPs become even more essential. There are several important criteria (e.g. size and size-distribution, charge, coating molecules, and plasma protein adsorption) that can be effectively tuned to control the in vivo pharmacokinetics and biodistribution of the IONPs. This paper reviews these crucial parameters, in light of biological barriers in the body, and the latest IONPs design strategies used to overcome them. A careful review of the long-term biodistribution and side effects of the IONPs in relation to nanoparticle design is also given. While the discussions presented in this review are specific to IONPs, some of the information can be readily applied to other nanoparticle systems, such as gold, silver, silica, calcium phosphates and various polymers.

Recent advances in superparamagnetic iron oxide nanoparticles (SPIONs) for in vitro and in vivo cancer nanotheranostics

Recently superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively used in cancer therapy and diagnosis (theranostics) via magnetic targeting, magnetic resonance imaging, etc. due to their remarkable magnetic properties, chemical stability, and biocompatibility. However, the magnetic properties of SPIONs are influenced by various physicochemical and synthesis parameters. So, this review mainly focuses on the influence of spin canting effects, introduced by the variations in size, shape, and organic/inorganic surface coatings, on the magnetic properties of SPIONs. This review also describes the several predominant chemical synthesis procedures and role of the synthesis parameters for monitoring the size, shape, crystallinity and composition of the SPIONs. Moreover, this review discusses about the latest developments of the inorganic materials and organic polymers for encapsulation of the SPIONs. Finally, the most recent advancements of the SPIONs and their nanopackages in combination with other imaging/therapeutic agents have been comprehensively discussed for their effective usage as in vitro and in vivo theranostic agents in cancer treatments.

Polysaccharide-Coated Magnetic Nanoparticles for Imaging and Gene Therapy

Today, nanotechnology plays a vital role in biomedical applications, especially for the diagnosis and treatment of various diseases. Among the many different types of fabricated nanoparticles, magnetic metal oxide nanoparticles stand out as unique and useful tools for biomedical applications, because of their imaging characteristics and therapeutic properties such as drug and gene carriers. Polymer-coated magnetic particles are currently of particular interest to investigators in the fields of nanobiomedicine and fundamental biomaterials. Theranostic magnetic nanoparticles that are encapsulated or coated with polymers not only exhibit imaging properties in response to stimuli, but also can efficiently deliver various drugs and therapeutic genes. Even though a large number of polymer-coated magnetic nanoparticles have been fabricated over the last decade, most of these have only been used for imaging purposes. The focus of this review is on polysaccharide-coated magnetic nanoparticles used for imaging and gene delivery.