Cell death induced by the application of alternating magnetic fields to nanoparticle-loaded dendritic cells

In Vitro Superparamagnetic Hyperthermia Employing Magnetite Gamma-Cyclodextrin Nanobioconjugates for Human Squamous Skin Carcinoma Therapy

In vitro alternative therapy of human epidermoid squamous carcinoma (A431) by superparamagnetic hyperthermia (SPMHT) using Fe3O4 (magnetite) superparamagnetic nanoparticles (SPIONs) with an average diameter of 15.8 nm, bioconjugated with hydroxypropyl gamma-cyclodextrins (HP-γ-CDs) by means of polyacrylic acid (PAA) biopolymer, is presented in this paper. The therapy was carried out at a temperature of 43 °C for 30 min using the concentrations of Fe3O4 ferrimagnetic nanoparticles from nanobioconjugates of 1, 5, and 10 mg/mL nanoparticles in cell suspension, which were previously found by us to be non-toxic for healthy cells (cell viabilities close to 100%), according to ISO standards (cell viability must be greater than 70%). The temperature for the in vitro therapy was obtained by the safe application (without exceeding the biological limit and cellular damage) of an alternating magnetic field with a frequency of 312.4 kHz and amplitudes of 168, 208, and 370 G, depending on the concentration of the magnetic nanoparticles. The optimal concentration of magnetic nanoparticles in suspension was found experimentally. The results obtained after the treatment show its high effectiveness in destroying the A431 tumor cells, up to 83%, with the possibility of increasing even more, which demonstrates the viability of the SPMHT method with Fe3O4-PAA-(HP-γ-CDs) nanobioconjugates for human squamous cancer therapy.

Multifunctional role of nanoparticles for the diagnosis and therapeutics of cardiovascular diseases

The increasing burden of cardiovascular disease (CVD) remains responsible for morbidity and mortality worldwide; their effective diagnostic or treatment methods are of great interest to researchers. The use of NPs and nanocarriers in cardiology has drawn much interest. The present comprehensive review provides deep insights into the use of current and innovative approaches in CVD diagnostics to offer practical ways to utilize nanotechnological interventions and the critical elements in the CVD diagnosis, associated risk factors, and management strategies of patients with chronic CVDs. We proposed a decision tree-based solution by discussing the emerging applications of NPs for the higher number of rules to increase efficiency in treating CVDs. This review-based study explores the screening methods, tests, and toxicity to provide a unique way of creating a multi-parametric feature that includes cutting-edge techniques for identifying cardiovascular problems and their treatments. We discussed the benefits and drawbacks of various NPs in the context of cost, space, time and complexity that have been previously suggested in the literature for the diagnosis of CVDs risk factors. Also, we highlighted the advances in using NPs for targeted and improved drug delivery and discussed the evolution toward the nano-cardiovascular potential for medical science. Finally, we also examined the mixed-based diagnostic approaches crucial for treating cardiovascular disorders, broad applications and the potential future applications of nanotechnology in medical sciences.

Nanotechnology-based non-viral vectors for gene delivery in cardiovascular diseases

Gene therapy is a technique that rectifies defective or abnormal genes by introducing exogenous genes into target cells to cure the disease. Although gene therapy has gained some accomplishment for the diagnosis and therapy of inherited or acquired cardiovascular diseases, how to efficiently and specifically deliver targeted genes to the lesion sites without being cleared by the blood system remains challenging. Based on nanotechnology development, the non-viral vectors provide a promising strategy for overcoming the difficulties in gene therapy. At present, according to the physicochemical properties, nanotechnology-based non-viral vectors include polymers, liposomes, lipid nanoparticles, and inorganic nanoparticles. Non-viral vectors have an advantage in safety, efficiency, and easy production, possessing potential clinical application value when compared with viral vectors. Therefore, we summarized recent research progress of gene therapy for cardiovascular diseases based on commonly used non-viral vectors, hopefully providing guidance and orientation for future relevant research.

Near infrared-emitting multimodal nanosystem for in vitro magnetic hyperthermia of hepatocellular carcinoma and dual imaging of in vivo liver fibrosis

Prolonged usage of traditional nanomaterials in the biological field has posed several short- and long-term toxicity issues. Over the past few years, smart nanomaterials (SNs) with controlled physical, chemical, and biological features have been synthesized in an effort to allay these challenges. The current study seeks to develop theranostic SNs based on iron oxide to enable simultaneous magnetic hyperthermia and magnetic resonance imaging (MRI), for chronic liver damage like liver fibrosis which is a major risk factor for hepatocellular carcinoma. To accomplish this, superparamagnetic iron oxide nanoparticles (SPIONs) were prepared, coated with a biocompatible and naturally occurring polysaccharide, alginate. The resultant material, ASPIONs were evaluated in terms of physicochemical, magnetic and biological properties. A hydrodynamic diameter of 40 nm and a transverse proton relaxation rate of 117.84 mM-1 s-1 pronounces the use of ASPIONs as an efficient MRI contrast agent. In the presence of alternating current of 300 A, ASPIONs could elevate the temperature to 45 °C or more, with the possibility of hyperthermia based therapeutic approach. Magnetic therapeutic and imaging potential of ASPIONs were further evaluated respectively in vitro and in vivo in HepG2 carcinoma cells and animal models of liver fibrosis, respectively. Finally, to introduce dual imaging capability along with magnetic properties, ASPIONs were conjugated with near infrared (NIR) dye Atto 700 and evaluated its optical imaging efficiency in animal model of liver fibrosis. Histological analysis further confirmed the liver targeting efficacy of the developed SNs for Magnetic theranostics and optical imaging as well as proved its short-term safety, in vivo.

Interaction between iron oxide nanoparticles (IONs) and primary human immune cells: An up-to-date review of the literature

Nanotechnology has been gaining more and more momentum lately and the potential use of nanomaterials such as nanoparticles (NPs) continues to grow in a variety of activity sectors. Among the NPs, iron oxide nanoparticles (IONs) have retained an increasing interest from the scientific community and industrials due to their superparamagnetic properties allowing their use in many fields, including medicine. However, some undesired effects of IONs and potential risk for human health are becoming increasingly reported in several studies. Although many in vivo studies reported that IONs induce immunotoxicity in different animal models, it is not clear how IONs can alter the biology of primary human immune cells. In this article, we will review the works that have been done regarding the interaction between IONs and primary immune cells. This review also outlines the importance of using primary immune cells in risk assessment of NPs as a reliable strategy for encouraging non-animal studies approaches, to determine risks that might affect the human immune system following different exposure scenarios. Taken all together, the reported observations help to get a more global picture on how IONs alter the human immune system especially the fact that inflammation, known to involve several immune cell types, is frequently reported as an undesired effect of IONs.

Tailored cancer therapy by magnetic nanoparticle hyperthermia: A virtual scenario simulation method

BACKGROUND AND OBJECTIVE

Hyperthermia is a cancer treatment aiming to induce cell death by directly warming cancerous tissues above 40 °C. This technique can be applied both individually and together with other cancer therapies. The main challenge for researchers and medics is to heat only tumoral cells avoiding global or localized heating of sane tissues. The objective in this study is to provide a realistic virtual scenario to develop an optimized multi-site injection plan for tailored magnetic nanoparticle-mediated hyperthermia applications.

METHODS

A three-dimensional model of a cat's back was tested in three different simulation scenarios, showing the impact of magnetic nanoparticles in each specific environment configuration.

RESULTS

As a result of this study. This simulation method can, minimising the affection to healthy tissue.

CONCLUSIONS

This virtual method will help real and personalized therapy planning and tailor the dose and distribution of magnetic nanoparticles for an enhanced hyperthermia cancer treatment.

Understanding MNPs Behaviour in Response to AMF in Biological Milieus and the Effects at the Cellular Level: Implications for a Rational Design That Drives Magnetic Hyperthermia Therapy toward Clinical Implementation

Simple Summary

Magnetic hyperthermia therapy is an alternative treatment for cancer that complements traditional therapies and that has shown great promise in recent years. In this review, we assess the current applications of this therapy in order to understand why its translation from the laboratory to the clinic has been less smooth than was anticipated, identifying the possible bottlenecks and proposing solutions to the problems encountered.

Abstract

Hyperthermia has emerged as a promising alternative to conventional cancer therapies and in fact, traditional hyperthermia is now commonly used in combination with chemotherapy or surgery during cancer treatment. Nevertheless, non-specific application of hyperthermia generates various undesirable side-effects, such that nano-magnetic hyperthermia has arisen a possible solution to this problem. This technique to induce hyperthermia is based on the intrinsic capacity of magnetic nanoparticles to accumulate in a given target area and to respond to alternating magnetic fields (AMFs) by releasing heat, based on different principles of physics. Unfortunately, the clinical implementation of nano-magnetic hyperthermia has not been fluid and few clinical trials have been carried out. In this review, we want to demonstrate the need for more systematic and basic research in this area, as many of the sub-cellular and molecular mechanisms associated with this approach remain unclear. As such, we shall consider here the biological effects that occur and why this theoretically well-designed nano-system fails in physiological conditions. Moreover, we will offer some guidelines that may help establish successful strategies through the rational design of magnetic nanoparticles for magnetic hyperthermia.

Advances in Cancer Therapeutics: Conventional Thermal Therapy to Nanotechnology-Based Photothermal Therapy

In this review, advancement in cancer therapy that shows a transition from conventional thermal therapies to laser-based photothermal therapies is discussed. Laser-based photothermal therapies are gaining popularity in cancer therapeutics due to their overall outcomes. In photothermal therapy, light is converted into heat to destruct the various types of cancerous growth. The role of nanoparticles as a photothermal agent is emphasized in this review article. Magnetic, as well as non-magnetic, nanoparticles have been effectively used in the photothermal-based cancer therapies. The discussion includes a critical appraisal of in vitro and in vivo, as well as the latest clinical studies completed in this area. Plausible evidence suggests that photothermal therapy is a promising avenue in the treatment of cancer.

Rapidly Transducing and Spatially Localized Magnetofection Using Peptide-Mediated Non-Viral Gene Delivery Based on Iron Oxide Nanoparticles

Non-viral delivery systems are generally of low efficiency, which limits their use in gene therapy and editing applications. We previously developed a technology termed glycosaminoglycan (GAG)-binding enhanced transduction (GET) to efficiently deliver a variety of cargos intracellularly; our system employs GAG-binding peptides, which promote cell targeting, and cell penetrating peptides (CPPs), which enhance endocytotic cell internalization. Herein, we describe a further modification by combining gene delivery and magnetic targeting with the GET technology. We associated GET peptides, plasmid (p)DNA, and iron oxide superparamagnetic nanoparticles (MNPs), allowing rapid and targeted GET-mediated uptake by application of static magnetic fields in NIH3T3 cells. This produced effective transfection levels (significantly higher than the control) with seconds to minutes of exposure and localized gene delivery two orders of magnitude higher in targeted over non-targeted cell monolayers using magnetic fields (in 15 min exposure delivering GFP reporter pDNA). More importantly, high cell membrane targeting by GET-DNA and MNP co-complexes and magnetic fields allowed further enhancement to endocytotic uptake, meaning that the nucleic acid cargo was rapidly internalized beyond that of GET complexes alone (GET-DNA). Magnetofection by MNPs combined with GET-mediated delivery allows magnetic field-guided local transfection in vitro and could facilitate focused gene delivery for future regenerative and disease-targeted therapies in vivo.

The Intracellular Number of Magnetic Nanoparticles Modulates the Apoptotic Death Pathway after Magnetic Hyperthermia Treatment

Magnetic hyperthermia is a cancer treatment based on the exposure of magnetic nanoparticles to an alternating magnetic field in order to generate local heat. In this work, 3D cell culture models were prepared to observe the effect that a different number of internalized particles had on the mechanisms of cell death triggered upon the magnetic hyperthermia treatment. Macrophages were selected by their high capacity to uptake nanoparticles. Intracellular nanoparticle concentrations up to 7.5 pg Fe/cell were measured both by elemental analysis and magnetic characterization techniques. Cell viability after the magnetic hyperthermia treatment was decreased to <25% for intracellular iron contents above 1 pg per cell. Theoretical calculations of the intracellular thermal effects that occurred during the alternating magnetic field application indicated a very low increase in the global cell temperature. Different apoptotic routes were triggered depending on the number of internalized particles. At low intracellular magnetic nanoparticle amounts (below 1 pg Fe/cell), the intrinsic route was the main mechanism to induce apoptosis, as observed by the high Bax/Bcl-2 mRNA ratio and low caspase-8 activity. In contrast, at higher concentrations of internalized magnetic nanoparticles (1-7.5 pg Fe/cell), the extrinsic route was observed through the increased activity of caspase-8. Nevertheless, both mechanisms may coexist at intermediate iron concentrations. Knowledge on the different mechanisms of cell death triggered after the magnetic hyperthermia treatment is fundamental to understand the biological events activated by this procedure and their role in its effectiveness.

Enhanced Cellular Transduction of Nanoparticles Resistant to Rapidly Forming Plasma Protein Coronas

Nanoparticles (NPs) are increasingly being developed as biomedical platforms for drug/nucleic acid delivery and imaging. However, in biological fluids, NPs interact with a wide range of proteins that form a coating known as protein corona. Coronae can critically influence self-interaction and binding of other molecules, which can affect toxicity, promote cell activation, and inhibit general or specific cellular uptake. Glycosaminoglycan (GAG)-binding enhanced transduction (GET) is developed to efficiently deliver a variety of cargoes intracellularly; employing GAG-binding peptides, which promote cell targeting, and cell penetrating peptides (CPPs) which enhance endocytotic cell internalization. Herein, it is demonstrated that GET peptide coatings can mediate sustained intracellular transduction of magnetic NPs (MNPs), even in the presence of serum or plasma. NP colloidal stability, physicochemical properties, toxicity and cellular uptake are investigated. Using label-free snapshot proteomics, time-resolved profiles of human plasma coronas formed on functionalized GET-MNPs demonstrate that coronae quickly form (<1 min), with their composition relatively stable but evolving. Importantly GET-MNPs present a subtly different corona composition to MNPs alone, consistent with GAG-binding activities. Understanding how NPs interact with biological systems and can retain enhanced intracellular transduction will facilitate novel drug delivery approaches for cell-type specific targeting of new nanomaterials.

Nanoparticle-Mediated Drug Delivery for the Treatment of Cardiovascular Diseases

Cardiovascular diseases (CVDs) are one of the foremost causes of high morbidity and mortality globally. Preventive, diagnostic, and treatment measures available for CVDs are not very useful, which demands promising alternative methods. Nanoscience and nanotechnology open a new window in the area of CVDs with an opportunity to achieve effective treatment, better prognosis, and less adverse effects on non-target tissues. The application of nanoparticles and nanocarriers in the area of cardiology has gathered much attention due to the properties such as passive and active targeting to the cardiac tissues, improved target specificity, and sensitivity. It has reported that more than 50% of CVDs can be treated effectively through the use of nanotechnology. The main goal of this review is to explore the recent advancements in nanoparticle-based cardiovascular drug carriers. This review also summarizes the difficulties associated with the conventional treatment modalities in comparison to the nanomedicine for CVDs.

Magnetic and Photocatalytic Curcumin Bound Carbon Nitride Nanohybrids for Enhanced Glioma Cell Death

A mesoporous magnetic nanohybrid functionalized with 14 wt % carbon nitride (CN) and loaded with curcumin (Cur) has been developed as a combination platform for photodynamic therapy and magnetic hyperthermia. CN-Cur complexes on the nanoparticle surface facilitate fast charge separation of hole-electron pairs under blue LED light irradiation and subsequent singlet oxygen generation. Cur release from the nanoparticle was significant only when exposed to both lysosomal pH (pH = 5.2) and an alternating current magnetic field (AMF). The mesoporous magnetic carbon nitride (MMCN) caused a 350% increase in the level of intracellular ROS as compared to the light exposed untreated control group. The nanohybrid was non-hemolytic and found to be biocompatible with HUVEC cells at concentrations up to 360 μg/mL. A similar concentration under AMF exposure caused a localized temperature rise of 4.2 °C and resulted in a 60% reduction in C6 cell viability. The cancer cell death further increased up to 80% under sequential exposure to light and AMF. The combinatorial treatment exerted significant cytoskeletal and nuclear damage in the cancer cells as assessed by confocal microscopy. The nanohybrid also exhibited relaxivity of 88 mM^-1 s^-1, imparting significant T₂ weighted contrast to the cancer cells.

Remote Magnetic Control of Autophagy in Mouse B-Lymphoma Cells with Iron Oxide Nanoparticles

Autophagy is the spontaneous degradation of intracellular proteins and organelles in response to nutrient deprivation. The phagocytosis of iron oxide nanoparticles (IONPs) results in intracellular degradation that can be exploited for use in cancer treatment. Non-invasive magnetic control has emerged as an important technology, with breakthroughs achieved in areas such as magneto-thermal therapy and drug delivery. This study aimed to regulate autophagy in mouse B-lymphoma cells (A20) through the incorporation of IONPs-quantum dots (QDs). We hypothesized that with the application of an external magnetic field after phagocytosis of IONPs-QDs, autophagy of intracellular IONPs-QDs could be regulated in a non-invasive manner and subsequently modulate the regulation of inflammatory responses. The potential of this approach as a cancer treatment method was explored. The application of IONPs and an external magnetic force enabled the non-invasive regulation of cell autophagy and modulation of the self-regulatory function of cells. The combination of non-invasive magnetic fields and nanotechnology could provide a new approach to cancer treatment.

A perspective on magnetic core-shell carriers for responsive and targeted drug delivery systems

Magnetic core-shell nanocarriers have been attracting growing interest owing to their physicochemical and structural properties. The main principles of magnetic nanoparticles (MNPs) are localized treatment and stability under the effect of external magnetic fields. Furthermore, these MNPs can be coated or functionalized to gain a responsive property to a specific trigger, such as pH, heat, or even enzymes. Current investigations have been focused on the employment of this concept in cancer therapies. The evaluation of magnetic core-shell materials includes their magnetization properties, toxicity, and efficacy in drug uptake and release. This review discusses some categories of magnetic core-shell drug carriers based on Fe2O3 and Fe3O4 as the core, and different shells such as poly(lactic-co-glycolic acid), poly(vinylpyrrolidone), chitosan, silica, calcium silicate, metal, and lipids. In addition, the review addresses their recent potential applications for cancer treatment.

Cell-Promoted Nanoparticle Aggregation Decreases Nanoparticle-Induced Hyperthermia under an Alternating Magnetic Field Independently of Nanoparticle Coating, Core Size, and Subcellular Localization

Magnetic hyperthermia has a significant potential to be a new breakthrough for cancer treatment. The simple concept of nanoparticle-induced heating by the application of an alternating magnetic field has attracted much attention, as it allows the local heating of cancer cells, which are considered more susceptible to hyperthermia than healthy cells, while avoiding the side effects of traditional hyperthermia. Despite the potential of this therapeutic approach, the idea that local heating effects due to the application of alternating magnetic fields on magnetic nanoparticle-loaded cancer cells can be used as a treatment is controversial. Several studies indicate that the heating capacity of magnetic nanoparticles is largely reduced in the cellular environment because of increased viscosity, aggregation, and dipolar interactions. However, an increasing number of studies, both in vitro and in vivo, show evidence of successful magnetic hyperthermia treatment on several different types of cancer cells. This apparent contradiction might be due to the use of different experimental conditions. Here, we analyze the effects of several parameters on the cytotoxic efficiency of magnetic nanoparticles as heat inductors under an alternating magnetic field. Our results indicate that the cell-nanoparticle interaction reduces the cytotoxic effects of magnetic hyperthermia, independent of nanoparticle coating and core size, the cell line used, and the subcellular localization of nanoparticles. However, there seems to occur a synergistic effect between the application of an external source of heat and the presence of magnetic nanoparticles, leading to higher toxicities than those induced by heat alone or the accumulation of nanoparticles within cells.

Nanoclusters of crystallographically aligned nanoparticles for magnetic thermotherapy: aqueous ferrofluid, agarose phantoms and ex vivo melanoma tumour assessment

Magnetic hyperthermia is an oncological therapy where magnetic nanostructures, under a radiofrequency field, act as heat transducers increasing tumour temperature and killing cancerous cells. Nanostructure heating efficiency depends both on the field conditions and on the nanostructure properties and mobility inside the tumour. Such nanostructures are often incorrectly bench-marketed in the colloidal state and using field settings far off from the recommended therapeutic values. Here, we prepared nanoclusters composed of iron oxide magnetite nanoparticles crystallographically aligned and their specific absorption rate (SAR) values were calorimetrically determined in physiological fluids, agarose-gel-phantoms and ex vivo tumours extracted from mice challenged with B16-F0 melanoma cells. A portable, multipurpose applicator using medical field settings; 100 kHz and 9.3 kA m^-1, was developed and the results were fully analysed in terms of nanoclusters' structural and magnetic properties. A careful evaluation of the nanoclusters' heating capacity in the three milieus clearly indicates that the SAR values of fluid suspensions or agarose-gel-phantoms are not adequate to predict the real tissue temperature increase or the dosage needed to heat a tumour. Our results show that besides nanostructure mobility, perfusion and local thermoregulation, the nanostructure distribution inside the tumour plays a key role in effective heating. A suppression of the magnetic material effective heating efficiency appears in tumour tissue. In fact, dosage had to be increased considerably, from the SAR values predicted from fluid or agarose, to achieve the desired temperature increase. These results represent an important contribution towards the design of more efficient nanostructures and towards the clinical translation of hyperthermia.

Magnetic properties of nanoparticles as a function of their spatial distribution on liposomes and cells

The aggregation processes of magnetic nanoparticles in biosystems are analysed by comparing the magnetic properties of three systems with different spatial distributions of the nanoparticles. The first one is iron oxide nanoparticles (NPs) of 14 nm synthesized by coprecipitation with two coatings, (3-aminopropyl)trimethoxysilane (APS) and dimercaptosuccinic acid (DMSA). The second one is liposomes with encapsulated nanoparticles, which have different configurations depending on the NP coating (NPs attached to the liposome surface or encapsulated in its aqueous volume). The last system consists of two cell lines (Pan02 and Jurkat) incubated with the NPs. Dynamic magnetic behaviour (AC) was analysed in liquid samples, maintaining their colloidal properties, while quasi-static (DC) magnetic measurements were performed on lyophilised samples. AC measurements provide a direct method for determining the effect of the environment on the magnetization relaxation of nanoparticles. Thus, the imaginary (χ'') component shifts to lower frequencies as the aggregation state increases from free nanoparticles to those attached or embedded into liposomes in cell culture media and more pronounced when internalized by the cells. DC magnetization curves show no degradation of the NPs after interaction with biosystems in the analysed timescale. However, the blocking temperature is shifted to higher temperatures for the nanoparticles in contact with the cells, regardless of the location, the incubation time, the cell line and the nanoparticle coating, supporting AC susceptibility data. These results indicate that the simple fact of being in contact with the cells makes the nanoparticles aggregate in a non-controlled way, which is not the same kind of aggregation caused by the contact with the cell medium nor inside liposomes.

Comparative effects of magnetic and water-based hyperthermia treatments on human osteosarcoma cells

INTRODUCTION

Hyperthermia (HT) based on magnetic nanoparticles (MNPs) represents a promising approach to induce the apoptosis/necrosis of tumor cells through the heat generated by MNPs submitted to alternating magnetic fields. However, the effects of temperature distribution on the cancer cells' viability as well as heat resistance of various tumor cell types warrant further investigation.

METHODS

In this work, the effects induced by magnetic hyperthermia (MHT) and conventional water-based hyperthermia (WHT) on the viability of human osteosarcoma cells at different temperatures (37°C-47°C) was comparatively investigated. Fe-Cr-Nb-B magnetic nanoparticles were submitted either to alternating magnetic fields or to infrared radiation generated by a water-heated incubator.

RESULTS

In terms of cell viability, significant differences could be observed after applying the two HT treatment methods. At about equal equilibrium temperatures, MHT was on average 16% more efficient in inducing cytotoxicity effects compared to WHT, as assessed by MTT cytotoxicity assay.

CONCLUSION

We propose the phenomena can be explained by the significantly higher cytotoxic effects initiated during MHT treatment in the vicinity of the heat-generating MNPs compared to the effects triggered by the homogeneously distributed temperature during WHT. These in vitro results confirm other previous findings regarding the superior efficiency of MHT over WHT and explain the cytotoxicity differences observed between the two antitumor HT methods.

Nanoparticle-Mediated Mechanical Destruction of Cell Membranes: A Coarse-Grained Molecular Dynamics Study

The effects of binding mode, shape, binding strength, and rotational speed of actively rotating nanoparticles on the integrity of cell membranes have been systematically studied using dissipative particle dynamics simulations. With theoretical analyses of lipid density, surface tension, stress distribution, and water permeation, we demonstrate that the rotation of nanoparticles can provide a strong driving force for membrane rupture. The results show that nanoparticles embedded inside a cell membrane via endocytosis are more capable of producing large membrane deformations under active rotation than nanoparticles attached on the cell membrane surface. Nanoparticles with anisotropic shapes produce larger deformation and have a higher rupture efficiency than those with symmetric shapes. Our findings provide useful design guidelines for a general strategy based on utilizing mechanical forces to rupture cell membranes and therefore destroy the integrity of cells.

Recent advances in magnetoliposome for heart drug delivery

Magnetic nanoparticles (NPs) also have been subject of interest to the therapeutic and imaging field because of their unique magnetic properties. Magnetoliposomes (MLs) are made up of a combination of liposomes and magnetic NPs, and they have been proven to be a potential biomaterial to fields like magnetic-targeted drug delivery, MRI, etc. The efficiency of a drug delivery system to the heart determines the treatment strategy for most of the heart diseases. In this review article, we summarize the recent development and updates in the application of MLs as a drug delivery system for heart/cardiac diseases.

Coordination polymer hybridized Au nanocages: a nanoplatform for dual-modality imaging guided near-infrared driven photothermal therapy in vivo

Coordination polymer hybridized Au nanocages (AuNC@CPs) were prepared, which were used for near-infrared (NIR)-driven photothermal therapy (PTT) guided by photoacoustic (PA) and magnetic resonance (MR) imaging in vivo.

Targeted Magnetic Nanoparticles for Mechanical Lysis of Tumor Cells by Low-Amplitude Alternating Magnetic Field

Currently available cancer therapies can cause damage to healthy tissue. We developed a unique method for specific mechanical lysis of cancer cells using superparamagnetic iron oxide nanoparticle rotation under a weak alternating magnetic field. Iron oxide core nanoparticles were coated with cetuximab, an anti-epidermal growth factor receptor antibody, for specific tumor targeting. Nude mice bearing a head and neck tumor were treated with cetuximab-coated magnetic nanoparticles (MNPs) and then received a 30 min treatment with a weak external alternating magnetic field (4 Hz) applied on alternating days (total of seven treatments, over 14 days). This treatment, compared to a pure antibody, exhibited a superior cell death effect over time. Furthermore, necrosis in the tumor site was detected by magnetic resonance (MR) images. Thermal camera images of head and neck squamous cell carcinoma cultures demonstrated that cell death occurred purely by a mechanical mechanism.

Thermal therapy with magnetic nanoparticles for cell destruction

In this article we suggest a new concept for cell destruction based upon manipulating magnetic nanoparticles (MNPs) by applying external, low frequency alternating magnetic field (AMF) that oscillates the particles, together with focused laser illumination. Assessment of temperature profiles in a head and neck squamous cell carcinoma sample showed that cells with MNPs, treated with AMF (3 Hz, 300 mW) and laser irradiation (30 mW), reached 42°C after 4.5 min, as opposed to cells treated with laser but without AMF. Moreover, a theoretical model was developed to assess the overall theoretical temperature rise, which was shown to be 50% lower than the experimental temperature. Furthermore, we found that the combination of laser irradiation and AMF decreased the number of live cells by ~50%. Thus, the concentrated assembly of laser heating with AMF-induced MNP oscillations leads to more rapid and efficient cell death. These results suggest that the manipulated MNP technique can serve as a superior agent for PTT, with improved cell death capabilities.

Functionalized magnetic nanowires for chemical and magneto-mechanical induction of cancer cell death

Exploiting and combining different properties of nanomaterials is considered a potential route for next generation cancer therapies. Magnetic nanowires (NWs) have shown good biocompatibility and a high level of cellular internalization. We induced cancer cell death by combining the chemotherapeutic effect of doxorubicin (DOX)-functionalized iron NWs with the mechanical disturbance under a low frequency alternating magnetic field. (3-aminopropyl)triethoxysilane (APTES) and bovine serum albumin (BSA) were separately used for coating NWs allowing further functionalization with DOX. Internalization was assessed for both formulations by confocal reflection microscopy and inductively coupled plasma-mass spectrometry. From confocal analysis, BSA formulations demonstrated higher internalization and less agglomeration. The functionalized NWs generated a comparable cytotoxic effect in breast cancer cells in a DOX concentration-dependent manner, (~60% at the highest concentration tested) that was significantly different from the effect produced by free DOX and non-functionalized NWs formulations. A synergistic cytotoxic effect is obtained when a magnetic field (1 mT, 10 Hz) is applied to cells treated with DOX-functionalized BSA or APTES-coated NWs, (~70% at the highest concentration). In summary, a bimodal method for cancer cell destruction was developed by the conjugation of the magneto-mechanical properties of iron NWs with the effect of DOX producing better results than the individual effects.

Effectiveness of magnetic fluid hyperthermia against Candida albicans cells

Candida albicans is one of the most frequently isolated fungal pathogens causing opportunistic infections in humans. Targeted magnetic fluid hyperthermia (MFH) is a promising method in thermal therapy facilitating selective heating of pathogen cells like C. albicans. In the paper, we used meso-2,3-dimercaptosuccinic acid (DMSA)-coated magnetic nanoparticles (MNPs) and functionalised anti-C. albicans immunomagnetic nanoparticles (IMNPs) to investigate the potential of MFH in combating C. albicans cells in vitro. Using Mössbauer spectroscopy it was found that synthesised MNPs exhibited superparamagnetic phenomena. On the basis of calorimetric experiments, the maximum SAR (specific absorption rate) was found and a proper concentration of MNPs was established to control the temperature. MFH based on both DMSA-coated MNPs and functionalised anti-C. albicans IMNPs was more effective in combating C. albicans cells in vitro than thermostat hyperthermia. Especially promising results were obtained using functionalised IMNPs, which eradicated most of the pathogen colonies at the temperature of 43 °C.

An integrated nanoplatform for theranostics via multifunctional core–shell ferrite nanocubes

A novel integrated nanoplatform facilitates excellent targeted MR imaging guided synergism of magnetothermal and chemotherapy based on magnetic core–shell ferrite nanocubes (MNCs).

Multifunctional nano manganese ferrite ferrofluid for efficient theranostic application

Ferrofluid-based manganese (Mn(2+)) substituted superparamagnetic iron oxide nanoparticles stabilized by surface coating with trisodium citrate (MnIOTCs) were synthesized for enhanced hyperthermic activity and use as negative magnetic resonance imaging (MRI) contrast media intended for applications in theranostics. The synthesized MnIOTC materials were characterized based on their physicochemical and biological features. The crystal size and the particle size at the nano level were studied using XRD and TEM. The presence of citrate molecules on the crystal surface of the iron oxide was established by FTIR, TGA, DLS and zeta potential measurements. The superparamagnetic property of MnIOTCs was measured using a vibrating sample magnetometer. Superparamagnetic iron oxide substituted with Mn(2+) with a 3:1 molar concentration of Mn(2+) to Fe(2+) and surface modified with trisodium citrate (MnIO75TC) that exhibited a high T2 relaxivity of 184.6mM(-1)s(-1) and showed excellent signal intensity variation in vitro. Hyperthermia via application of an alternating magnetic field to MnIO75TC in a HeLa cell population induced apoptosis, which was further confirmed by FACS and cLSM observations. The morphological features of the cells were highly disrupted after the hyperthermia experiment, as evidenced from E-SEM images. Biocompatibility evaluation was performed using an alamar blue assay and hemolysis studies, and the results indicated good cytocompatibility and hemocompatibility for the synthesized particles. In the current study, the potential of MnIO75TC as a negative MRI contrast agent and a hyperthermia agent was demonstrated to confirm its utility in the burgeoning field of theranostics.

Towards nanomedicines of the future: Remote magneto-mechanical actuation of nanomedicines by alternating magnetic fields

The paper describes the concept of magneto-mechanical actuation of single-domain magnetic nanoparticles (MNPs) in super-low and low frequency alternating magnetic fields (AMFs) and its possible use for remote control of nanomedicines and drug delivery systems. The applications of this approach for remote actuation of drug release as well as effects on biomacromolecules, biomembranes, subcellular structures and cells are discussed in comparison to conventional strategies employing magnetic hyperthermia in a radio frequency (RF) AMF. Several quantitative models describing interaction of functionalized MNPs with single macromolecules, lipid membranes, and proteins (e.g. cell membrane receptors, ion channels) are presented. The optimal characteristics of the MNPs and an AMF for effective magneto-mechanical actuation of single molecule responses in biological and bio-inspired systems are discussed. Altogether, the described studies and phenomena offer opportunities for the development of novel therapeutics both alone and in combination with magnetic hyperthermia.

Stimuli-responsive cancer therapy based on nanoparticles

Nanoparticles (NPs) have recently been well investigated for cancer therapy. Among them, those that are responsive to internal or external stimuli are promising due to their flexibility. In this feature article, we provide an overview on stimuli-sensitive cancer therapy, using pH- and reduction-sensitive NPs, as well as light- and magnetic field-responsive NPs.

Deciphering intracellular events triggered by mild magnetic hyperthermia in vitro and in vivo

AIM

To assess the cell response to magnetic nanoparticles under an alternating magnetic field by molecular quantification of heat responsive transcripts in two model systems.

MATERIALS & METHODS

Melanoma cells and Hydra vulgaris treated with magnetic nanoparticles were subjected to an alternating magnetic field or to macroscopic heating. Effect to these treatments were assessed at animal, cellular and molecular levels.

RESULTS

By comparing hsp70 expression following both treatments, thermotolerance pathways were found in both systems in absence of cell ablation or global temperature increment.

CONCLUSION

Analysis of hsp70 transcriptional activation can be used as molecular thermometer to sense cells' response to magnetic hyperthermia. Similar responses were found in cells and Hydra, suggesting a general mechanism to the delivery of sublethal thermal doses.

Non-chemotoxic induction of cancer cell death using magnetic nanowires

In this paper, we show that magnetic nanowires with weak magnetic fields and low frequencies can induce cell death via a mechanism that does not involve heat production. We incubated colon cancer cells with two concentrations (2.4 and 12 μg/mL) of nickel nanowires that were 35 nm in diameter and exposed the cells and nanowires to an alternating magnetic field (0.5 mT and 1 Hz or 1 kHz) for 10 or 30 minutes. This low-power field exerted a force on the magnetic nanowires, causing a mechanical disturbance to the cells. Transmission electron microscopy images showed that the nanostructures were internalized into the cells within 1 hour of incubation. Cell viability studies showed that the magnetic field and the nanowires separately had minor deleterious effects on the cells; however, when combined, the magnetic field and nanowires caused the cell viability values to drop by up to 39%, depending on the strength of the magnetic field and the concentration of the nanowires. Cell membrane leakage experiments indicated membrane leakage of 20%, suggesting that cell death mechanisms induced by the nanowires and magnetic field involve some cell membrane rupture. Results suggest that magnetic nanowires can kill cancer cells. The proposed process requires simple and low-cost equipment with exposure to only very weak magnetic fields for short time periods.

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

In this research work, DEXTRAN- and polyethylene glycol (PEG)-coated iron-oxide superparamagnetic nanoparticles were synthetized and their cytotoxicity and biodistribution assessed. Well-crystalline hydrophobic Fe3 O4 SPIONs were formed by a thermal decomposition process with d = 18 nm and σ = 2 nm; finally, the character of SPIONs was changed to hydrophilic by a post-synthesis procedure with the functionalization of the SPIONs with PEG or DEXTRAN. The nanoparticles present high saturation magnetization and superparamagnetic behavior at room temperature, and the hydrodynamic diameters of DEXTRAN- and PEG-coated SPIONs were measured as 170 and 120 nm, respectively. PEG- and DEXTRAN-coated SPIONs have a Specific Power Absorption SPA of 320 and 400 W/g, respectively, in an ac magnetic field with amplitude of 13 kA/m and frequency of 256 kHz. In vitro studies using VERO and MDCK cell lineages were performed to study the cytotoxicity and cell uptake of the SPIONs. For both cell lineages, PEG- and DEXTRAN-coated nanoparticles presented high cell viability for concentrations as high as 200 μg/mL. In vivo studies were conducted using BALB/c mice inoculating the SPIONs intravenously and exposing them to the presence of an external magnet located over the tumour. It was observed that the amount of PEG-coated SPIONs in the tumor increased by up to 160% when using the external permanent magnetic as opposed to those animals that were not exposed to the external magnetic field.

Induced cell toxicity originates dendritic cell death following magnetic hyperthermia treatment

Magnetic hyperthermia (MH) is based on the use of magnetic nanoparticles (MNPs) to selectively increase the temperature of MNP-loaded target tissues when applying an alternating magnetic field (AMF) in the range of radiofrequency. To date, all MH research has focused on heat generation in an attempt to elucidate the mechanisms for the death of MNP-loaded cells submitted to AMF. However, recent in vitro studies have demonstrated the feasibility of inducing dramatic cell death without increasing the macroscopic temperature during AMF exposure. Here, we show that the cell death observed following AMF exposure, specifically that of MNP-loaded dendritic cells (DCs) in culture, was caused by the release of toxic agents into the cell culture supernatants and not due to a macroscopic temperature increase. We performed MH in vitro experiments to demonstrate that the supernatant of the cell culture following AMF exposure was highly toxic when added to control unloaded DCs, as this treatment led to nearly 100% cell death. Therefore, our results demonstrate that heat is not the only agent responsible for triggering cell death following MH treatment. This finding offers new perspectives for the use of DCs as the proverbial Trojan horse to vectorise MNPs to the target tumour area and these results further support the use of DCs as therapeutic agents against cancer when submitted to AMF. Furthermore, this discovery may help in understanding the mechanism of cell death mediated by exposure to AMF.

Application of magnetically induced hyperthermia in the model protozoan Crithidia fasciculata as a potential therapy against parasitic infections

Background

Magnetic hyperthermia is currently a clinical therapy approved in the European Union for treatment of tumor cells, and uses magnetic nanoparticles (MNPs) under time-varying magnetic fields (TVMFs). The same basic principle seems promising against trypanosomatids causing Chagas disease and sleeping sickness, given that the therapeutic drugs available have severe side effects and that there are drug-resistant strains. However, no applications of this strategy against protozoan-induced diseases have been reported so far. In the present study, Crithidia fasciculata, a widely used model for therapeutic strategies against pathogenic trypanosomatids, was targeted with Fe₃O₄ MNPs in order to provoke cell death remotely using TVMFs.

Methods

Iron oxide MNPs with average diameters of approximately 30 nm were synthesized by precipitation of FeSO₄ in basic medium. The MNPs were added to C. fasciculata choanomastigotes in the exponential phase and incubated overnight, removing excess MNPs using a DEAE-cellulose resin column. The amount of MNPs uploaded per cell was determined by magnetic measurement. The cells bearing MNPs were submitted to TVMFs using a homemade AC field applicator (f = 249 kHz, H = 13 kA/m), and the temperature variation during the experiments was measured. Scanning electron microscopy was used to assess morphological changes after the TVMF experiments. Cell viability was analyzed using an MTT colorimetric assay and flow cytometry.

Results

MNPs were incorporated into the cells, with no noticeable cytotoxicity. When a TVMF was applied to cells bearing MNPs, massive cell death was induced via a nonapoptotic mechanism. No effects were observed by applying TVMF to control cells not loaded with MNPs. No macroscopic rise in temperature was observed in the extracellular medium during the experiments.

Conclusion

As a proof of principle, these data indicate that intracellular hyperthermia is a suitable technology to induce death of protozoan parasites bearing MNPs. These findings expand the possibilities for new therapeutic strategies combating parasitic infection.

Controlled cell death by magnetic hyperthermia: effects of exposure time, field amplitude, and nanoparticle concentration

PURPOSE

To investigate the effects of alternating magnetic fields (AMF) on the death rate of dendritic cells (DCs) loaded with magnetic nanoparticles (MNPs) as heating agents. AMF exposure time and amplitude as well as the MNPs concentration were screened to assess the best conditions for a controlled field-induced cell death.

METHODS

Human-monocyte-derived DCs were co-incubated with dextran-coated MNPs. The cells were exposed to AMF (f = 260 kHz; 0 < H(0) < 12.7 kA/m) for intervals from 5 to 15 min. Morphology changes were assessed by scanning electron microscopy. Cell viability was measured by Trypan blue and fluorescence-activated cell sorting (FACS) using Annexin-propidium iodide markers.

RESULTS

We were able to control the DCs viability by a proper choice AMF amplitude and exposure time, depending on the amount of MNPs uploaded. About 20% of cells showed Annexin-negative/PI-positive staining after 5-10 min of AMF exposure.

CONCLUSIONS

Controlled cell death of MNP-loaded DCs can be obtained by adequate tuning of the physical AMF parameters and MNPs concentration. Necrotic-like populations were observed after exposure times as short as 10 min, suggesting a fast underlying mechanism for cell death. Power absorption by the MNPs might locally disrupt endosomic membranes, thus provoking irreversible cell damage.

Cytotoxicity of release products from magnetic nanocomposites in targeted drug delivery

The efficacy of chemotherapy can be significantly improved if the therapeutic agent remains localized at the afflicted area and released at controlled rates. Such a targeted drug delivery can be achieved using magnetic nanocomposite (MNC), which incorporates drug and magnetic nanoparticles in biodegradable polymer microspheres. Reported here are results from an in vitro study on drug release rate and cytotoxicity of other release products from MNC. The model system contains an anti-cancer chemotherapy agent 5-flurouracil (5-FU) and (Co(0.5)Zn(0.5))Fe(2)O(4) in poly(lactic-co-glycolic acid) (PLGA) matrix produced by an oil/oil emulsion technique. Cell proliferation data indicate a sustained release of 5-FU for mouse macrophage cell eradication, whereas other microsphere components of magnetic nanoparticles and PLGA have little cytotoxic effects.