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

Synergistic Strategies in Prostate Cancer Therapy: Electrochemotherapy and Electromagnetic Hyperthermia

Prostate cancer is a significant global health problem, being the second most common cancer and the fifth leading cause of death in men worldwide. Standard chemotherapy, though effective, often lacks selectivity for tumor cells, resulting in dose-limiting side effects. To address this, innovative biomedical approaches such as electrochemotherapy and electromagnetic hyperthermia have emerged. Electrochemotherapy improves drug delivery by facilitating electroporation, thereby increasing intracellular concentrations of chemotherapeutic agents. This approach reduces dosages and associated adverse effects. Meanwhile, electromagnetic hyperthermia raises the temperature of tumor cells, enhancing their sensitivity to chemotherapy. While previous research has demonstrated the inhibitory effects of magnetic hyperthermia on prostate cancer cell growth both in vitro and in vivo, and its synergy with chemotherapy has shown enhanced tumor remission, limited studies have focused on electrochemotherapy alone or in combination with hyperthermia in prostate cancer models. This study aims to assess the synergistic effects of electromagnetic hyperthermia, with superparamagnetic iron oxide nanoparticles (SPIONs) and electrochemotherapy, with electroporation and the chemotherapeutic drugs bleomycin and cisplatin, on the prostate cancer-derived cell line DU-145/GFP and prostate-derived cell line RWPE-1. Results indicate enhanced cytotoxicity with both treatments (bleomycin and cisplatin) by adding electroporation, demonstrating a particularly pronounced effect with bleomycin. Combining electroporation with hyperthermia significantly augments cytotoxicity. Moreover, electroporation effectively reduced the time of exposure to electromagnetic hyperthermia while magnifying its cytotoxic effects. Future research in in vivo trials may reveal additional insights into the combined effects of these therapies.

Reversal of Multidrug Resistance by the Synergistic Effect of Reversan and Hyperthermia to Potentiate the Chemotherapeutic Response of Doxorubicin in Glioblastoma and Glioblastoma Stem Cells

The glioblastoma stem cell (GSC) population in glioblastoma multiforme (GBM) poses major complication in clinical oncology owing to increased resistance to chemotherapeutic drugs, thereby limiting treatment in patients with recurring glioblastoma. To completely eradicate glioblastoma, a single therapy module is not enough; therefore, there is a need to develop a multimodal approach to eliminate bulk tumors along with the CSC population. With an aim to target transporters associated with multidrug resistance (MDR), such as P-glycoprotein (P-gp), a small-molecule inhibitor, reversan (RV) was used along with multifunctional magnetic nanoparticles (MNPs) for hyperthermia (HT) therapy and targeted drug delivery. Higher efflux of free doxorubicin (Dox) from the cells was stabilized by encapsulation in PPS-MnFe nanoparticles, whose physicochemical properties were determined by dynamic light scattering (DLS) and transmission electron microscopy (TEM). Treatment with RV also enhanced the cellular uptake of PPS-MnFe-Dox, whereas RV and magnetic hyperthermia (MHT) together showed prolonged retention of fluorescence dye, Rhodamine123 (R123), in glioblastoma cells compared with individual treatment. Overall, in this work, we demonstrated the synergistic action of RV and HT to combat MDR in GBM and GSCs, and chemo-hyperthermia therapy enhanced the cytotoxic effect of the chemotherapeutic drug Dox (with lower effective concentration) and induced a higher degree of apoptosis compared to single-drug dosage.

Tumor size dependent MNP dose evaluation in realistic breast tumor models for effective magnetic hyperthermia

The goal of the current investigation is to determine the breast tumor size-dependent MNP (Magnetic nano-particle) dose (mg/cm3) that can induce the required therapeutic effects during magnetic nanoparticle hyperthermia (MNH). The investigation is done through the MNH simulations on the tumor models generated from DCE_MRI DICOM images of breast cancer from TCIA ('The Cancer Imaging Archive'). Five tumor models are created from MRI data using 3D slicer software having size range of 3 cm3 to 15 cm3. The FEM-based solver (COMSOL multi-physics) is used to simulate bioheat transfer physics in all five extracted models. Single and multi-point injection strategies have been adopted to induce MNP in tumor tissues. The required MNP dose that may induce necessary therapeutic effects is evaluated by comparing the therapeutic effects produced by constant dose (CD) (5 mg/cm3) and variable reduced dose (RD) (5.5-2.8 mg/cm3) methodologies. Results show that for the requisite therapeutic effects, injected MNP doses (mg/cm3) should not remain constant as the size of the tumor increases. In fact, MNP dose  (mg/cm3) should be reduced as the size of the tumor increases. Results also show that RD works better with a multi-injection strategy than a single injection of MNP. It has been found that the effective MNP dose  (mg/cm3) is reduced by 50 % for the biggest tumor size (15 cm3) using multi-injection MNP delivery with respect to the smallest tumor (3 cm3) selected in this study.

Visible Laser Light Mediated Cancer Therapy via Photothermal Effect of Tannin-Stabilized Magnetic Iron Oxide Nanoparticles

Super-paramagnetic iron oxide nanoparticles (SPIONs/Fe₃O₄) were synthesized in aqueous medium under a nitrogen atmosphere. These particles were made water-dispersible by cladding them with tannic acid (TA). The synthesized nanoparticles were characterized for their size and surface charge using HRTEM and zetasizer. It was found that the size of the particles formed was around 15 nm with almost spherical morphology and negative surface charge. Vibrating sample magnetometer (VSM) data attributed a super-paramagnetic nature to these nanoparticles. The photo-thermal dynamics of these magnetite (Fe₃O₄) nanoparticles was characterized by exciting their dispersions with laser radiation in the visible region (635 nm). Remarkably, 17 min of laser irradiation of the dispersion raised its temperature by ~25 °C (25 to 49.8 °C), whereas for the solvent, it was limited to not more than 4 °C (after 60 min). Thus, the Fe₃O₄ nanoparticles generated localized hyperthermia for potential use in cancer therapy of tumor management. The photo-thermal dynamics of these nanoparticles was investigated in-vitro for cancer therapy, and it was clearly shown that cancer cell growth was inhibited, and considerable cellular damage occurred when cells were incubated with laser-activated magnetic nanoparticles. No noticeable innate toxicity of the nanoparticles was observed on cancer cell lines. The effectiveness of these nanoparticles was studied on several malignant cell lines, and an acceptable Fe₃O₄ concentration range was subsequently determined for generating substantial cell death by hyperthermia, but not inherent toxicity. Therefore, we concluded that this nano-system is effective and less time consuming for the treatment of malignant diseases such as cancer.

Paclitaxel-Loaded Lipid-Coated Magnetic Nanoparticles for Dual Chemo-Magnetic Hyperthermia Therapy of Melanoma

Melanoma is the most aggressive and metastasis-prone form of skin cancer. Conventional therapies include chemotherapeutic agents, either as small molecules or carried by FDA-approved nanostructures. However, systemic toxicity and side effects still remain as major drawbacks. With the advancement of nanomedicine, new delivery strategies emerge at a regular pace, aiming to overcome these challenges. Stimulus-responsive drug delivery systems might considerably reduce systemic toxicity and side-effects by limiting drug release to the affected area. Herein, we report the development of paclitaxel-loaded lipid-coated manganese ferrite magnetic nanoparticles (PTX-LMNP) as magnetosomes synthetic analogs, envisaging the combined chemo-magnetic hyperthermia treatment of melanoma. PTX-LMNP physicochemical properties were verified, including their shape, size, crystallinity, FTIR spectrum, magnetization profile, and temperature profile under magnetic hyperthermia (MHT). Their diffusion in porcine ear skin (a model for human skin) was investigated after intradermal administration via fluorescence microscopy. Cumulative PTX release kinetics under different temperatures, either preceded or not by MHT, were assessed. Intrinsic cytotoxicity against B16F10 cells was determined via neutral red uptake assay after 48 h of incubation (long-term assay), as well as B16F10 cells viability after 1 h of incubation (short-term assay), followed by MHT. PTX-LMNP-mediated MHT triggers PTX release, allowing its thermal-modulated local delivery to diseased sites, within short timeframes. Moreover, half-maximal PTX inhibitory concentration (IC50) could be significantly reduced relatively to free PTX (142,500×) and Taxol® (340×). Therefore, the dual chemo-MHT therapy mediated by intratumorally injected PTX-LMNP stands out as a promising alternative to efficiently deliver PTX to melanoma cells, consequently reducing systemic side effects commonly associated with conventional chemotherapies.

Testing the Effects of Magnetic Hyperthermia in 2D Cell Culture

Magnetic hyperthermia is an innovative thermal therapy for the treatment of solid malignancies. This treatment approach utilizes magnetic nanoparticles that are stimulated by alternating magnetic fields to induce temperature elevations in tumor tissue, resulting in cell death. Magnetic hyperthermia is clinically approved for treating glioblastoma in Europe and is undergoing clinical evaluation for prostate cancer in the United States. Numerous studies have also demonstrated efficacy in other cancers, however, and its potential utility extends far beyond its current clinical indications. Despite this great promise, assessing the initial efficacy of magnetic hyperthermia in vitro is a complicated endeavor, with multiple hurdles worth considering, such as accurate thermal monitoring, accounting for nanoparticle interference, and a myriad of treatment controls that make robust experimental planning essential to evaluate treatment outcome. Presented here is an optimized magnetic hyperthermia treatment protocol to test the primary mechanism of cell death in vitro. This protocol can be applied to any cell line and ensures accurate temperature measurements, minimal nanoparticle interference, and controls for multiple factors that can influence experimental outcome.

Effect of Cobalt Ferrite Nanoparticles in a Hydrophilic Shell on the Conductance of Bilayer Lipid Membrane

We measured the conductance of bilayer lipid membranes of diphytanoylphosphatidylcholine induced by interaction with cubic magnetic nanoparticles (MNPs) of cobalt ferrite 12 and 27 nm in size and coated with a hydrophilic shell. The MNP coating is human serum albumin (HSA) or polyethylene glycol (PEG). The interaction of nanoparticles added to the bulk solution with the lipid bilayer causes the formation of metastable conductive pores, which, in turn, increases the integral conductance of the membranes. The increase in conductance with increasing MNP concentration was practically independent of the particle size. The dependence of the bilayer conductance on the concentration of PEG-coated MNPs was much weaker than that on the concentration with a shell of HSA. Analyzing the current traces, we believe that the conductive pores formed as a result of the interaction of nanoparticles with the membrane can change their size, remaining metastable. The form of multilevel current traces allows us to assume that there are several metastable pore states close in energy. The average radius of the putative cylindrical pores is in the range of 0.4-1.3 nm.

Expansion of thermometry in magnetic hyperthermia cancer therapy: antecedence and aftermath

Magnetic hyperthermia cancer therapy (MHCT) is a promising antitumor therapy based on the generation of heat by magnetic nanoparticles under the influence of an alternating-current magnetic field. However, an often-overlooked factor hindering the translation of MHCT to clinics is the inability to accurately monitor temperature, thereby leading to erroneous thermal control. It is significant to address 'thermometry' during magnetic hyperthermia because numerous factors are affected by the magnetic fields employed, rendering traditional thermometry methods unsuitable for temperature estimation. Currently, there is a dearth of literature describing appropriate techniques for thermometry during MHCT. This review offers a general outline of the various modes of conventional thermometry as well as cutting-edge techniques operating at cellular/nanoscale levels (nanothermometry) as prospective thermometers for MHCT in the future.

Polyethyleneimine Functionalized Mesoporous Magnetic Nanoparticles with Enhanced Antibacterial and Antibiofilm Activity in an Alternating Magnetic Field

Despite a lot of research on the antibacterial effect of Fe₃O₄ nanoparticles, their interactions with biofilm matrix have not been well understood. The surface charge of nanoparticles mainly determines their ability to adhere on the biofilm. In this work, negatively charged Fe₃O₄ nanoparticles were synthesized via a trisodium citrate-assisted solvothermal method and then the surfaces were functionalized using polyethyleneimine (PEI) to obtain positively charged Fe₃O₄ nanoparticles. The antibacterial and antibiofilm activities of both negatively and positively charged Fe₃O₄ nanoparticles in an alternating magnetic field were then systematically investigated. The positively charged Fe₃O₄ nanoparticles showed a strong self-adsorbed attachment ability to the planktonic and sessile cells, resulting in a better antibacterial activity and enhanced biofilm eradication performance compared to the conventional Fe₃O₄ nanoparticles with negative charges. Fe₃O₄@PEI nanoparticles produced physical stress and thermal damage in response to an alternating magnetic field, inducing the accumulation of intracellular reactive oxygen species into live bacterial cells, bacterial membrane damage, and biofilm dispersion. Utilizing an alternating magnetic field along with positively charged nanoparticles leads to a synergistic antibacterial approach to improve the antibiofilm performance of magnetic nanoparticles.

Individual particle heating of interacting magnetic nanoparticles at nonzero temperature

Interaction phenomena have become a hot topic in nanotechnology due to their influence on the performance of magnetic nanostructures for biomedical applications. Hysteresis loops give a good account of the particles' magnetic behaviour, providing valuable clues on subsequent improvements. Nevertheless, the individual hysteresis loops of these systems are also influenced by any potential energy exchanged between the particles, and in contrast to non-interacting particles, are no longer a good measure for the local heat generated by each particle. As of today, there is no method capable of analysing the heat dissipation resulting from the nanoscale magnetisation dynamics in its full generality, i.e. in the presence of interactions and at nonzero temperature (allowing for thermally induced switching), and therefore the means of exploiting these dynamics remain hampered by a lack of understanding. In this work we address this problem by proposing and validating an equation that can be used to resolve the individual heat dissipation of interacting nanoparticles at nonzero temperature. After assessing this equation for different model systems, we have found that the proportion of heat dissipated in each individual particle tends to become more uniformly distributed for larger fields. Our results might have implications for magnetic particle hyperthermia where one of the most long-standing challenges is to achieve a homogeneous therapeutic temperature distribution in the target region during a treatment. Although tackling this issue involves a number of aspects related to the tissues involved, the injected nanoparticles, and the applied magnetic field, we believe that a more homogeneous heating of the particles inside the tumour will help to overcome this challenge.

A Perspective on Modelling Metallic Magnetic Nanoparticles in Biomedicine: From Monometals to Nanoalloys and Ligand-Protected Particles

The focus of this review is on the physical and magnetic properties that are related to the efficiency of monometallic magnetic nanoparticles used in biomedical applications, such as magnetic resonance imaging (MRI) or magnetic nanoparticle hyperthermia, and how to model these by theoretical methods, where the discussion is based on the example of cobalt nanoparticles. Different simulation systems (cluster, extended slab, and nanoparticle models) are critically appraised for their efficacy in the determination of reactivity, magnetic behaviour, and ligand-induced modifications of relevant properties. Simulations of the effects of nanoscale alloying with other metallic phases are also briefly reviewed.

Fundamentals to Apply Magnetic Nanoparticles for Hyperthermia Therapy

The activation of magnetic nanoparticles in hyperthermia treatment by an external alternating magnetic field is a promising technique for targeted cancer therapy. The external alternating magnetic field generates heat in the tumor area, which is utilized to kill cancerous cells. Depending on the tumor type and site to be targeted, various types of magnetic nanoparticles, with variable coating materials of different shape and surface charge, have been developed. The tunable physical and chemical properties of magnetic nanoparticles enhance their heating efficiency. Moreover, heating efficiency is directly related with the product values of the applied magnetic field and frequency. Protein corona formation is another important parameter affecting the heating efficiency of MNPs in magnetic hyperthermia. This review provides the basics of magnetic hyperthermia, mechanisms of heat losses, thermal doses for hyperthermia therapy, and strategies to improve heating efficiency. The purpose of this review is to build a bridge between the synthesis/coating of magnetic nanoparticles and their practical application in magnetic hyperthermia.

Therapeutic strategies of iron-based nanomaterials for cancer therapy

Iron-based nanomaterials have appeared in various cancer treatments owing to their promising functions and safety. Various sophisticated iron-based nanomaterials have been designed to exhibit great therapeutic effects through different strategies. Given the rapid progression, there is a great need to integrate the recent advances to learn about the latest innovation in this field. In this review, we classified the strategies of iron-based nanomaterials for cancer treatment into the following categories: immunotherapy, ferroptosis, magnetic hyperthermia and magneto-mechanical destruction. On the one hand, we discussed the underlining mechanism of iron-based nanomaterials in these therapies and applications; on the other hand, we analyzed the feasible combination of these applications and other therapies. Finally, the current challenges and expectation of iron-based nanomaterials in this field were highlighted.

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.

Smart magnetic nanopowder based on the manganite perovskite for local hyperthermia

For many medical applications related to diagnosis and treatment of cancer disease, hyperthermia plays an increasingly important role as a local heating method, where precise control of temperature and parameters of the working material is strongly required. Obtaining a smart material with "self-controlled" heating in a desirable temperature range is a relevant task. For this purpose, the nanopowder of manganite perovskite with super-stoichiometric manganese has been synthesized, which consists of soft spherical-like ferromagnetic nanoparticles with an average size of 65 nm and with a narrow temperature range of the magnetic phase transition at 42 °C. Based on the analysis of experimental magnetic data, a specific loss power has been calculated for both quasi-stable and relaxation hysteresis regions. It has been shown that the local heating of the cell structures to 42 °C may occur for a short time (∼1.5 min.) Upon reaching 42 °C, the heating is stopped due to transition of the nanopowder to the paramagnetic state. The obtained results demonstrate the possibility of using synthesized nanopowder as a smart magnetic nanomaterial for local hyperthermia with automatic heating stabilization in the safe range of hyperthermia without the risk of mechanical damage to cell structures.

Trigger-responsive engineered-nanocarriers and image-guided theranostics for rheumatoid arthritis

Rheumatoid Arthritis (RA), one of the leading causes of disability due to progressive autoimmune destruction of synovial joints, affects ∼1% of the global population. Standard therapy helps in reducing inflammation and delaying the progression of RA but is limited by non-responsiveness on long-term use and several side-effects. The conventional nanocarriers (CNCs), to some extent, minimize toxicity associated with free drug administration while improving the therapeutic efficacy. However, the uncontrolled release of the encapsulated drug even at off-targeted organs limits the application of CNCs. To overcome these challenges, trigger-responsive engineered nanocarriers (ENCs) have been recently explored for RA treatment. Unlike CNCs, ENCs enable precise control over on-demand drug release due to endogenous triggers in arthritic paws like pH, enzyme level, oxidative stress, or exogenously applied triggers like near-infrared light, magnetic field, ultrasonic waves, etc. As the trigger is selectively applied to the inflamed joint, it potentially reduces toxicity at off-target locations. Moreover, ENCs have been strategically coupled with imaging probe(s) for simultaneous monitoring of ENCs inside the body and facilitate an 'image-guided-co-trigger' for site-specific action in arthritic paws. In this review, the progress made in recently emerging 'trigger-responsive' and 'image-guided theranostics' ENCs for RA treatment has been explored with emphasis on the design strategies, mechanism, current status, challenges, and translational perspectives.

Magnetic Measurement and Stimulation of Cellular and Intracellular Structures

From single-pole magnetic tweezers to robotic magnetic-field generation systems, the development of magnetic micromanipulation systems, using electromagnets or permanent magnets, has enabled a multitude of applications for cellular and intracellular measurement and stimulation. Controlled by different configurations of magnetic-field generation systems, magnetic particles have been actuated by an external magnetic field to exert forces/torques and perform mechanical measurements on the cell membrane, cytoplasm, cytoskeleton, nucleus, intracellular motors, etc. The particles have also been controlled to generate aggregations to trigger cell signaling pathways and produce heat to cause cancer cell apoptosis for hyperthermia treatment. Magnetic micromanipulation has become an important tool in the repertoire of toolsets for cell measurement and stimulation and will continue to be used widely for further explorations of cellular/intracellular structures and their functions. Existing review papers in the literature focus on fabrication and position control of magnetic particles/structures (often termed micronanorobots) and the synthesis and functionalization of magnetic particles. Differently, this paper reviews the principles and systems of magnetic micromanipulation specifically for cellular and intracellular measurement and stimulation. Discoveries enabled by magnetic measurement and stimulation of cellular and intracellular structures are also summarized. This paper ends with discussions on future opportunities and challenges of magnetic micromanipulation in the exploration of cellular biophysics, mechanotransduction, and disease therapeutics.

Comparing the Effects of Intracellular and Extracellular Magnetic Hyperthermia on the Viability of BxPC-3 Cells

Magnetic hyperthermia involves the use of iron oxide nanoparticles to generate heat in tumours following stimulation with alternating magnetic fields. In recent times, this treatment has undergone numerous clinical trials in various solid malignancies and subsequently achieved clinical approval to treat glioblastoma and prostate cancer in 2011 and 2018, respectively. However, despite recent clinical advances, many questions remain with regard to the underlying mechanisms involved in this therapy. One such query is whether intracellular or extracellular nanoparticles are necessary for treatment efficacy. Herein, we compare the effects of intracellular and extracellular magnetic hyperthermia in BxPC-3 cells to determine the differences in efficacy between both. Extracellular magnetic hyperthermia at temperatures between 40–42.5 °C could induce significant levels of necrosis in these cells, whereas intracellular magnetic hyperthermia resulted in no change in viability. This led to a discussion on the overall relevance of intracellular nanoparticles to the efficacy of magnetic hyperthermia therapy.

Biocompatible chitosan-based composites with properties suitable for hyperthermia therapy

Sustainably made, flexible and biocompatible composites, having environmentally friendly compositions and multifunctional capabilities, are promising materials for several emerging biomedical applications.

Microswimmers with Heat Delivery Capacity for 3D Cell Spheroid Penetration

Micro- and nanoswimmers are a fast emerging concept that changes how colloidal and biological systems interact. They can support drug delivery vehicles, assist in crossing biological barriers, or improve diagnostics. We report microswimmers that employ collagen, a major extracellular matrix (ECM) constituent, as fuel and that have the ability to deliver heat via incorporated magnetic nanoparticles when exposed to an alternating magnetic field (AMF). Their assembly and heating properties are outlined followed by the assessment of their calcium-triggered mobility in aqueous solution and collagen gels. It is illustrated that the swimmers in collagen gel in the presence of a steep calcium gradient exhibit fast and directed mobility. The experimental data are supported with theoretical considerations. Finally, the successful penetration of the swimmers into 3D cell spheroids is shown, and upon exposure to an AMF, the cell viability is impaired due to the locally delivered heat. This report illustrates an opportunity to employ swimmers to enhance tissue penetration for cargo delivery via controlled interaction with the ECM.

Carbon nanoparticle lymph node tracer improves the outcomes of surgical treatment in papillary thyroid cancer

BACKGROUND

Papillary thyroid carcinoma (PTC) is the most common thyroid malignancy which is generally accompanied by lymph node metastasis.

OBJECTIVE

Our study evaluated whether carbon nanoparticle lymph node tracer can improve the outcomes of surgical treatment in papillary thyroid cancer (PTC).

METHODS

Ninety-two patients were selected and underwent total thyroidectomy and lymph node resection. Our study placed 45 individuals into the treatment group (carbon nanoparticle group) and 47 cohorts in the control group (no carbon nanoparticle group).

RESULTS

Carbon nanoparticle application remarkably improved lymph nodes detection rate in patients (4.7 ± 3.0; P< 0.05) compared to those in control groups (3.5 ± 2.3). The rate of parathyroid accidental resection in the carbon nanoparticle group significantly decreased (6.67%) compared to the control group (21.28%). Incidents of hypoparathyroidism and hypocalcaemia significantly decreased among the carbon nanoparticle cohorts.

CONCLUSIONS

Our study definitively showed that carbon nanoparticles can be used to effectively treat lymphatic carcinoma. Our study presented clinical evidences for potential application of carbon nanoparticle in improving the management of PTC patients.

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.

Evaluation of in vitro cytotoxicity of superparamagnetic poly(thioether-ester) nanoparticles on erythrocytes, non-tumor (NIH3T3), tumor (HeLa) cells and hyperthermia studies

Magnetic nanoparticles encapsulated in biocompatible and biodegradable polymeric matrices are promising materials for biomedical applications, such as transport of antitumoral drugs and cancer treatment by hyperthermia. In this study, biobased poly(thioether-ester), PTEe, was obtained by thiol-ene polymerization and superparamagnetic nanoparticles, MNPs, were successfully incorporated in PTEe nanoparticles by miniemulsification followed by solvent evaporation. MNPs-PTEe nanoparticles with average diameter around 150 nm presented superparamagnetic behavior as confirmed by magnetization curves analysis. MNPs-PTEe nanoparticles did not present hemolytic damage on human red blood cells when incubated for 24 h. According to the cell viability assays, nanoparticles did not present any cytotoxic effect on murine fibroblast cell (NIH3T3) and human cervical cancer (HeLa). Hyperthermia assays were applied, demonstrating that AC magnetic field application (110 KHz-500 Oe) for 20 min significantly reduced the cells viability. The morphology evaluation of HeLa showed a hypoxia region one hour after hyperthermia application. Therefore, the results indicated that the superparamagnetic poly(thioether-ester) nanoparticles can be an excellent alternative for the targeted delivery of antitumor drugs and cancer treatment for hyperthermia.

High Frequency Hysteresis Losses on γ-Fe₂O₃ and Fe₃O₄: Susceptibility as a Magnetic Stamp for Chain Formation

In order to understand the properties involved in the heating performance of magnetic nanoparticles during hyperthermia treatments, a systematic study of different γ-Fe₂O₃ and Fe₃O₄ nanoparticles has been done. High-frequency hysteresis loops at 50 kHz carried out on particles with sizes ranging from 6 to 350 nm show susceptibility χ increases from 9 to 40 for large particles and it is almost field independent for the smaller ones. This suggests that the applied field induces chain ordering in large particles but not in the smaller ones due to the competition between thermal and dipolar energy. The specific absorption rate (SAR) calculated from hysteresis losses at 60 mT and 50 kHz ranges from 30 to 360 W/g_Fe, depending on particle size, and the highest values correspond to particles ordered in chains. This enhanced heating efficiency is not a consequence of the intrinsic properties like saturation magnetization or anisotropy field but to the spatial arrangement of the particles.

Size-selected Fe3O4-Au hybrid nanoparticles for improved magnetism-based theranostics

Size-selected Fe₃O₄-Au hybrid nanoparticles with diameters of 6-44 nm (Fe₃O₄) and 3-11 nm (Au) were prepared by high temperature, wet chemical synthesis. High-quality Fe₃O₄ nanocrystals with bulk-like magnetic behavior were obtained as confirmed by the presence of the Verwey transition. The 25 nm diameter Fe₃O₄-Au hybrid nanomaterial sample (in aqueous and agarose phantom systems) showed the best characteristics for application as contrast agents in magnetic resonance imaging and for local heating using magnetic particle hyperthermia. Due to the octahedral shape and the large saturation magnetization of the magnetite particles, we obtained an extraordinarily high r ₂-relaxivity of 495 mM^-1·s^-1 along with a specific loss power of 617 W·g_Fe ^-1 and 327 W·g_Fe ^-1 for hyperthermia in aqueous and agarose systems, respectively. The functional in vitro hyperthermia test for the 4T1 mouse breast cancer cell line demonstrated 80% and 100% cell death for immediate exposure and after precultivation of the cells for 6 h with 25 nm Fe₃O₄-Au hybrid nanomaterials, respectively. This confirms that the improved magnetic properties of the bifunctional particles present a next step in magnetic-particle-based theranostics.

Recent applications of the combination of mesoporous silica nanoparticles with nucleic acids: development of bioresponsive devices, carriers and sensors

The discovery and control of the biological roles mediated by nucleic acids have turned them into a powerful tool for the development of advanced biotechnological materials. Such is the importance of these gene-keeping biomacromolecules that even nanomaterials have succumbed to the claimed benefits of DNA and RNA. Currently, there could be found in the literature a practically intractable number of examples reporting the use of combination of nanoparticles with nucleic acids, so boundaries are demanded. Following this premise, this review will only cover the most recent and powerful strategies developed to exploit the possibilities of nucleic acids as biotechnological materials when in combination with mesoporous silica nanoparticles. The extensive research done on nucleic acids has significantly incremented the technological possibilities for those biomacromolecules, which could be employed in many different applications, where substrate or sequence recognition or modulation of biological pathways due to its coding role in living cells are the most promising. In the present review, the chosen counterpart, mesoporous silica nanoparticles, also with unique properties, became a reference material for drug delivery and biomedical applications due to their high biocompatibility and porous structure suitable for hosting and delivering small molecules. Although most of the reviews dealt with significant advances in the use of nucleic acid and mesoporous silica nanoparticles in biotechnological applications, a rational classification of these new generation hybrid materials is still uncovered. In this review, there will be covered promising strategies for the development of living cell and biological sensors, DNA-based molecular gates with targeting, transfection or silencing properties, which could provide a significant advance in current nanomedicine.

Magnetic Nanotransducers in Biomedicine

Owing to their abilities to identify diseased conditions, to modulate biological processes, and to control cellular activities, magnetic nanoparticles have become one of the most popular nanomaterials in the biomedical field. Targeted drug delivery, controlled drug release, hyperthermia treatment, imaging, and stimulation of several biological entities are just some of the several tasks that can be accomplished by taking advantage of magnetic nanoparticles in tandem with magnetic fields. The huge interest towards this class of nanomaterials arises from the possibility to physically drive their spatiotemporal localization inside the body, and to deliver an externally applied stimulation at a target site. They in fact behave as actual nanotransducers, converting energy stemming from the external magnetic field into heat and mechanical forces, which act as signals for therapeutic processes such as hyperthermia and controlled drug release. Magnetic nanoparticles are a noninvasive tool that enables the remote activation of biological processes, besides behaving as formidable tracers for different imaging modalities, thus allowing to simultaneously carry out diagnosis and therapy. In view of all this, owing to their multifunctional and multitasking nature, magnetic nanoparticles are already one of the most important nanotechnological protagonists in medicine and biology, enabling an actual theranostic approach in many pathological conditions. In this Concept, we first provide a brief introduction on some physical properties of magnetic materials and on important features that determine the physical properties of magnetic nanoparticles. Thereafter, we will consider some major biomedical applications: hyperthermia, drug delivery/release, and nanoparticle-mediated control of biological processes, even at subcellular level.

Cell damage produced by magnetic fluid hyperthermia on microglial BV2 cells

We present evidence on the effects of exogenous heating by water bath (WB) and magnetic hyperthermia (MHT) on a glial micro-tumor phantom. To this, magnetic nanoparticles (MNPs) of 30-40 nm were designed to obtain particle sizes for maximum heating efficiency. The specific power absorption (SPA) values (f = 560 kHz, H = 23.9 kA/m) for as prepared colloids (533-605 W/g) dropped to 98-279 W/g in culture medium. The analysis of the intracellular MNPs distribution showed vesicle-trapped MNPs agglomerates spread along the cytoplasm, as well as large (~0.5-0.9 μm) clusters attached to the cell membrane. Immediately after WB and MHT (T = 46 °C for 30 min) the cell viability was ≈70% and, after 4.5 h, decreased to 20-25%, demonstrating that metabolic processes are involved in cell killing. The analysis of the cell structures after MHT revealed a significant damage of the cell membrane that is correlated to the location of MNPs clusters, while local cell damage were less noticeable after WB without MNPs. In spite of the similar thermal effects of WB and MHT on the cell viability, our results suggest that there is an additional mechanism of cell damage related to the presence of MNPs at the intracellular space.

Cell Mechanosensors and the Possibilities of Using Magnetic Nanoparticles to Study Them and to Modify Cell Fate

The use of magnetic nanoparticles (MNPs) is a promising technique for future advances in biomedical applications. This idea is supported by the availability of MNPs that can target specific cell components, the variety of shapes of MNPs and the possibility of finely controlling the applied magnetic forces. To examine this opportunity, here we review the current developments in the use of MNPs to mechanically stimulate cells and, specifically, the cell mechanotransduction systems. We analyze the cell components that may act as mechanosensors and their effect on cell fate and we focus on the promising possibilities of controlling stem-cell differentiation, inducing cancer-cell death and treating nervous-system diseases.

Towards improved magnetic fluid hyperthermia: major-loops to diminish variations in local heating

A low anisotropy constant allows us to decrease local heating dispersion for a given applied magnetic field amplitude.

Folic acid on iron oxide nanoparticles: platform with high potential for simultaneous targeting, MRI detection and hyperthermia treatment of lymph node metastases of prostate cancer

Folic acid directly bound to the surface of iron oxide nanoparticles with simultaneously high targeting, MRI relaxivity and heating efficacy.

In-situ particles reorientation during magnetic hyperthermia application: Shape matters twice

Promising advances in nanomedicine such as magnetic hyperthermia rely on a precise control of the nanoparticle performance in the cellular environment. This constitutes a huge research challenge due to difficulties for achieving a remote control within the human body. Here we report on the significant double role of the shape of ellipsoidal magnetic nanoparticles (nanorods) subjected to an external AC magnetic field: first, the heat release is increased due to the additional shape anisotropy; second, the rods dynamically reorientate in the orthogonal direction to the AC field direction. Importantly, the heating performance and the directional orientation occur in synergy and can be easily controlled by changing the AC field treatment duration, thus opening the pathway to combined hyperthermic/mechanical nanoactuators for biomedicine. Preliminary studies demonstrate the high accumulation of nanorods into HeLa cells whereas viability analysis supports their low toxicity and the absence of apoptotic or necrotic cell death after 24 or 48 h of incubation.

Drug-loaded liposome-capped mesoporous core-shell magnetic nanoparticles for cellular toxicity study

Liposome-capped core-shell mesoporous silica-coated superparamagnetic iron oxide nanoparticles called 'magnetic protocells' were prepared as novel nanocomposites and used for loading anticancer drug doxorubicin (DOX) for cellular toxicity study. Cytotoxicity of the magnetic protocells with or without DOX was tested in vitro on commercial MCF7 and U87 cell lines under alternating magnetic field. MCF7 cell line treated with the DOX-loaded nanoparticles under alternating magnetic field exhibited nearly 20% lower survival rate after 24 h compared with cells treated with free DOX and similarly, it was around 24% when applied to U87. The results indicate that the magnetic protocells could be useful for future cancer treatment in vivo by the combination of targeted drug delivery and magnetic hyperthermia.

Synergetic effects of silver and gold nanoparticles in the presence of radiofrequency radiation on human kidney cells

OBJECTIVE

The aim of this study was to compare the effects of radiofrequency radiation (RF) in synergism with gold (Au) and silver (Ag) nanoparticles (NPs) on the survival fraction of human normal kidney (HNK) and human embryonic kidney (HEK) cells.

MATERIALS AND METHODS

HNK and HEK cells were divided into three groups as control, 1 and 2 h/day-irradiated groups for 8 days. To compare the effects of RF in the presence of Au-NPs and Ag-NPs, the cells were incubated with NPs during the irradiation. In other words, six other groups were designed for the cell incubated with Au-NPs and Ag-NPs including control, 1 and 2 h/day-irradiated groups for 8 days. Generalized estimating equation model was applied to consider the natural correlation of repeated measurements over the time.

RESULTS

The mean survival fractions of HNK + Ag-NPs and HEK + Au-NPs were 0.098 less, 0.184 and 0.055 more than HEK cells, respectively. Along with the time, the mean fraction in HEK + Ag-NPs and HEK + Au-NPs groups in comparison with the HEK increased by the rate of 0.005 and decreased by the rates of 0.01 and 0.005, respectively. The mean survival fractions in HEK + Ag-NPs and HEK + Au-NPs were significantly less than that of HEK cells (P < 0.05).

CONCLUSIONS

RF radiation can affect both HNK and HEK cells when irradiated for 2 h/day for 8 days. The results showed that the Ag-NPs do not increase the synergistic effects of RF compared to the Au-NPs. RF radiation at the presence of Au-NPs can be used as an efficient treatment for melanoma.

Chitosan nanoparticles for combined drug delivery and magnetic hyperthermia: From preparation to in vitro studies

Chitosan nanoparticles (CSNPs) ionically crosslinked with tripolyphosphate salts (TPP) were employed as nanocarriers in combined drug delivery and magnetic hyperthermia (MH) therapy. To that aim, three different ferrofluid concentrations and a constant 5-fluorouracil (5-FU) concentration were efficiently encapsulated to yield magnetic CSNPs with core-shell morphology. In vitro experiments using normal cells, fibroblasts (FHB) and cancer cells, human glioblastoma A-172, showed that CSNPs presented a dose-dependent cytotoxicity and that they were successfully uptaken into both cell lines. The application of a MH treatment in A-172 cells resulted in a cell viability of 67-75% whereas no significant reduction of cell viability was observed for FHB. However, the A-172 cells showed re-growth populations 4h after the application of the MH treatment when CSNPs were loaded only with ferrofluid. Finally, a combined effect of MH and 5-FU release was observed with the application of a second MH treatment for CSNPs exhibiting a lower amount of released 5-FU. This result demonstrates the potential of CSNPs for the improvement of MH therapies.

Quantifying intra- and extracellular aggregation of iron oxide nanoparticles and its influence on specific absorption rate

A promising route to cancer treatment is hyperthermia, facilitated by superparamagnetic iron oxide nanoparticles (SPIONs). After exposure to an alternating external magnetic field, SPIONs generate heat, quantified by their specific absorption rate (SAR, in W g(-1) Fe). However, without surface functionalization, commercially available, high SAR SPIONs (EMG 308, Ferrotec, USA) aggregate in aqueous suspensions; this has been shown to reduce SAR. Further reduction in SAR has been observed for SPIONs in suspensions containing cells, but the origin of this further reduction has not been made clear. Here, we use image analysis methods to quantify the structures of SPION aggregates in the extra- and intracellular milieu of LNCaP cell suspensions. We couple image characterization with nanoparticle tracking analysis and SAR measurements of SPION aggregates in cell-free suspensions, to better quantify the influence of cellular uptake on SPION aggregates and ultimately its influence on SAR. We find that in both the intra- and extracellular milieu, SPION aggregates are well-described by a quasifractal model, with most aggregates having fractal dimensions in the 1.6-2.2 range. Intracellular aggregates are found to be significantly larger than extracellular aggregates and are commonly composed of more than 10(3) primary SPION particles (hence they are "superaggregates"). By using high salt concentrations to generate such superaggregates and measuring the SAR of suspensions, we confirm that it is the formation of superaggregates in the intracellular milieu that negatively impacts SAR, reducing it from above 200 W g(-1) Fe for aggregates composed of fewer than 50 primary particles to below 50 W g(-1) for superaggregates. While the underlying physical mechanism by which aggregation leads to reduction in SAR remains to be determined, the methods developed in this study provide insight into how cellular uptake influences the extent of SPION aggregation, and enable estimation of the reduction of SAR brought about via uptake induced aggregation.

The role of size polydispersity in magnetic fluid hyperthermia: average vs. local infra/over-heating effects

An efficient and safe hyperthermia cancer treatment requires the accurate control of the heating performance of magnetic nanoparticles, which is directly related to their size. However, in any particle system the existence of some size polydispersity is experimentally unavoidable, which results in a different local heating output and consequently a different hyperthermia performance depending on the size of each particle. With the aim to shed some light on this significant issue, we have used a Monte Carlo technique to study the role of size polydispersity in heat dissipation at both the local (single particle) and global (macroscopic average) levels. We have systematically varied size polydispersity, temperature and interparticle dipolar interaction conditions, and evaluated local heating as a function of these parameters. Our results provide a simple guide on how to choose, for a given polydispersity degree, the more adequate average particle size so that the local variation in the released heat is kept within some limits that correspond to safety boundaries for the average-system hyperthermia performance. All together we believe that our results may help in the design of more effective magnetic hyperthermia applications.

Design of iron oxide-based nanoparticles for MRI and magnetic hyperthermia

Iron oxide nanoparticles are widely used for biological applications thanks to their outstanding balance between magnetic properties, surface-to-volume ratio suitable for efficient functionalization and proven biocompatibility. Their development for MRI or magnetic particle hyperthermia concentrates much of the attention as these nanomaterials are already used within the health system as contrast agents and heating mediators. As such, the constant improvement and development for better and more reliable materials is of key importance. On this basis, this review aims to cover the rational design of iron oxide nanoparticles to be used as MRI contrast agents or heating mediators in magnetic hyperthermia, and reviews the state of the art of their use as nanomedicine tools.

Mean-field and linear regime approach to magnetic hyperthermia of core-shell nanoparticles: can tiny nanostructures fight cancer?

The phenomenon of heat dissipation by magnetic materials interacting with an alternating magnetic field, known as magnetic hyperthermia, is an emergent and promising therapy for many diseases, mainly cancer. Here, a magnetic hyperthermia model for core-shell nanoparticles is developed. The theoretical calculation, different from previous models, highlights the importance of heterogeneity by identifying the role of surface and core spins on nanoparticle heat generation. We found that the most efficient nanoparticles should be obtained by selecting materials to reduce the surface to core damping factor ratio, increasing the interface exchange parameter and tuning the surface to core anisotropy ratio for each material combination. From our results we propose a novel heat-based hyperthermia strategy with the focus on improving the heating efficiency of small sized nanoparticles instead of larger ones. This approach might have important implications for cancer treatment and could help improving clinical efficacy.

Magnetic nanoparticles in cancer diagnosis and treatment: a review

Diagnosis and treatment of lung cancer have been characterized with a variety of challenges. However, with the advancement in magnetic nanoparticle (MNP) technology, many challenges in the diagnosis and treatment of lung cancer are on the decline. The MNPs have led to many break-through in cancer therapy. This paper seeks to establish the role of MNPs in diagnosis and treatment of lung cancer. It proposes that the existing challenges in the diagnosis and treatment of lung cancer can be addressed through application of MNPs in the process.