Magnetic Hyperthermia Research Articles

Single-Walled (Magnetic) Carbon Nanotubes in a Pectin Matrix in the Design of an Allantoin Delivery System.

Single-walled carbon nanotubes (SWCNTs) outperform other materials due to their high conductivity, large specific surface area, and chemical resistance. They have numerous biomedical applications, including the magnetization of the SWCNT (mSWCNT). The drug loading and release properties of see-through pectin hydrogels doped with SWCNTs and mSWCNTs were evaluated in this study. The active molecule in the hydrogel structure is allantoin, and calcium chloride serves as a cross-linker. In addition to mixing, absorption, and swelling techniques, drug loading into carbon nanotubes was also been studied. To characterize the films, differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR) spectroscopy, surface contact angle measurements, and opacity analysis were carried out. Apart from these, a rheological analysis was also carried out to examine the flow properties of the hydrogels. The study was also expanded to include N-(9-fluorenyl methoxycarbonyl)glycine-coated SWCNTs and mSWCNTs as additives to evaluate the efficiency of the drug-loading approach. Although the CNT additive was used at a 1:1000 weight ratio, it had a significant impact on the hydrogel properties. This effect, which was first observed in the thermal properties, was confirmed in rheological analyses by increasing solution viscosity. Additionally, rheological analysis and drug release profiles show that the type of additive causes a change in the matrix structure. According to TGA findings, even though SWCNTs and mSWCNTs were not coated more than 5%, the coating had a significant effect on drug release control. In addition to all findings, cell viability tests revealed that hydrogels with various additives could be used for visual wound monitoring, hyperthermia treatment, and allantoin release in wound treatment applications.

Mild magnetic hyperthermia-activated immuno-responses for primary bladder cancer therapy

Surgical intervention followed by chemotherapy is the principal treatment strategy for bladder cancer, which is hindered by significant surgical risks, toxicity from chemotherapy, and high rates of recurrence after surgery. In this context, a novel approach using mild magnetic hyperthermia therapy (MHT) for bladder cancer treatment through the intra-bladder delivery of magnetic nanoparticles is presented for the first time. This method overcomes the limitations of low magnetic thermal efficiency, inadequate tumor targeting, and reduced therapeutic effectiveness associated with the traditional intravenous administration of magnetic nanoparticles. Core-shell Zn–CoFe2O4@Zn–MnFe2O4 (MNP) nanoparticles were developed and further modified with hyaluronic acid (HA) to enhance their targeting ability toward tumor cells. The application of controlled mild MHT using MNP-HA at temperatures of 43–44 °C successfully suppressed the proliferation of bladder tumor cells and tumor growth, while also decreasing the expression levels of heat shock protein 70 (HSP70). Crucially, this therapeutic approach also activated the body's innate immune response involving macrophages, as well as the adaptive immune responses of dendritic cells (DCs) and T cells, thereby reversing the immunosuppressive environment of the bladder tumor and effectively reducing tumor recurrence. This study uncovers the potential immune-activating mechanism of mild MHT in the treatment of bladder cancer and confirms the effectiveness and safety of this strategy, indicating its promising potential for the clinical management of bladder cancer with a high tendency for relapse.

Review on Medical Applications of Manganese Oxide (Mn2+, Mn3+, and Mn4+) Magnetic Nanoparticles

Apart from our imagination, the nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nanoelectronics, environmental remediation, and medical healthcare. In the medical field, magnetic materials play vital roles such as magnetic resonance imaging (MRI), hyperthermia, and magnetic drug delivery. Among them, manganese oxide garnered great interest in biomedical applications due to its different oxidation states (Mn2+, Mn3+, and Mn4+). Manganese oxide nanostructures are widely explored for medical applications due to their availability, diverse morphologies, and tunable magnetic properties. In this review, cogent contributions of manganese oxides in medical applications are summarized. The crystalline structure and oxidation states of Mn oxides are highlighted. The synthesis approaches of Mn-based nanoparticles are outlined. The important medical applications of manganese-based nanoparticles like magnetic hyperthermia, MRI, and drug delivery are summarized. This review is conducted to cover the future impact of MnOx in diagnostic and therapeutic applications.

Smart composite scaffold to synchronize magnetic hyperthermia and chemotherapy for efficient breast cancer therapy

Combination of different therapies is an attractive approach for cancer therapy. However, it is a challenge to synchronize different therapies for maximization of therapeutic effects. In this work, a smart composite scaffold that could synchronize magnetic hyperthermia and chemotherapy was prepared by hybridization of magnetic Fe3O4 nanoparticles and doxorubicin (Dox)-loaded thermosensitive liposomes with biodegradable polymers. Irradiation of alternating magnetic field (AMF) could not only increase the scaffold temperature for magnetic hyperthermia but also trigger the release of Dox for chemotherapy. The two functions of magnetic hyperthermia and chemotherapy were synchronized by switching AMF on and off. The synergistic anticancer effects of the composite scaffold were confirmed by in vitro cell culture and in vivo animal experiments. The composite scaffold could efficiently eliminate breast cancer cells under AMF irradiation. Moreover, the scaffold could support proliferation and adipogenic differentiation of mesenchymal stem cells for adipose tissue reconstruction after anticancer treatment. In vivo regeneration experiments showed that the composite scaffolds could effectively maintain their structural integrity and facilitate the infiltration and proliferation of normal cells within the scaffolds. The composite scaffold possesses multi-functions and is attractive as a novel platform for efficient breast cancer therapy.

Simple thermal treatment to improve the MRI and magnetic hyperthermia performance of hybrid iron Oxide-Mesoporous silica nanocarriers

The design of multifunctional nanocomposites (NCs), incorporating a variety of controllable properties from nanostructured materials, spans their applicability as nanotools in biomedical applications. Santa Barbara Amorphous (SBA-15) mesoporous silica has showcased remarkable capabilities, ranging from bone regeneration to drug delivery. Its synergy with magnetic nanoparticles (MNPs) further broadens its scope as a theranostic agent, seamlessly integrating both therapeutic and diagnostic functions. However, efficiency issues arise due to MNP anchoring, necessitating novel solutions for optimization. This study focuses on enhancing the magnetic properties of hybrid iron oxide-SBA-15 mesoporous silica NCs through a simplified thermal procedure. The aim is to optimize their magnetic performance for dual functionality as contrast agents for magnetic resonance imaging (MRI) and as effective heaters in magnetic hyperthermia (MH) processes, while preserving the cylindrical mesoporous structure, high surface area, and high loading capacity compared to conventional ceramics. The investigation highlights that the impact of heat treatment on physicochemical properties varies depending on the compositions of the NCs. Specifically, the transversal relaxivity in MRI was doubled, accompanied by an enhanced Néel contribution in MH. This enhancement was achieved while maintaining the same biocompatibility as non-treated NCs, as demonstrated in evaluations with two cancer cell lines (HeLa and T-731 astrocytes), revealing low toxicity at concentrations up to 200 μg/mL.

Dual-stimuli-responsive poly(vinyl alcohol) nanofibers for localized cancer treatment: Magnetic hyperthermia and drug release studies

Smart materials are a promising option for a more personalized cancer treatment approach. In particular, materials that can respond to an external stimulus may be manipulated to provide a tailored response when and where it is needed. This work confined thermoresponsive poly (N-isopropyl acrylamide) microgels and superparamagnetic iron oxide nanoparticles into poly (vinyl alcohol) nanofibrous membranes. Physical and chemical crosslinking methods were tested to obtain membranes stable in physiological environments for long-term applications, and their effect on the membranes' morphology, swelling, and mechanical properties was evaluated. The results demonstrated that thermal crosslinking for 10 min is enough to obtain a robust membrane for biomedical applications that retain their components' magnetic and thermal responses. The swelling degree decreases with the increase of crosslinking time and is even smaller for chemically crosslinked membranes. Similarly, a high crosslinking degree is associated with more brittle membranes than ductile membranes with thermal crosslinking. Drug delivery assays using doxorubicin as a model drug demonstrated that only membranes with a smaller crosslinking degree are suitable for drug delivery purposes, with about 10 % of doxorubicin released for 15 days. Additionally, magnetic hyperthermia assays showed that composite membranes can increase the surrounding temperature by 10 °C in only 10 min of applying an alternating magnetic field. This work demonstrates the potential of combining stimuli-responsive materials using a simple, low-cost, and easily scalable technique (electrospinning) to produce smart materials for biomedical applications.

Numerical study on temperature distribution during magnetic hyperthermia of different tumor tissues

In recent years, nanotechnology has made an invasion in biomedical applications which has gained much more attention because of its high efficiency and low side effects.One such applicationis magnetic hyperthermia (MHT) where magnetic nanoparticles (MNPs) are used to generate heat to kill the cancerous tissues over an alternating magnetic field.The heat generated by the nanoparticles is caused by hysteresis and Neel and Brownian relaxation.In this paper, a finite element method-based numerical modelling with the help of COMSOL is used to obtain temperature distribution on different tumor tissues (liver, lungs, and kidney) embedded with nanoparticles during magnetic hyperthermia by varying different magnetic field strengths (4000–6000 A/m), different frequencies (100–500 kHz) and different volume fractions of nanoparticles (0.1––0.5 %). Results show that at 500 kHz frequency, the temperature at the centre of the tumor is elevated marginally by 8 %, 4 %, and 2 % for the lungs, liver, and kidney respectively. Similarly, at 6000 A/m magnetic field strength, the temperature at the given point of tumor enhances moderately by 25 %, 14 %, and 8 % in the case of lungs, liver, and kidney respectively. The temperature at the same location increases majorly by 81 %, 45 %, and 20 % for the case of lungs, liver, and kidney respectively at 0.5 % volume fraction of nanoparticles. In the study, the effect of the volume fraction of nanoparticles on temperature rise is found to be more significant compared to other cases. The heat transfer rate is maximum in the lungs followed by the liver and kidney respectively.

Treatment Temperature and Magnetic Field Distribution for Magnetic Hyperthermia Using Magnetic Nanoparticles

A minimally invasive cancer treatment method utilizing magnetic nanoparticles (MNPs) and magnetic coils, magnetic hyperthermia, generates heat locally inside the body to degenerate cancer cells. The uniformity of the coil's magnetic field is a crucial factor in enhancing the therapeutic effect. In this study, we evaluated the temperature distribution of MNPs on induction heating experiments at various distances using two types of coils. We found that the 2‐turn coil with a larger outer diameter and higher magnetic field uniformity resulted in a treatment temperature region approximately twice as wide as the 4‐turn coil, indicating the enhancement of the treatment effect under the uniform magnetic field distributions. © 2024 Institute of Electrical Engineer of Japan and Wiley Periodicals LLC.

Smart Design of ZnFe and ZnFe@Fe Nanoparticles for MRI-Tracked Magnetic Hyperthermia Therapy: Challenging Classical Theories of Nanoparticles Growth and Nanomagnetism.

Iron Oxide Nanoparticles (IONPs) hold the potential to exert significant influence on fighting cancer through their theranostics capabilities as contrast agents (CAs) for magnetic resonance imaging (MRI) and as mediators for magnetic hyperthermia (MH). In addition, these capabilities can be improved by doping IONPs with other elements. In this work, the synthesis and characterization of single-core and alloy ZnFe novel magnetic nanoparticles (MNPs), with improved magnetic properties and more efficient magnetic-to-heat conversion, are reported. Remarkably, the results challenge classical nucleation and growth theories, which cannot fully predict the final size/shape of these nanoparticles and, consequently, their magnetic properties, implying the need for further studies to better understand the nanomagnetism phenomenon. On the other hand, leveraging the enhanced properties of these new NPs, successful tumor therapy by MH is achieved following their intravenous administration and tumor accumulation via the enhanced permeability and retention (EPR) effect. Notably, these results are obtained using a single low dose of MNPs and a single exposure to clinically suitable alternating magnetic fields (AMF). Therefore, as far as the authors are aware, for the first time, the successful application of intravenously administered MNPs for MRI-tracked MH tumor therapy in passively targeted tumor xenografts using clinically suitable conditions is demonstrated.

Injectable Magnetic Hydrogel Filler for Synergistic Bone Tumor Hyperthermia Chemotherapy.

The therapeutic efficacy of bone tumor treatment is primarily limited by inadequate tumor resection, resulting in recurrence and metastasis, as well as the deep location of tumors. Herein, an injectable doxorubicin (DOX)-loaded magnetic alginate hydrogel (DOX@MAH) was developed to evaluate the efficacy of an alternating magnetic field (AMF)-responsive, chemothermal synergistic therapy for multimodality treatment of bone tumors. The prepared hydrogel exhibits a superior drug-loading capacity and a continuous DOX release. This multifunctionality can be attributed to the combined use of DOX for chemotherapy and iron oxide nanoparticle-containing alginate hydrogels as magnetic hyperthermia agents to generate hyperthermia for tumor elimination without the limit on penetration depth. Moreover, the hydrogel can be formed when in contact with the calcium ions, which are abundant in bone tissues; therefore, this hydrogel could perfectly fit the bone defects caused by the surgical removal of the bone tumor tissue, and the hydrogel could tightly attach the surgical margin of the bone to realize a high efficacy residual tumor tissue elimination treated by chemothermal synergistic therapy. The hydrogel demonstrates excellent hyperthermia performance, as evidenced by in vitro cytotoxicity tests on tumor cells. These tests reveal that the combined therapy based on DOX@MAH under AMF significantly induces cell death compared to single magnetic hyperthermia or chemotherapy. In vivo antitumor effects in tumor-bearing mice demonstrate that DOX@MAH injection at the tumor site effectively inhibits tumor growth and leads to tumor necrosis. This work not only establishes an effective DOX@MAH system as a synergistic chemothermal therapy platform for treating bone tumors but also sheds light on the application of alginate to combine calcium ions of the bone to treat bone defect diseases.

Ferritin-nanocaged aggregation-induced emission nanoaggregates for NIR-II fluorescence-guided noninvasive, controllable male contraception

Controllable contraception in male animals was demonstrated through the utilization of gold nanorods' photothermal effect to accomplish mild testicular hyperthermia. However, the challenges arising from testicular administration and the non-biodegradability of nanoparticles hinder further clinical implementation. Therefore, a straightforward, non-invasive, and enhanced contraception approach is required. This study explores the utilization of human heavy chain ferritin (HFn) nanocarriers loaded with aggregation-induced emission luminogens (AIEgens) for noninvasive, controllable male contraception guided by Near-Infrared-II (NIR-II) fluorescence imaging. The HFn-caged AIEgens (HFn@BBT) are delivered via intravenous injection and activated by near-infrared irradiation. Lower hyperthermia treatment induces partial damage to the testes and seminiferous tubules, reducing fertility indices by approximately 100% on the 7th day, which gradually recovers to 80% on the 60th day. Conversely, implementation of elevated hyperthermia therapy causes total destruction of both testes and seminiferous tubules, leading to a complete loss of fertility on the 60th day. Additionally, the use of AIEgens in NIR-II imaging offers improved fluorescence efficiency and penetration depth. The findings of this study hold significant promise for the advancement of safe and effective male contraceptive methods, addressing the need for noninvasive and controllable approaches to reproductive health and population control.

Heating efficiency of PEGylated Mn–Zn ferrite nanoparticles for magnetic fluid hyperthermia

Heating efficiency of PEGylated Mn–Zn ferrite nanoparticles for magnetic fluid hyperthermia

Bionic Bilayer Scaffold for Synchronous Hyperthermia Therapy of Orthotopic Osteosarcoma and Osteochondral Regeneration.

Large osseous void, postsurgical neoplastic recurrence, and slow bone-cartilage repair rate raise an imperative need to develop functional scaffold in clinical osteosarcoma treatment. Herein, a bionic bilayer scaffold constituting croconaine dye-polyethylene glycol@sodium alginate hydrogel and poly(l-lactide)/hydroxyapatite polymer matrix is fabricated to simultaneously achieve a highly efficient killing of osteosarcoma and an accelerated osteochondral regeneration. First, biomimetic osteochondral structure along with adequate interfacial interaction of the bilayer scaffold provide a structural reinforcement for transverse osseointegration and osteochondral regeneration, as evidenced by upregulated specific expressions of collagen type-I, osteopontin, and runt-related transcription factor 2. Meanwhile, thermal ablation of the synthesized nanoparticles and mitochondrial dysfunction caused by continuously released hydroxyapatite induce residual tumor necrosis synergistically. To validate the capabilities of inhibiting tumor growth and promoting osteochondral regeneration of our proposed scaffold, a novel orthotopic osteosarcoma model simulating clinical treatment scenarios of bone tumors is established on rats. Based on amounts of in vitro and in vivo results, an effective killing of osteosarcoma and a suitable osteal-microenvironment modulation of such bionic bilayer composite scaffold are achieved, which provides insightful implications for photonic hyperthermia therapy against osteosarcoma and following osseous tissue regeneration.

Alginate functionalized magnetic-silica composites for pH-responsive drug delivery and magnetic hyperthermia applications

A biopolymer sodium alginate (Alg) functionalized core–shell magnetic silica composite (FeNP@SiOH@Alg) has been proposed for pH-responsive drug delivery and magnetic hyperthermia applications. Various instruments such as XRD, FTIR, SEM, and TGA analysis were accessed to characterize the FeNP@SiOH@Alg. Under the alternating magnetic field (AMF), the magnetic hyperthermia and pH-responsive drug delivery efficiency of the prepared FeNP@SiOH@Alg were examined using doxorubicin (Dox) as a modal drug. Furthermore, the in vitro biocompatibility of the FeNP@SiOH@Alg on MDA-MB-231 cells was examined. All the findings indicated that FeNP@SiOH@Alg is effective for magnetic hyperthermia-based chemotherapy applications in cancer therapy.

Optical Microscopy Using the Faraday Effect Reveals in Situ Magnetization Dynamics of Magnetic Nanoparticles in Biological Samples.

The study of exogenous and endogenous nanoscale magnetic material in biology is important for developing biomedical nanotechnology as well as for understanding fundamental biological processes such as iron metabolism and biomineralization. Here, we exploit the magneto-optical Faraday effect to probe intracellular magnetic properties and perform magnetic imaging, revealing the location-specific magnetization dynamics of exogenous magnetic nanoparticles within cells. The opportunities enabled by this method are shown in the context of magnetic hyperthermia; an effect where local heating is generated in magnetic nanoparticles exposed to high-frequency AC magnetic fields. Magnetic hyperthermia has the potential to be used as a cellular-level thermotherapy for cancer, as well as for other biomedical applications that target heat-sensitive cellular function. However, previous experiments have suggested that the cellular environment modifies the magnetization dynamics of nanoparticles, thus dramatically altering their heating efficiency. By combining magneto-optical and fluorescence measurements, we demonstrate a form of biological microscopy that we used here to study the magnetization dynamics of nanoparticles in situ, in both histological samples and living cancer cells. Correlative magnetic and fluorescence imaging identified aggregated magnetic nanoparticles colocalized with cellular lysosomes. Nanoparticles aggregated within these lysosomes displayed reduced AC magnetic coercivity compared to the same particles measured in an aqueous suspension or aggregated in other areas of the cells. Such measurements reveal the power of this approach, enabling investigations of how cellular location, nanoparticle aggregation, and interparticle magnetic interactions affect the magnetization dynamics and consequently the heating response of nanoparticles in the biological milieu.

Multifunctional platform for photothermal therapy combined with luminescence nanothermometry probes

The design of multifunctional magnetic nanoparticles (NPs) that can generate and monitor heat release in real-time during thermal therapy is a major challenge in nanomedicine. In this work, a trimodal system that combines magnetic hyperthermia (MH), photothermal therapy (PT) and luminescence nano-thermometry (LT) has been set up in a single platform. Magnetite NPs were optimized focusing on MH and PT; then, the NPs have been coated with embedded Nd3+ cations to enhance the PT and to act as LT probe. Nd3+ is an interesting luminescent probe, with excitation around 800 nm and emission at the second biological window. Such hybrid system could act as heat mediator and imaging probe for in situ thermometer during the PT and MH, since these wavelengths belong to the biological windows.

LGR5 as a Therapeutic Target of Antibody-Functionalized Biomimetic Magnetoliposomes for Colon Cancer Therapy.

The lack of specificity of conventional chemotherapy is one of the main difficulties to be solved in cancer therapy. Biomimetic magnetoliposomes are successful chemotherapy controlled-release systems, hyperthermia, and active targeting agents by functionalization of their surface with monoclonal antibodies. The membrane receptor Leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5) stands out as colorectal cancer (CRC) biomarker and appears to be related to treatment resistance and the development of metastasis. The aim of this study was to assess the effectiveness and safety of LGR5-targeted biomimetic magnetoliposomes loaded with oxaliplatin (OXA) or 5-fluorouracil (5-FU) in the selective treatment of CRC and their possible application in hyperthermia. Synthesis, characterization and determination of heating capacity of magnetoliposomes transporting OXA or 5-FU (with and without LGR5 functionalization) were conducted. In vitro antitumoral activity was assayed in multiple colorectal cell lines at different times of exposition. In addition to this, cell internalization was studied by Prussian Blue staining, flow cytometry and fluorescence microscopy. In vivo acute toxicity of magnetoliposomes was performed to evaluate iron-related toxicity. OXA and 5-FU loaded magnetoliposomes functionalized with LGR5 antibody showed higher cellular uptake than non-targeted nanoformulation with a reduction of the percentage of proliferation in colon cancer cell lines up to 3.2-fold of the IC50 value compared to that of free drug. The differences between non-targeted and targeted nanoformulations were more evident after short exposure times (4 and 8 hours). Interestingly, assays in the MC38 transduced cells with reduced LGR5 expression (MC38-L(-)), showed lower cell internalization of LGR5-targeted magnetoliposomes compared to non-transduced MC38 cell line. In addition, magnetoliposomes showed an in vitro favorable heating response under magnetic excitation and great iron-related biocompatibility data in vivo. Drug-loaded magnetoliposomes functionalized with anti-LGR5 antibodies could be a promising CRC treatment strategy for LGR5+ targeted chemotherapy, magnetic hyperthermia, and both in combination.

Resolution of inflammation in chronic disease via restoration of the heat shock response (HSR).

Effective resolution of inflammation via the heat shock response (HSR) is pivotal in averting the transition to chronic inflammatory states. This transition characterizes a spectrum of debilitating conditions, including insulin resistance, obesity, type 2 diabetes, nonalcoholic fatty liver disease, and cardiovascular ailments. This manuscript explores a range of physiological, pharmacological, and nutraceutical interventions aimed at reinstating the HSR in the context of chronic low-grade inflammation, as well as protocols to assess the HSR. Monitoring the progression or suppression of the HSR in patients and laboratory animals offers predictive insights into the organism's capacity to combat chronic inflammation, as well as the impact of exercise and hyperthermic treatments (e.g., sauna or hot tub baths) on the HSR. Interestingly, a reciprocal correlation exists between the expression of HSR components in peripheral blood leukocytes (PBL) and the extent of local tissue proinflammatory activity in individuals afflicted by chronic inflammatory disorders. Therefore, the Heck index, contrasting extracellular 70kDa family of heat shock proteins (HSP70) (proinflammatory) and intracellular HSP70 (anti-inflammatory) in PBL, serves as a valuable metric for HSR assessment. Our laboratory has also developed straightforward protocols for evaluating HSR by subjecting whole blood samples from both rodents and human volunteers to ex vivo heat challenges. Collectively, this discussion underscores the critical role of HSR disruption in the pathogenesis of chronic inflammatory states and emphasizes the significance of simple, cost-effective tools for clinical HSR assessment. This understanding is instrumental in the development of innovative strategies for preventing and managing chronic inflammatory diseases, which continue to exert a substantial global burden on morbidity and mortality.

Optimization and chemical free fabrication of green synthesized iron nanoparticles as potential MRI contrast agent.

The current research article has investigated the synthesis and characterization of novel iron nanoparticles (INPs) from neem and betel leaves extract combination using response surface methodology-central composite design and coated with chitosan-curcumin (CCINPs) as a biocompatible and contrast agent for magnetic resonance imaging (MRI). The coating of INPs with chitosan and curcumin (CCINPs) was carried out using a simple, easy, chemical-free ultrasonication method and characteristics were confirmed by UV-visible (Vis) spectrophotometer (UV-Vis), Fourier-transform infrared spectroscopy, X-ray diffraction, scanning electron microscope, atomic force microscopy, and vibrating sample magnetometer. The biocompatibility of the particles was ensured by conducting hemolytic and cell viability assays. The nanoparticle was found to be nonhemolytic (<5%) up to 150μg/mL for both INPs and CCINPs. The cell viability was stable (peripheral blood mononuclear cells-PBMCs) till 48h at 150μg/mL of INPs and CCINPs. Both the test results produced were found to be biocompatible and additionally, an in vitro MRI study of INPs and CCINPs demonstrated the efficiency of the nanoparticle as a negative contrast agent with enhanced contrast nature in CCINPs. Thus, overall results indicate that the green synthesized chemical-free novel CCINPs could be a potential candidate for a wide range of applications such as MRI, drug delivery, and in magnetic fluid hyperthermia.

A nudge over the relaxation plateau: effect of pH, particle concentration, and medium viscosity on the AC induction heating efficiency of biocompatible chitosan-coated Fe3O4 nanoparticles

The effects of pH, MNP concentration, and medium viscosity on the magnetic fluid hyperthermia (MFH) properties of chitosan-coated superparamagnetic Fe3O4 nanoparticles (MNPs) are probed here. Due to the protonation of the amide groups, the MNPs are colloidally stable at lower pH (∼2), but form aggregates at higher pH (∼8). The increased aggregate size at higher pH causes the Brownian relaxation time (τ B) to increase, leading to a decrease in specific absorption rate (SAR). For colloidal conditions ensuring Brownian-dominated relaxation dynamics, an increase in MNP concentrations or medium viscosity is found to increase the τ B. SAR decreases with increasing MNP concentration, whereas it exhibits a non-monotonic variation with increasing medium viscosity. Dynamic hysteresis loop-based calculations are found to be in agreement with the experimental results. The findings provide a greater understanding of the variation of SAR with the colloidal properties and show the importance of relaxation dynamics on MFH efficiency, where variations in the frequency-relaxation time product across the relaxation plateau cause significant variations in SAR. Further, the in vitro cytotoxicity studies show good bio-compatibility of the chitosan-coated Fe3O4 MNPs. Higher SAR at acidic pH for bio-medically acceptable field parameters makes the bio-compatible chitosan-coated Fe3O4 MNPs suitable for MFH applications.