Water-Dispersible Sugar-Coated Iron Oxide Nanoparticles. An Evaluation of their Relaxometric and Magnetic Hyperthermia Properties

Advances in magnetic nanoparticles for molecular medicine

Magnetic nanoparticles (MNPs) are highly versatile nanomaterials in nanomedicine, owing to their diverse magnetic properties, which can be tailored through variations in size, shape, composition, and exposure to inductive magnetic fields. Over four decades of research have led to the clinical approval or ongoing trials of several MNP formulations, fueling continued innovation. Beyond traditional applications in drug delivery, imaging, and cancer hyperthermia, MNPs have increasingly advanced into molecular medicine. Under external magnetic fields, MNPs can generate mechano- or thermal stimuli to modulate individual molecules or cells deep within tissue, offering precise, remote control of biological processes at cellular and molecular levels. These unique capabilities have opened new avenues in emerging fields such as genome editing, cell therapies, and neuroscience, underpinned by a growing understanding of nanomagnetism and the molecular mechanisms responding to mechanical and thermal cues. Research on MNPs as a versatile synthetic material capable of engineering control at the cellular and molecular levels holds great promise for advancing the frontiers of molecular medicine, including areas such as genome editing and synthetic biology. This review summarizes recent clinical studies showcasing the classical applications of MNPs and explores their integration into molecular medicine, with the goal of inspiring the development of next-generation MNP-based platforms for disease treatment.

Delivery of Avocado Seed Extract Using Novel Charge-Switchable Mesoporous Silica Nanoparticles with Galactose Surface Modified to Target Sorafenib-Resistant Hepatocellular Carcinoma

Background

Sorafenib-resistant (SR) hepatocellular carcinoma (HCC) is a current serious problem in liver cancer treatment. Numerous phytochemicals derived from plants exhibit anticancer activity but have never been tested against drug-resistant cells.

Methods

Avocado seed extract (APE) isolated by maceration was analysed for its phytochemical composition and anticancer activity. Novel design charge-switchable pH-responsive nanocarriers of aminated mesoporous silica nanoparticles with conjugated galactose (GMSN) were synthesised for delivering APE and their physicochemical properties were characterized. The drug loading efficiency (%LE) and entrapment efficiency (%EE) were evaluated. Anticancer activity of APE loaded GMSN was measured against HCC (HepG2, Huh-7) and SR-HCC (SR-HepG2).

Results

Anticancer activity of APE against non-resistant HepG2 (IC50 50.9 ± 0.83 μg mL-1), Huh-7 (IC50 42.41 ± 1.88 μg mL-1), and SR-HepG2 (IC50 62.58 ± 2.29 μg mL-1) cells was confirmed. The APE loaded GMSN had a diameter of 131.41 ± 14.41 nm with 41.08 ± 2.09%LE and 44.96 ± 2.26%EE. Galactose functionalization (55%) did not perturb the original mesoporous structure. The GMSN imparted positive surface charges, 10.3 ± 0.61mV at acidic medium pH 5.5 along with rapid release of APE 45% in 2 h. The GMSN boosted cellular uptake by HepG2 and SR-HepG2 cells, whereas the amine functionalized facilitated their endosomal escape. Their anticancer activity was demonstrated in non-resistant HCC and SR-HCC cells with IC50 values at 30.73 ± 3.14 (HepG2), 21.86 ± 0.83 (Huh-7), 35.64 ± 1.34 (SR-HepG2) μg mL-1, respectively, in comparison to the control and non-encapsulated APE.

Conclusion

APE loaded GMSN is highly effective against both non-resistant HCC and SR-HCC and warrants further in vivo investigation.

Semisynthetic ferritin-based nanoparticles with high magnetic anisotropy for spatial magnetic manipulation and inductive heating

The human iron storage protein ferritin represents an appealing template to obtain a semisynthetic magnetic nanoparticle (MNP) for spatial manipulation or inductive heating applications on a nanoscale. Ferritin consists of a protein cage of well-defined size (12 nm), which is genetically modifiable and biocompatible, and into which a magnetic core is synthesised. Here, we probed the magnetic response and hence the MNP's suitability for (bio-)nanotechnological or nanomedical applications when the core is doped with 7% cobalt or 7% zinc in comparison with the undoped iron oxide MNP. The samples exhibit almost identical core and hydrodynamic sizes, along with their tunable magnetic core characteristics as verified by structural and magnetic characterisation. Cobalt doping significantly increased the MNP's anisotropy and hence the heating power in comparison with other magnetic cores with potential application as a mild heat mediator. Spatial magnetic manipulation was performed with MNPs inside droplets, the cell cytoplasm, or the cell nucleus, where the MNP surface conjugation with mEGFP and poly(ethylene glycol) gave rise to excellent intracellular stability and traceability within the complex biological environment. A magnetic stimulus (smaller than fN forces) results in the quick and reversible redistribution of the MNPs. The obtained data suggest that semisynthetic ferritin MNPs are highly versatile nanoagents and promising candidates for theranostic or (bio-)nanotechnological applications.

Cytotoxic evaluation of pure and doped iron oxide nanoparticles on cancer cells: a magnetic fluid hyperthermia perspective

The need of the hour with respect to cancer treatment is a targeted approach with minimal or nil ramifications. Apropos, magnetic fluid hyperthermia (MFH) is emerging as a potential therapeutic strategy with anticipated reduced side effects for solid tumors. MFH causes cytotoxicity due to the heat generated owing to Hysteresis, Neel, and Brownian relaxation losses once magnetic nanoparticles (MNPs) carrying cancer cells are placed under an alternating magnetic field. With respect to MFH, iron oxide-based MNPs have been most extensively studied to date compared to other metal oxides with magnetic properties. The effectiveness of MFH relies on the composition, coating, size, physical and biocompatible properties of the MNPs. Pure iron oxide and doped iron oxide MNPs have been utilized to study their effects on cancer cell killing through MFH. This review evaluates the biocompatibility of pure and doped iron oxide MNPs and their subsequent hyperthermic effect for effectively killing cancer cells in vitro and in vivo.

Fundamentals and Recent Progress in Magnetic Field Assisted CO2 Capture and Conversion

CO2 capture and conversion technology are highly promising technologies that definitely play a part in the journey towards carbon neutrality. Releasing CO2 by mild stimulation and the development of high efficiency catalytic processes are urgently needed. The magnetic field, as a thermodynamic parameter independent of temperature and pressure, is vital in the enhancement of CO2 capture and conversion process. In this review, the recent progress of magnetic field-enhanced CO2 capture and conversion is comprehensively summarized. The theoretical fundamentals of magnetic field on CO2 adsorption, release and catalytic reduction process are discussed, including the magnetothermal, magnetohydrodynamic, spin selection, Lorentz forces, magnetoresistance and spin relaxation effects. Additionally, a thorough review of the current progress of the enhancement strategies of magnetic field coupled with a variety of fields (including thermal, electricity, and light) is summarized in the aspect of CO2 related process. Finally, the challenges and prospects associated with the utilization of magnetic field-assisted techniques in the construction of CO2 capture and conversion systems are proposed. This review offers a reference value for the future design of catalysts, mechanistic investigations, and practical implementation for magnetic field enhanced CO2 capture and conversion.

Colorectal cancer cell membrane biomimetic ferroferric oxide nanomaterials for homologous bio-imaging and chemotherapy application

The research of nanomaterials for bio-imaging and theranostic are very active nowadays with unprecedented advantages in nanomedicine. Homologous targeting and bio-imaging greatly improve the ability of targeted drug delivery and enhance active targeting and treatment ability of nanomedicine for the tumor. In this work, lycorine hydrochloride (LH) and magnetic iron oxide nanoparticles coated with a colorectal cancer (CRC) cell membrane (LH-Fe3O4@M) were prepared, for homologous targeting, magnetic resonance imaging (MRI), and chemotherapy. Results showed that the LH-Fe3O4@M and Fe3O4@M intensity at HT29 tumor was significantly higher than that Fe3O4@PEG, proving the superior selectivity of cancer cell membrane-camouflaged nanomedicine for homologous tumors and the MRI effect of darkening contrast enhancement were remarkable at HT29 tumor. The LH-Fe3O4@M exhibited excellent chemotherapy effect in CRC models as well as LH alone and achieved a high tumor ablation rate but no damage to normal tissues and cells. Therefore, our biomimetic system achieved a homologous targeting, bio-imaging, and efficient therapeutic effect of CRC.

Rational Design of Biomaterials to Potentiate Cancer Thermal Therapy

Cancer thermal therapy, also known as hyperthermia therapy, has long been exploited to eradicate mass lesions that are now defined as cancer. With the development of corresponding technologies and equipment, local hyperthermia therapies such as radiofrequency ablation, microwave ablation, and high-intensity focused ultrasound, have has been validated to effectively ablate tumors in modern clinical practice. However, they still face many shortcomings, including nonspecific damages to adjacent normal tissues and incomplete ablation particularly for large tumors, restricting their wide clinical usage. Attributed to their versatile physiochemical properties, biomaterials have been specially designed to potentiate local hyperthermia treatments according to their unique working principles. Meanwhile, biomaterial-based delivery systems are able to bridge hyperthermia therapies with other types of treatment strategies such as chemotherapy, radiotherapy and immunotherapy. Therefore, in this review, we discuss recent progress in the development of functional biomaterials to reinforce local hyperthermia by functioning as thermal sensitizers to endow more efficient tumor-localized thermal ablation and/or as delivery vehicles to synergize with other therapeutic modalities for combined cancer treatments. Thereafter, we provide a critical perspective on the further development of biomaterial-assisted local hyperthermia toward clinical applications.

Cascade strategy for triggered radical release by magnetic nanoparticles grafted with thermosensitive alkoxyamine

The design of smart nanoplatforms presenting well-definite structures able to achieve controlled cascade action remotely triggered by external stimuli presents a great challenge. We report here a new nanosystem consisting of magnetic iron oxide nanoparticles covalently grafted with a thermosensitive radical initiator alkoxyamine, able to provide controlled and localized release of free radicals triggered by an alternating current (ac) magnetic field. These nanoparticles exhibit a high intrinsic loss power of 4.73 nHm² kg^-1 providing rapid heating of their surface under the action of an ac field, inducing the homolysis of alkoxyamine C-ON bond and then the oxygen-independent formation of radicals. This latter was demonstrated by electronic paramagnetic resonance spectroscopy, and the kinetics of homolysis has been investigated allowing a comparison of the temperature of alkoxyamine's homolysis with the one measured during the magnetothermia process.

MRI Contrast Agents in Glycobiology

Molecular recognition involving glycoprotein-mediated interactions is ubiquitous in both normal and pathological natural processes. Therefore, visualization of these interactions and the extent of expression of the sugars is a challenge in medical diagnosis, monitoring of therapy, and drug design. Here, we review the literature on the development and validation of probes for magnetic resonance imaging using carbohydrates either as targeting vectors or as a target. Lectins are important targeting vectors for carbohydrate end groups, whereas selectins, the asialoglycoprotein receptor, sialic acid end groups, hyaluronic acid, and glycated serum and hemoglobin are interesting carbohydrate targets.

The Hybrid System for the Magnetic Characterization of Superparamagnetic Nanoparticles

The characterization of nanoparticles is crucial in several medical applications, such as hyperthermic therapy, which heats superparamagnetic nanoparticles with an external electromagnetic field. The knowledge of heating ability (magnetic losses) in AC magnetic field frequency function allows for selecting the optimal excitation. A hybrid system for the characterization of superparamagnetic nanoparticles was designed and tested. The proposed setup consists of an excitation coil and two sensing probes: calorimetric and magnetic. The measurements of the imaginary part of the complex magnetic susceptibility of superparamagnetic nanoparticles are possible in the kilohertz range. The system was verified using a set of nanoparticles with different diameters. The measurement procedure was described and verified. The results confirmed that an elaborated sensor system and measuring procedures could properly characterize the magnetic characteristics of nanoparticles. The main advantage of this system is the ability to compare both characteristics and confirm the selection of optimal excitation parameters.

Water-Dispersible Carboxymethyl Dextran-Coated Melamine Nanoparticles for Biosensing Applications

In this study, we developed a simple method for preparing highly dispersed, stable, and streptavidin (SA)-functionalized carboxymethyl dextran (CMD)-coated melamine nanoparticles (MNPs) in an aqueous buffer at neutral pH. Dynamic light scattering (DLS) revealed the agglomeration of MNPs in an aqueous buffer at neutral pH. When CMD, N-hydroxysuccinimide (NHS), and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) were simultaneously mixed with the MNPs, CMD was bound to the MNPs, promoting their dispersibility. Preparation of SA-CMD-MNPs was accomplished simply by adding SA solution to the CMD-MNPs. The amount of SA bound to the CMD-MNPs was quantified by the bicinchoninic assay, and the amount of SA molecules bound to each CMD-MNP was 417 ± 4. SA-CMD-MNPs exhibited high dispersity (polydispersity index = 0.058) in a neutral phosphate buffer and maintained it for 182 days with dispersion using a probe sonicator (5 s) before DLS characterization. The performance of the SA-CMD-MNPs in biosensing was evaluated by immunohistochemistry, which revealed that the nanoparticles could specifically stain MCF-7 cells derived from breast cancer cells with low HER2 expression. This study provides an effective method for synthesizing highly dispersible nanoparticles for biosensing.

Hardening of Cobalt Ferrite Nanoparticles by Local Crystal Strain Release: Implications for Rare Earth Free Magnets

In this work, we demonstrate that the reduction of the local internal stress by a low-temperature solvent-mediated thermal treatment is an effective post-treatment tool for magnetic hardening of chemically synthesized nanoparticles. As a case study, we used nonstoichiometric cobalt ferrite particles of an average size of 32(8) nm synthesized by thermal decomposition, which were further subjected to solvent-mediated annealing at variable temperatures between 150 and 320 °C in an inert atmosphere. The postsynthesis treatment produces a 50% increase of the coercive field, without affecting neither the remanence ratio nor the spontaneous magnetization. As a consequence, the energy product and the magnetic energy storage capability, key features for applications as permanent magnets and magnetic hyperthermia, can be increased by ca. 70%. A deep structural, morphological, chemical, and magnetic characterization reveals that the mechanism governing the coercive field improvement is the reduction of the concomitant internal stresses induced by the low-temperature annealing postsynthesis treatment. Furthermore, we show that the medium where the mild annealing process occurs is essential to control the final properties of the nanoparticles because the classical annealing procedure (T > 350 °C) performed on a dried powder does not allow the release of the lattice stress, leading to the reduction of the initial coercive field. The strategy here proposed, therefore, constitutes a method to improve the magnetic properties of nanoparticles, which can be particularly appealing for those materials, as is the case of cobalt ferrite, currently investigated as building blocks for the development of rare-earth free permanent magnets.

Magneto-Induced Hyperthermia and Temperature Detection in Single Iron Oxide Core-Silica/Tb3+/Eu3+(Acac) Shell Nano-Objects

Multifunctional nano-objects containing a magnetic heater and a temperature emissive sensor in the same nanoparticle have recently emerged as promising tools towards personalized nanomedicine permitting hyperthermia-assisted treatment under local temperature control. However, a fine control of nano-systems' morphology permitting the synthesis of a single magnetic core with controlled position of the sensor presents a main challenge. We report here the design of new iron oxide core-silica shell nano-objects containing luminescent Tb³⁺/Eu³⁺-(acetylacetonate) moieties covalently anchored to the silica surface, which act as a promising heater/thermometer system. They present a single magnetic core and a controlled thickness of the silica shell, permitting a uniform spatial distribution of the emissive nanothermometer relative to the heat source. These nanoparticles exhibit the Tb³⁺ and Eu³⁺ characteristic emissions and suitable magnetic properties that make them efficient as a nanoheater with a Ln³⁺-based emissive self-referencing temperature sensor covalently coupled to it. Heating capacity under an alternating current magnetic field was demonstrated by thermal imaging. This system offers a new strategy permitting a rapid heating of a solution under an applied magnetic field and a local self-referencing temperature sensing with excellent thermal sensitivity (1.64%·K^-1 (at 40 °C)) in the range 25-70 °C, good photostability, and reproducibility after several heating cycles.

Synthesis and preclinical application of a Prussian blue-based dual fluorescent and magnetic contrast agent (CA)

The aim of this study was to develop and characterize a Prussian Blue based biocompatible and chemically stable T1 magnetic resonance imaging (MRI) contrast agent with near infrared (NIR) optical contrast for preclinical application. The physical properties of the Prussian blue nanoparticles (PBNPs) (iron (II); iron (III);octadecacyanide) were characterized with dynamic light scattering (DLS), zeta potential measurement, atomic force microscopy (AFM), and transmission electron microscopy (TEM). In vitro contrast enhancement properties of PBNPs were determined by MRI. In vivo T1-weighted contrast of the prepared PBNPs was investigated by MRI and optical imaging modality after intravenous administration into NMRI-Foxn1 nu/nu mice. The biodistribution studies showed the presence of PBNPs predominantly in the cardiovascular system. Briefly, in this paper we show a novel approach for the synthesis of PBNPs with enhanced iron content for T1 MRI contrast. This newly synthetized PBNP platform could lead to a new diagnostic agent, replacing the currently used Gadolinium based substances.

LAPONITE® nanodisk-"decorated" Fe3O4 nanoparticles: a biocompatible nano-hybrid with ultrafast magnetic hyperthermia and MRI contrast agent ability

Magnetic Fe₃O₄ nanoparticles "decorated" by LAPONITE® nanodisks have been materialized utilizing the Schikorr reaction following a facile approach and tested as mediators of heat for localized magnetic hyperthermia (MH) and as magnetic resonance imaging (MRI) agents. The synthetic protocol involves the interaction between two layered inorganic compounds, ferrous hydroxide, Fe(OH)₂, and the synthetic smectite LAPONITE® clay Na_0.7⁺[(Si₈Mg_5.5Li_0.3)O₂₀(OH)₄]_0.7^-, towards the formation of superparamagnetic Fe₃O₄ nanoparticles, which are well decorated by the diamagnetic clay nanodisks. The latter imparts high negative ζ-potential values (up to -34.1 mV) to the particles, which provide stability against flocculation and precipitation, resulting in stable water dispersions. The obtained LAPONITE®-"decorated" Fe₃O₄ nanohybrids were characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), Mössbauer spectroscopy, dynamic light scattering (DLS) and vibrating sample magnetometry (VSM) at room temperature, revealing superior magnetic hyperthermia performance with specific absorption rate (SAR) values reaching 540 W g_Fe^-1 (28 kA m^-1, 150 kHz) for the hybrid material with a magnetic loading of 50 wt% Fe₃O₄/LAPONITE®. Toxicity studies were also performed with human glioblastoma (GBM) cells and human foreskin fibroblasts (HFF), which show negligible to no toxicity. Furthermore, T₂-weighted MR imaging of rodent brain shows that the LAPONITE®-"decorated" Fe₃O₄ nanohybrids predominantly affected the transverse T₂ relaxation time of tissue water, which resulted in a signal drop on the MRI T₂-weighted imaging, allowing for imaging of the magnetic nanoparticles.

Functionalized iron oxide nanoparticles: Synthesis through ultrasonic-assisted co-precipitation and performance as hyperthermic agents for biomedical applications

Dual-functional iron oxide nanoparticles (IONPs), displaying self-heating and antibacterial effects are highly desired for biomedical application. This study involved the synthesis of functionalized IONPs coated with 3-aminopropyltriethoxysilane and polyethylene glycol via ultrasonic-assisted co-precipitation technique. The synthesized IONPs were then characterized by using Fourier-transform infrared spectroscopy, X-ray diffraction, dynamic light scattering, scanning electron microscopy, zeta potential, vibrating sample magnetometer and thermogravimetric analysis techniques. In addition, the effect of the synthesized IONPs on bacterial growth (S. aureus and E. coli) was studied. The influence of magnetic field power, as well as the viscous carriers on the heating efficiency of the synthesized IONPs was investigated. The specific absorption rate values increased as the power increased and decreased with the increase in the carrier viscosity. These characteristics render the synthesized iron oxide nanoparticles synthesized in the present study suitable for biomedical application as hyperthermic agents.

Nanotheranostics for Image-Guided Cancer Treatment

Image-guided nanotheranostics have the potential to represent a new paradigm in the treatment of cancer. Recent developments in modern imaging and nanoparticle design offer an answer to many of the issues associated with conventional chemotherapy, including their indiscriminate side effects and susceptibility to drug resistance. Imaging is one of the tools best poised to enable tailoring of cancer therapies. The field of image-guided nanotheranostics has the potential to harness the precision of modern imaging techniques and use this to direct, dictate, and follow site-specific drug delivery, all of which can be used to further tailor cancer therapies on both the individual and population level. The use of image-guided drug delivery has exploded in preclinical and clinical trials although the clinical translation is incipient. This review will focus on traditional mechanisms of targeted drug delivery in cancer, including the use of molecular targeting, as well as the foundations of designing nanotheranostics, with a focus on current clinical applications of nanotheranostics in cancer. A variety of specially engineered and targeted drug carriers, along with strategies of labeling nanoparticles to endow detectability in different imaging modalities will be reviewed. It will also introduce newer concepts of image-guided drug delivery, which may circumvent many of the issues seen with other techniques. Finally, we will review the current barriers to clinical translation of image-guided nanotheranostics and how these may be overcome.

Ferrofluids and bio-ferrofluids: looking back and stepping forward

Ferrofluids investigated along for about five decades are ultrastable colloidal suspensions of magnetic nanoparticles, which manifest simultaneously fluid and magnetic properties. Their magnetically controllable and tunable feature proved to be from the beginning an extremely fertile ground for a wide range of engineering applications. More recently, biocompatible ferrofluids attracted huge interest and produced a considerable increase of the applicative potential in nanomedicine, biotechnology and environmental protection. This paper offers a brief overview of the most relevant early results and a comprehensive description of recent achievements in ferrofluid synthesis, advanced characterization, as well as the governing equations of ferrohydrodynamics, the most important interfacial phenomena and the flow properties. Finally, it provides an overview of recent advances in tunable and adaptive multifunctional materials derived from ferrofluids and a detailed presentation of the recent progress of applications in the field of sensors and actuators, ferrofluid-driven assembly and manipulation, droplet technology, including droplet generation and control, mechanical actuation, liquid computing and robotics.

Magnetic Nanoparticle-Mediated Heating for Biomedical Applications

Magnetic nanoparticles, especially superparamagnetic nanoparticles (SPIONs), have attracted tremendous attention for various biomedical applications. Facile synthesis and functionalization together with easy control of the size and shape of SPIONS to customize their unique properties, have made it possible to develop different types of SPIONs tailored for diverse functions/applications. More recently, considerable attention has been paid to the thermal effect of SPIONs for the treatment of diseases like cancer and for nanowarming of cryopreserved/banked cells, tissues, and organs. In this mini-review, recent advances on the magnetic heating effect of SPIONs for magnetothermal therapy and enhancement of cryopreservation of cells, tissues, and organs, are discussed, together with the non-magnetic heating effect (i.e., high Intensity focused ultrasound or HIFU-activated heating) of SPIONs for cancer therapy. Furthermore, challenges facing the use of magnetic nanoparticles in these biomedical applications are presented.

Magnetic Ordering in Ultrasmall Potassium Ferrite Nanoparticles Grown on Graphene Nanoflakes

Magnetic nanoparticles are central to the development of efficient hyperthermia treatments, magnetic drug carriers, and multimodal contrast agents. While the magnetic properties of small crystalline iron oxide nanoparticles are well understood, the superparamagnetic size limit constitutes a significant barrier for further size reduction. Iron (oxy)hydroxide phases, albeit very common in the natural world, are far less studied, generally due to their poor crystallinity. Templating ultrasmall nanoparticles on substrates such as graphene is a promising method to prevent aggregation, typically an issue for both material characterization and applications. We generate ultrasmall nanoparticles, directly on the carbon framework by the reaction of a graphenide potassium solution, charged graphene flakes, with iron(II) salts. After mild water oxidation, the obtained composite material consists of ultrasmall potassium ferrite nanoparticles bound to the graphene nanoflakes. Magnetic properties as evidenced by magnetometry and X-ray magnetic circular dichroism, with open magnetic hysteresis loops near room temperature, are widely different from classical ultrasmall superparamagnetic iron oxide nanoparticles. The large value obtained for the effective magnetic anisotropy energy density K_eff accounts for the presence of magnetic ordering at rather high temperatures. The synthesis of ultrasmall potassium ferrite nanoparticles under such mild conditions is remarkable given the harsh conditions used for the classical syntheses of bulk potassium ferrites. Moreover, the potassium incorporation in the crystal lattice occurs in the presence of potassium cations under mild conditions. A transfer of this method to related reactions would be of great interest, which underlines the synthetic value of this study. These findings also give another view on the previously reported electrocatalytic properties of these nanocomposite materials, especially for the sought-after oxygen reduction/evolution reaction. Finally, their longitudinal and transverse proton NMR relaxivities when dispersed in water were assessed at 37 °C under a magnetic field of 1.41 T, allowing potential applications in biological imaging.

Smart Magnetic Nanocarriers for Multi-Stimuli On-Demand Drug Delivery

In this study, we report the realization of drug-loaded smart magnetic nanocarriers constituted by superparamagnetic iron oxide nanoparticles encapsulated in a dual pH- and temperature-responsive poly (N-vinylcaprolactam-co-acrylic acid) copolymer to achieve highly controlled drug release and localized magnetic hyperthermia. The magnetic core was constituted by flower-like magnetite nanoparticles with a size of 16.4 nm prepared by the polyol approach, with good saturation magnetization and a high specific absorption rate. The core was encapsulated in poly (N-vinylcaprolactam-co-acrylic acid) obtaining magnetic nanocarriers that revealed reversible hydration/dehydration transition at the acidic condition and/or at temperatures above physiological body temperature, which can be triggered by magnetic hyperthermia. The efficacy of the system was proved by loading doxorubicin with very high encapsulation efficiency (>96.0%) at neutral pH. The double pH- and temperature-responsive nature of the magnetic nanocarriers facilitated a burst, almost complete release of the drug at acidic pH under hyperthermia conditions, while a negligible amount of doxorubicin was released at physiological body temperature at neutral pH, confirming that in addition to pH variation, drug release can be improved by hyperthermia treatment. These results suggest this multi-stimuli-sensitive nanoplatform is a promising candidate for remote-controlled drug release in combination with magnetic hyperthermia for cancer treatment.

Double-Layer Fatty Acid Nanoparticles as a Multiplatform for Diagnostics and Therapy

Today, public health is one of the most important challenges in society. Cancer is the leading cause of death, so early diagnosis and localized treatments that minimize side effects are a priority. Magnetic nanoparticles have shown great potential as magnetic resonance imaging contrast agents, detection tags for in vitro biosensing, and mediators of heating in magnetic hyperthermia. One of the critical characteristics of nanoparticles to adjust to the biomedical needs of each application is their polymeric coating. Fatty acid coatings are known to contribute to colloidal stability and good surface crystalline quality. While monolayer coatings make the particles hydrophobic, a fatty acid double-layer renders them hydrophilic, and therefore suitable for use in body fluids. In addition, they provide the particles with functional chemical groups that allow their bioconjugation. This work analyzes three types of self-assembled bilayer fatty acid coatings of superparamagnetic iron oxide nanoparticles: oleic, lauric, and myristic acids. We characterize the particles magnetically and structurally and study their potential for resonance imaging, magnetic hyperthermia, and labeling for biosensing in lateral flow immunoassays. We found that the myristic acid sample reported a large r2 relaxivity, superior to existing iron-based commercial agents. For magnetic hyperthermia, a significant specific absorption rate value was obtained for the oleic sample. Finally, the lauric acid sample showed promising results for nanolabeling.

Influence of Coating and Size of Magnetic Nanoparticles on Cellular Uptake for In Vitro MRI

Iron oxide nanoparticles (IONPs) are suitable materials for contrast enhancement in magnetic resonance imaging (MRI). Their potential clinical applications range from diagnosis to therapy and follow-up treatments. However, a deeper understanding of the interaction between IONPs, culture media and cells is necessary for expanding the application of this technology to different types of cancer therapies. To achieve new insights of these interactions, a set of IONPs were prepared with the same inorganic core and five distinct coatings, to study their aggregation and interactions in different physiological media, as well as their cell labelling efficiency. Then, a second set of IONPs, with six different core sizes and the same coating, were used to study how the core size affects cell labelling and MRI in vitro. Here, IONPs suspended in biological media experience a partial removal of the coating and adhesion of molecules. The FBS concentration alters the labelling of all types of IONPs and hydrodynamic sizes ≥ 300 nm provide the greatest labelling using the centrifugation-mediated internalization (CMI). The best contrast for MRI results requires a core size range between 12–14 nm coated with dimercaptosuccinic acid (DMSA) producing R₂^* values of 393.7 s⁻¹ and 428.3 s⁻¹, respectively. These findings will help to bring IONPs as negative contrast agents into clinical settings.

Stable Iron Oxide Nanoflowers with Exceptional Magnetic Heating Efficiency: Simple and Fast Polyol Synthesis

Magnetically induced hyperthermia has reached a milestone in medical nanoscience and in phase III clinical trials for cancer treatment. As it relies on the heat generated by magnetic nanoparticles (NPs) when exposed to an external alternating magnetic field, the heating ability of these NPs is of paramount importance, so is their synthesis. We present a simple and fast method to produce iron oxide nanostructures with excellent heating ability that are colloidally stable in water. A polyol process yielded biocompatible single core nanoparticles and nanoflowers. The effect of parameters such as the precursor concentration, polyol molecular weight as well as reaction time was studied, aiming to produce NPs with the highest possible heating rates. Polyacrylic acid facilitated the formation of excellent nanoheating agents iron oxide nanoflowers (IONFs) within 30 min. The progressive increase of the size of the NFs through applying a seeded growth approach resulted in outstanding enhancement of their heating efficiency with intrinsic loss parameter up to 8.49 nH m² kg_Fe^-1. The colloidal stability of the NFs was maintained when transferring to an aqueous solution via a simple ligand exchange protocol, replacing polyol ligands with biocompatible sodium tripolyphosphate to secure the IONPs long-term colloidal stabilization.

A brief insight to the role of glyconanotechnology in modern day diagnostics and therapeutics

Carbohydrate-protein and carbohydrate-carbohydrate interactions are very important for various biological processes. Although the magnitude of these interactions is low compared to that of protein-protein interaction, the magnitude can be boosted by multivalent approach known as glycocluster effect. Nanoparticle platform is one of the best ways to present diverse glycoforms in multivalent manner and thus, the field of glyconanotechnology has emerged as an important field of research considering their potential applications in diagnostics and therapeutics. Considerable advances in the field have been achieved through development of novel techniques, use of diverse metallic and non-metallic cores for better efficacy and application of ever-increasing number of carbohydrate ligands for site-specific interaction. The present review encompasses the recent developments in the area of glyconanotechnology and their future promise as diagnostic and therapeutic tools.

Lipid Cubic Mesophases Combined with Superparamagnetic Iron Oxide Nanoparticles: A Hybrid Multifunctional Platform with Tunable Magnetic Properties for Nanomedical Applications

Hybrid materials composed of superparamagnetic iron oxide nanoparticles (SPIONs) and lipid self-assemblies possess considerable applicative potential in the biomedical field, specifically, for drug/nutrient delivery. Recently, we showed that SPIONs-doped lipid cubic liquid crystals undergo a cubic-to-hexagonal phase transition under the action of temperature or of an alternating magnetic field (AMF). This transition triggers the release of drugs embedded in the lipid scaffold or in the water channels. In this contribution, we address this phenomenon in depth, to fully elucidate the structural details and optimize the design of hybrid multifunctional carriers for drug delivery. Combining small-angle X-ray scattering (SAXS) with a magnetic characterization, we find that, in bulk lipid cubic phases, the cubic-to-hexagonal transition determines the magnetic response of SPIONs. We then extend the investigation from bulk liquid-crystalline phases to colloidal dispersions, i.e., to lipid/SPIONs nanoparticles with cubic internal structure ("magnetocubosomes"). Through Synchrotron SAXS, we monitor the structural response of magnetocubosomes while exposed to an AMF: the magnetic energy, converted into heat by SPIONs, activates the cubic-to-hexagonal transition, and can thus be used as a remote stimulus to spike drug release "on-demand". In addition, we show that the AMF-induced phase transition in magnetocubosomes steers the realignment of SPIONs into linear string assemblies and connect this effect with the change in their magnetic properties, observed at the bulk level. Finally, we assess the internalization ability and cytotoxicity of magnetocubosomes in vitro on HT29 adenocarcinoma cancer cells, in order to test the applicability of these smart carriers in drug delivery applications.

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.

Mild Magnetic Hyperthermia-Activated Innate Immunity for Liver Cancer Therapy

Magnetic hyperthermia therapy (MHT) is noninvasive and features excellent tissue penetration for deep-seated tumors, but unfortunately, it suffers the low therapeutic efficacy due to the limited magneto-thermal efficiency and insufficient intratumor accumulation of conventional intravenous-injected magnetic nanoparticles, which are actually mostly sequestered by the mononuclear phagocyte system, especially the liver. Such a disadvantageous characteristic of preferential liver uptake is here exploited, for the first time as far as we know, to treat orthotopic liver cancer by mild MHT using specially designed composite magnetic nanoparticles. A kind of core-shell-structured and Zn²⁺-doped Zn-CoFe₂O₄@Zn-MnFe₂O₄ superparamagnetic nanoparticles (ZCMF) has been synthesized which exhibits excellent and highly controllable magnetic hyperthermia performance owing to an exchange-coupled magnetism between the core and shell, and Zn²⁺ doping. The controllable mild MHT at 43-44 °C based on ZCMF demonstrates almost complete inhibition of liver cancer cell proliferation and tumor growth, which is associated with the suppression of heat shock protein 70 (HSP70) expression. More importantly, the mild MHT-treated liver cancer cells are capable of activating natural killer (NK) cells by dramatically upregulating the expression of UL16-binding proteins (ULBPs), ligands of natural killer group 2 member D (NKG2D). As a result, the growth of both xenograft tumors and orthotopic liver tumors were almost completely suppressed under mild MHT via induced NK-cell-related antitumor immunity in vivo. This work not only evidences the great potential of mild MHT but also reveals the underlying immunity activation mechanism in liver cancer treatment by mild MHT.

The Role of Anisotropy in Distinguishing Domination of Néel or Brownian Relaxation Contribution to Magnetic Inductive Heating: Orientations for Biomedical Applications

Magnetic inductive heating (MIH) has been a topic of great interest because of its potential applications, especially in biomedicine. In this paper, the parameters characteristic for magnetic inductive heating power including maximum specific loss power (SLP_max), optimal nanoparticle diameter (D_c) and its width (ΔD_c) are considered as being dependent on magnetic nanoparticle anisotropy (K). The calculated results suggest 3 different Néel-domination (N), overlapped Néel/Brownian (NB), and Brownian-domination (B) regions. The transition from NB- to B-region changes abruptly around critical anisotropy K_c. For magnetic nanoparticles with low K (K < K_c), the feature of SLP peaks is determined by a high value of D_c and small ΔD_c while those of the high K (K > K_c) are opposite. The decreases of the SLP_max when increasing polydispersity and viscosity are characterized by different rates of d(SLP_max)/dσ and d(SLP_max)/dη depending on each domination region. The critical anisotropy K_c varies with the frequency of an alternating magnetic field. A possibility to improve heating power via increasing anisotropy is analyzed and deduced for Fe₃O₄ magnetic nanoparticles. For MIH application, the monodispersity requirement for magnetic nanoparticles in the B-region is less stringent, while materials in the N- and/or NB-regions are much more favorable in high viscous media. Experimental results on viscosity dependence of SLP for CoFe₂O₄ and MnFe₂O₄ ferrofluids are in good agreement with the calculations. These results indicated that magnetic nanoparticles in the N- and/or NB-regions are in general better for application in elevated viscosity media.

Magneto-fluorescent nanocomposites: experimental and theoretical linkage for the optimization of magnetic hyperthermia

Magneto-fluorescent nanocomposites have been recognized as an emerging class of materials displaying great potential for improved magnetic hyperthermia assisted by optical imaging. In this study, we have designed a series of hybrid composites that consist of zinc doped Zn_xFe_3-xO₄ ferrites functionalized by polyethylene-glycol (PEG8000) and an orange-emitting platinum complex [Pt(phen)Cl₂]. Experimental and theoretical studies on the optimization of their magnetically-mediated heating properties were conducted. PEG was assembled around particles' surface by two different approaches; in situ and post-PEGylation. PEGylation ensured the optimal distance between the magnetic core and Pt(ii)-complex to maintain significant luminescence in the composite. The successful inclusion of the complex to the organic matrix was confirmed by a variety of spectroscopic techniques. A theoretical model was developed, based on linear response theory, in order to examine the composites' power losses dependence on their properties. Within this model, inter-particle interactions were quantified by inserting a mean dipolar energy term in the estimation of Néel relaxation time, and consequently, the size and concentration that maximize power loss were derived (20 nm and 4 mg mL^-1). Moreover, a decrease in the anisotropy of nanoparticles resulted in an increase in specific loss power values. Theoretical estimations are validated by experimental data when heating aqueous dispersions of composites in 24 kA m^-1, 765 kHz AMF for various values of concentration and size. Magnetic hyperthermia results showed that the theory-predicted values of optimum concentration and size delivered the maximum-specific loss power which was found equal to 545 W g^-1. By the present approach, a quantitative link between the particles' dipolar interactions and their heating properties is established, while opening new perspectives to nanotheranostic applications.

Effect of Matrix-Modulating Enzymes on The Cellular Uptake of Magnetic Nanoparticles and on Magnetic Hyperthermia Treatment of Pancreatic Cancer Models In Vivo

Magnetic hyperthermia can cause localized thermal eradication of several solid cancers. However, a localized and homogenous deposition of high concentrations of magnetic nanomaterials into the tumor stroma and tumor cells is mostly required. Poorly responsive cancers such as the pancreatic adenocarcinomas are hallmarked by a rigid stroma and poor perfusion to therapeutics and nanomaterials. Hence, approaches that enhance the infiltration of magnetic nanofluids into the tumor stroma convey potentials to improve thermal tumor therapy. We studied the influence of the matrix-modulating enzymes hyaluronidase and collagenase on the uptake of magnetic nanoparticles by pancreatic cancer cells and 3D spheroids thereof, and the overall impact on magnetic heating and cell death. Furthermore, we validated the effect of hyaluronidase on magnetic hyperthermia treatment of heterotopic pancreatic cancer models in mice. Treatment of cultured cells with the enzymes caused higher uptake of magnetic nanoparticles (MNP) as compared to nontreated cells. For example, hyaluronidase caused a 28% increase in iron deposits per cell. Consequently, the thermal doses (cumulative equivalent minutes at 43 °C, CEM43) increased by 15–23% as compared to heat dose achieved for cells treated with magnetic hyperthermia without using enzymes. Likewise, heat-induced cell death increased. In in vivo studies, hyaluronidase-enhanced infiltration and distribution of the nanoparticles in the tumors resulted in moderate heating levels (CEM43 of 128 min as compared to 479 min) and a slower, but persistent decrease in tumor volumes over time after treatment, as compared to comparable treatment without hyaluronidase. The results indicate that hyaluronidase, in particular, improves the infiltration of magnetic nanoparticles into pancreatic cancer models, impacts their thermal treatment and cell depletion, and hence, will contribute immensely in the fight against pancreatic and many other adenocarcinomas.

Establishing Rules for Self-Adhesion and Aggregation of N-Glycan Sugars Using Virus Glycan Shields

The surfaces of cells and pathogens are covered with short polymers of sugars known as glycans. Complex N-glycans have a core of three mannose sugars with distal repeats of N-acetylglucosamine and galactose sugars terminating with sialic acid (SA). Long-range tough and short-range brittle self-adhesions were observed between SA and mannose residues, respectively, in ill-defined artificial monolayers. We investigated if and how these adhesions translate when the residues are presented in N-glycan architecture with SA at the surface and mannose at the core and with other glycan sugars. Two pseudotyped viruses with complex N-glycan shields were brought together in force spectroscopy (FS). At higher ramp rates, slime-like adhesions were observed between the shields, whereas Velcro-like adhesions were observed at lower rates. The higher approach rates compress the virus as a whole, and the self-adhesion between the surface SA is sampled. At the lower ramp rates, however, the complex glycan shield is penetrated and adhesion from the mannose core is accessed. The slime-like and Velcro-like adhesions were lost when SA and mannose were cleaved, respectively. While virus self-adhesion in forced contact was modulated by glycan penetrability, the self-aggregation of the freely diffusing virus was only determined by the surface sugar. Mannose-terminal viruses self-aggregated in solution, and SA-terminal ones required Ca2+ ions to self-aggregate. Viruses with galactose or N-acetylglucosamine surfaces did not self-aggregate, irrespective of whether or not a mannose core was present below the N-acetylglucosamine surface. Well-defined rules appear to govern the self-adhesion and -aggregation of N-glycosylated surfaces, regardless of whether the sugars are presented in an ill-defined monolayer, or N-glycan, or even polymer architecture.

Understanding the influence of experimental factors on bio-interactions of nanoparticles: Towards improving correlation between in vitro and in vivo studies

Bionanotechnology has developed rapidly over the past two decades, owing to the extensive and versatile, functionalities and applicability of nanoparticles (NPs). Fifty-one nanomedicines have been approved by FDA since 1995, out of the many NPs based formulations developed to date. The general conformation of NPs consists of a core with ligands coating their surface, that stabilizes them and provides them with added functionalities. The physicochemical properties, especially the surface composition of NPs influence their bio-interactions to a large extent. This review discusses recent studies that help understand the nano-bio interactions of iron oxide and gold NPs with different surface compositions. We discuss the influence of the experimental factors on the outcome of the studies and, thus, the importance of standardization in the field of nanotechnology. Recent studies suggest that with careful selection of experimental parameters, it is possible to improve the positive correlation between in vitro and in vivo studies. This provides a fundamental understanding of the NPs which helps in assessing their potential toxic side effects and may aid in manipulating them further to improve their biocompatibility and biosafety.

Multifunctional Fe3O4-Au Nanoparticles for the MRI Diagnosis and Potential Treatment of Liver Cancer

Heterodimeric nanoparticles comprising materials with different functionalities are of great interest for fundamental research and biomedical/industrial applications. In this work, Fe₃O₄-Au nano-heterostructures were synthesized by a one-step thermal decomposition method. The hybrid nanoparticles comprise a highly crystalline 12 nm magnetite octahedron decorated with a single noble metal sphere of 6 nm diameter. Detailed analysis of the nanoparticles was performed by UV-visible spectroscopy, magnetometry, calorimetry and relaxometry studies. The cytotoxic effect of the nanoparticles in the human hepatic cell line Huh7 and PLC/PRF/5-Alexander was also assessed. These Fe₃O₄-Au bifunctional nanoparticles showed no significant cytotoxicity in these two cell lines. The nanoparticles showed a good theranostic potential for liver cancer treatment, since the r₂ relaxivity (166.5 mM⁻¹·s⁻¹ and 99.5 mM⁻¹·s⁻¹ in water and HepG2 cells, respectively) is higher than the corresponding values for commercial T₂ contrast agents and the Specific Absorption Rate (SAR) value obtained (227 W/g_Fe) is enough to make them suitable as heat mediators for Magnetic Fluid Hyperthermia. The gold counterpart can further allow the conjugation with different biomolecules and the optical sensing.

Surface engineering of magnetic iron oxide nanoparticles by polymer grafting: synthesis progress and biomedical applications

Magnetic iron oxide nanoparticles (IONPs) have wide applications in magnetic resonance imaging (MRI), biomedicine, drug delivery, hyperthermia therapy, catalysis, magnetic separation, and others. However, these applications are usually limited by irreversible agglomeration of IONPs in aqueous media because of their dipole-dipole interactions, and their poor stability. A protecting polymeric shell provides IONPs with not only enhanced long-term stability, but also the functionality of polymer shells. Therefore, polymer-grafted IONPs have recently attracted much attention of scientists. In this tutorial review, we will present the current strategies for grafting polymers onto the surface of IONPs, basically including "grafting from" and "grafting to" methods. Available functional groups and chemical reactions, which could be employed to bind polymers onto the IONP surface, are comprehensively summarized. Moreover, the applications of polymer-grafted IONPs will be briefly discussed. Finally, future challenges and perspectives in the synthesis and application of polymer-grafted IONPs will also be discussed.

Transdermal Composite Microneedle Composed of Mesoporous Iron Oxide Nanoraspberry and PVA for Androgenetic Alopecia Treatment

The transdermal delivery of therapeutic agents amplifying a local concentration of active molecules have received considerable attention in wide biomedical applications, especially in vaccine development and medical beauty. Unlike oral or subcutaneous injections, this approach can not only avoid the loss of efficacy of oral drugs due to the liver's first-pass effect but also reduce the risk of infection by subcutaneous injection. In this study, a magneto-responsive transdermal composite microneedle (MNs) with a mesoporous iron oxide nanoraspberry (MIO), that can improve the drug delivery efficiency, was fabricated by using a 3D printing-molding method. With loading of Minoxidil (Mx, a medication commonly used to slow the progression of hair loss and speed the process of hair regrowth), MNs can break the barrier of the stratum corneum through the puncture ability, and control the delivery dose for treating androgenetic alopecia (AGA). By 3D printing process, the sizes and morphologies of MNs is able to be, easily, architected. The MIOs were embedded into the tip of MNs which can deliver Mx as well as generate mild heating for hair growth, which is potentially attributed by the expansion of hair follicle and drug penetration. Compared to the mice without any treatments, the hair density of mice exhibited an 800% improvement after being treated by MNs with MF at 10-days post-treatment.

Multifunctional magnetic iron oxide nanoparticles: an advanced platform for cancer theranostics

Multifunctional magnetic nanoparticles and derivative nanocomposites have aroused great concern for multimode imaging and cancer synergistic therapies in recent years. Among the rest, functional magnetic iron oxide nanoparticles (Fe3O4 NPs) have shown great potential as an advanced platform because of their inherent magnetic resonance imaging (MRI), biocatalytic activity (nanozyme), magnetic hyperthermia treatment (MHT), photo-responsive therapy and drug delivery for chemotherapy and gene therapy. Magnetic Fe3O4 NPs can be synthesized through several methods and easily surface modified with biocompatible materials or active targeting moieties. The MRI capacity could be appropriately modulated to induce response between T1 and T2 modes by controlling the size distribution of Fe3O4 NPs. Besides, small-size nanoparticles are also desired due to the enhanced permeation and retention (EPR) effect, thus the imaging and therapeutic efficiency of Fe3O4 NP-based platforms can be further improved. Here, we firstly retrospect the typical synthesis and surface modification methods of magnetic Fe3O4 NPs. Then, the latest biomedical application including responsive MRI, multimodal imaging, nanozyme, MHT, photo-responsive therapy and drug delivery, the mechanism of corresponding treatments and cooperation therapeutics of multifunctional Fe3O4 NPs are also be explained. Finally, we also outline a brief discussion and perspective on the possibility of further clinical translations of these multifunctional nanomaterials. This review would provide a comprehensive reference for readers to understand the multifunctional Fe3O4 NPs in cancer diagnosis and treatment.

Comprehensive understanding of magnetic hyperthermia for improving antitumor therapeutic efficacy

Magnetic hyperthermia (MH) has been introduced clinically as an alternative approach for the focal treatment of tumors. MH utilizes the heat generated by the magnetic nanoparticles (MNPs) when subjected to an alternating magnetic field (AMF). It has become an important topic in the nanomedical field due to their multitudes of advantages towards effective antitumor therapy such as high biosafety, deep tissue penetration, and targeted selective tumor killing. However, in order for MH to progress and to realize its paramount potential as an alternative choice for cancer treatment, tremendous challenges have to be overcome. Thus, the efficiency of MH therapy needs enhancement. In its recent 60-year of history, the field of MH has focused primarily on heating using MNPs for therapeutic applications. Increasing the thermal conversion efficiency of MNPs is the fundamental strategy for improving therapeutic efficacy. Recently, emerging experimental evidence indicates that MNPs-MH produces nano-scale heat effects without macroscopic temperature rise. A deep understanding of the effect of this localized induction heat for the destruction of subcellular/cellular structures further supports the efficacy of MH in improving therapeutic therapy. In this review, the currently available strategies for improving the antitumor therapeutic efficacy of MNPs-MH will be discussed. Firstly, the recent advancements in engineering MNP size, composition, shape, and surface to significantly improve their energy dissipation rates will be explored. Secondly, the latest studies depicting the effect of local induction heat for selectively disrupting cells/intracellular structures will be examined. Thirdly, strategies to enhance the therapeutics by combining MH therapy with chemotherapy, radiotherapy, immunotherapy, photothermal/photodynamic therapy (PDT), and gene therapy will be reviewed. Lastly, the prospect and significant challenges in MH-based antitumor therapy will be discussed. This review is to provide a comprehensive understanding of MH for improving antitumor therapeutic efficacy, which would be of utmost benefit towards guiding the users and for the future development of MNPs-MH towards successful application in medicine.

Magnetic force fields of isolated small nanoparticle clusters

The usage of magnetic nanoparticles (NPs) in applications necessitates a precise mastering of their properties at the single nanoparticle level. There has been a lot of progress in the understanding of the magnetic properties of NPs, but incomparably less when interparticle interactions govern the overall magnetic response. Here, we present a quantitative investigation of magnetic fields generated by small clusters of NPs assembled on a dielectric non-magnetic surface. Structures ranging from individual NPs to fifth-fold particulate clusters are investigated in their magnetization saturation state by magnetic force microscopy and numerical calculations. It is found that the magnetic stray field does not increase proportionally with the number of NPs in the cluster. Both measured and calculated magnetic force fields underline the great importance of the exact spatial arrangement of NPs, shedding light on the magnetic force field distribution of particulate clusters, which is relevant for the quantitative evaluation of their magnetization and perceptibly for many applications.

Magnetic Nanoparticle Systems for Nanomedicine—A Materials Science Perspective

Iron oxide nanoparticles are the basic components of the most promising magneto-responsive systems for nanomedicine, ranging from drug delivery and imaging to hyperthermia cancer treatment, as well as to rapid point-of-care diagnostic systems with magnetic nanoparticles. Advanced synthesis procedures of single- and multi-core iron-oxide nanoparticles with high magnetic moment and well-defined size and shape, being designed to simultaneously fulfill multiple biomedical functionalities, have been thoroughly evaluated. The review summarizes recent results in manufacturing novel magnetic nanoparticle systems, as well as the use of proper characterization methods that are relevant to the magneto-responsive nature, size range, surface chemistry, structuring behavior, and exploitation conditions of magnetic nanosystems. These refer to particle size, size distribution and aggregation characteristics, zeta potential/surface charge, surface coating, functionalization and catalytic activity, morphology (shape, surface area, surface topology, crystallinity), solubility and stability (e.g., solubility in biological fluids, stability on storage), as well as to DC and AC magnetic properties, particle agglomerates formation, and flow behavior under applied magnetic field (magnetorheology).

Luminophore and Magnetic Multicore Nanoassemblies for Dual-Mode MRI and Fluorescence Imaging

Nanoassemblies encompass a large variety of systems (organic, crystalline, amorphous and porous). The nanometric size enables these systems to interact with biological entities and cellular organelles of similar dimensions (proteins, cells, …). Over the past 20 years, the exploitation of their singular properties as contrast agents has led to the improvement of medical imaging. The use of nanoprobes also allows the combination of several active units within the same nanostructure, paving the way to multi-imaging. Thus, the nano-object provides various additional information which helps simplify the number of clinical procedures required. In this review, we are interested in the combination between fluorescent units and magnetic nanoparticles to perform dual-mode magnetic resonance imaging (MRI) and fluorescent imaging. The effect of magnetic interaction in multicore iron oxide nanoparticles on the MRI contrast agent properties is highlighted.

Magnetic Iron Oxide Nanoparticles for Disease Detection and Therapy

Magnetic iron oxide nanoparticles (MIONs) are among the first generation of nanomaterials that have advanced to clinic use. A broad range of biomedical techniques has been developed by combining the versatile nanomagnetism of MIONs with various forms of applied magnetic fields. MIONs can generate imaging contrast and provide mechanical/thermal energy in vivo in response to an external magnetic field, a special feature that distinguishes MIONs from other nanomaterials. These properties offer unique opportunities for nanomaterials engineering in biomedical research and clinical interventions. The past few decades have witnessed the evolution of the applications of MIONs from conventional drug delivery and hyperthermia to the regulation of molecular and cellular processes in the body. Here we review the most recent development in this field, including clinical studies of MIONs and the emerging techniques that may contribute to future innovation in medicine.

Controlled Anchoring of Iron Oxide Nanoparticles on Polymeric Nanofibers: Easy Access to Core@Shell Organic-Inorganic Nanocomposites for Magneto-Scaffolds

Composites combining superparamagnetic iron oxide nanoparticles (SPIONs) and polymers are largely present in modern (bio)materials. However, although SPIONs embedded in polymer matrices are classically reported, the mechanical and degradation properties of the polymer scaffold are impacted by the SPIONs. Therefore, the controlled anchoring of SPIONs onto polymer surfaces is still a major challenge. Herein, we propose an efficient strategy for the direct and uniform anchoring of SPIONs on the surface of functionalized-polylactide (PLA) nanofibers via a simple free ligand exchange procedure to design PLA@SPIONs core@shell nanocomposites. The resulting PLA@SPIONs hybrid biomaterials are characterized by electron microscopy (scanning electron microscopy and transmission electron microscopy) and energy-dispersive X-ray spectroscopy analysis to probe the morphology and detect elements present at the organic-inorganic interface, respectively. A monolayer of SPIONs with a complete and homogeneous coverage is observed on the surface of PLA nanofibers. Magnetization experiments show that magnetic properties of the nanoparticles are well preserved after their grafting on the PLA fibers and that the size of the nanoparticles does not change. The absence of cytotoxicity, combined with a high sensitivity of detection in magnetic resonance imaging both in vitro and in vivo, makes these hybrid nanocomposites attractive for the development of magnetic biomaterials for biomedical applications.