Exosome Isolation Using Chitosan Oligosaccharide Lactate-1-Pyrenecarboxylic Acid-Based Self-Assembled Magnetic Nanoclusters

Exosomes are small extracellular vesicles that play a crucial role in intercellular communication and offer significant potential for a wide range of biomedical applications. However, conventional methods for exosome isolation have limitations in terms of purity, scalability, and preservation of exosome structural integrity. To address these challenges, an exosome isolation platform using chitosan oligosaccharide lactate conjugated 1-pyrenecarboxylic acid (COL-Py) based self-assembled magnetic nanoclusters (CMNCs), is presented. CMNCs are characterized to optimize their size, stability, and interaction dynamics with exosomes. The efficiency of CMNCs in isolating exosomes is systematically evaluated using various analytical methods to demonstrate their ability to capture exosomes based on amphiphilic lipid bilayers. CMNC-based exosome isolation consistently yields exosomes with structural integrity and purity similar to those obtained using traditional methods. The reusability of CMNCs over multiple exosome isolation cycles underscores their scalability and offers an efficient solution for biomedical applications. These results are supported by western blot analysis, which demonstrated the superiority of CMNC-based isolation in terms of purity compared to conventional methods. By providing a scalable and efficient exosome isolation process that preserves both structural integrity and purity, CMNCs can constitute a new platform that can contribute to the field of exosome studies.

Iron oxide magnetic aggregates: Aspects of synthesis, computational approaches and applications

Superparamagnetic magnetite nanoparticles have been central to numerous investigations in the past few decades for their use in many applications, such as drug delivery, medical diagnostics, magnetic separation, and material science. However, the properties of single magnetic nanoparticles are sometimes not sufficient to accomplish tasks where a strong magnetic response is required. In light of this, aggregated magnetite nanoparticles have been proposed as an alternative advanced material, which may expand and combine some of the advantages of single magnetic nanoparticles, including superparamagnetism, with an enhanced magnetic moment and increased colloidal stability. This review comprehensively discusses the current literature on aggregates made of magnetic iron oxide nanoparticles. This review is divided into three sections. First, the current synthetic strategies for magnetite nanoparticle aggregates are discussed, together with the influence of different stabilizers on the primary crystals and the final aggregate size and morphology. The second section is dedicated to computational approaches, such as density functional methods (which permit accurate predictions of electronic and magnetic properties and shed light on the behavior of surfactant molecules on iron oxide surfaces) and molecular dynamics simulations (which provide additional insight into the influence of ligands on the surface chemistry of iron oxide nanocrystals). The last section discusses current and possible future applications of iron oxide magnetic aggregates, including wastewater treatment, water purification, medical applications, and magnetic aggregates for materials displaying structural colors.

Synthesis and Functional Characterization of CoxFe3-xO4-BaTiO3 Magnetoelectric Nanocomposites for Biomedical Applications

Nowadays, magnetoelectric nanomaterials are on their way to finding wide applications in biomedicine for various cancer and neurological disease treatment, which is mainly restricted by their relatively high toxicity and complex synthesis. This study for the first time reports novel magnetoelectric nanocomposites of Co_xFe_3-xO₄-BaTiO₃ series with tuned magnetic phase structures, which were synthesized via a two-step chemical approach in polyol media. The magnetic Co_xFe_3-xO₄ phases with x = 0.0, 0.5, and 1.0 were obtained by thermal decomposition in triethylene glycol media. The magnetoelectric nanocomposites were synthesized by the decomposition of barium titanate precursors in the presence of a magnetic phase under solvothermal conditions and subsequent annealing at 700 °C. X-ray diffraction revealed the presence of both spinel and perovskite phases after annealing with average crystallite sizes in the range of 9.0-14.5 nm. Transmission electron microscopy data showed two-phase composite nanostructures consisting of ferrites and barium titanate. The presence of interfacial connections between magnetic and ferroelectric phases was confirmed by high-resolution transmission electron microscopy. Magnetization data showed expected ferrimagnetic behavior and σ_s decrease after the nanocomposite formation. Magnetoelectric coefficient measurements after the annealing showed non-linear change with a maximum of 89 mV/cm*Oe with x = 0.5, 74 mV/cm*Oe with x = 0, and a minimum of 50 mV/cm*Oe with x = 0.0 core composition, that corresponds with the coercive force of the nanocomposites: 240 Oe, 89 Oe and 36 Oe, respectively. The obtained nanocomposites show low toxicity in the whole studied concentration range of 25-400 μg/mL on CT-26 cancer cells. The synthesized nanocomposites show low cytotoxicity and high magnetoelectric effects, therefore they can find wide applications in biomedicine.

Nanoparticles for Magnetic Heating: When Two (or More) Is Better Than One

The increasing use of magnetic nanoparticles as heating agents in biomedicine is driven by their proven utility in hyperthermia therapeutic treatments and heat-triggered drug delivery methods. The growing demand of efficient and versatile nanoheaters has prompted the creation of novel types of magnetic nanoparticle systems exploiting the magnetic interaction (exchange or dipolar in nature) between two or more constituent magnetic elements (magnetic phases, primary nanoparticles) to enhance and tune the heating power. This process occurred in parallel with the progress in the methods for the chemical synthesis of nanostructures and in the comprehension of magnetic phenomena at the nanoscale. Therefore, complex magnetic architectures have been realized that we classify as: (a) core/shell nanoparticles; (b) multicore nanoparticles; (c) linear aggregates; (d) hybrid systems; (e) mixed nanoparticle systems. After a general introduction to the magnetic heating phenomenology, we illustrate the different classes of nanoparticle systems and the strategic novelty they represent. We review some of the research works that have significantly contributed to clarify the relationship between the compositional and structural properties, as determined by the synthetic process, the magnetic properties and the heating mechanism.

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.

Magnetic Nanoparticle Composites: Synergistic Effects and Applications

Composite materials are made from two or more constituent materials with distinct physical or chemical properties that, when combined, produce a material with characteristics which are at least to some degree different from its individual components. Nanocomposite materials are composed of different materials of which at least one has nanoscale dimensions. Common types of nanocomposites consist of a combination of two different elements, with a nanoparticle that is linked to, or surrounded by, another organic or inorganic material, for example in a core-shell or heterostructure configuration. A general family of nanoparticle composites concerns the coating of a nanoscale material by a polymer, SiO2 or carbon. Other materials, such as graphene or graphene oxide (GO), are used as supports forming composites when nanoscale materials are deposited onto them. In this Review we focus on magnetic nanocomposites, describing their synthetic methods, physical properties and applications. Several types of nanocomposites are presented, according to their composition, morphology or surface functionalization. Their applications are largely due to the synergistic effects that appear thanks to the co-existence of two different materials and to their interface, resulting in properties often better than those of their single-phase components. Applications discussed concern magnetically separable catalysts, water treatment, diagnostics-sensing and biomedicine.

Multifunctional theranostic nanoparticles for biomedical cancer treatments - A comprehensive review

Modern-day search for the novel agents (their preparation and consequent implementation) to effectively treat the cancer is mainly fuelled by the historical failure of the conventional treatment modalities. Apart from that, the complexities such as higher rate of cell mutations, variable tumor microenvironment, patient-specific disparities, and the evolving nature of cancers have made this search much stronger in the latest times. As a result of this, in about two decades, the theranostic nanoparticles (TNPs) - i.e., nanoparticles that integrate therapeutic and diagnostic characteristics - have been developed. The examples for TNPs include mesoporous silica nanoparticles, luminescence nanoparticles, carbon-based nanomaterials, metal nanoparticles, and magnetic nanoparticles. These TNPs have emerged as single and powerful cancer-treating multifunctional nanoplatforms, as they widely provide the necessary functionalities to overcome the previous/conventional limitations including lack of the site-specific delivery of anti-cancer drugs, and real-time continuous monitoring of the target cancer sites while performing therapeutic actions. This has been mainly possible due to the association of the as-developed TNPs with the already-available unique diagnostic (e.g., luminescence, photoacoustic, and magnetic resonance imaging) and therapeutic (e.g., photothermal, photodynamic, hyperthermia therapy) modalities in the biomedical field. In this review, we have discussed in detail about the recent developments on the aforementioned important TNPs without/with targeting ability (i.e., attaching them with ligands or tumor-specific antibodies) and also the strategies that are implemented to increase their tumor accumulation and to enhance their theranostic efficacies for effective biomedical cancer treatments.

Molecular Engineering of Metal Alkoxides for Solution Phase Synthesis of High-Tech Metal Oxide Nanomaterials

The 'bottom-up' synthesis of inorganic nanomaterials with precision at the atomic/molecular level offers many opportunities for the design and improvement of the nanomaterials for various applications. Molecular engineering during soft chemical processing for the synthesis of functional nanomaterials enables the desired chemical and physical properties of the precursors, such as solubility or volatility, clean decomposition, control of stoichiometry for multimetallic species to name a few, and leads to easy control of uniform particle size distribution, stoichiometry…. This Minireview illustrates some important aspects of the molecular engineering in light of some recent developments from the molecular synthesis of nanomaterials involving non-silicon metal alkoxide systems for high-tech applications.

Magnetic Hyperthermia for Cancer Treatment: Main Parameters Affecting the Outcome of In Vitro and In Vivo Studies

Magnetic hyperthermia (MHT) is being investigated as a cancer treatment since the 1950s. Recent advancements in the field of nanotechnology have resulted in a notable increase in the number of MHT studies. Most of these studies explore MHT as a stand-alone treatment or as an adjuvant therapy in a preclinical context. However, despite all the scientific effort, only a minority of the MHT-devoted nanomaterials and approaches made it to clinical context. The outcome of an MHT experiment is largely influenced by a number of variables that should be considered when setting up new MHT studies. This review highlights and discusses the main parameters affecting the outcome of preclinical MHT, aiming to provide adequate assistance in the design of new, more efficient MHT studies.

Preparation and Application of Iron Oxide Nanoclusters

Magnetic iron oxide nanoclusters, which refers to a group of individual nanoparticles, have recently attracted much attention because of their distinctive behaviors compared to individual nanoparticles. In this review, we discuss preparation methods for creating iron oxide nanoclusters, focusing on synthetic procedures, formation mechanisms, and the quality of the products. Then, we discuss the emerging applications for iron oxide nanoclusters in various fields, covering traditional and novel applications in magnetic separation, bioimaging, drug delivery, and magnetically responsive photonic crystals.

Shaping the Assembly of Superparamagnetic Nanoparticles

Superparamagnetism exists only in nanocrystals, and to endow micro/macro-materials with superparamagnetism, superparamagnetic nanoparticles have to be assembled into complex materials. Most techniques currently used to produce such assemblies are inefficient in terms of time and material. Herein, we used evaporation-guided assembly to produce superparamagnetic supraparticles by drying ferrofluid droplets on a superamphiphobic substrate in the presence of an external magnetic field. By tuning the concentration of ferrofluid droplets and controlling the magnetic field, barrel-like, cone-like, and two-tower-like supraparticles were obtained. These assembled supraparticles preserved the superparamagnetism of the original nanoparticles. Moreover, other colloids can easily be integrated into the ferrofluid suspension to produce, by co-assembly, anisotropic binary supraparticles with additional functions. Additionally, the magnetic and anisotropic nature of the resulting supraparticles was harnessed to prepare magnetically actuable microswimmers.

Therapeutic applications of iron oxide based nanoparticles in cancer: basic concepts and recent advances

Nanotechnology has introduced new techniques and phototherapy approaches to fabricate and utilize nanoparticles for cancer therapy. These phototherapy approaches, such as photothermal therapy (PTT) and photodynamic therapy (PDT), hold great promise to overcome the limitations of traditional treatment methods. In phototherapy, magnetic iron oxide nanoparticles (IONPs) are of paramount importance due to their wide range of biomedical applications. This review discusses the basic concepts, various therapy approaches (PTT, PDT, magnetic hyperthermia therapy (MHT), chemotherapy and immunotherapy), intrinsic properties, and mechanisms of cell death of IONPs; it also provides a brief overview of recent developments in IONPs, with focus on their therapeutic applications. Much attention is devoted to elaborating the various parameters, intracellular behaviors and limitations of MHT. Bimodal therapies which act alone or in combination with other modalities are also discussed. The review highlights some limitations in the explored research areas and suggests future directions to overcome these limitations.

Functionalized Hydrophilic Superparamagnetic Iron Oxide Nanoparticles for Magnetic Fluid Hyperthermia Application in Liver Cancer Treatment

In this work, we report the synthesis of hydrophilic and surface-functionalized superparamagnetic iron oxide nanoparticles (SPIOs) to utilize them as nanomedicines for treating liver cancer via magnetic fluid hyperthermia (MFH)-based thermotherapy. For this purpose, initially, we have synthesized the SPIOs through co-precipitation/thermolysis methods, followed by in situ surface functionalization with short-chained molecules, such as 1,4-diaminobenzene (14DAB), 4-aminobenzoic acid (4ABA) and 3,4-diaminobenzoic acid (34DABA) and their combination with terephthalic acid (TA)/2-aminoterephthalic acid (ATA)/trimesic acid (TMA)/pyromellitic acid (PMA) molecules. The as-prepared SPIOs are investigated for their structure, morphology, water dispersibility, and magnetic properties. The heating efficacies of the SPIOs are studied in calorimetric MFH (C-MFH) with respect to their concentrations, surface coatings, dispersion medium, and applied alternating magnetic fields (AMFs). Although all of the as-prepared SPIOs have exhibited superparamagnetic behavior, only 14DAB-, 4ABA-, 34DABA-, and 4ABA-TA-coated SPIOs have shown higher magnetization values (M_s = 55-71 emu g^-1) and good water dispersibility. In C-MFH studies, 34DABA-coated SPIO-based aqueous ferrofluid (AFF) has revealed faster thermal response to the applied AMF and reached therapeutic temperature even at the lowest concentration (0.5 mg mL^-1) compared with 14DAB-, 4ABA-, and 4ABA-TA-coated SPIO-based AFFs. Moreover, 34DABA-coated SPIO-based AFF has exhibited high heating efficacies (i.e., specific absorption rate/intrinsic loss power values of 432.1 W g_Fe^-1/5.2 nHm² kg^-1 at 0.5 mg mL^-1), which could be mainly due to (i) enhanced π-π conjugation paths of surface-attached 34DABA coating molecules because of intrafunctional group attractions and (ii) improved anisotropy from the formation of clusters/linear chains of the SPIOs in ferrofluid suspensions, owing to interfunctional group attractions/interparticle interactions. Moreover, the 34DABA-coated SPIOs have demonstrated (i) very good cytocompatibility for 24/48 h incubation periods and (ii) higher killing efficiency of 61-88% (via MFH) in HepG2 liver cancer cells as compared to their treatment with only AMF/water-bath-based thermotherapy. In summary, the 34DABA-coated SPIOs are very promising heat-inducing agents for MFH-based thermotherapy and thus could be used as effective nanomedicines for cancer treatments.

Synthesis of Iron Oxide Nanoclusters by Thermal Decomposition

Herein, we report a novel one-step solvothermal synthesis of magnetite nanoclusters (MNCs). In this report, we discuss the synthesis, structure, and properties of MNCs and contrast enhancement in T₂-weighted MR images using magnetite nanoclusters. The effect of different organic acids, used as surfactants, on the size and shape of MNCs was investigated. The structure and properties of samples were determined by magnetic measurements, TGA, TEM, HRTEM, XRD, FTIR, and MRI. Magnetic measurements show that obtained MNCs have relatively high saturation magnetization values (65.1-81.5 emu/g) and dependence of the coercive force on the average size of MNCs was established. MNCs were transferred into an aqueous medium by Pluronic F-127, and T₂-relaxivity values were determined. T₂-Weighted MR phantom images clearly demonstrated that such magnetite nanoclusters can be used as contrast agents for MRI.

On the thermotropic and magnetotropic phase behavior of lipid liquid crystals containing magnetic nanoparticles

The inclusion of superparamagnetic iron oxide nanoparticles (SPIONs) in lipid mesophases is a promising strategy for drug-delivery applications, combining the innate biocompatibility of lipid architectures with SPIONs' response to external magnetic fields. Moreover, the organization of SPIONs within the lipid scaffold can lead to locally enhanced SPIONs concentration and improved magnetic response, which is key to overcome the current limitations of hyperthermic treatments. Here we present a Small-Angle X-ray Scattering (SAXS) structural investigation of the thermotropic and magnetotropic behavior of glyceryl monooleate (GMO)/water mesophases, loaded with hydrophobic SPIONs. We prove that even very low amounts of SPIONs deeply alter the phase behavior and thermotropic properties of the mesophases, promoting a cubic to hexagonal phase transition, which is similarly induced upon application of an Alternating Magnetic Field (AMF). Moreover, in the hexagonal phase SPIONs spontaneously self-assemble within the lipid scaffold into a linear supraparticle. This phase behavior is interpreted in the framework of the Helfrich's theory, which shows that SPIONs affect the mesophase both from a viscoelastic and from a structural standpoint. Finally, the dispersion of these cubic phases into stable magnetic colloidal particles, which retain their liquid crystalline internal structure, is addressed as a promising route towards magneto-responsive drug-delivery systems (DDS).

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

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

Iron oxide nanoparticles - In vivo/in vitro biomedical applications and in silico studies

The review presents a broad overview of the biomedical applications of surface functionalized iron oxide nanoparticles (IONPs) as magnetic resonance imaging (MRI) agents for sensitive and precise diagnosis tool and synergistic combination with other imaging modalities. Then, the recent progress in therapeutic applications, such as hyperthermia is discussed and the available toxicity data of magnetic nanoparticles concerning in vitro and in vivo biomedical applications are addressed. This review also presents the available computer models using molecular dynamics (MD), Monte Carlo (MC) and density functional theory (DFT), as a basis for a complete understanding of the behaviour and morphology of functionalized IONPs, for improving NPs surface design and expanding the potential applications in nanomedicine.

Precursor dissolution temperature as a size-controller in Fe3O4 submicrospheres syntheses and their effect in the catalytic degradation of Rhodamine B

Iron oxides submicrospheres have been synthesized by a solvothermal method.

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

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

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

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

Architectured design of superparamagnetic Fe3O4nanoparticles for application as MRI contrast agents: mastering size and magnetism for enhanced relaxivity

Superparamagnetic Fe₃O₄nanomaterials with enhanced relaxivity were prepared by coprecipitation using different alkanolamine bases, which mastered the materials' surface magnetic properties upon size reduction.

Reduction-resistant and reduction-catalytic double-crown nickel nanoclusters

In this work, an attempt to synthesize zero-valent Ni nanoclusters using the Brust method resulted in an unexpected material, Ni₆(SCH₂CH₂Ph)₁₂, which is a nanoscale Ni(ii)-phenylethanethiolate complex and a hexameric, double-crown-like structure, as determined by a series of characterizations, including mass spectrometry (MS), thermal gravimetric analysis (TGA), single-crystal X-ray diffraction (XRD), and X-ray photoelectron spectrometry (XPS). An interesting finding is that this complex is resistant to aqueous BH4(-). Investigations into other metal-phenylethanethiolate and Ni-thiolate complexes reveal that this property is not universal and appears only in complexes with a double-crown-like structure, indicating the correlation between this interesting property and the complexes' special structure. Another interesting finding is that the reduction-resistant Ni₆(SCH₂CH₂Ph)₁₂ exhibits remarkably higher catalytic activity than a well-known catalyst, Au₂₅(SCH₂₂Ph)₁₈, toward the reduction of 4-nitrophenol at low temperature (e.g., 0 °C). This work will help stimulate more research on the properties and applications of less noble metal nanoclusters.

Enhanced magnetic fluid hyperthermia by micellar magnetic nanoclusters composed of Mn(x)Zn(1-x)Fe(2)O(4) nanoparticles for induced tumor cell apoptosis

Monodispersed MnxZn1-xFe2O4 magnetic nanoparticles of 8 nm are synthesized and encapsulated in amphiphilic block copolymer for development of the hydrophilic magnetic nanoclusters (MNCs). These MNCs exhibit superparamagnetic characteristics, high specific absorption rate (SAR), large saturation magnetization (Ms), excellent stability, and good biocompatibility. MnFe2O4 and Mn0.6Zn0.4Fe2O4 are selected as optimum compositions for the MNCs (MnFe2O4/MNC and Mn0.6Zn0.4Fe2O4/MNC) and employed for magnetic fluid hyperthermia (MFH) in vitro. To ensure biosafety of MFH, the parameters of alternating magnetic field (AMF) and exposure time are optimized with low frequency, f, and strength of applied magnetic field, Happlied. Under optimized conditions, MFH of MnFe2O4/MNC and Mn0.6Zn0.4Fe2O4/MNC result in cancer cell death rate up to 90% within 15 min. The pathway of cancer cell death is identified as apoptosis, which occurs in mild hyperthermia near 43 °C. Both MnFe2O4/MNC and Mn0.6Zn0.4Fe2O4/MNC show similar efficiencies on drug-sensitive and drug-resistant cancer cells. On the basis of these findings, those MnxZn1-xFe2O4 nanoclusters can serve as a promising candidate for effective targeting, diagnosis, and therapy of cancers. The multimodal cancer treatment is also possible as amphiphilic block copolymer can encapsulate, in a similar fashion, different nanoparticles, hydrophobic drugs, and other functional molecules.

pH- and thermosensitive thin lipid layer coated mesoporous magnetic nanoassemblies as a dual drug delivery system towards thermochemotherapy of cancer

A new pH-sensitive and thermosensitive dual drug delivery system consisting of thin lipid layer encapsulated mesoporous magnetite nanoassemblies (MMNA) has been developed which can deliver two anticancer drugs simultaneously. The formulation of lipid layer used is 5:2:2:2 w/w, DPPC:cholesterol:DSPE-PEG2000:MMNA. The structure, morphology and magnetic properties of MMNA and lipid coated MMNA (LMMNA) were thoroughly characterized. This hybrid system was investigated for its ability to carry two anticancer drugs as well as its ability to provide heat under an alternating current magnetic field (ACMF). A very high loading efficiency of up to ∼81% of doxorubicin hydrochloride (DOX) with an ∼0.02 mg mg(-1) loading capacity and ∼60% of paclitaxel (TXL) with an ∼0.03 mg mg(-1) loading capacity are obtained with LMMNA. A sustained release of drug is observed over a period of 172 h, with better release, of ∼88:53% (DOX:TXL), at pH 4.3 compared to the ∼28:26% (DOX:TXL) in physiological conditions (pH 7.4). An enhanced release of ∼72 and ∼68% is recorded for DOX and TXL, respectively, during the first hour with the application of an ACMF (∼43°C). A greater in vitro cytotoxic effect is observed with the two drugs compared to them individually in HeLa, MCF-7 and HepG2 cancer cells. With the application of an ACMF for 10 min, the cell killing efficiency is improved substantially due to simultaneous thermo- and chemotherapy. Confocal microscopy confirms the internalization of drug loaded MMNA and LMMNA by cells and their morphological changes during thermochemotherapy.

Assembly-mediated interplay of dipolar interactions and surface spin disorder in colloidal maghemite nanoclusters

Controlled assembly of single-crystal, colloidal maghemite nanoparticles is facilitated via a high-temperature polyol-based pathway. Structural characterization shows that size-tunable nanoclusters of 50 and 86 nm diameters (D), with high dispersibility in aqueous media, are composed of ∼13 nm (d) crystallographically oriented nanoparticles. The interaction effects are examined against the increasing volume fraction, φ, of the inorganic magnetic phase that goes from individual colloidal nanoparticles (φ = 0.47) to clusters (φ = 0.72). The frozen-liquid dispersions of the latter exhibit weak ferrimagnetic behaviour at 300 K. Comparative Mössbauer spectroscopic studies imply that intra-cluster interactions come into play. New insight emerges from the clusters' temperature-dependent ac susceptibility that displays two maxima in χ''(T), with strong frequency dispersion. Scaling-law analysis together with the observed memory effects suggests that a superspin-glass state settles-in at TB ∼ 160-200 K, while at lower-temperatures, surface spin-glass freezing is established at Tf ∼ 40-70 K. In such nanoparticle-assembled systems, with increased φ, Monte Carlo simulations corroborate the role of the inter-particle dipolar interactions and that of the constituent nanoparticles' surface spin disorder in the emerging spin-glass dynamics.

Synergy effects of magnetic silica nanostructures for drug delivery applications

This article presents a capable strategy of using hybrid nanostructures to improve the magnetic-based performance jointly with the internalization process into cells, for drug delivery applications.

Colloidal assemblies of oriented maghemite nanocrystals and their NMR relaxometric properties

¹H-NMR relaxometric experiments over an extended frequency range show that ferrimagnetic colloidal nanoclusters exhibit enhanced transverse relaxivity, r₂.

Fluorescent magnetic Fe3 O4 /rare Earth colloidal nanoparticles for dual-modality imaging

Fluorescent magnetic colloidal nanoparticles (FMCNPs) are produced by a two-step, seed emulsifier-free emulsion polymerization in the presence of oleic acid and sodium undecylenate-modified Fe3 O4 nanoparticles (NPs). The Fe3 O4 /poly(St-co-GMA) nanoparticles are first synthesized as the seed and Eu(AA)3 Phen is copolymerized with the remaining St and GMA to form the fluorescent polymer shell in the second step. The uniform core-shell structured FMCNPs with a mean diameter of 120 nm exhibit superparamagnetism with saturation magnetization of 1.92 emu/g. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2-photon confocal scanning laser microscopy. The in vitro cytotoxicity test conducted using the MTT assay shows good cytocompatibility and the T2 relaxivity of the FMCNPs is 353.86 mM(-1) S(-1) suggesting its potential in magnetic resonance imaging (MRI). In vivo MRI studies based on a rat model show significantly enhanced T2 -weighted images of the liver after administration and prussian blue staining of the liver tissue slice reveals accumulation of FMCNPs in the organ. The cytocompatibility, superparamagnetism, and excellent fluorescent properties of FMCNPs make them suitable for biological imaging probes in MRI and optical imaging.

Cooperative organization in iron oxide multi-core nanoparticles potentiates their efficiency as heating mediators and MRI contrast agents

In the pursuit of optimized magnetic nanostructures for diagnostic and therapeutic applications, the role of nanoparticle architecture has been poorly investigated. In this study, we demonstrate that the internal collective organization of multi-core iron oxide nanoparticles can modulate their magnetic properties in such a way as to critically enhance their hyperthermic efficiency and their MRI T(1) and T(2) contrast effect. Multi-core nanoparticles composed of maghemite cores were synthesized through a polyol approach, and subsequent electrostatic colloidal sorting was used to fractionate the suspensions by size and hence magnetic properties. We obtained stable suspensions of citrate-stabilized nanostructures ranging from single-core 10 nm nanoparticles to multi-core magnetically cooperative 30 nm nanoparticles. Three-dimensional oriented attachment of primary cores results in enhanced magnetic susceptibility and decreased surface disorder compared to individual cores, while preserving a superparamagnetic-like behavior of the multi-core structures and potentiating thermal losses. Exchange coupling in the multi-core nanoparticles modifies the dynamics of the magnetic moment in such a way that both the longitudinal and transverse NMR relaxivities are also enhanced. Long-term MRI detection of tumor cells and their efficient destruction by magnetic hyperthermia can be achieved thanks to a facile and nontoxic cell uptake of these iron oxide nanostructures. This study proves for the first time that cooperative magnetic behavior within highly crystalline iron oxide superparamagnetic multi-core nanoparticles can improve simultaneously therapeutic and diagnosis effectiveness over existing nanostructures, while preserving biocompatibility.

Recent progress in the synthesis of inorganic nanoparticles

Nanoparticles probably constitute the largest class of nanomaterials. Nanoparticles of several inorganic materials have been prepared by employing a variety of synthetic strategies. Besides synthesizing nanoparticles, there has been considerable effort to selectively prepare nanoparticles of different shapes. In view of the great interest in inorganic nanoparticles evinced in the last few years, we have prepared this perspective on the present status of the synthesis of inorganic nanoparticles. This article includes a brief discussion of methods followed by reports on the synthesis of nanoparticles of various classes of inorganic materials such as metals, alloys, oxides chalcogenides and pnictides. A brief section on core-shell nanoparticles is also included.