Biocompatible Magnetic Fluids of Co-Doped Iron Oxide Nanoparticles with Tunable Magnetic Properties

HMGB1 derived from lung epithelial cells after cobalt nanoparticle exposure promotes the activation of lung fibroblasts

We have previously demonstrated that exposure to cobalt nanoparticles (Nano-Co) caused extensive interstitial fibrosis and inflammatory cell infiltration in mouse lungs. However, the underlying mechanisms of Nano-Co-induced pulmonary fibrosis remain unclear. In this study, we investigated the role of high-mobility group box 1 (HMGB1) in the epithelial cell-fibroblast crosstalk in Nano-Co-induced pulmonary fibrosis. Our results showed that Nano-Co exposure caused remarkable production and release of HMGB1, as well as nuclear accumulation of HIF-1α in human bronchial epithelial cells (BEAS-2B) in a dose- and a time-dependent manner. Pretreatment with CAY10585, an inhibitor against HIF-1α, significantly blocked the overexpression of HMGB1 in cell lysate and the release of HMGB1 in the supernatant of BEAS-2B cells induced by Nano-Co exposure, indicating that Nano-Co exposure induces HIF-1α-dependent HMGB1 overexpression and release. In addition, treatment of lung fibroblasts (MRC-5) with conditioned media from Nano-Co-exposed BEAS-2B cells caused increased RAGE expression, MAPK signaling activation, and enhanced expression of fibrosis-associated proteins, such as fibronectin, collagen 1, and α-SMA. However, conditioned media from Nano-Co-exposed BEAS-2B cells with HMGB1 knockdown had no effects on the activation of MRC-5 fibroblasts. Finally, inhibition of ERK1/2, p38, and JNK all abolished MRC-5 activation induced by conditioned media from Nano-Co-exposed BEAS-2B cells, suggesting that MAPK signaling might be a key downstream signal of HMGB1/RAGE to promote MRC-5 fibroblast activation. These findings have important implications for understanding the pro-fibrotic potential of Nano-Co.

Synthesis, Surface Modification and Magnetic Properties Analysis of Heat-Generating Cobalt-Substituted Magnetite Nanoparticles

Here, we present the results of the synthesis, surface modification, and properties analysis of magnetite-based nanoparticles, specifically Co0.047Fe2.953O4 (S1) and Co0.086Fe2.914O4 (S2). These nanoparticles were synthesized using the co-precipitation method at 80 °C for 2 h. They exhibit a single-phase nature and crystallize in a spinel-type structure (space group Fd3¯m). Transmission electron microscopy analysis reveals that the particles are quasi-spherical in shape and approximately 11 nm in size. An observed increase in saturation magnetization, coercivity, remanence, and blocking temperature in S2 compared to S1 can be attributed to an increase in magnetocrystalline anisotropy due to the incorporation of Co ions in the crystal lattice of the parent compound (Fe3O4). The heating efficiency of the samples was determined by fitting the Box-Lucas equation to the acquired temperature curves. The calculated Specific Loss Power (SLP) values were 46 W/g and 23 W/g (under HAC = 200 Oe and f = 252 kHz) for S1 and S2, respectively. Additionally, sample S1 was coated with citric acid (Co0.047Fe2.953O4@CA) and poly(acrylic acid) (Co0.047Fe2.953O4@PAA) to obtain stable colloids for further tests for magnetic hyperthermia applications in cancer therapy. Fits of the Box-Lucas equation provided SLP values of 21 W/g and 34 W/g for CA- and PAA-coated samples, respectively. On the other hand, X-ray photoelectron spectroscopy analysis points to the catalytically active centers Fe2+/Fe3+ and Co2+/Co3+ on the particle surface, suggesting possible applications of the samples as heterogeneous self-heating catalysts in advanced oxidation processes under an AC magnetic field.

Polyrhodanine-based nanomaterials for biomedical applications: A review

Rhodanine is a heterocyclic organic compound that has been investigated for its potential biomedical applications, particularly in drug discovery. Rhodanine derivatives have been examined as the medication options for numerous illnesses, including cancer, inflammation, and infectious diseases. Some rhodanine derivatives have also shown promising activity against drug-resistant strains of bacteria and viruses. One of these derivatives is polyrhodanine (PR), a conducting polymer that has gained attention for its biomedical properties. This review article summarises the latest advancements in creating biomaterials based on PR for biosensing, antimicrobial treatments, and anticancer therapies. The distinctive characteristics of PR, such as biocompatibility, biodegradability, and good conductivity, render it an attractive candidate for these applications. The article also explores obstacles and potential future paths for advancing biomaterials made with PR, including synthesis modifications, characterisation techniques, and in vivo evaluation of biocompatibility and efficacy. Overall, as an emerging research topic, this review emphasises the potential of PR as a promising biomaterial for various biomedical applications and provides insights into the contemporary state of research and prospective directions for investigation.

Does Magnetic Field Influence the Surface Tension of Ferrofluid?

Studying the physical properties of ferrofluids is a challenging task, especially when conventional experimental techniques are adapted to the presence of a magnetic field. To date, there has been no definitive understanding of how the magnetic field affects the surface energy of ferrofluid interfaces. In this study, we perform a direct experimental investigation to assess the effect of magnetic fields on the surface tension of ferrofluids. For this purpose, a modified capillary wave technique was modified for use in the presence of an external magnetic field. A decrease in the wavelength of the capillary wave was observed when the magnetic field was oriented perpendicular to the ferrofluid surface, and an increase was recorded when the magnetic field was parallel. We note that the capillary wave pattern elongates along the magnetic field force lines. The observed effect is attributed to the varying influence of the magnetic field along and across the propagating capillary wave. Analysis of the dispersion relation and evaluation of the impacts of various mechanisms influencing capillary waves revealed, that the changes in the surface tension of ferrofluids in the presence of a magnetic field are responsible for the observed behavior. It is shown that the surface tension of the MK 8-40 ferrofluid gradually increases with the applied magnetic field and reaches a grouth up to 10% in a magnetic field of ∼10 kA/m. Thus, the surface tension is found to be influenced by an external magnetic field.

High-Dose Exposure to Polymer-Coated Iron Oxide Nanoparticles Elicits Autophagy-Dependent Ferroptosis in Susceptible Cancer Cells

Ferroptosis, a form of iron-dependent, lipid peroxidation-driven cell death, has been extensively investigated in recent years, and several studies have suggested that the ferroptosis-inducing properties of iron-containing nanomaterials could be harnessed for cancer treatment. Here we evaluated the potential cytotoxicity of iron oxide nanoparticles, with and without cobalt functionalization (Fe₂O₃ and Fe₂O₃@Co-PEG), using an established, ferroptosis-sensitive fibrosarcoma cell line (HT1080) and a normal fibroblast cell line (BJ). In addition, we evaluated poly (ethylene glycol) (PEG)-poly(lactic-co-glycolic acid) (PLGA)-coated iron oxide nanoparticles (Fe₃O₄-PEG-PLGA). Our results showed that all the nanoparticles tested were essentially non-cytotoxic at concentrations up to 100 μg/mL. However, when the cells were exposed to higher concentrations (200-400 μg/mL), cell death with features of ferroptosis was observed, and this was more pronounced for the Co-functionalized nanoparticles. Furthermore, evidence was provided that the cell death triggered by the nanoparticles was autophagy-dependent. Taken together, the exposure to high concentrations of polymer-coated iron oxide nanoparticles triggers ferroptosis in susceptible human cancer cells.

Optimization of Magnetic Cobalt Ferrite Nanoparticles for Magnetic Heating Applications in Biomedical Technology

Using magnetic nanoparticles for extracorporeal magnetic heating applications in bio-medical technology allows higher external field amplitudes and thereby the utilization of particles with higher coercivities (H_C). In this study, we report the synthesis and characterization of high coercivity cobalt ferrite nanoparticles following a wet co-precipitation method. Particles are characterized with magnetometry, X-ray diffraction, Mössbauer spectroscopy, transmission electron microscopy (TEM) and calorimetric measurements for the determination of their specific absorption rate (SAR). In the first series, Co_xFe_3-xO₄ particles were synthesized with x = 1 and a structured variation of synthesis conditions, including those of the used atmosphere (O₂ or N₂). In the second series, particles with x = 0 to 1 were synthesized to study the influence of the cobalt fraction on the resulting magnetic and structural properties. Crystallite sizes of the resulting particles ranged between 10 and 18 nm, while maximum coercivities at room temperatures of 60 kA/m for synthesis with O₂ and 37 kA/m for N₂ were reached. Magnetization values at room temperature and 2 T (M_RT,2T) up to 60 Am²/kg under N₂ for x = 1 can be achieved. Synthesis parameters that lead to the formation of an additional phase when they exceed specific thresholds have been identified. Based on XRD findings, the direct correlation between high-field magnetization, the fraction of this antiferromagnetic byphase and the estimated transition temperature of this byphase, extracted from the Mössbauer spectroscopy series, we were able to attribute this contribution to akageneite. When varying the cobalt fraction x, a non-monotonous correlation of H_C and x was found, with a linear increase of H_C up to x = 0.8 and a decrease for x > 0.8, while magnetometry and in-field Mössbauer experiments demonstrated a moderate degree of spin canting for all x, yielding high magnetization. SAR values up to 480 W/g (@290 kHz, 69 mT) were measured for immobilized particles with x = 0.3, whit the external field amplitude being the limiting factor due to the high coercivities of our particles.

The effect of size, shape, coating and functionalization on nuclear relaxation properties in iron oxide core-shell nanoparticles: a brief review of the situation

In this perspective article, we present a short selection of some of the most significant case studies on magnetic nanoparticles for potential applications in nanomedicine, mainly magnetic resonance. For almost 10 years, our research activity focused on the comprehension of the physical mechanisms on the basis of the nuclear relaxation of magnetic nanoparticles in the presence of magnetic fields; taking advantage of the insights gathered over this time span, we report on the dependence of the relaxation behaviour on the chemico-physical properties of magnetic nanoparticles and discuss them in full detail. In particular, a critical review is carried out on the correlations between their efficiency as contrast agents in magnetic resonance imaging and the magnetic core of magnetic nanoparticles (mainly iron oxides), their size and shape, and the coating and solvent used for making them biocompatible and well dispersible in physiological media. Finally, the heuristic model proposed by Roch and coworkers is presented, as it was extensively adopted to describe most of the experimental data sets. The large amount of data analyzed allowed us to highlight both the advantages and limitations of the model.

Effect of Europium Substitution on the Structural, Magnetic and Relaxivity Properties of Mn-Zn Ferrite Nanoparticles: A Dual-Mode MRI Contrast-Agent Candidate

Magnetic nanoparticles (MNPs) have been widely applied as magnetic resonance imaging (MRI) contrast agents. MNPs offer significant contrast improvements in MRI through their tunable relaxivities, but to apply them as clinical contrast agents effectively, they should exhibit a high saturation magnetization, good colloidal stability and sufficient biocompatibility. In this work, we present a detailed description of the synthesis and the characterizations of europium-substituted Mn-Zn ferrite (Mn_0.6Zn_0.4Eu_xFe_2-xO₄, x = 0.00, 0.02, 0.04, 0.06, 0.08, 0.10, and 0.15, herein named MZF for x = 0.00 and EuMZF for others). MNPs were synthesized by the coprecipitation method and subsequent hydrothermal treatment, coated with citric acid (CA) or pluronic F127 (PF-127) and finally characterized by X-ray Diffraction (XRD), Inductively Coupled Plasma (ICP), Vibrating Sample Magnetometry (VSM), Fourier-Transform Infrared (FTIR), Dynamic Light Scattering (DLS) and MRI Relaxometry at 3T methods. The XRD studies revealed that all main diffraction peaks are matched with the spinel structure very well, so they are nearly single phase. Furthermore, XRD study showed that, although there are no significant changes in lattice constants, crystallite sizes are affected by europium substitution significantly. Room-temperature magnetometry showed that, in addition to coercivity, both saturation and remnant magnetizations decrease with increasing europium substitution and coating with pluronic F127. FTIR study confirmed the presence of citric acid and poloxamer (pluronic F127) coatings on the surface of the nanoparticles. Relaxometry measurements illustrated that, although the europium-free sample is an excellent negative contrast agent with a high r₂ relaxivity, it does not show a positive contrast enhancement as the concentration of nanoparticles increases. By increasing the europium to x = 0.15, r₁ relaxivity increased significantly. On the contrary, europium substitution decreased r₂ relaxivity due to a reduction in saturation magnetization. The ratio of r₂/r₁ decreased from 152 for the europium-free sample to 11.2 for x = 0.15, which indicates that Mn_0.6Zn_0.4Eu_0.15Fe_1.85O₄ is a suitable candidate for dual-mode MRI contrast agent potentially. The samples with citric acid coating had higher r₁ and lower r₂ relaxivities than those of pluronic F127-coated samples.

An Advanced Thermal Decomposition Method to Produce Magnetic Nanoparticles with Ultrahigh Heating Efficiency for Systemic Magnetic Hyperthermia

Due to the limited heating efficiency of available magnetic nanoparticles, it is difficult to achieve therapeutic temperatures above 44 °C in relatively inaccessible tumors during magnetic hyperthermia following systemic administration of nanoparticles at clinical dosage (≤10 mg kg-1 ). To address this, a method for the preparation of magnetic nanoparticles with ultrahigh heating capacity in the presence of an alternating magnetic field (AMF) is presented. The low nitrogen flow rate of 10 mL min-1 during the thermal decomposition reaction results in cobalt-doped nanoparticles with a magnetite (Fe3 O4 ) core and a maghemite (γ-Fe2 O3 ) shell that exhibit the highest intrinsic loss power reported to date of 47.5 nH m2 kg-1 . The heating efficiency of these nanoparticles correlates positively with increasing shell thickness, which can be controlled by the flow rate of nitrogen. Intravenous injection of nanoparticles at a low dose of 4 mg kg-1 elevates intratumoral temperatures to 50 °C in mice-bearing subcutaneous and metastatic cancer grafts during exposure to AMF. This approach can also be applied to the synthesis of other metal-doped nanoparticles with core-shell structures. Consequently, this method can potentially be used for the development of novel nanoparticles with high heating performance, further advancing systemic magnetic hyperthermia for cancer treatment.

A guide to the design of magnetic particle imaging tracers for biomedical applications

Magnetic Particle Imaging (MPI) is a novel and emerging non-invasive technique that promises to deliver high quality images, no radiation, high depth penetration and nearly no background from tissues. Signal intensity and spatial resolution in MPI are heavily dependent on the properties of tracers. Hence the selection of these nanoparticles for various applications in MPI must be carefully considered to achieve optimum results. In this review, we will provide an overview of the principle of MPI and the key criteria that are required for tracers in order to generate the best signals. Nanoparticle materials such as magnetite, metal ferrites, maghemite, zero valent iron@iron oxide core@shell, iron carbide and iron-cobalt alloy nanoparticles will be discussed as well as their synthetic pathways. Since surface modifications play an important role in enabling the use of these tracers for biomedical applications, coating options including the transfer from organic to inorganic media will also be discussed. Finally, we will discuss different biomedical applications and provide our insights into the most suitable tracer for each of these applications.

Crossover From Individual to Collective Magnetism in Dense Nanoparticle Systems: Local Anisotropy Versus Dipolar Interactions

Dense systems of magnetic nanoparticles may exhibit dipolar collective behavior. However, two fundamental questions remain unsolved: i) whether the transition temperature may be affected by the particle anisotropy or it is essentially determined by the intensity of the interparticle dipolar interactions, and ii) what is the minimum ratio of dipole-dipole interaction (E_dd ) to nanoparticle anisotropy (K_ef V, anisotropy⋅volume) energies necessary to crossover from individual to collective behavior. A series of particle assemblies with similarly intense dipolar interactions but widely varying anisotropy is studied. The K_ef  is tuned through different degrees of cobalt-doping in maghemite nanoparticles, resulting in a variation of nearly an order of magnitude. All the bare particle compacts display collective behavior, except the one made with the highest anisotropy particles, which presents "marginal" features. Thus, a threshold of K_ef V/E_dd  ≈ 130 to suppress collective behavior is derived, in good agreement with Monte Carlo simulations. This translates into a crossover value of ≈1.7 for the easily accessible parameter T_MAX (interacting)/T_MAX (non-interacting) (ratio of the peak temperatures of the zero-field-cooled magnetization curves of interacting and dilute particle systems), which is successfully tested against the literature to predict the individual-like/collective behavior of any given interacting particle assembly comprising relatively uniform particles.

Ferrimagnetic Large Single Domain Iron Oxide Nanoparticles for Hyperthermia Applications

This paper describes the preparation and obtained magnetic properties of large single domain iron oxide nanoparticles. Such ferrimagnetic particles are particularly interesting for diagnostic and therapeutic applications in medicine or (bio)technology. The particles were prepared by a modified oxidation method of non-magnetic precursors following the green rust synthesis and characterized regarding their structural and magnetic properties. For increasing preparation temperatures (5 to 85 °C), an increasing particle size in the range of 30 to 60 nm is observed. Magnetic measurements confirm a single domain ferrimagnetic behavior with a mean saturation magnetization of ca. 90 Am²/kg and a size-dependent coercivity in the range of 6 to 15 kA/m. The samples show a specific absorption rate (SAR) of up to 600 W/g, which is promising for magnetic hyperthermia application. For particle preparation temperatures above 45 °C, a non-magnetic impurity phase occurs besides the magnetic iron oxides that results in a reduced net saturation magnetization.

Structural, magnetic and hyperthermia properties and their correlation in cobalt-doped magnetite nanoparticles

Cobalt doped magnetite nanoparticles (Co_xFe_3−xO₄ NPs) are investigated extensively because of their potential hyperthermia application. However, the complex interrelation among chemical compositions and particle size means their correlation with the magnetic and heating properties is not trivial to predict. Here, we prepared Co_xFe_3−xO₄ NPs (0 ≤ x ≤ 1) to investigate the effects of cobalt content and particle size on their magnetic and heating properties. A detailed analysis of the structural features indicated the similarity between the crystallite and particle sizes as well as their non-monotonic change with the increase of Co content. Magnetic measurements for the Co_xFe_3−xO₄ NPs (0 ≤ x ≤ 1) showed that the blocking temperature, the saturation magnetization, the coercivity, and the anisotropy constant followed a similar trend with a maximum at x = 0.7. Moreover, ⁵⁷Fe Mössbauer spectroscopy adequately explained the magnetic behaviour, the anisotropy constant, and saturation magnetization of low Co content samples. Finally, our study shows that the relaxation loss is a primary contributor to the SAR in Co_xFe_3−xO₄ NPs with low Co contents as well as their potential application in magnetic hyperthermia.

The interrelation among chemical compositions, structure, and heating properties of cobalt doped magnetite nanoparticles (Co_xFe_3−xO₄ NPs) for their potential hyperthermia application.

Inorganic Materials and Metal-Organic Frameworks: Editorial Announcement

Dear Readers, [...].

Heat dissipation in Sm3+ and Zn2+ co-substituted magnetite (Zn0.1SmxFe2.9-xO4) nanoparticles coated with citric acid and pluronic F127 for hyperthermia application

In this work, Sm³⁺ and Zn²⁺ co-substituted magnetite Zn_0.1Sm_xFe_2.9-xO₄ (x = 0.0, 0.01, 0.02, 0.03, 0.04 and 0.05) nanoparticles, have been prepared via co-precipitation method and were electrostatically and sterically stabilized by citric acid and pluronic F127 coatings. The coated nanoparticles were well dispersed in an aqueous solution (pH 5.5). Magnetic and structural properties of the nanoparticles and their ferrofluids were studied by different methods. XRD studies illustrated that all as-prepared nanoparticles have a single phase spinel structure, with lattice constants affected by samarium cations substitution. The temperature dependence of the magnetization showed that Curie temperatures of the uncoated samples monotonically increased from 430 to 480 °C as Sm³⁺ content increased, due to increase in A-B super-exchange interactions. Room temperature magnetic measurements exhibited a decrease in saturation magnetization of the uncoated samples from 98.8 to 71.9 emu/g as the Sm³⁺ content increased, which is attributed to substitution of Sm³⁺ (1.5 µB) ions for Fe³⁺ (5 µB) ones in B sublattices. FTIR spectra confirmed that Sm³⁺ substituted Zn_0.1Sm_xFe_2.9-xO₄ nanoparticles were coated with both citric acid and pluronic F127 properly. The mean particle size of the coated nanoparticles was 40 nm. Calorimetric measurements showed that the maximum SLP and ILP values obtained for Sm³⁺ substituted nanoparticles were 259 W/g and 3.49 nHm²/kg (1.08 mg/ml, measured at f = 290 kHz and H = 16kA/m), respectively, that are related to the sample with x = 0.01. Magnetic measurements revealed coercivity, which indicated that hysteresis loss may represent a substantial portion in heat generation. Our results show that these ferrofluids are potential candidates for magnetic hyperthermia applications.

Ferromagnetic Liquid Droplet on a Superhydrophobic Surface for the Transduction of Mechanical Energy to Electricity Based on Electromagnetic Induction

Ferromagnetic liquids undergo reversible magnetization changes upon varying external magnetic field levels. The movement of ferromagnetic liquid droplets across a coil under an external magnetic field holds promise as an energy transducer from mechanical force to electricity; however, it suffers from an adhesive issue between the ferromagnetic liquid and the solid pedestal. We introduce a superhydrophobic support that uses antiwetting surfaces to remarkably reduce adhesion during the movement of ferromagnetic liquid droplets. Maxwell numerical simulation was utilized to analyze the working mechanism and improve further electrical outputs. By controlling the droplet size, the strength of the magnetic bottom and the tilting speed of the test condition, we generated a ferromagnetic liquid droplet-based superhydrophobic magnetoelectric energy transducer (FLD-SMET) that can convert vibrational energy to electricity. When a 100 μL ferromagnetic liquid droplet was used for FLD-SMET under a 13 mT magnetic field, an electrical voltage response of 280 μV and electrical current response of ∼7.5 μA were generated using a shaking machine with a tilting speed of 9.5°/s. We thus show that such a device can serve as a self-powered light buoy floating on a water surface. Our study presents an applied concept for the design of droplet-based energy harvesters to convert surrounding vibrational energy to electricity.

Theoretical Study on Specific Loss Power and Heating Temperature in CoFe2O4 Nanoparticles as Possible Candidate for Alternative Cancer Therapy by Superparamagnetic Hyperthemia

In this paper, we present a theoretical study on the maximum specific loss power in the admissible biological limit (PsM)l for CoFe2O4 ferrimagnetic nanoparticles, as a possible candidate in alternative and non-invasive cancer therapy by superparamagnetic hyperthermia. The heating time of the nanoparticles (Δto) at the optimum temperature of approx. 43 °C for the efficient destruction of tumor cells in a short period of time, was also studied. We found the maximum specific loss power PsM (as a result of superparamegnetic relaxation in CoFe2O4 nanoparticles) for very small diameters of the nanoparticles (Do), situated in the range of 5.88–6.67 nm, and with the limit frequencies (fl) in the very wide range of values of 83–1000 kHz, respectively. Additionally, the optimal heating temperature (To) of 43 °C was obtained for a very wide range of values of the magnetic field H, of 5–60 kA/m, and the corresponding optimal heating times (Δto) were found in very short time intervals in the range of ~0.3–44 s, depending on the volume packing fraction (ε) of the nanoparticles. The obtained results, as well as the very wide range of values for the amplitude H and the frequency f of the external alternating magnetic field for which superparamagnetic hyperthermia can be obtained, which are great practical benefits in the case of hyperthermia, demonstrate that CoFe2O4 nanoparticles can be successfully used in the therapy of cancer by superaparamagnetic hyperthermia. In addition, the very small size of magnetic nanoparticles (only a few nm) will lead to two major benefits in cancer therapy via superparamagnetic hyperthermia, namely: (i) the possibility of intracellular therapy which is much more effective due to the ability to destroy tumor cells from within and (ii) the reduced cell toxicity.

Light-Interacting iron-based nanomaterials for localized cancer detection and treatment

To improve the prognosis of cancer patients, methods of local cancer detection and treatment could be implemented. For that, iron-based nanomaterials (IBN) are particularly well-suited due to their biocompatibility and the various ways in which they can specifically target a tumor, i.e. through passive, active or magnetic targeting. Furthermore, when it is needed, IBN can be associated with well-known fluorescent compounds, such as dyes, clinically approved ICG, fluorescent proteins, or quantum dots. They may also be excited and detected using well-established optical methods, relying on scattering or fluorescent mechanisms, depending on whether IBN are associated with a fluorescent compound or not. Systems combining IBN with optical methods are diverse, thus enabling tumor detection in various ways. In addition, these systems provide a wealth of information, which is inaccessible with more standard diagnostic tools, such as single tumor cell detection, in particular by combining IBN with near-field scanning optical microscopy, dark-field microscopy, confocal microscopy or super-resolution microscopy, or the highlighting of certain dynamic phenomena such as the diffusion of a fluorescent compound in an organism, e.g. using fluorescence lifetime imaging, fluorescence resonance energy transfer, fluorescence anisotropy, or fluorescence tomography. Furthermore, they can in some cases be complemented by a therapeutic approach to destroy tumors, e.g. when the fluorescent compound is a drug, or when a technique such as photo-thermal or photodynamic therapy is employed. This review brings forward the idea that iron-based nanomaterials may be associated with various optical techniques to form a commercially available toolbox, which can serve to locally detect or treat cancer with a better efficacy than more standard medical approaches. STATEMENT OF SIGNIFICANCE: New tools should be developed to improve cancer treatment outcome. For that, two closely-related aspects deserve to be considered, i.e. early tumor detection and local tumor treatment. Here, I present various types of iron-based nanomaterials, which can achieve this double objective when they interact with a beam of light under specific and accurately chosen conditions. Indeed, these materials are biocompatible and can be used/combined with most standard microscopic/optical methods. Thus, these systems enable on the one hand tumor cell detection with a high sensitivity, i.e. down to single tumor cell level, and on the other hand tumor destruction through various mechanisms in a controlled and localized manner by deciding whether or not to apply a beam of light and by having these nanomaterials specifically target tumor cells.

Magnetic nanoparticles in developing electrochemical sensors for pharmaceutical and biomedical applications

A revolutionary impact on the pharmaceutical and biomedical applications has been arisen in the few years to come as a result of the advances made in magnetic nanoparticles (MNPs) research. The use of MNPs opens wide opportunities in diagnostics, drug and gene delivery, in vivo imaging, magnetic separation, and hyperthermia therapy, etc. Besides, their possible integration in sensors makes them an ideal essential element of innovative pharmaceutical and biomedical applications. Nowadays, MNPs-based electrochemical sensors have attracted great attention to pharmaceutical and biomedical applications owing to their high sensitivity, stability. Selectivity towards the target as well as their simplicity of manufacture. Therefore, this review focus on recent advances with cutting-edge approaches dealing with the synthesis, design, and advantageous analytical performance of MNPs in the electrochemical sensors utilized for pharmaceutical and biomedical applications between 2015 and 2020. The challenges existing in this research area and some potential strategies/future perspectives for the rational design of electrochemical sensors are also outlined.

Probing the catalytic activity of highly efficient sulfonic acid fabricated cobalt ferrite magnetic nanoparticles for the clean and scalable synthesis of dihydro, spiro and bis quinazolinones

An exceptionally productive, rapid, simple, and eco-friendly approach for the synthesis of 2,3-dihydroquinazolin-4(1H)-one has been developed utilizing acidic magnetically retrievable cobalt ferrite nanoparticles (CFNP@SO3H).

Structural perspective on revealing heat dissipation behavior of CoFe2O4-Pd nanohybrids: great promise for magnetic fluid hyperthermia

Loss mechanisms in fluid heating of cobalt ferrite (CFO) nanoparticles and CFO-Pd heterodimer colloidal suspensions are investigated as a function of particle size, fluid concentration and magnetic field amplitude. The specific absorption rate (SAR) is found to vary with increasing particle size due to a change in dominant heating mechanism from susceptibility to hysteresis and frictional loss. The maximum SAR is obtained for particle diameters of 11-15 nm as a result of synergistic contributions of susceptibility loss, including Néel and Brownian relaxation and especially hysteresis loss, thereby validating the applicability of linear response theory to superparamagnetic CFO nanoparticles. Our results show that the ferrofluid concentration and magnetic field amplitude alter interparticle interactions and associated heating efficiency. The SAR of the CFO nanoparticles could be maximized by adjusting the synthesis parameters. Despite the paramagnetic properties of individual palladium nanoparticles, CFO-Pd heterodimer suspensions were observed to have surprisingly improved magnetization as well as SAR values, when compared with CFO ferrofluids. This difference is attributed to interfacial interactions between the magnetic moments of paramagnetic Pd and superparamagnetic/ferrimagnetic CFO. SAR values measured from CFO-Pd heterodimer suspensions were found to be 47-52 W gFerrite-1, which is up to a factor of two higher than the SAR values of commercially available ferrofluids, demonstrating their potential as efficient heat mediators. Our results provide insight into the utilization of CFO-Pd heterodimer suspensions as potential nanoplatforms for diagnostic and therapeutic biomedical applications, e.g., in cancer hyperthermia, cryopreserved tissue warming, thermoablative therapy, drug delivery and bioimaging.

Coating Effect on the 1H-NMR Relaxation Properties of Iron Oxide Magnetic Nanoparticles

We present a ¹H Nuclear Magnetic Resonance (NMR) relaxometry experimental investigation of two series of magnetic nanoparticles, constituted of a maghemite core with a mean diameter d_TEM = 17 ± 2.5 nm and 8 ± 0.4 nm, respectively, and coated with four different negative polyelectrolytes. A full structural, morpho-dimensional and magnetic characterization was performed by means of Transmission Electron Microscopy, Atomic Force Microscopy and DC magnetometry. The magnetization curves showed that the investigated nanoparticles displayed a different approach to the saturation depending on the coatings, the less steep ones being those of the two samples coated with P(MAA-stat-MAPEG), suggesting the possibility of slightly different local magnetic disorders induced by the presence of the various polyelectrolytes on the particles’ surface. For each series, ¹H NMR relaxivities were found to depend very slightly on the surface coating. We observed a higher transverse nuclear relaxivity, r₂, at all investigated frequencies (10 kHz ≤ ν_L ≤ 60 MHz) for the larger diameter series, and a very different frequency behavior for the longitudinal nuclear relaxivity, r₁, between the two series. In particular, the first one (d_TEM = 17 nm) displayed an anomalous increase of r₁ toward the lowest frequencies, possibly due to high magnetic anisotropy together with spin disorder effects. The other series (d_TEM = 8 nm) displayed a r₁ vs. ν_L behavior that can be described by the Roch’s heuristic model. The fitting procedure provided the distance of the minimum approach and the value of the Néel reversal time (τ ≈ 3.5 ÷ 3.9·10⁻⁹ s) at room temperature, confirming the superparamagnetic nature of these compounds.