Relaxivity of manganese ferrite nanoparticles

Near Infrared Biomimetic Hybrid Magnetic Nanocarrier for MRI-Guided Thermal Therapy

Cell-membrane hybrid nanoparticles (NPs) are designed to improve drug delivery, thermal therapy, and immunotherapy for several diseases. Here, we report the development of distinct biomimetic magnetic nanocarriers containing magnetic nanoparticles encapsulated in vesicles and IR780 near-infrared dyes incorporated in the membranes. Distinct cell membranes are investigated, red blood cell (RBC), melanoma (B16F10), and glioblastoma (GL261). Hybrid nanocarriers containing synthetic lipids and a cell membrane are designed. The biomedical applications of several systems are compared. The inorganic nanoparticle consisted of Mn-ferrite nanoparticles with a core diameter of 15 ± 4 nm. TEM images show many multicore nanostructures (∼40 nm), which correlate with the hydrodynamic size. Ultrahigh transverse relaxivity values are reported for the magnetic NPs, 746 mM-1s-1, decreasing respectively to 445 mM-1s-1 and 278 mM-1s-1 for the B16F10 and GL261 hybrid vesicles. The ratio of relaxivities r2/r1 decreased with the higher encapsulation of NPs and increased for the biomimetic liposomes. Therapeutic temperatures are achieved by both, magnetic nanoparticle hyperthermia and photothermal therapy. Photothermal conversion efficiency ∼25-30% are reported. Cell culture revealed lower wrapping times for the biomimetic vesicles. In vivo experiments with distinct routes of nanoparticle administration were investigated. Intratumoral injection proved the nanoparticle-mediated PTT efficiency. MRI and near-infrared images showed that the nanoparticles accumulate in the tumor after intravenous or intraperitoneal administration. Both routes benefit from MRI-guided PTT and demonstrate the multimodal theranostic applications for cancer therapy.

Green synthesis and characterization of polyphenol-coated magnesium-substituted manganese ferrite nanoparticles: Antibacterial and antioxidant properties

Magnesium-substituted manganese ferrite (Mn0.9Mg0.1Fe2O4) nanoparticles were obtained through a wet chemical method and coated with green-extracted polyphenol from Punica granatum peel. The obtained spinel nanocomposite was fully characterized. The X-ray diffraction pattern revealed a single phase with an average crystalline size of 3.33-8.74 nm, confirming the cubic-spinel structure. The FESEM micrograph showed a quasi-spherical shape with nearly uniform particles, indicating mild agglomeration. The mean size of the Mn0.9Mg0.1Fe2O4 was 13.66 nm with a standard deviation of 2.05. The BET isotherms indicated a surface area of 85.45 m2/g. The basic groups attached to the external surface of Mg-doped spinel ferrite were discovered. The resulted superparamagnetic modified doped-nanoferrite particles showed antibacterial activity as well as antioxidant efficiency through studying Catalase (CAT), Glutathione (GSH), and Glutathione Peroxidase (GSH-Px) parameters. The outcomes highlight the promising potential of polyphenol-functionalized Mn0.9Mg0.1Fe2O4 magnetite nanosized particles for the development of novel anti-biofilm agents.

Magnetic Properties and Magnetocaloric Effect of Polycrystalline and Nano-Manganites Pr0.65Sr(0.35-x)CaxMnO3 (x ≤ 0.3)

Here we report investigations of bulk and nano-sized Pr_0.65Sr_(0.35-x)Ca_xMnO₃ compounds (x ≤ 0.3). Solid-state reaction was implemented for polycrystalline compounds and a modified sol-gel method was used for nanocrystalline compounds. X-ray diffraction disclosed diminishing cell volume with increasing Ca substitution in Pbnm space group for all samples. Optical microscopy was used for bulk surface morphology and transmission electron microscopy was utilized for nano-sized samples. Iodometric titration showed oxygen deficiency for bulk compounds and oxygen excess for nano-sized particles. Measurements of resistivity of bulk samples revealed features at temperatures associated with grain boundary condition and with ferromagnetic (FM)/paramagnetic (PM) transition. All samples exhibited negative magnetoresistivity. Magnetic critical behavior analysis suggested the polycrystalline samples are governed by a tricritical mean field model while nanocrystalline samples are governed by a mean field model. Curie temperatures values lower with increasing Ca substitution from 295 K for the parent compound to 201 K for x = 0.2. Bulk compounds exhibit high entropy change, with the highest value of 9.21 J/kgK for x = 0.2. Magnetocaloric effect and the possibility of tuning the Curie temperature by Ca substitution of Sr make the investigated bulk polycrystalline compounds promising for application in magnetic refrigeration. Nano-sized samples possess wider effective entropy change temperature (ΔT_fwhm) and lower entropy changes of around 4 J/kgK which, however, puts in doubt their straightforward potential for applications as magnetocaloric materials.

High spin Fe(III)-doped nanostructures as T1 MR imaging probes

Magnetic Resonance Imaging (MRI) T₁ contrast agents based on Fe(III) as an alternative to Gd-based compounds have been under intense scrutiny in the last 6-8 years and a number of nanostructures have been designed and proposed for in vivo diagnostic and theranostic applications. Excluding the large family of superparamagnetic iron oxides widely used as T₂ -MR imaging agents that will not be covered by this review, a considerable number and type of nanoparticles (NPs) have been employed, ranging from amphiphilic polymer-based NPs, NPs containing polyphenolic binding units such as melanin-like or polycatechols, mixed metals such as Fe/Gd or Fe/Au NPs and perfluorocarbon nanoemulsions. Iron(III) exhibits several favorable magnetic properties, high biocompatibility and improved toxicity profile that place it as the paramagnetic ion of choice for the next generation of nanosized MRI and theranostic contrast agents. An analysis of the examples reported in the last decade will show the opportunities for relaxivity and MR-contrast enhancement optimization that could bring Fe(III)-doped NPs to really compete with Gd(III)-based nanosystems. This article is categorized under: Diagnostic Tools > In Vivo Nanodiagnostics and Imaging Diagnostic Tools > Diagnostic Nanodevices Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

1H-NMR Relaxation of Ferrite Core-Shell Nanoparticles: Evaluation of the Coating Effect

We investigated the effect of different organic coatings on the ¹H-NMR relaxation properties of ultra-small iron-oxide-based magnetic nanoparticles. The first set of nanoparticles, with a magnetic core diameter ds1 = 4.4 ± 0.7 nm, was coated with polyacrylic acid (PAA) and dimercaptosuccinic acid (DMSA), while the second set, ds2 = 8.9 ± 0.9 nm, was coated with aminopropylphosphonic acid (APPA) and DMSA. At fixed core diameters but different coatings, magnetization measurements revealed a similar behavior as a function of temperature and field. On the other hand, the ¹H-NMR longitudinal r1 nuclear relaxivity in the frequency range ν = 10 kHz ÷ 300 MHz displayed, for the smallest particles (diameter ds1), an intensity and a frequency behavior dependent on the kind of coating, thus indicating different electronic spin dynamics. Conversely, no differences were found in the r1 relaxivity of the biggest particles (ds2) when the coating was changed. It is concluded that, when the surface to volume ratio, i.e., the surface to bulk spins ratio, increases (smallest nanoparticles), the spin dynamics change significantly, possibly due to the contribution of surface spin dynamics/topology.

Smart Biomimetic Nanozymes for Precise Molecular Imaging: Application and Challenges

New nanotechnologies for imaging molecules are widely being applied to visualize the expression of specific molecules (e.g., ions, biomarkers) for disease diagnosis. Among various nanoplatforms, nanozymes, which exhibit enzyme-like catalytic activities in vivo, have gained tremendously increasing attention in molecular imaging due to their unique properties such as diverse enzyme-mimicking activities, excellent biocompatibility, ease of surface tenability, and low cost. In addition, by integrating different nanoparticles with superparamagnetic, photoacoustic, fluorescence, and photothermal properties, the nanoenzymes are able to increase the imaging sensitivity and accuracy for better understanding the complexity and the biological process of disease. Moreover, these functions encourage the utilization of nanozymes as therapeutic agents to assist in treatment. In this review, we focus on the applications of nanozymes in molecular imaging and discuss the use of peroxidase (POD), oxidase (OXD), catalase (CAT), and superoxide dismutase (SOD) with different imaging modalities. Further, the applications of nanozymes for cancer treatment, bacterial infection, and inflammation image-guided therapy are discussed. Overall, this review aims to provide a complete reference for research in the interdisciplinary fields of nanotechnology and molecular imaging to promote the advancement and clinical translation of novel biomimetic nanozymes.

Boron Vehiculating Nanosystems for Neutron Capture Therapy in Cancer Treatment

Boron neutron capture therapy is a low-invasive cancer therapy based on the neutron fission process that occurs upon thermal neutron irradiation of ¹⁰B-containing compounds; this process causes the release of alpha particles that selectively damage cancer cells. Although several clinical studies involving mercaptoundecahydro-closo-dodecaborate and the boronophenylalanine-fructose complex are currently ongoing, the success of this promising anticancer therapy is hampered by the lack of appropriate drug delivery systems to selectively carry therapeutic concentrations of boron atoms to cancer tissues, allowing prolonged boron retention therein and avoiding the damage of healthy tissues. To achieve these goals, numerous research groups have explored the possibility to formulate nanoparticulate systems for boron delivery. In this review. we report the newest developments on boron vehiculating drug delivery systems based on nanoparticles, distinguished on the basis of the type of carrier used, with a specific focus on the formulation aspects.

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.

Magnetic and Magnetocaloric Properties of Nano- and Polycrystalline Manganites La(0.7-x)EuxBa0.3MnO3

Here, we report synthesis and investigations of bulk and nano-sized La_(0.7-x)Eu_xBa_0.3MnO₃ (x ≤ 0.4) compounds. The study presents a comparison between the structural and magnetic properties of the nano- and polycrystalline manganites La_(0.7-x)Eu_xBa_0.3MnO₃, which are potential magnetocaloric materials to be used in domestic magnetic refrigeration close to room temperature. The parent compound, La_0.7Ba_0.3MnO₃, has Curie temperature T_C = 340 K. The magnetocaloric effect is at its maximum around T_C. To reduce this temperature below 300 K, we partially replaced the La ions with Eu ions. A solid-state reaction was used to prepare bulk polycrystalline materials, and a sol-gel method was used for the nanoparticles. X-ray diffraction was used for the structural characterization of the compounds. Transmission electron spectroscopy (TEM) evidenced nanoparticle sizes in the range of 40-80 nm. Iodometry and inductively coupled plasma optical emission spectrometry (ICP-OES) was used to investigate the oxygen content of the studied compounds. Critical exponents were calculated for all samples, with bulk samples being governed by tricritical mean field model and nanocrystalline samples governed by the 3D Heisenberg model. The bulk sample with x = 0.05 shows room temperature phase transition T_C = 297 K, which decreases with increasing x for the other samples. All nano-sized compounds show lower T_C values compared to the same bulk samples. The magnetocaloric effect in bulk samples revealed a greater magnetic entropy change in a relatively narrow temperature range, while nanoparticles show lower values, but in a temperature range several times larger. The relative cooling power for bulk and nano-sized samples exhibit approximately equal values for the same substitution level, and this fact can substantially contribute to applications in magnetic refrigeration near room temperature. By combining the magnetic properties of the nano- and polycrystalline manganites, better magnetocaloric materials can be obtained.

Tailoring the Magnetic and Structural Properties of Manganese/Zinc Doped Iron Oxide Nanoparticles through Microwaves-Assisted Polyol Synthesis

Tuning the fundamental properties of iron oxide magnetic nanoparticles (MNPs) according to the required biomedical application is an unsolved challenge, as the MNPs' properties are affected by their composition, their size, the synthesis process, and so on. In this work, we studied the effect of zinc and manganese doping on the magnetic and structural properties of MNPs synthesized by the microwave-assisted polyol process, using diethylene glycol (DEG) and tetraethylene glycol (TEG) as polyols. The detailed morpho-structural and magnetic characterization showed a correspondence between the higher amounts of Mn and smaller crystal sizes of the MNPs. Such size reduction was compensated by an increase in the global magnetic moment so that it resulted in an increase of the saturation magnetization. Saturation magnetization MS values up to 91.5 emu/g and NMR transverse relaxivities r2 of 294 s-1mM-1 were obtained for Zn and Mn- doped ferrites having diameters around 10 nm, whereas Zn ferrites with diameters around 15 nm reached values of MS∼ 97.2 emu/g and of r2∼ 467 s-1mM-1, respectively. Both kinds of nanoparticles were synthesized by a simple, reproducible, and more sustainable method that makes them very interesting for diagnostic applications as MRI contrast agents.

Design and Development of Gold-Loaded and Boron-Attached Multicore Manganese Ferrite Nanoparticles as a Potential Agent in Biomedical Applications

Early diagnosis and effective treatment of cancer are significant issues that should be focused on since it is one of the most deadly diseases. Multifunctional nanomaterials can offer new cancer diagnoses and treatment possibilities. These nanomaterials with diverse functions, including targeting, imaging, and therapy, are being studied extensively in a way that minimize overcoming the limitations associated with traditional cancer diagnosis and treatment. Therefore, the goal of this study is to prepare multifunctional nanocomposites possessing the potential to be used simultaneously in imaging such as magnetic resonance imaging (MRI) and dual cancer therapy such as photothermal therapy (PTT) and boron neutron capture therapy (BNCT). In this context, multi-core MnFe₂O₄ nanoparticles, which can be used as a potential MRI contrast agent and target the desired region in the body via a magnetic field, were successfully synthesized via the solvothermal method. Then, multi-core nanoparticles were coated with polydopamine (PDA) to reduce gold nanoparticles, bind boron on the surface, and ensure the biocompatibility of all materials. Finally, gold nanoparticles were reduced on the surface of PDA-coated MnFe₂O₄, and boric acid was attached to the hybrid materials for also possessing the ability to be used as a potential agent in PTT and BNCT applications in addition to being an MRI agent. According to the cell viability assay, treatment of the glioblastoma cell line (T98G) with MnFe₂O₄@PDA-Au-BA for 24 and 48 h did not cause any significant cell death, indicating good biocompatibility. All analysis results showed that the developed MnFe₂O₄@PDA-Au-BA multifunctional material could be a helpful candidate for biomedical applications such as MRI, PTT, and BNCT.

Facile synthesis of superparamagnetic nickel-doped iron oxide nanoparticles as high-performance T1 contrast agents for magnetic resonance imaging

Small-sized iron oxide nanoparticles (IONPs) are excellent alternative to clinical gadolinium-based contrast agents (GBCAs) in T1-weighted magnetic resonance imaging (MRI) due to their biosafety. However, the relaxation efficiency and contrast...