Low-cost one-pot synthesis of hydrophobic and hydrophilic monodispersed iron oxide nanoparticles

The synthesis of Superparamagnetic Iron Oxide Nanoparticles (SPIONs) with size and shape tunability, which is also industrially scalable, remains challenging. Surface functionalization of the nanoparticles is yet another active research subject. Although a variety of inorganic and organometallic precursors have been tried, which are demanding in terms of both cost and effort, the use of iron hydroxide, a simple and cheap iron precursor, has not been explored in detail for the synthesis of SPIONs following a thermal decomposition route. Here, we outline a simple one-pot thermal decomposition route that avoids separate precursor preparation and purification steps and, consequently, is easily scalable. The method involves the alcoholic hydrolysis of a simple iron salt into iron hydroxide, which, on addition of oleic acid, forms the precursor oleate complex in situ, which is subsequently thermally decomposed to produce monodispersed SPIONS. Minor modifications allow for particle dimensions (5-20 nm) and morphology (spheroid or cuboid) to be controlled. Additionally, we explored a simple ligand exchange process for rendering the hydrophobic nanoparticles hydrophilic. Trisodium nitrilotriacetate (NTA), a readily available polycarboxylate, can efficiently transfer the oleate-coated SPIONs to water without the need for separation from the crude reaction mixture. X-ray Rietveld refinement showed that particles obtained by this method had both the magnetite and wustite phases of iron oxide present. Magnetic measurements confirm that the iron oxide particles are superparamagnetic at room temperature, with typical blocking temperatures of 183 K for the spherical and 212 K for the cuboid ones.

Feature Matching of Microsecond-Pulsed Magnetic Fields Combined with Fe3O4 Particles for Killing A375 Melanoma Cells

The combination of magnetic fields and magnetic nanoparticles (MNPs) to kill cancer cells by magneto-mechanical force represents a novel therapy, offering advantages such as non-invasiveness, among others. Pulsed magnetic fields (PMFs) hold promise for application in this therapy due to advantages such as easily adjustable parameters; however, they suffer from the drawback of narrow pulse width. In order to fully exploit the potential of PMFs and MNPs in this therapy, while maximizing therapeutic efficacy within the constraints of the narrow pulse width, a feature-matching theory is proposed, encompassing the matching of three aspects: (1) MNP volume and critical volume of Brownian relaxation, (2) relaxation time and pulse width, and (3) MNP shape and the intermittence of PMF. In the theory, a microsecond-PMF generator was developed, and four kinds of MNPs were selected for in vitro cell experiments. The results demonstrate that the killing rate of the experimental group meeting the requirements of the theory is at least 18% higher than the control group. This validates the accuracy of our theory and provides valuable guidance for the further application of PMFs in this therapy.

Magnetic and/or Radiopaque Functionalization of Self-Unfolding Foils for Improved Applicability within Oral Drug Delivery

Various types of microfabricated devices have been proposed for overcoming the gastrointestinal (GI) challenges associated with oral administration of pharmaceutical compounds. However, unidirectional drug release in very close forced proximity to the intestinal wall still appears to be an unresolved issue for many of these microdevices, which typically show low drug absorption and thereby low bioavailabilities. This work explores how recently developed and promising self-unfolding foils (SUFs) can be magnetically and/or radiopaquely (M/R-) functionalized, by the addition of BaSO4 or Fe3O4 nanoparticles, for improving their applicability within oral drug delivery. Through surface characterization, mechanical testing, and X-ray imaging, the (M/R-)SUFs are generally inspected and their overall properties compared. Furthermore, R-SUFs are being used in an in vivo rat X-ray imaging study, whereas in situ rat testing of MR-SUFs are attempted together with an investigation of their general magnetic properties. Unfolding of the R-SUF, and its very close forced proximity to the small intestine, is very easily observed 2 h post-administration by applying both computed tomography scanning and planar X-ray imaging. In addition, MR-SUFs show a great magnetic response in water, which suggests the possibility for controlled motion and retention in the GI tract. However, the magnetic response does not seem strong enough for in situ rat testing, but most likely a strong magnetization of the MR-SUFs using for example an impulse magnetizer can be made for increasing the magnetic response. All of the results presented herein are highly relevant and applicable for future usage of (M/R-)SUFs, as well as similar devices, in pre-clinical studies and potential clinical trials.

Magnetic Nanoparticles for Protein Separation and Purification

Proteins are essential for various functions such as brain activity and muscle contraction in humans. Even though food is a source of proteins, the bioavailability of proteins in most foods is usually limited due to matrix interaction with other biomolecules. Thus, it is essential to extract these proteins and provide them as a nutraceutical supplement to maintain protein levels and avoid protein deficiency. Hence, protein purification and extraction from natural sources are highly significant in biomedical applications. Chromatography, crude mechanical disruption, use of extractive chemicals, and electrophoresis are some of the methods applied to isolate specific proteins. Even though these methods possess several advantages, they are unable to extract specific proteins with high purity. A suitable alternative is the use of nanoparticles, which can be beneficial in protein purification and extraction. Notably, magnetic iron and iron-based nanoparticles have been employed in protein extraction processes and can be reused via demagnetization due to their magnetic property, smaller size, morphology, high surface-to-volume ratio, and surface charge-mediated property. This chapter is a summary of various magnetic nanoparticles (MNPs) that can be used for the biomolecular separation of proteins.

Magnetic Nanoparticles: Current Advances in Nanomedicine, Drug Delivery and MRI

Magnetic nanoparticles (MNPs) have evolved tremendously during recent years, in part due to the rapid expansion of nanotechnology and to their active magnetic core with a high surface-to-volume ratio, while their surface functionalization opened the door to a plethora of drug, gene and bioactive molecule immobilization. Taming the high reactivity of the magnetic core was achieved by various functionalization techniques, producing MNPs tailored for the diagnosis and treatment of cardiovascular or neurological disease, tumors and cancer. Superparamagnetic iron oxide nanoparticles (SPIONs) are established at the core of drug-delivery systems and could act as efficient agents for MFH (magnetic fluid hyperthermia). Depending on the functionalization molecule and intrinsic morphological features, MNPs now cover a broad scope which the current review aims to overview. Considering the exponential expansion of the field, the current review will be limited to roughly the past three years.

Macrophages Loaded with Fe Nanoparticles for Enhanced Photothermal Ablation of Tumors

Magnetic iron nanoparticle-based theranostics agents have attracted much attention due to their good magnetism and biocompatibility. However, efficiently enriching tumors with iron nanoparticles to enhance the treatment effect remains a pressing challenge. Herein, based on the targeting and high phagocytosis of macrophages, an Fe nanoparticle-loaded macrophage delivery system was designed and constructed to efficiently deliver iron nanoparticles to tumors. Hydrophilic Fe@Fe₃O₄ nanoparticles with a core-shell structure were synthesized by pyrolysis and ligand exchange strategy. Subsequently, they were loaded into macrophages (RAW264.7 cells) using a co-incubation method. After loading into RAW264.7, the photothermal performance of Fe@Fe₃O₄ nanoparticles were significantly enhanced. In addition, Fe@Fe₃O₄ nanoparticles loaded into the macrophage RAW264.7 (Fe@Fe₃O₄@RAW) exhibited a good T₂-weighted MRI contrast effect and clear tumor imaging in vivo due to the tumor targeting tendency of macrophages. More importantly, after being intravenously injected with Fe@Fe₃O₄@RAW and subjected to laser irradiation, the tumor growth was effectively inhibited, indicating that macrophage loading could enhance the tumor photothermal ablation ability of Fe@Fe₃O₄. The macrophage mediated delivery strategy for Fe@Fe₃O₄ nanoparticles was able to enhance the treatment effect, and has great potential in tumor theranostics.

Naproxen release from carbon dot coated magnetite nanohybrid as versatile theranostics for HeLa cancer cells

Nanohybrid magnetite carbon dots (Fe₃O₄@CDs) were successfully synthesized to improve their applicability in multi-response bioimaging. The nanohybrid was prepared via pyrolysis and further loaded with naproxen (NAP) to promote drug delivery features. The characterization of the synthesized Fe₃O₄@CDs demonstrated the existence of Fe₃O₄ crystals by matching with JCPDS 75-0033 and its narrow size distribution at 11.30 nm; further, FTIR spectra confirmed the presence of Fe–O groups, C–O stretching, C–H sp², and C–O bending, along with dual-active fluorescence and magnetic responses. The nanohybrids also exhibit particular properties such as a maximum wavelength of 230.5 nm, maximum emission in the 320–420 nm range, and slight superparamagnetic reduction (Fe₃O₄: 0.93620 emu per g; Fe₃O₄@CDs: 0.64784 emu per g). The cytotoxicity assessment of the nanohybrid revealed an excellent half-maximal inhibitory concentration (IC₅₀) of 17 671.5 ± 1742.6 μg mL⁻¹. Then, the incorporation of NAP decreased the cell viability to below 10%. The kinetic release properties of NAP are also confirmed as pH-dependent, and they follow the Korsmeyer–Peppas kinetics model. These results indicated that the proposed Fe₃O₄@CDs can be used as a new model for theranostic treatment.

Nanohybrid magnetite carbon dots (Fe₃O₄@CDs) were successfully synthesized to improve their applicability in multi-response bioimaging.