Numerical modeling and in situ small angle X-ray scattering characterization of ultra-small SPION magnetophoresis in a high field and gradient separator

Magnetic nanoparticles (MNPs) have recently gained significant attention in various fields, including chemical and biomedical applications, due to their exceptional properties. However, separating MNPs from solution via magnetophoresis is challenging when MNPs are smaller than 50 nm as Brownian forces become on the order of the magnetic forces. In this study, we successfully separated small MNPs (5-30 nm) by utilizing high magnetic fields and gradients generated by economical permanent magnets. In situ small angle X-ray scattering (SAXS) was used to investigate the time-dependent concentration changes in the ferrofluid, and the results validated that only the 30 nm particles experienced particle aggregation or agglomeration, indicating that dipole-dipole interactions did not play a discernable role in the separation process for particles smaller than ∼15 nm. However, numerical simulations have provided further validation that in the absence of particle-particle interactions, even MNPs with diameters less than 15 nm exhibited magnetophoresis that effectively counteracted the effects of Brownian motion.

Design and development of a magnetic field-enabled platform for delivering polymer-coated iron oxide nanoparticles to breast cancer cells

The current literature mostly contains relatively vague descriptions of techniques for implementing in vitro magnetic targeting delivery of iron oxide nanoparticles (IONPs), leading to irreproducible processes and incomparable findings. This discrepancy often arises from the varying exposure of IONPs to the non-uniform magnetic field and differences in the concentration of the polymer-coated IONPs. Hence, we meticulously designed and built a system comprising a platform constructed from polyoxymethylene sheets, which securely holds the permanent magnets, and the cell culture plate. We also tailored the preparation process of the IONPs and the in vitro toxicity studies. The inherent characteristics of IONPs are further enhanced by their coating with natural polymers, alginate (Alg) and chitosan (CS).•The design and construction of the platform were carried out using a laser engraving/cutting machine along with graphic design software. The precise locations of the permanent magnets relative to the cell culture plate were determined via a Gaussmeter.•The quantities of the components in the formulation and the method for fabricating the CS/Alg-coated IONPs (CS/Alg-IONPs) were optimized to ensure that the desired physicochemical properties were obtained.•The cultivation and cytotoxicity evaluation of the fabricated CS/Alg-IONPs against MCF-7 breast cancer cells were described.

Lutein-loaded chitosan/alginate-coated Fe3O4 nanoparticles as effective targeted carriers for breast cancer treatment

Magnetic drug targeting can be a strategy for effectively delivering phytochemicals in cancer treatment. Here, we demonstrate the benefit of magnetic targeting with superparamagnetic iron oxide nanoparticles for cytotoxicity enhancement of lutein (LUT) against breast cancer cells. Fabrication of LUT-loaded chitosan/alginate iron oxide nanoparticles (LUT-CS/Alg-Fe₃O₄-NPs) was optimized by a statistical approach using response surface methodology based on the Box-Behnken design. The optimized LUT-CS/Alg-Fe₃O₄-NPs with a balance among LUT concentration, copolymer coating, and iron ion concentration exhibited controlled size, narrow size distribution, better crystallinity, excellent saturation magnetization, and sustained-release profile. The negligible magnetic coercivity and remanent magnetization confirmed the superparamagnetism of the prepared NPs. The optimized LUT-CS/Alg-Fe₃O₄-NPs were biocompatible while exhibiting a significantly enhanced cytotoxicity towards breast cancer MCF-7 cells upon exposure to a permanent magnet compared to free LUT with a 4-fold increase, suggesting the potential of LUT-CS/Alg-Fe₃O₄-NPs as magnetically targeted delivery for breast cancer.

Self-Assembly and sedimentation of 5 nm SPIONs using horizontal, high magnetic fields and gradients

Superparamagnetic iron oxide nanoparticles (SPIONs) are employed in multiple applications, especially within medical and chemical engineering fields. However, their magnetic separation is very challenging as the magnetophoretic motion is hindered by thermal energy and viscous drag. Recent studies have addressed the recovery of SPIONs by a combination of cooperative magnetophoresis and sedimentation. Nevertheless, the effect of horizontal, high fields and gradients on the vertical sedimentation of SPIONs has not been described. In this work, we report, for the first time, the magnetically facilitated sedimentation of 5 nm particles by applying fields and gradients perpendicular to gravity. The magnetic field was generated by quadrupole magnetic sorters and the process was measured with time by tracking the concentration along the length of a channel contacting the 5 nm SPIONs within the quadrupole field. Our experimental data suggest that aggregates of 60-90 particles are formed in the system; thus, particle agglomeration by dipole-dipole interactions was promoted, and these clusters settled down as a result of gravitational forces. Multiple variables and parameters were evaluated, including the initial SPION concentration, the temperature, the magnetic field and gradient and operation time. It was found that the process was improved by decreasing the initial concentration and the temperature, but the magnitude of the magnetic field and gradient did not significantly affect the sedimentation. Finally, the separation process was rapid, with the systems reaching the equilibrium in approximately 20 minutes, which is a significant advantage in comparison to other systems that require longer times and larger particle sizes.

Targeted magnetic separation of biomolecules and cells using earthicle-based ferrofluids

Targeting specific molecular or cell populations within single tissues or multicomponent in vitro systems is a most sought goal in biomedicine. Here we report on targeted magnetic separation of cells and biomolecules using a ferrofluid comprising superparamagnetic iron-oxide/silicate/carbon core/shell/crust nanoparticles in combination with a handheld, 2.5 cm³ NdFeB magnet (≤180 mT) and one minute exposure time. Ferrofluids were highly effective at separating (i) biomolecules, (ii) bacteria and (iii) eukaryotic cells from solutions, and they also exhibited selectivity in the separation of all three families of entities. Specifically, they were more effective at separating the negatively charged protein, albumin in the presence of the external magnetic field, but were more effective at precipitating the positively charged protein, lysozyme without the application of the external field. Because of the more effective sorption of proteins than carbohydrates on carbon and the shielding of peptidoglycans by the transmembrane proteins and hydrophilic heads of the outer membrane amphiphiles in Gram-negative bacteria, they were separated more effectively than their Gram-positive counterparts. Ferrofluids were also more efficient at separating the clinical isolate, methicillin-resistant version of S. aureus (MRSA) than its regular, lab strain and the effect is thought to be due to structural changes to the cell envelope caused by the overexpression of efflux pumps or by the higher rate of conjugation conditioning horizontal gene transfer in MRSA than in the regular, nonresistant strain. Ferrofluids also displayed a greater affinity for the cancer cells than for the normal, primary cells and allowed for targeted separation of the former after the cells were allowed to uptake the nanoparticles for 24 h. This selectivity should allow for an effective separation of cancer cells interspersed within a healthy cell population. Interaction with bacterial and eukaryotic cells was driven neither by electrostatic attraction nor chemisorption, but by weaker, van der Waals and π-interactions. Adsorption was also endothermic, irreversible for the most part, and more favorable at high concentrations, as inferred by comparison with Langmuir, Freundlich, Temkin and Dubinin-Radushkevich isotherms. These targeted effects are relevant for numerous fields of biomedicine and biotechnologies and require further insight for optimization and translation.