Encapsulation Of Magnetic Nanoparticles Research Articles

Biodegradation by Cancer Cells of Magnetite Nanoflowers with and without Encapsulation in PS-b-PAA Block Copolymer Micelles.

Magnetomicelles were produced by the self-assembly of magnetite iron oxide nanoflowers and the amphiphilic poly(styrene)-b-poly(acrylic acid) block copolymer to deliver a multifunctional theranostic agent. Their bioprocessing by cancer cells was investigated in a three-dimensional spheroid model over a 13-day period and compared with nonencapsulated magnetic nanoflowers. A degradation process was identified and monitored at various scales, exploiting different physicochemical fingerprints. At a collective level, measurements were conducted using magnetic, photothermal, and magnetic resonance imaging techniques. At the nanoscale, transmission electron microscopy was employed to identify the morphological integrity of the structures, and X-ray absorption spectroscopy was used to analyze the degradation at the crystalline phase and chemical levels. All of these measurements converge to demonstrate that the encapsulation of magnetic nanoparticles in micelles effectively mitigates their degradation compared to individual nonencapsulated magnetic nanoflowers. This protective effect consequently resulted in better maintenance of their therapeutic photothermal potential. The structural degradation of magnetomicelles occurred through the formation of an oxidized iron phase in ferritin from the magnetic nanoparticles, leaving behind empty spherical polymeric ghost shells. These results underscore the significance of encapsulation of iron oxides in micelles in preserving nanomaterial integrity and regulating degradation, even under challenging physicochemical conditions within cancer cells.

Magnetically Retrievable Organocatalyst: An Emergent Green Method for The Rapid Formation of Biodynamically Significant Quinolines

AbstractHerein, highly efficient organocatalyst arginine coupled magnetic nanoparticles have been synthesized and aiming to catalyze synthesis of biodynamically significant quinolines. Results indicate that the catalyst is compatible with a wide range of functional groups and generates various quinoline derivatives in good to excellent yields under solvent free condition. Superior activity of the reported catalyst can be combine with the synergistic effect of the following factors: Firstly use of iron oxide nanoparticles as supports provide large surface areas, high surface‐to‐volume ratio, high reactivity and selectivity and lower consumption of energy, Secondly encapsulation of MNPs (Magnetic Nanoparticles) with L‐arginine not only prevent magnetic aggregation but also imparts many desirable properties like high thermal and chemical stability, finely disperse active sites and enhanced activity. Thirdly use of environmentally more benign, non‐toxic and much cheaper L‐arginine amino acid for coating agent need simple handling and storage. Fourthly potential recovery of this catalytic system by an external magnet, reduces waste, labour and cost, thus satisfy the requirements of green chemistry. Moreover such coating also provides sites for functionalization with other organic groups and thereby broaden their applicability in various research areas such as drug delivery, magnetic resonance imaging, biomedicine and especially in the field of heterocatalysis.

Synthesis of a thermoresponsive crosslinked MEO2MA polymer coating on microclusters of iron oxide nanoparticles

Encapsulation of magnetic nanoparticles (MNPs) of iron (II, III) oxide (Fe3O4) with a thermopolymeric shell of a crosslinked poly(2-(2-methoxyethoxy)ethyl methacrylate) P(MEO2MA) is successfully developed. Magnetic aggregates of large size, around 150–200 nm are obtained during the functionalization of the iron oxide NPs with vinyl groups by using 3-butenoic acid in the presence of a water soluble azo-initiator and a surfactant, at 70 °C. These polymerizable groups provide a covalent attachment of the P(MEO2MA) shell on the surface of the MNPs while a crosslinked network is achieved by including tetraethylene glycol dimethacrylate in the precipitation polymerization synthesis. Temperature control is used to modulate the swelling-to-collapse transition volume until a maximum of around 21:1 ratio between the expanded: shrunk states (from 364 to 144 nm in diameter) between 9 and 49 °C. The hybrid Fe3O4@P(MEO2MA) microgel exhibits a lower critical solution temperature of 21.9 °C below the corresponding value for P(MEO2MA) (bulk, 26 °C). The MEO2MA coating performance in the hybrid microgel is characterized by dynamic light scattering and transmission electron microscopy. The content of preformed MNPs [up to 30.2 (wt%) vs. microgel] was established by thermogravimetric analysis while magnetic properties by vibrating sample magnetometry.

In vitro characterization of a novel magnetic fibrin-agarose hydrogel for cartilage tissue engineering

The encapsulation of cells into biopolymer matrices enables the preparation of engineered substitute tissues. Here we report the generation of novel 3D magnetic biomaterials by encapsulation of magnetic nanoparticles and human hyaline chondrocytes within fibrin-agarose hydrogels, with potential use as articular hyaline cartilage-like tissues. By rheological measurements we observed that, (i) the incorporation of magnetic nanoparticles resulted in increased values of the storage and loss moduli for the different times of cell culture; and (ii) the incorporation of human hyaline chondrocytes into nonmagnetic and magnetic fibrin-agarose biomaterials produced a control of their swelling capacity in comparison with acellular nonmagnetic and magnetic fibrin-agarose biomaterials. Interestingly, the in vitro viability and proliferation results showed that the inclusion of magnetic nanoparticles did not affect the cytocompatibility of the biomaterials. What is more, immunohistochemistry showed that the inclusion of magnetic nanoparticles did not negatively affect the expression of type II collagen of the human hyaline chondrocytes. Summarizing, our results suggest that the generation of engineered hyaline cartilage-like tissues by using magnetic fibrin-agarose hydrogels is feasible. The resulting artificial tissues combine a stronger and stable mechanical response, with promising in vitro cytocompatibility. Further research would be required to elucidate if for longer culture times additional features typical of the extracellular matrix of cartilage could be expressed by human hyaline chondrocytes within magnetic fibrin-agarose hydrogels.

Comprehensive Evaluation of Gene Expression in Negative and Positive Trigger-based Targeting Niosomes in HEK-293 Cell Line.

An efficient gene delivery system has some critical factors that enhance the efficiency of nanocarrier. These factors are low production cost, high bioavailability, high encapsulation efficiency, controllable release, and targeting ability. Niosome (the nonionic surfactant vesicles) was considered as a promising gene delivery system. Niosome can increase stability and uptake of active agents. We used all mentioned factors in one optimized formulation entitled plasmid- loaded magnetic niosomes (PMN). To increase the bioavailability of niosomes, we used ergosterol (a natural lipid) instead of cholesterol in structure of niosome. Also, cetyl trimethyl ammonium bromide (CTAB) in different concentrations was used to improve encapsulation of plasmid and compared to niosomes that did not have CTAB (negative niosome). Afterward, magnetic nanoparticle (Fe3O4@SiO2) was synthesized and loaded into niosome to obtain targeting ability. Prepared formulations were evaluated regarding size, zeta potential, morphology, encapsulation of magnetic nanoparticles and plasmid (Pm-cherry-N1), release rate, and transfection efficiency. Results demonstrated that optimum formulation (Nio/CTAB3%/Fe/P) has a nanometric size (118 ± 2.31 nm, positive zeta potential (+25 ± 0.67 mV), high loading of plasmid (72%), and good gene expression (35%). Interestingly, after applying a magnetic field below the cell plate, we obtained ac increased gene expression from 35% to 42%. These results showed that this new formulation would have a promising future and also can be used for delivering the other drugs and active agents.

Functional film by trigger-free self-assembly of adhesive soft microgels at skin temperature

Trigger-free self-assembly of oligo(ethylene glycol) OEG-based responsive microgels is for the first time described via simple solvent evaporation process at skin temperature and ambient pressure. This unique behaviour is attributed to the intrensic OEG microgel structure and properties due to a negative glass transition temperature, a high adhesion energy, an elastic mechanical property and a high interpenetration of microgels, combined in an all-in-one building block. Furthermore, the encapsulation of magnetic nanoparticles (NPs) into the OEG-based microgels introduced interferential photonic and magnetic properties to the films. These microgels exhibiting simultaneously spontaneous film-forming and colored photonic properties open up the development of a unique easy-to-handle material for cosmetic applications, but also smart patches for healthcare or medicine.

Design of parenteral MNP-loaded PLGA nanoparticles by a low-energy emulsification approach as theragnostic platforms for intravenous or intratumoral administration

Encapsulation of magnetic nanoparticles (MNP) into PLGA nanoparticles has been achieved by nano-emulsion templating using for the first time both, a low-energy emulsification method as well as biocompatible components accepted for pharmaceuticals intended for human use. The incorporation of MNP by nano-emulsion templating method proposed in this work has been investigated in two different systems applying mild process conditions and is shown to be simple and versatile, providing stable MNP-loaded PLGA nanoparticles with tunable size and MNP concentration. MNP-loaded PLGA nanoparticles showed sizes below 200nm by DLS and 50nm by TEM, and mean MNP loading per PLGA nanoparticle of 1 to 4, depending on the nanoparticle dispersion composition. Physical-chemical features suggest that the MNP-loaded PLGA nanoparticles obtained are good candidates for intravenous or intratumoral administration.

Magnetically‐Confined Fe‐Mn Bimetallic Oxide Encapsulation as an Efficient and Recoverable Adsorbent for Arsenic(III) Removal

Synthesis of bimetallic‐oxide‐encapsulated magnetic nanoparticles is still significantly challenging and has rarely been attempted previously, due to the effects of lattice mismatch, weak chemical interactions and variances in growth rates between different components, as well as the difficulty in process control for uniform co‐deposition. In the present work, Fe‐Mn bimetallic oxide (FMBO) nanoplatelet encapsulated magnetic nanoparticles (Mag‐FeMn) are prepared by controlled engineering of the interparticle coupling of Fe3O4 and FMBO, with its multifunctional capabilities highlighted in terms of the potentially superior As(III) sequestration and convenient recoverability. Multiple characterization techniques are employed to examine the derived morphologies and to accurately resolve both compositionally and magnetically the hierarchical structure in detail. The synthesized magnetic composites retain highly porous structure with the main components of Fe2O3, FeOOH, Fe3O4, and Mn3O4. Mag‐FeMn exhibits a quite competitive high capacity for As(III) capture (56.1 mg g–1), whereby As(III) oxidation coupled with synchronous sorption contributes to the improved performance. The unique heterostructure of FMBO encapsulation with an embedded magnetic core would be applicable to help with rational synthesis of other bimetallic oxide encapsulated magnetic nanoparticles, and definitely shows promise for the development of new nanotechnology enabled approaches for adsorption‐based water purification.

One-pot synthesis of dual-stimuli responsive hybrid PNIPAAm-chitosan microgels

Abstract The incorporation of magnetic nanoparticles into poly(N-isopropylacrylamide) (PNIPAAm) and chitosan microgels gives rise to hybrid systems that combine the microgels swelling capacity with the interesting features presented in magnetic nanoparticles. The presence of chitosan that act as surfactant for magnetic nanoparticles provides a simplistic approach which allows the encapsulation of magnetic nanoparticles without any previous surface modification. Spherical and highly monodisperse microgels with diameters in the range of 200 to 500 nm were obtained. The encapsulation of magnetic nanoparticles in the polymer matrix was confirmed by high resolution Scanning Electron Microscopy in transmission mode. Volume phase transition of the microgels was accessed by Dynamic Light Scattering measurements. It was observed that the thermosensitivity of the PNIPAM microgels still persists in the hybrid microgels; however, the swelling ability is compromised in the microgels with highest chitosan content. The heating performance of the hybrid magnetic microgels, when submitted to an alternating magnetic field, was also evaluated demonstrating the potential of these systems for hyperthermia treatments.

Composite Chitosan/Agarose Ferrogels for Potential Applications in Magnetic Hyperthermia.

Composite ferrogels were obtained by encapsulation of magnetic nanoparticles at two different concentrations (2.0 and 5.0 % w/v) within mixed agarose/chitosan hydrogels having different concentrations of agarose (1.0, 1.5 and 2.0% (w/v)) and a fixed concentration of chitosan (0.5% (w/v)). The morphological characterization carried out by scanning electron microscopy showed that dried composite ferrogels present pore sizes in the micrometer range. Thermogravimetric measurements showed that ferrogels present higher degradation temperatures than blank chitosan/agarose hydrogels without magnetic nanoparticles. In addition, measurements of the elastic moduli of the composite ferrogels evidenced that the presence of magnetic nanoparticles in the starting aqueous solutions prevents to some extent the agarose gelation achieved by simply cooling chitosan/agarose aqueous solutions. Finally, it is shown that composite chitosan/agarose ferrogels are able to heat in response to the application of an alternating magnetic field so that they can be considered as potential biomaterials to be employed in magnetic hyperthermia treatments.

Encapsulation of magnetic nanoparticles in poly(methyl methacrylate) by miniemulsion and evaluation of hyperthermia in U87MG cells

Magnetic nanoparticles (MNPs) are promising materials for hyperthermia treatment and magnetic targeting systems. The objective of this work was to synthesize and characterize magnetic nanoparticles coated with oleic acid (MNPsOA) loaded with poly(methyl methacrylate) prepared by miniemulsion polymerization (MNPs-PMMA) and evaluate their cytotoxicity in murine fibroblast (L929) cells, blood biocompatibility (hemolysis assay) and hyperthermia (HPT) in human glioblastoma (U87MG) cells. The MNPs-PMMA nanoparticles presented average mean diameter of 99±1.9nm with a polydispersity index (PdI) of 0.13±0.15 and saturation magnetization (Ms) value of 34emu/g of iron oxide, as well as superparamagnetic proprieties. The MNPs-PMMA nanoparticles did not present cytotoxicity in murine fibroblast (L929) and U87MG cells. HPT assays were applied, demonstrating that AC magnetic field application (1MHz and 40Oe) for 3min or 6min reduced the viability cells by 75% and 52% respectively. Morphological analyses showed that U87MG cells treated with 0.1μgmL−1 of MNPs-PMMA nanoparticles shrank after AC magnetic field application for 6min, resulting in a region of hypoxia. Hemolysis assay showed that MNPs-PMMA nanoparticles presented high blood biocompatibility. Our results indicate that MNPs-PMMA nanoparticles obtained by miniemulsion polymerization have the potential to be used as carrier systems for HPT.

Large-scale synthesis and characterization of magnetic poly(acrylic acid) nanogels via miniemulsion polymerization

A facile method for the large-scale preparation of poly(acrylic acid) (PAA) nanogels was reported by miniemulsion polymerization. After the encapsulation of magnetic nanoparticles, magnetic PAA nanogels were fabricated successfully.

Chitosan/maghemite composite: A magsorbent for the adsorption of methyl orange

In this study, magnetic beads were prepared by encapsulation of magnetic nanoparticles in epichlorohydrin cross-linked chitosan beads. Their adsorption characteristics were assessed by using methyl orange (MO) as an adsorbate. MO adsorption onto chitosan beads was found to be optimal in the pH range of 3–5. The adsorption isotherm was well described by the Langmuir model and showed high MO adsorption capacity (2.38mmol/g, i.e. 779mg/g). MO adsorption kinetics followed a pseudo-second-order kinetic model, indicating that adsorption was the rate-limiting step. At 0.305mmol/L, only 19min was required to reach 90% adsorption and 50% of the MO was adsorbed in 2min. Desorption studies of MO using NaOH showed the reusability of the magsorbent. No release of iron species was observed at pH>2.4.

Encapsulation of magnetic nanoparticles in a pH-sensitive poly(4-vinyl pyridine) polymer: a step forward to a multi-responsive system

A multiresponsive system that consists on pH-responsive polymer microspheres with encapsulated iron oxide magnetic nanoparticles that rendered the core magnetic to enable externally controlled actuation under magnetic induction has been developed. The inorganic nanoparticles were first prepared and, then, further encapsulated in a pH-sensitive poly(4-vinylpyridine). These spheres have been obtained by a modification of the simple, rapid and high-reproducible nanoprecipitation method. Magnetic measurements showed that the iron oxide nanoparticles are superparamagnetic and, therefore, able to undergo a local increase of the temperature when an oscillating magnetic field is applied. Magnetically triggered heating and pH sensitivity can be useful for biomedical applications.

Shape-Memory Properties of Nanocomposites based on Poly(ω-pentadecalactone) and Magnetic Nanoparticles

ABSTRACTMagneto-sensitive shape-memory polymers (SMP) obtained by incorporating magnetic nanoparticles in a SMP matrix are an emerging class of multifunctional materials. The incorporation of the nanoparticles enhanced the mechanical properties and in addition enabled remote actuation by exposure to alternating magnetic fields. Here, we report on the thermallyinduced shape-memory properties of such magneto-sensitive nanocomposites based on poly(ω- pentadecalactone) (PPDL) switching segments and magnetic nanoparticles. A series of nanocomposites were prepared by crosslinking of poly(ω-pentadecalactone)dimethacrylate (Mn = 2800 g·mol-1and 5100 g·mol-1) in the presence of silica encapsulated magnetic nanoparticles. The silica shell of the nanoparticles was selected to enhance the distribution and compatibility of the nanoparticles with the polymer matrix. Thermal and mechanical properties of the nanocomposites were explored as a function of PPDL chain length and nanoparticle weight content. All nanocomposites exhibited excellent shape-memory properties with shape fixity rates between 86% and 93% and shape recovery rates above 97%. Potential applications for such shape-memory nanocomposites include smart implants, medical instruments, which could be controlled on demand by thermal or indirect magnetic heating.

PH-responsive polymeric-cargo encapsulated magnetic nanoparticles for selective release and imaging

Stichodactyla helianthus neurotoxin (ShK) is an immunomodulatory peptide currently under development for the treatment of autoimmune diseases, including multiple sclerosis and rheumatoid arthritis by parenteral administration. To overcome the low patient compliance of conventional self-injections, we have investigated the potential of the buccal mucosa as an alternative delivery route for ShK both in vitro and in vivo. After application of fluorescent 5-Fam-ShK to untreated porcine buccal mucosa, there was no detectable peptide in the receptor chamber using an in vitro Ussing chamber model. However, the addition of the surfactants sodium taurodeoxycholate hydrate or cetrimide, and formulation of ShK in a chitosan mucoadhesive gel, led to 0.05–0.13% and 1.1% of the applied dose, respectively, appearing in the receptor chamber over 5 h. Moreover, confocal microscopic studies demonstrated significantly enhanced buccal mucosal retention of the peptide (measured by mucosal fluorescence associated with 5-Fam-ShK) when enhancement strategies were employed. Administration of 5-Fam-ShK to mice (10 mg/kg in a mucoadhesive chitosan-based gel (3%, w/v) with or without cetrimide (5%, w/w)) resulted in average plasma concentrations of 2.6–16.2 nM between 2 and 6 h, which were substantially higher than the pM concentrations required for therapeutic activity. This study demonstrated that the buccal mucosa is a promising administration route for the systemic delivery of ShK for the treatment of autoimmune diseases.

Selective preparation of novel fluoroalkyl end-capped co-oligomeric nanocomposite-encapsulated magnetites and magnetite-adsorbing co-oligomeric nanoparticles

New crosslinked fluoroalkyl end-capped co-oligomeric nanocomposite-encapsulated magnetic nanoparticles, prepared by the deprotecting reactions of corresponding fluorinated co-oligomers containing oxime-blocked segments in the presence of magnetic nanoparticles, were produced with nanometer-scale diameters (with diameters in the range of 154–192 nm). The nanoparticles exhibited good dispersibility in traditional organic solvents. They were applied as a surface modification to poly(methyl methacrylate), resulting in good oleophobicity imparted by the fluorine and magnetic properties arising from the encapsulated magnetic nanoparticles. Fluoroalkyl end-capped 2-acrylamido-2-methylpropanesulfonic acid co-oligomers containing adamantane segments form nanometer-sized controlled fine particles in methanol and can interact with magnetic nanoparticles to form fluorinated betaine-type co-oligomeric nanocomposite-encapsulated magnetic nanoparticles (with an average particle size of 25–183 nm). These fluorinated betaine-type nanocomposite-encapsulated magnetic nanoparticles exhibit the lower critical solution temperature (LCST) characteristic in organic media such as t-butyl alcohol and were found to effectively decrease the LCST through the encapsulation of magnetic nanoparticles in fluorinated co-oligomeric nanoparticle cores. Interestingly, transmission electron microscopy images show that magnetic nanoparticles can be encapsulated inside the crosslinked fluorinated co-oligomeric nanocomposite cores; in contrast, magnetic nanoparticles are adsorbed on the surface of fluorinated betaine-type co-oligomeric nanocomposite cores.

A Novel Process to Prepare Magnetic Polymer Microspheres

Abstract A new process for preparation of magnetic microspheres was investigated. In this process, the formation and the encapsulation of magnetic nanoparticles were accomplished in one step. The magnetic polymer microspheres exhibited superparamagnetic property and had a spherical shape with a smooth surface. This method can be used to prepare inorganic and organic composite particle when the inorganic particles can be prepared by chemical coprecipitation reaction.

Synthesis and characteristics of carbon encapsulated magnetic nanoparticles produced by a hydrothermal reaction

A novel process to synthesize carbon encapsulated magnetic nanoparticles was developed by heating an aqueous glucose solution containing Fe@Au (Au coated Fe nanoparticles) or Ni nanoparticles at 160–180 °C for 2 h. In comparison with traditional methods, such a hydrothermal approach is not only simple but also able to provide functional groups such as –OH on the surface of carbon sphere. Only pure Fe nanoparticles did not favor the formation of carbon encapsulated magnetic nanoparticles due to the oxidation of Fe nanoparticles by H 2O during the reaction and their surfaces had to be coated by an Au shell in advance. The results of TEM, HRTEM, XRD, XPS and vibration sample magnetometer characterization show that uniform carbon spheres containing some embedded Fe@Au nanoparticles with a saturation of 14.6 emu/g are obtained and the size of a typical product is 200 nm. Carbon encapsulated Ni nanoparticles have been successfully prepared in the same way.

Some Immobilization Modes of Biologically Active Substances to Fine Magnetic Particles

Summary This paper describes the preparation, characterization and compare of three different modes for coupling biologically active substances to magnetic particles: (i) covalently bound proteins and enzymes to freshly prepared magnetite in the presence of carbodiimide (CDI), (ii) the encapsulation of magnetic nanoparticles and drugs in lipid mixture dipalmitoylphosphatidylcholine (DPPC) and (iii) the encapsulation of magnetic nanoparticles and drugs in biodegradable poly D,L-lactide polymer (PLA).