Monodisperse Magnetic Nanoparticles Research Articles

Ionizable copolymer functionalized magnetic nanocomposite as an adsorbent for boosting the extraction selectivity of aristolochic acids.

Aristolochic acid nephropathy (AAN) has drawn increasing public attention. Organic anion transporters (OATs) are considered to be responsible for mediating nephrotoxicity of aristolochic acids (AAs), as AAs are typical OAT1 substrates that exhibit anionic properties and contain one hydrophobic domain. Inspired by the OAT1 three-dimensional structure or substrate/protein interactions involved in transport, we designed a magnetic polymeric hybrid, mimicking the effect of basic and aromatic residues of OAT1, for efficient enriching aristolochic acid I (AA I) and aristolochic acid II (AA II) in Traditional Chinese patent medicines (TCPM). N, N-dimethylaminopropyl acrylamide (DMAPAm) was used as a cationic monomer and copolymerized with divinylbenzene (DVB) onto the surface of monodisperse magnetic nanoparticles (denoted as MNs@SiO2T-DvbDam). The magnetic polymer hybrid demonstrated high selectivity and capacity for AAs, which was mainly attributed to (1) electrostatic interactions from the cationic or basic moiety of DMAPAm and (2) the hydrophobic and π-π stacking interactions from the aromatic ring of DVB. Additionally, the surface of the hybrid exhibited amphiphilic property according to the ionization of DMAPAm, thus improving the compatibility of the adsorbent with the aqueous sample matrix. This strategy was proven to be robust in the analysis of real drug samples, which was characterized by a good linearity, high recovery and satisfactory reusability. This work confirmed that the proposed tool could be a promising candidate for enhancing the extraction selectivity of AAs in Traditional Chinese medicines (TCM).

New polymer brush-coated monodisperse magnetic nanoparticles prepared via interface-mediated RAFT polymerization for high-throughput DNA extraction from pathogen bacteria

Polymerase chain reaction (PCR) is gold-standard method for molecular detection of pathogens. DNA extraction from a complex biological medium is a crucial process for PCR based detection. Recently, magnetic nanoparticles-based methods are of great interest for genetic material isolation. In our work, we offer new magnetic nanoparticles based high-throughput DNA extraction method for pathogen detection in biofluids. For this purpose, first time polymer brush coated monodisperse magnetic nanoparticles were prepared with interface-mediated RAFT polymerization to be used in DNA extraction process. After synthesizing Fe3O4 nanoparticles, silica shell was coated on the magnetic nanoparticle core. Polymer brushes was immobilized on the amine functionalized silica layer using RAFT agent. Subsequently, the resulting particles with poly(vinylbenzyltrimethylammonium chloride) (PVBTAC) grafted were finalized through interface-mediated RAFT polymerization. The functional groups on the nanoparticles were characterized using FTIR spectroscopy. Size distribution and zeta potential analysis of the particles were performed by TEM and Zeta-sizer respectively. Adsorption and recovery studies of plasmid DNA were carried out on the polymer-coated magnetic nanoparticles. The developed particle provided both the rapid extraction of DNA and high-yield DNA recovery without requiring extended incubation and elution time. The maximum adsorption capacity was determined as 238.1 μg/mg. About 90 % of the input DNA was recovered. The total time of DNA extraction took just 20 min. We have successfully demonstrated the extraction of dsDNA of Enterococcus faecalis spiked to reference blood sample using the developed magnetic particles. The extracted plasmid DNA and dsDNA were confirmed by gel electrophoresis and qPCR methods respectively. The results showed that the proposed magnetic iron oxide nanoparticles (MIONp) will be a strong candidate for DNA extraction process from biological matrices.

Small-angle X-ray scattering to quantify the incorporation and analyze the disposition of magnetic nanoparticles inside cells

Access to detailed information on cells loaded with nanoparticles with nanoscale precision is of a long-standing interest in many areas of nanomedicine. In this context, designing a single experiment able to provide statistical mean data from a large number of living unsectioned cells concerning information on the nanoparticle size and aggregation inside cell endosomes and accurate nanoparticle cell up-take is of paramount importance. Small-angle X-ray scattering (SAXS) is presented here as a tool to achieve such relevant data. Experiments were carried out in cultures of B16F0 murine melanoma and A549 human lung adenocarcinoma cell lines loaded with various iron oxide nanostructures displaying distinctive structural characteristics. Five systems of water-dispersible magnetic nanoparticles (MNP) of different size, polydispersity and morphology were analyzed, namely, nearly monodisperse MNP with 11 and 13 nm mean size coated with meso-2,3-dimercaptosuccinic acid, more polydisperse 6 nm colloids coated with citric acid and two nanoflowers (NF) systems of 24 and 27 nm in size resulting from the aggregation of 8 nm MNP. Up-take was determined for each system using B16F0 cells. Here we show that SAXS pattern provides high resolution information on nanoparticles disposition inside endosomes of the cytoplasm through the structure factor analysis, on nanoparticles size and dispersity after their incorporation by the cell and on up-take quantification from the extrapolation of the intensity in absolute scale to null scattering vector. We also report on the cell culture preparation to reach sensitivity for the observation of MNP inside cell endosomes using high brightness SAXS synchrotron source. Our results show that SAXS can become a valuable tool for analyzing MNP in cells and tissues.

Improved Solvothermal Synthesis of γ-Fe2O3 Magnetic Nanoparticles for SiO2 Coating.

Monodisperse magnetic γ-Fe2O3 nanoparticles (MNPs) were prepared by a simple, improved, one-pot solvothermal synthesis using SDS and PEG 6000 as double capping reagents. This double protecting layer afforded better MNP uniformity (Z average 257 ± 11.12 nm, PDI = 0.18) and colloidal stability. Materials were characterized by DLS, SEM, TEM, XPS, and XRD. The use of these MNPs in the synthesis of core–shell structures with uniform and tunable silica coatings was demonstrated, as silica coated MNPs are important for use in a range of applications, including magnetic separation and catalysis and as platforms for templated nanogel synthesis.

Deep eutectic solvent electrolysis for preparing water-soluble magnetic iron oxide nanoparticles.

Magnetic iron oxide nanoparticles have been proven to have versatile applications in biomedicine. Although numerous strategies have been developed to synthesize hydrophilic magnetic nanoparticles, there is still a challenge in the quantity and controllability of preparation of highly dispersible, stably water-dispersive magnetic nanoparticles. The current work presents a deep-eutectic solvent electrolysis to synthesize magnetic nanoparticles. In the electrolysis process, iron atoms at the anode electrode are oxidized to ferric ions, and then the ferric ions are combined with reactive oxygen species that derived from the decomposition of deep-eutectic solvents to form iron oxide nanocrystals. Concomitantly, hydrophilic radicals of amine groups produced by electrolyte decomposition are grafted on the particles. The monodisperse nanoparticle size ranged from 6 to 9 nm. The hydrophilic group loaded nanoparticles can be highly dispersed in water with neither surface post-modification nor organic stabilizers. The hydrodynamic particle diameter is between 20 and 30 nm. The transparent aqueous dispersions can be maintained for more than 600 days without precipitation.

Carboxymethyl group activation of dextran cross-linked superparamagnetic iron oxide nanoparticles

Synthesis of monodispersed magnetic nanoparticles with a highly stable and biocompatible were developed for biomedical applications in nanomedicine. In this work, the hydrophilic colloidal SPIONs was synthesized in the presence of dextran matrix by in-situ co-precipitation method. In this way, agglomeration of magnetic nanoparticles due to their intrinsic magnetic force was avoided. Moreover, a facial stepwise process was developed for carboxymethyl activated cross-linked superparamagnetic iron oxide nanoparticles (CM-CL-SPIONs). Image analysis results show that the average core particle diameter is around 5.7 nm once formed, and does not change significantly during both crosslinking and carboxymethylation process. The results of FT-IR spectra imply that the surface of SPIONs is successively modified with dextran molecules and their activation with carboxylic groups. The endothermic peak shift determined by DSC provides a supplementary evidence of the successful crosslinking and activation of CMD. The cytotoxicity of particles is examined by MTT assay, which is performed after incubation of human osteosarcoma cells with CL-SPIONs and CM-CL-SPIONs for 24 h in vitro. MG63 cells incubated with CL-SPIONs and CM-CL-SPIONs show similar cell viability and morphologies to that of controls, demonstrating that CM-CL-SPIONs do not have any significant adverse effect on cells. The introduction of a carboxylic functional group into the coating layer after crosslinking extends the feasibility of covalent attachment of bioactive molecules, such as proteins, peptides and oligonucleotides to SPIONs, while minimizing the potential problem of dissociation. The CM-CL-SPIONs can be used as versatile backbone nanocarriers in potential biomedical applications. Several characterization techniques are used to prove the step-by-step success of the synthetic procedure.

Injectable ferrimagnetic silk fibroin hydrogel for magnetic hyperthermia ablation of deep tumor

Due to the well-recognized biocompatibility, silk fibroin hydrogels have been developed for biomedical applications including bone regeneration, drug delivery and cancer therapy. For the treatment of cancer, silk-based photothermal agents exhibit the high photothermal conversion efficiency, but the limited light penetration depth of photothermal therapy restricts the treatment of some tumors in deep positions, such as liver tumor and glioma. To provide an alternative strategy, here we developed an injectable magnetic hydrogel based on silk fibroin and iron oxide nanocubes (IONCs). The as-prepared ferrimagnetic silk fibroin hydrogel could be easily injected through a syringe into tumor, especially rabbit hepatocellular carcinoma in deeper positions using ultrasound-guided interventional treatment. Compared with photothermal agents, the embedded IONCs endowed the ferrimagnetic silk fibroin hydrogel with remote hyperthermia performance under an alternating magnetic field, resulting in the effective magnetic hyperthermia of deep tumors including subcutaneously implanted tumor model in Balb/c mouse after the coverage of a fresh pork tissue and orthotopic transplantation liver tumor in rabbit. Furthermore, due to the confinement of IONCs in silk fibroin hydrogel, the undesired thermal damage toward normal tissue could be avoided compared with directly administrating monodispersed magnetic nanoparticles.

Synthesis and Characterization of Monodisperse Magnetic Nanoparticles by a Scanning Susceptometer

Synthesis and Characterization of Monodisperse Magnetic Nanoparticles by a Scanning Susceptometer

Phosphate glasses containing monodisperse Fe3−δO4@SiO2 stellate nanoparticles obtained by melt-quenching process

The challenge to obtain stable glasses containing monodisperse magnetic nanoparticles with controlled size and shape is an exciting and almost unexplored field of research. Such new materials can be used in magneto-photonics or ultra-sensitive magnetic sensors. In this work, for the first time, colorless and transparent bulk glasses containing monodisperse 20 nm Fe3−δO4 nanoparticles were prepared by a melt-quenching route. Magnetic nanoparticles were synthesized by thermal decomposition and covered with a stellate mesoporous silica shell in order to protect them against dissolution during the glass melting process. The incorporation of nanoparticles into glasses and the ideal parameters obtained for this system are discussed. The new nanocomposite materials were characterized in order to investigate the structure, thermal, and magnetic properties. Such an original approach is a very promising way to incorporate a wide panel of nanoparticles, including metallic, bimetallic and metal oxide nanoparticles, into a variety of glasses providing new properties to these materials.

Characterization and Relaxation Properties of a Series of Monodispersed Magnetic Nanoparticles.

Magnetic iron oxide nanoparticles are relatively advanced nanomaterials, and are widely used in biology, physics and medicine, especially as contrast agents for magnetic resonance imaging. Characterization of the properties of magnetic nanoparticles plays an important role in the application of magnetic particles. As a contrast agent, the relaxation rate directly affects image enhancement. We characterized a series of monodispersed magnetic nanoparticles using different methods and measured their relaxation rates using a 0.47 T low-field Nuclear Magnetic Resonance instrument. Generally speaking, the properties of magnetic nanoparticles are closely related to their particle sizes; however, neither longitudinal relaxation rate nor transverse relaxation rate changes monotonously with the particle size . Therefore, size can affect the magnetism of magnetic nanoparticles, but it is not the only factor. Then, we defined the relaxation rates (i = 1 or 2) using the induced magnetization of magnetic nanoparticles, and found that the correlation relationship between relaxation rate and relaxation rate is slightly worse, with a correlation coefficient of = 0.8939, while the correlation relationship between relaxation rate and relaxation rate is very obvious, with a correlation coefficient of = 0.9983. The main reason is that relaxation rate is related to the magnetic field inhomogeneity, produced by magnetic nanoparticles; however relaxation rate is mainly a result of the direct interaction of hydrogen nucleus in water molecules and the metal ions in magnetic nanoparticles to shorten the relaxation time, so it is not directly related to magnetic field inhomogeneity.

Magnetic cationic liposomal nanocarriers for the efficient drug delivery of a curcumin-based vanadium complex with anticancer potential

In this work novel magnetic cationic liposomal nanoformulations were synthesized for the encapsulation of a crystallographically defined ternary V(IV)-curcumin-bipyridine (VCur) complex with proven bioactivity, as potential anticancer agents. The liposomal vesicles were produced via the thin film hydration method employing N-[1-(2,3-dioleoyloxy)propyl]-N,N,N-trimethylammonium (DOTAP) and egg phosphatidylcholine lipids and were magnetized through the addition of citric acid surface-modified monodispersed magnetite colloidal magnetic nanoparticles. The obtained nanoformulations were evaluated for their structural and textural properties and shown to have exceptional stability and enhanced solubility in physiological media, demonstrated by the entrapment efficiency and loading capacity results and the in vitro release studies of their cargo. Furthermore, the generated liposomal formulations preserved the superparamagnetic behavior of the employed magnetic core maintaining the physicochemical and morphological requirements for targeted drug delivery applications. The novel nanomaterials were further biologically evaluated for their DNA interaction potential and were found to act as intercalators. The findings suggest that the positively charged magnetic liposomal nanoformulations can generate increased concentration of their cargo at the DNA site, offering a further dimension in the importance of cationic liposomes as nanocarriers of hydrophobic anticancer metal ion complexes for the development of new multifunctional pharmaceutical nanomaterials with enhanced bioavailability and targeted antitumor activity.

A robust method for fabrication of monodisperse magnetic mesoporous silica nanoparticles with core-shell structure as anticancer drug carriers

This paper presents a novel method based on an inverse microemulsion system to synthesize monodisperse magnetic mesoporous silica nanoparticles (MMSN) with core-shell structure. In this method, the water-in-oil microemulsion system was prepared using of cyclohexane containing silica precursor as a continuous oil phase, discrete water droplets containing magnetic seeds (Fe3O4 nanoparticles) and urea as an aqueous phase, and cetyltrimethylammonium bromide (CTAB) and 1-butanol as a surfactant and co-surfactant, respectively. Unlike the traditional reverse microemulsion method, the magnetic seeds used in this system were first covered by a self-organized two-layer surfactant including oleic acid and CTAB as a good host for silica formation. Hence, by removing the CTAB template from the silica structure, a mesoporous silica shell remains on the surface of Fe3O4 nanoparticles. The effects of catalyst types (urea and NaOH), TEOS content, and reaction temperature on the morphology and size of the prepared samples were investigated. It was found that by rising the reaction temperature from 70 to 120 °C, the thickness of the silica layer was increased from 3 to 17 nm. Moreover, a thicker silica coating (26 nm) was obtained by increasing the TEOS content. Also, the performance of the prepared nanocomposite for drug delivery applications was investigated using 5-fluorouracil (5-Fu) as a drug model in a physiological medium. The obtained results showed that the prepared magnetic mesoporous silica nanocomposite has great potential for biomedical applications.

Immobilization of Protein A on Monodisperse Magnetic Nanoparticles for Biomedical Applications

We presented synthesis and physical characterization of iron oxide magnetic nanoparticles (Fe3O4) for biomedical applications in the size range of 10-30 nm. Magnetic nanoparticles were synthesized by the coprecipitation method, and the particles’ size was controlled by two different injection methods of sodium hydroxide (NaOH). The synthesized magnetic nanoparticles were then modified by using series of linkers including tetraethyl orthosilicate (TEOS), 3-aminopropyltriethoxysilane (APTES), and glutaraldehyde (GA) to generate the structure of Fe3O4/SiO2/NH2/CHO, which can be used for immobilization of protein A. Additionally, we used transmission electron microscopy (TEM), X-ray powder diffraction (XRD), vibrating-sample magnetometry (VSM), and Fourier-transform infrared spectroscopy (FTIR), for characterization of properties and structure of the nanoparticles. An immobilization of protein A on magnetic nanoparticles was studied with a UV-Vis spectrum (UV-Vis) and fluorescence electron microscopy and Bradford method. Results showed that an XRD spectrum with a peak at (311) corresponded to the standard peak of magnetic nanoparticles. In addition, the magnetic nanoparticles withd≥30 nm have higher saturation magnetizations in comparison with the smaller ones withd≤10 nm. However, the smaller magnetic nanoparticles offered higher efficiency for binding of protein A, due to the high surface/volume ratio. These particles with functional groups on their surface are promising candidates for biomedical applications, e.g., drug delivery, controlled drug release, or disease diagnosis in point-of-care test.

Shape-controlled synthesis of magnetic Fe3O4 nanoparticles with different iron precursors and capping agents.

This paper describes a modified method to prepare monodisperse Fe3O4 magnetic nanoparticles with different shapes (cube, octahedron, and sphere). The shape of the magnetic nanoparticles could be conveniently controlled by changing the types of precursor/capping agent and concentration of capping agent. The prepared samples were characterized using scanning electron microscopy, X-ray diffraction and vibrating sample magnetometry. Cubes and octahedra were formed using ferrous sulfate heptahydrate as an iron source, ethylene glycol as a solvent and potassium hydroxide (KOH) as a capping agent while spheres were formed by using ferric chloride hexahydrate as an iron source, ethylene glycol as a solvent and ammonium acetate as a capping agent. By varying KOH concentration (0.5 M, 1 M, 1.5 M, and 5 M), the shape was transformed from cubes to octahedra because octahedra are developed dominantly at higher concentration of KOH within the reaction mixture. The magnetic studies show superparamagnetic behavior for all samples at room temperature. The Fe3O4 nanoparticles show the magnetic saturation values of 87 emu g−1, 85 emu g−1, and 82 emu g−1 for spheres, cubes, and octahedrons, respectively.

Preparation of water-soluble magnetic nanoparticles with controllable silica coating

Abstract This work provides a general method for preparing monodisperse, water-soluble and paramagnetic magnetic nanoparticles which are easy to be modified. Firstly, magnetic silica with core-shell structure was prepared according to a previous work. Then, the magnetic silica was treated with alkali solution to afford magnetic nanoparticles. With the increase of calcination temperature for the preparation of magnetic silica, the crystallinity and the magnetic responsibility of magnetic silica strengthened, meanwhile, the corresponding magnetic nanoparticles kept monodisperse without any aggregation. The magnetic nanoparticles are comprised of cobalt ferrite and a silica coating. The silica coating on the cobalt ferrite facilitates the magnetic nanoparticles well-dissolved and monodisperse in water, and easily modified.

Fabrication of monodisperse magnetic nanoparticles released in solution using a block copolymer template

This paper describes a fabrication process of monodisperse magnetic nanoparticles released in solution, based on combined ‘top-down’ and ‘bottom-up’ approaches. The process involves the use of a self-assembled PS-PMMA block copolymer formed on a sacrificial layer. Such an approach was so far mostly explored for the preparation of patterned magnetic media for ultrahigh density magnetic storage. It is here extended to the preparation of released monodisperse nanoparticles for biomedical applications. A special sacrificial layer had to be developed compatible with the copolymer self-organization. The resulting nanoparticles exhibit very narrow size dispersion (≈7%) and can be good candidates as contrast agents for medical imaging i.e. magnetic resonance imaging or magnetic particle imaging. The approach provides a great freedom in the choice of the particles shapes and compositions. In particular, they can be made of biocompatible magnetic material.

Editorial for Special Issue: Advances in Microfluidic Devices for Cell Handling and Analysis

Microfluidics is a technology that is expanding rapidly in many areas of research, especially in the biological areas of cell handling and analysis.[...]

Molecular imaging of activated platelets via antibody-targeted ultra-small iron oxide nanoparticles displaying unique dual MRI contrast.

Magnetic resonance imaging (MRI) is a powerful and indispensable tool in medical research, clinical diagnosis, and patient care due to its high spatial resolution and non-limited penetration depth. The simultaneous use of positive and negative MRI imaging that employs the same contrast agents will significantly improve detection accuracy. Here we report the development of functional multimodal iron oxide nanoparticles for targeted MRI of atherothrombosis using a combination of chemical and biological conjugation techniques. Monodisperse, water-soluble and biocompatible ultra-small magnetic dual contrast iron oxide nanoparticles (DCIONs) were generated using a high-temperature co-precipitation route and appeared to be efficient positive and negative dual contrast agents for magnetic resonance imaging. Using a unique chemo-enzymatic approach involving copper-free click chemistry and Staphylococcus aureus sortase A enzyme conjugation, DCIONs were functionalized with single-chain antibodies (scFv) directed against activated platelets for targeting purposes. The DCIONs were also labelled with fluorescent molecules to allow for optical imaging. The antigen binding activity of the scFv was retained and resulted in the successful targeting of contrast agents to thrombosis as demonstrated in a range of invitro and invivo experiments. T1- and T2-weighted MRI of thrombi was recorded and demonstrated the great potential of dual T1/T2 contrast iron oxide particles in imaging of cardiovascular disease.

Nuclear-Targeted Multifunctional Magnetic Nanoparticles for Photothermal Therapy.

The pursuit of multifunctional, innovative, more efficient, and safer cancer treatment has gained increasing interest in the research of preclinical nanoparticle-mediated photothermal therapy (PTT). Cell nucleus is recognized as the ideal target for cancer treatment because it plays a central role in genetic information and the transcription machinery reside. In this work, an efficient nuclear-targeted PTT strategy is proposed using transferrin and TAT peptide (TAT: YGRKKRRQRRR) conjugated monodisperse magnetic nanoparticles, which can be readily functionalized and stabilized for potential diagnostic and therapeutic applications. The monodisperse magnetic nanoparticles exhibit high photothermal conversion efficiency (≈37%) and considerable photothermal stability. They also show a high magnetization value and transverse relaxivity (207.1 mm-1 s-1 ), which could be applied for magnetic resonance imaging. The monodisperse magnetic nanoparticles conjugated with TAT peptides can efficiently target the nucleus and achieve the imaging-guided function, efficient cancer cells killing ability. Therefore, this work may present a practicable strategy to develop subcellular organelle targeted PTT agents for simultaneous cancer targeting, imaging, and therapy.

Synthesis and application of monodisperse hydrophobic magnetite nanoparticles as an oil spill collector using an ionic liquid

In this work, a new facile green method was proposed to prepare monodisperse magnetic nanoparticles at room temperature with controlled shape and size.