One-step hydrothermal synthesis of highly water-soluble secondary structural Fe3O4 nanoparticles

Magnetite nanoparticles (MNPs) were prepared using the ferric acetylacetonate as the sole iron source in a facile hydrothermal route, while poly(acrylic acid) (PAA) was chosen as the stabilizer via one-step functionalized MNPs for better hydrophilic properties. The orthogonal was used in the paper for the experimental parameters optimization, including the solvent, the reaction time, the amount of stabilizer and the presynthesis. The obtained highly water dispersible MNPs with uniform size from about 50 to about 100 nm was individually composed of many monodisperse magnetite crystallites approximately 6 nm in size. And the MNPs show high magnetic properties, whose magnetite content was up to 76.76% and the saturation magnetization was 39.0 emu/g. Later the formation mechanism of MNPs was also discussed. Thus the MNPs proved to be very promising for biomedical applications.     

Prospects of Utilizing Quantum Emitters to Control the Absorption of Non-Noble Plasmonic Metal Nanoparticles

Prospects of controlling the absorption of the cost-effective plasmonic metal nanoparticles (MNPs) Cu and Al using quantum emitters (QEs) are demonstrated semi-analytically. The resulting spectra are compared with the absorption of commonly used noble plasmonic metal nanoparticles Au and Ag under similar conditions. It is observed that Cu and Au based plasmonic nanoparticles exhibit largely similar exciton–plasmon Fano interaction signatures in addition to their similar spectral regions of operation (lower end of the visible range). Furthermore, the QE-enhanced maximum absorption (Fano maximum) of Cu based nanohybrids are seen to approach the maximum absorption level of isolated Au MNPs, with decreasing QE-Cu separation, increasing QE dipole element magnitude, and increasing medium permittivity, in the parameter region considered. This renders Cu based exciton–plasmon nanohybrids as more economical alternatives for Au MNPs and Au-based nanohybrids in absorption-based applications (such as thermoplasmonic), when stabilized in protective embedding media such as poly (methyl methacrylate) (PMMA).     

Layer-by-Layer self-assembly of polyaspartate and Poly(ethyleneimine) on magnetic nanoparticles: Characterization and adsorption of protein

Magnetic nanoparticles (MNPs) were modified by polyaspartate (PAA) and poly(ethyleneimine) (PEI) via Layer-by-Layer self-assembly. Two steps were involved in: the first was to coat MNPs by PAA at pH = 6; the second was to coat the former by PEI. The successful surface modification of MNPs was confirmed using X-ray photoelectron spectroscopy (XPS), thermogravimetric analysis (TGA) and fourier transform infrared (FTIR) measurements. The modified MNPs interact strongly with negative fibrinogen and weakly with neutral γ-globin and positive lysozyme.     

Preparation, characterization and MRI application of carboxymethyl dextran coated magnetic nanoparticles

Superparamagnetic nanoparticles functionalized with carboxymethyl dextran (CM-dextran) were synthesized by a two-step method. First, the magnetic nanoparticles (MNPs) coated with dextran (M_w ≈ 20000) were prepared by co-precipitation of Fe²⁺ and Fe³⁺ ions. Then, dextran on the surface of MNPs reacted with monochloroacetic acid (MCA) in alkaline condition. The influences of temperature and reactant concentration on the amount of -COOH on the surface of nanoparticles were systematically studied. The obtained MNPs coated with CM-dextran were stable over the entire range of pH and NaCl concentration. The MRI experiment indicated that the CM-dextran MNPs could potentially be used as MRI contrast agents for magnetic resonance molecular imaging.     

Layer-by-layer assembly of a magnetic nanoparticle shell on a thermoresponsive microgel core

We describe the surface modification of magnetic nanoparticles (MNPs), the coverage of poly(N-isopropylacrylamide) (PNiPAM) microgel with the MNPs and the inductive heating of these carriers. PNiPAM surface itself was modified using the layer-by-layer (LbL) assembly of polyelectrolytes to facilitate the deposition of surface-modified MNPs. One advantage of this concept is it allows the tuning of the magnetic and thermoresponsive properties of individual components (nanoparticles and microgels) separately before assembling them. Characterisations of the hybrid core–shell are discussed. In particular, it is shown that (i) each layer is successfully deposited and, more importantly, (ii) the coated microgel retains its thermoresponsive and magnetic behaviour.     

Preparation and rheological studies of uncoated and PVA-coated magnetite nanofluid

Experimental studies of rheological behavior of uncoated magnetite nanoparticles (MNPs)U and polyvinyl alcohol (PVA) coated magnetite nanoparticles (MNPs)C were performed. A Co-precipitation technique under N₂ gas was used to prevent undesirable critical oxidation of Fe²⁺. The results showed that smaller particles can be synthesized in both cases by decreasing the NaOH concentration which in our case this corresponded to 35 nm and 7 nm using 0.9 M NaOH at 750 rpm for (MNPs)U and (MNPs)C. The stable magnetic fluid contained well-dispersed Fe₃O₄/PVA nanocomposites which indicated fast magnetic response. The rheological measurement of magnetic fluid indicated an apparent viscosity range (0.1–1.2) pa s at constant shear rate of 20 s⁻¹ with a minimum value in the case of (MNPs)U at 0 T and a maximum value for (MNPs)C at 0.5 T. Also, as the shear rate increased from 20 s⁻¹ to 150 s⁻¹ at constant magnetic field, the apparent viscosity also decreased correspondingly. The water-based ferrofluid exhibited the non-Newtonian behavior of shear thinning under magnetic field.     

Applications of polymeric micelles with tumor targeted in chemotherapy

The chitosan-coated magnetic nanoparticles (CS MNPs) were in situ synthesized by cross-linking method. In this method; during the adsorption of cationic chitosan molecules onto the surface of anionic magnetic nanoparticles (MNPs) with electrostatic interactions, tripolyphosphate (TPP) is added for ionic cross-linking of the chitosan molecules with each other. The characterization of synthesized nanoparticles was performed by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS/ESCA), Fourier transform infrared spectroscopy (FTIR), transmission electron microscopy (TEM), dynamic light scattering (DLS), thermal gravimetric analysis (TGA), and vibrating sample magnetometry (VSM) analyses. The XRD and XPS analyses proved that the synthesized iron oxide was magnetite (Fe₃O₄). The layer of chitosan on the magnetite surface was confirmed by FTIR. TEM results demonstrated a spherical morphology. In the synthesis, at higher NH₄OH concentrations, smaller sized nanoparticles were obtained. The average diameters were generally between 2 and 8?nm for CS MNPs in TEM and between 58 and 103?nm in DLS. The average diameters of bare MNPs were found as around 18?nm both in TEM and DLS. TGA results indicated that the chitosan content of CS MNPs were between 15 and 23?% by weight. Bare and CS MNPs were superparamagnetic. These nanoparticles were found non-cytotoxic on cancer cell lines (SiHa, HeLa). The synthesized MNPs have many potential applications in biomedicine including targeted drug delivery, magnetic resonance imaging?(MRI), and magnetic hyperthermia.     

Effects of surfactants on properties of polymer-coated magnetic nanoparticles for drug delivery application

The objective of this research was to compare the effects of two different surfactants on the physicochemical properties of thermo-responsive poly(N-isopropylacrylamide-acrylamide-allylamine) (PNIPAAm-AAm-AH)-coated magnetic nanoparticles (MNPs). Sodium dodecyl sulfate (SDS) as a commonly used surfactant in nanoparticle formulation process and Pluronic F127 as an FDA approved material were used as surfactants to synthesize PNIPAAm-AAm-AH-coated MNPs (PMNPs). The properties of PMNPs synthesized using SDS (PMNPs-SDS) and PF127 (PMNPs-PF127) were compared in terms of size, polydispersity, surface charge, drug loading efficiency, drug release profile, biocompatibility, cellular uptake, and ligand conjugation efficiency. These nanoparticles had a stable core–shell structure with about a 100-nm diameter and were superparamagnetic in behavior with no difference in the magnetic properties in both types of nanoparticles. In vitro cell studies showed that PMNPs-PF127 were more cytocompatible and taken up more by prostate cancer cells than that of PMNPs-SDS. Cells internalized with these nanoparticles generated a dark negative contrast in agarose phantoms for magnetic resonance imaging. Furthermore, a higher doxorubicin release at 40 °C was observed from PMNPs-PF127, and the released drugs were pharmacologically active in killing cancer cells. Finally, surfactant type did not affect the conjugation efficiency to the nanoparticles when folic acid was used as a targeting ligand model. These results indicate that PF127 might be a better surfactant to form polymer-coated magnetic nanoparticles for targeted and controlled drug delivery.     

Systematic evaluation of biocompatibility of magnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles with six different mammalian cell lines

This article systematically evaluated the biocompatibility of multiple mammalian cell lines to 11-nm DMSA-coated Fe₃O₄ magnetic nanoparticles (MNPs). Cells including RAW264.7, THP-1, Hepa1-6, HepG2, HL-7702, and HeLa were incubated with six different concentrations (0, 20, 30, 40, 50, and 100 μg/mL) of MNPs for 48 h, and then the cell labeling, iron loading, cell viability, apoptosis, cycle, and oxidative stress were all quantitatively evaluated. The results revealed that all the cells were effectively labeled by the nanoparticles; however, the iron loading of RAW264.7 was significantly higher than that of other cells at any dose. The proliferations of all the cells were not significantly suppressed by MNPs at the studied dose except HepG2 that was exposed to 100 μg/mL MNPs. The investigation of oxidative stress demonstrated that the levels of total superoxide dismutase and xanthine oxidase had no significant changes in all the cells treated by all the doses of MNPs, while the levels of malonyldialdehyde activity of MNP-treated cells significantly increased. The nanoparticles did not produce any significant effect on cell cycles at any of the doses, but resulted in significant apoptosis of THP-1 and HepG2 cells at the highest concentration of 100 μg/mL. At a concentration of 30 μg/mL which was used in human studies with an intravascular nanoparticle imaging agent (Combidex), the nanoparticles efficiently labeled all the cells studied, but did not produce any significant influence on their viability, oxidative stress, and apoptosis and cycle. Therefore, the nanoparticles were concluded with better biocompatibility, which provided some useful information for its clinical applications.     

Second harmonic magnetoacoustic responses of magnetic nanoparticles in magnetoacoustic tomography with magnetic induction

Due to the unique magnetic, mechanical and thermal properties, magnetic nanoparticles(MNPs) have comprehensive applications as the contrast and therapeutic agents in biomedical imaging and magnetic hyperthermia. The linear and nonlinear magnetoacoustic responses determined by the magnetic properties of MNPs have attracted more and more attention in biomedical engineering. By considering the relaxation time of MNPs, we derive the formulae of second harmonic magnetoacoustic responses(2H-MARs) for a cylindrical MNP solution model based on the mechanical oscillations of MNPs in magnetoacoustic tomography with magnetic induction(MAT-MI). It is proved that only the second harmonic magnetoacoustic oscillations can be generated by MNPs under an alternating magnetic excitation. The acoustic pressure of the 2H-MAR is proportional to the square of the magnetic field intensity and exhibits a linear increase with the concentration of MNPs. Numerical simulations of the 2H-MAR are confirmed by the experimental measurements for various magnetic field intensities and solution concentrations using a laser vibrometer. The favorable results demonstrate the feasibility of the harmonic measurements without the fundamental interference of the electromagnetic excitation, and suggest a new harmonic imaging strategy of MAT-MI for MNPs with enhanced spatial resolution and improved signal-to-noise ratio in biomedical applications.     

Fabrication of Magnetically Stirrable Anisotropic Microparticles via the Microfluidic Method

A one‐step strategy to fabricate magnetically stirrable microparticles with geometric/chemical anisotropies via a microfluidic technique combined with partial phase separation is presented. Monodisperse oil‐in‐water microemulsions composed of magnetite nanoparticles (MNPs) and two polymers, polystyrene and poly(d ,l ‐lactide‐co‐glycolide) (PLGA), dissolved in chloroform are generated using the microfluidic method. Upon incubating the microemulsions in pure water at ambient conditions, the solvent contained in the microemulsions is gradually removed and partial phase separation between the two polymers occurs spontaneously. In the meantime, the microemulsion droplets are vertically aligned due to the density difference of the two polymer phases. During the spontaneous phase separation, the MNPs become unstable and the aggregated MNPs segregate downward by gravity to the denser PLGA phase. After complete removal of the solvent, the resulting particles adopt geometric/chemical anisotropies, and they are magnetically rotatable under an external magnetic field. It is demonstrated that the morphology of the anisotropic particles can be controlled readily by adjusting the ratio of the two polymers as well as the concentration of MNPs. It is believed that the developed method based on the partial phase separation and the gravity‐induced segregation of the MNPs enables large‐scale production of magnetically stirrable microparticles.     

Optimization of accurate controlled formation of Au MNPs via non-thermal microplasma continuous glow discharge within aqueous electrochemical (GDE) method

In this work, micro plasma-induced non-equilibrium liquid chemistry was utilized to synthesize and controlled formation of gold metallic nanoparticles (Au MNPs) by governing the concentration of (HAuCl₄). These new approaches based on both plasma and liquid electrolytes contain charged species, and the interactions between the two phases represent a unique combination of physics, chemistry, and materials science. Continuous and stable DC glow discharge was done in home–made cavity to synthesize the definite sizes of (Au MNPs) by means of (3 kV) discharge voltage and (2 mA) discharge current for a period of (7 min) in aqueous solution of HAuCl₄ with four different concentrations of about 1 mM, 5 mM, 10 mM and 20 mM at room temperature. The atmospheric pressure plasma discharge between stainless steel capillary tube cathode electrode over the (HAuCl₄) solution and platinum plate as an anode dipped in solution for rapid formation of colloidal Au MNPs. Morphology aspects of the synthesized Au MNPs layer were studied by examining the (FE-SEM), HR-TEM images and X-ray difraction (XRD) pattern. Optical features of (Au MNPs) were considered via a UV–Vis beam spectrophotometer. These measurements showed that Au MNPs were organized by governing the concentration of HAuCl₄, and uniform Au MNPs with specific exclusive sizes were acquired. Grain size, specific surface area and optical stability of Au MNPs strongly be affected by the HAuCl₄ concentrations.     

Highly hydrated poly(allylamine)/silica magnetic resin

The creation of multifunctional nanomaterials by combining organic and inorganic components is a growing trend in nanoscience. The unique size-dependent properties of magnetic nanoparticles (MNPs) make them amenable to numerous applications such as carriers of expensive biological catalysts, in magnetically assisted chemical separation of heavy metals and radionuclides from contaminated water sources. The separation of minor actinides from high-level radionuclide waste requires a sorbent stable in acidic pH, with ease of surface functionalization, and a high capacity for binding the molecules of interest. For the described experiments, the MNPs with 50 nm average size were used (size distribution from 20 to 100 nm and an iron content of 80–90 w/w%). The MNPs that have been double coated with an initial silica coating for protection against iron solubilization and oxidation in nitric acid solution (pH 1) and a second silica/polymer composite coating incorporating partially imbedded poly(allylamine) (PA). The final product is magnetic, highly swelling, containing >95% water, with >0.5 mmol amines g^?1 available for functionalization. The amine groups of the magnetic resin were functionalized with the chelating molecules diethylenetriaminepentaacetic acid (DTPA) and N,N-dimethyl-3-oxa-glutaramic acid (DMOGA) for separation of minor actinides from used nuclear fuel.     

Labelling of cultured macrophages with novel magnetic nanoparticles

Magnetic resonance (MR) imaging is capable of demonstrating human anatomy and pathological conditions. Iron oxide magnetic nanoparticles (MNPs) have been used in MR imaging as liver-specific contrast medium, cellular and molecular imaging probes. Because few studies focused on the MNPs other than iron oxides, we developed FeNi alloy MNPs coated with polyethylenimine (PEI). In this study, we demonstrated PEI-coated FeNi MNPs are able to label the cells, which could be detected in MR imaging. For labelling purpose, MNPs were incubated with mouse macrophage cell line (Raw 264.7) for 24 h and these PEI-labelled FeNi alloy MNPs can be uptaken by macrophages efficiently compared with Ferucarbotran, a commercialized superparamagnetic iron oxide (SPIO) under flow cytometry measurement. Besides, these cells labelled with MNPs could be imaged in MR with the identical potency as Ferucarbotran. Further investigation of the cells using Prussian blue staining revealed that FeNi alloy MNPs inside the cells is not oxidized. This phenomenon alleviated the consideration of potential risk of nickel toxicity. We conclude that PEI-coated FeNi MNPs could be candidate for MR contrast medium.     

Investigations and Modeling of the Effect of Magnetic Nanoparticles on MR Image Contrast

The investigations of nuclear magnetic resonance (NMR) relaxation of protons in aqueous solution and 2% agar–agar gel in the presence of magnetic nanoparticles were performed. To identify the effect of magnetic nanoparticles on the contrast of magnetic resonance images, the dependences of the MR signal intensity on the parameters of the two pulse radio-frequency (RF) sequences (spin-echo, gradient-echo) most commonly used in MRI for different values of the magnetic nanoparticle (MNP) concentration were simulated and analyzed. Recommendations for choosing the optimal values of pulse RF sequence parameters for MR imaging (MRI) in the presence of MNPs are formulated. MRI studies of phantom samples with 2% agar–agar gel containing MNPs have been performed for choosing the fast pulse RF sequence which shows the greatest contrast effect on MR images. A program for modeling magnetic resonance tomograms and determination of optimal values of pulse RF sequence parameters to achieve the best contrast of magnetic resonance images is developed. This program allows to reduce the time of MRI studies, to assess the possibility of using MNPs for contrast of MR images and to simulate the MR image in the presence of magnetic nanoparticles at the planning stage of procedures in MR-guided theranostics.     

Comparison of the behaviour of manufactured and other airborne nanoparticles and the consequences for prioritising research and regulation activities

Currently, there are no air quality regulations in force in any part of the world to control number concentrations of airborne atmospheric nanoparticles (ANPs). This is partly due to a lack of reliable information on measurement methods, dispersion characteristics, modelling, health and other environmental impacts. Because of the special characteristics of manufactured (also termed engineered or synthesised) nanomaterials or nanoparticles (MNPs), a substantial increase is forecast for their manufacture and use, despite understanding of safe design and use, and health and environmental implications being in its early stage. This article discusses a number of underlining technical issues by comparing the properties and behaviour of MNPs with anthropogenically produced ANPs. Such a comparison is essential for the judicious treatment of the MNPs in any potential air quality regulatory framework for ANPs.     

Assessment of the systemic distribution of a bioconjugated anti-Her2 magnetic nanoparticle in a breast cancer model by means of magnetic resonance imaging

The aim of this study was to determine the systemic distribution of magnetic nanoparticles of 100 nm diameter (MNPs) coupled to a specific monoclonal antibody anti-Her2 in an experimental breast cancer (BC) model. The study was performed in two groups of Sprague–Dawley rats: control (n = 6) and BC chemically induced (n = 3). Bioconjugated “anti-Her2-MNPs” were intravenously administered, and magnetic resonance imaging (MRI) monitored its systemic distribution at seven times after administration. Non-heme iron presence associated with the location of the bioconjugated anti-Her2-MNPs in splenic, hepatic, cardiac and tumor tissues was detected by Perl’s Prussian blue (PPB) stain. Optical density measurements were used to semiquantitatively determine the iron presence in tissues on the basis of a grayscale values integration of T1 and T2 MRI sequence images. The results indicated a delayed systemic distribution of MNPs in cancer compared to healthy conditions with a maximum concentration of MNPs in cancer tissue at 24 h post-infusion.     

Preparation of Cu<Superscript>2+</Superscript>/NTA-derivatized branch polyglycerol magnetic nanoparticles for protein adsorption

In this report, we described the preparation of Cu²⁺/nitrilotriacetic acids (NTA)-derivatized branch polyglycerol magnetic nanoparticles for protein adsorption with avoidance of nonspecific interactions at the same time. Magnetic nanoparticles (MNPs) were synthesized by the coprecipitation method. The transmission electron microscopy results showed that the average diameter of MNPs was 15.8 ± 4.6 nm. X-ray photoelectron spectroscopy and Fourier Transform infrared measurements indicated that branch polyglycerols were grafted on MNPs via the ring-opening polymerization of glycidol and that Cu²⁺ ions had been successfully immobilized on the surface of MNPs. The protein immobilization effect was characterized by UV–Vis spectrum. The results proved that Cu²⁺/NTA-derivatized branch polyglycerol magnetic nanoparticles effectively adsorbed bovine haemoglobin and rarely adsorbed lysozyme and γ-globin.     

Application of magnetic nanoparticles in full-automated chemiluminescent enzyme immunoassay

The magnetic nanoparticles (MNPs) Therma-Max™ were used as a carrier to develop an automated sandwich chemiluminescent enzyme immunoassay (CLEIA) to detect thyroid-stimulating hormone (TSH) in a sensitive and specific way. The Therma-Max™ particles allow for automation because, unlike magnetic microspheres, they are completely dispersed in aqueous solution and allow for accurate automatic handling. Signal intensities detected with MNPs were 8-fold higher than those found with conventional micron-sized magnetic particles. A reproducibility study suggests that these particles allow for a stable detection method, as the coefficient of variation (CV) is less than 6% (n=10).     

From polymer films to organic nanoparticles suspensions by means of excimer laser ablation in water

This study highlights the preparation of organic nanoparticles (NP) by laser ablation (LA) of polymeric materials in water. Experiments focused on poly(ethylene terephtalate) (PET) were carried out with the KrF laser pulse (248 nm). Size distribution and concentration of nanoparticles were deduced from suspensions turbidity measurements with the aid of Mie model, by Atomic Force Microscopy (AFM) on the basis of a statistical study and Scanning Electron Microscopy (SEM). The obtained results show that assemblies of spherical NP with a mean diameter 50 nm were synthesised. Composition and surface chemistry of NP were investigated using the Confocal Micro-Raman Spectroscopy (CMRS) and X-ray Photoelectron Spectroscopy (XPS). It indicates that NP are graphitic carbon rich and have a polymeric structure like polyacetylene. The possible mechanisms responsible of NP synthesis by under water LA of polymers was briefly discussed by investigating other polymers targets.