Facile Fabrication and Characterization of Amine-Functional Silica Coated Magnetic Iron Oxide Nanoparticles for Aqueous Carbon Dioxide Adsorption

Surface active amine-functionalized silica coated magnetic iron oxide nanoparticles were prepared by a simple two-step process for adsorbing CO2 gas from aqueous medium. First, oleic acid (OA) coated iron oxide magnetic particles (denoted as Fe3O4-OA) were prepared by a simple coprecipitation method. Then, the surface of the Fe3O4-OA particles was coated with silica by using tetraethyl orthosilicate. Finally, aminated Fe3O4/SiO2-NH2 nanoparticles were concomitantly formed by the reactions of 3-aminopropyl triethoxysilane with silica-coated particles. The formation of materials was confirmed by Fourier transform infrared spectral analysis. Transmission electron microscopic analysis revealed both spherical and needle-shaped morphologies of magnetic Fe3O4/SiO2-NH2 particles with an average size of 15 and 68.6 nm, respectively. The saturation magnetization of Fe3O4/SiO2-NH2 nanoparticles was found to be 33.6 emu g-1, measured by a vibrating sample magnetometer at ambient conditions. The crystallinity and average crystallite size (7.0 nm) of the Fe3O4/SiO2-NH2 particles were revealed from X-ray diffraction data analyses. Thermogravimetric analysis exhibited good thermal stability of the nanoadsorbent up to an elevated temperature. Zeta potential measurements revealed pH-sensitive surface activity of Fe3O4/SiO2-NH2 nanoparticles in aqueous medium. The produced magnetic Fe3O4/SiO2-NH2 nanoparticles also exhibited efficient proton capturing activity (92%). The particles were used for magnetically recyclable adsorption of aqueous CO2 at different pH values and temperatures. Fe3O4/SiO2-NH2 nanoparticles demonstrated the highest aqueous CO2 adsorption efficiency (90%) at 40 °C, which is clearly two times higher than that of nonfunctionalized Fe3O4-OA particles.

Polypyrrole Coating via Lemieux-von Rudloff Oxidation on Magnetite Nanoparticles for Highly Efficient Removal of Chromium(VI) from Wastewater

An alternative way for the coating of polypyrrole (PPy) polymer on hydrophobic magnetite (Fe3O4) nanoparticles is reported here to capture toxic chromium ions, Cr (VI), present in water. Iron oxide magnetic nanoparticles (Fe3O4) were synthesized by the conventional coprecipitation technique using FeCl3·6H2O and FeSO4·7H2O iron precursors and subsequently modified with oleic acid (OA). Then OA-Fe3O4 hydrophobic nanoparticles were oxidized using the Lemieux-von Rudloff reaction to transfer OA into hydrophilic azelaic acid (AA) (HOOC(CH2)7COOH-modified magnetic nanoparticles (AA-Fe3O4). Finally, a PPy polymer coating was formed by a seeded polymerization of pyrrole, using AA-Fe3O4 as seeds. The average size of PPy/Fe3O4 nanocomposites is 12.33 nm and is almost spherical in shape. The surface composition is confirmed by FTIR and thermogravimetry analyses. An X-ray diffraction study confirmed the formation of highly crystalline Fe3O4 nanoparticles, and the crystallinity was retained after the surface modification. The adsorption study suggested that the Cr(VI) ion adsorption is highly pH-dependent and the maximum amount of adsorption is obtained at pH 2.0. The adsorption results revealed that the Langmuir model provided the best fit for the isotherm, with a maximum adsorption capacity reaching approximately 173.22 mg g-1 at 323 K. Spontaneous and endothermic adsorption processes were confirmed by evaluating the thermodynamic parameters obtained in this investigation. The kinetics study showed that the interaction between Cr(VI) ions and magnetic nanocomposites was directed by a pseudo-second-order rate process indicating chemisorption. The prepared PPy/Fe3O4 nanocomposites would be promising adsorbents to purify water by eliminating Cr(VI) metal ions from wastewater.

Agglomerated serum albumin adsorbed protocatechuic acid coated superparamagnetic iron oxide nanoparticles as a theranostic agent

Iron oxide nanoparticles have been one of the most widely used nanomaterials in biomedical applications. However, the incomplete understanding of the toxicity mechanisms limits their use in diagnosis and treatment processes. Many parameters are associated with their toxicity such as size, surface modification, solubility, concentration and immunogenicity. Further research needs to be done to address toxicity-related concerns and to increase its effectiveness in various applications. Herein, colloidally stable nanoparticles were prepared by coating magnetic iron oxide nanoparticles (MIONPs) with protocatechuic acid (PCA) which served as a stabilizer and a linkage for a further functional layer. A new perfusion agent with magnetic imaging capability was produced by the adsorption of biocompatible passivating agent macro-aggregated albumin (MAA) on the PCA-coated MIONPs. PCA-coated MIONPs were investigated using infrared spectroscopy, thermogravimetric analysis and dynamic light scattering while adsorption of MAA was analysed by transmission electron microscopy, Fourier-transform infrared spectroscopy and x-ray diffraction methods. Magnetic measurements of samples indicated that all samples showed superparamagnetic behaviour. Cytotoxicity results revealed that the adsorption of MAA onto PCA-coated MIONPs provided an advantage by diminishing their toxicity against the L929 mouse fibroblast cell line compared to bare Fe₃O₄.

Electrospinning fabrication of magnetic nanoparticles-embedded polycaprolactone (PCL) sorbent with enhanced sorption capacity and recovery speed for spilled oil removal

The use of oil-soaked sorbents in the recovery and cleaning of oil spills presents challenges due to disposal. Recently, magnetic nanoparticle (MNP) based collection has been gaining interest as a new technique to lower the amount of labor required to treat oil spills. In this study, we devised a new method for the preparation of a magnetic nanoparticle (MNP) embedded polycaprolactone (PCL) sorbent with oleophilic and environmentally friendly features, capable of bring easily collected under a magnetic field. Compared with conventional polypropylene sorbents, the MNP embedded PCL sorbent (MNP/PCL) displayed excellent Arabian light (AL) crude oil sorption capacity (45.7 g g^-1) and decreased the absorption time of the oil-soaked sorbent due to its electrospun structure and efficient distribution of hydrophobic MNPs. Furthermore, the MNP/PCL based sorbent became fully pyrolyzed under certain temperatures and conditions. The MNP embedded PCL-based sorbent demonstrated broad applicability and utility in large scale oil spill projects.

From Low to High Saturation Magnetization in Magnetite Nanoparticles: The Crucial Role of the Molar Ratios Between the Chemicals

In this study, a comprehensive characterization of iron oxide nanoparticles synthesized by using a simple one-pot thermal decomposition route is presented. In order to obtain monodisperse magnetite nanoparticles with high saturation magnetization, close to the bulk material, the molar ratios between the starting materials (solvents, reducing agents, and surfactants) were varied. Two out of nine conditions investigated in this study resulted in monodisperse iron oxide nanoparticles with high saturation magnetization (90 and 93% of bulk magnetite). The X-ray diffraction analyses along with the inspection of the lattice structure through transmission electron micrographs revealed that the main cause of the reduced magnetization in the other seven samples is likely due to the presence of distortion and microstrain in the particles. Although the thermogravimetric analysis, Raman and Fourier transform infrared spectroscopies confirmed the presence of covalently bonded oleic acid on the surface of all the samples, the particles with higher polydispersity and the lowest surface coating molecules showed the lowest saturation magnetization. Based on the observed results, it could be speculated that the changes in the kinetics of the reactions, induced by varying the molar ratio of the starting chemicals, can lead to the production of the particles with higher polydispersity and/or lattice deformation in their crystal structures. Finally, it was concluded that the experimental conditions for obtaining high-quality iron oxide nanoparticles, particularly the molar ratios and the heating profile, should not be chosen independently; for any specific molar ratio, there may exist a specific heating profile or vice versa. Because this synthetic consideration has rarely been reported in the literature, our results can give insights into the design of iron oxide nanoparticles with high saturation magnetization for different applications.

Synthesis conditions and characterization of superparamagnetic iron oxide nanoparticles with oleic acid stabilizer

Superparamagnetic iron oxide nanoparticles (SPIONs), part of magnetic nanoparticles, have been widely used in biomedical applications. Biocompatibility and magnetic properties make the SPIONs developed further by a lot of researchers. However, in the synthesis process, SPIONs can run into agglomeration. Oleic acid (OA) is one of the stabilizers to prevent agglomeration. This research aims to optimize the synthesis conditions and characterization of SPIONs with OA as a stabilizer. The synthesis of Superparamagnetic Iron Oxide Nanoparticles-Oleic Acid (SPIONs-OA) was performed using the coprecipitation method and was prepared with the addition of 0.75, 1.5, and 3%^v/_v OA and stirring rate of 750, 1500, 3000, 6000, 9000, and 12,000 rpm. The characterization of hydrodynamic size and polydispersity index was evaluated by dynamic light scattering. Meanwhile, the crystal structure was observed by X-ray diffraction. Then, Fourier transform infrared spectroscopy (FTIR) was used to analyze structures. The results showed that the hydrodynamic size was dependent on OA concentrations and stirring rate. The addition of 1.5%^v/_v OA and stirring conditions of 750 rpm resulted in the smallest hydrodynamic size and polydispersity index (83.71 ± 0.70 nm and 0.215 ± 0.01 nm, respectively). Based on the crystal structure analysis, the crystal shape was magnetic cubic, and the size of Fe₃O₄ crystallite changed from 11.38 to 5.61 nm. The FTIR indicated a strong chemical bond between the hydroxyl group of SPIONs and carboxylic acid of OA. In conclusion, the SPIONs-OA was successfully prepared with 1.5%^v/_v OA concentrations and a stirring rate of 750 rpm.

A zinc ferrite nanodrug carrier for delivery of docetaxel: Synthesis, characterization and in vitro tests on C6 glioma cells

AIM

Docetaxel (DTX) loaded bio-compatible PLGA-PEG encapsulated zinc ferrite nanoparticles (ZFNP) formulation was developed and evaluated against C6 glioma cells.

METHODS

The ZFNP were characterized using XRD, FE-SEM, TEM etc. A series of drug formulations were fabricated by conjugating hydrothermally synthesized ZFNP with DTX in a PLGA-PEG matrix and optimized for drug loading. FTIR and DLS analysis of the formulation along with in vitro drug release, cytotoxicity, cellular uptake and haemolytic effect were evaluated.

RESULTS

Spherical, monodisperse, crystalline ZFNP with an average size of ∼28 nm were formed. The optimized formulation showed hydrodynamic diameter of ∼147 nm, surface charge of -34.8 mV, a drug loading of 6.9% (w/w) with prolonged drug release property and higher toxicity in C6 glioma cells compared to free DTX along with good internalization and negligible hemolysis.

CONCLUSION

The results indicate ZFNP could be effectively used as nanodrug carrier for delivery of docetaxel to glioma cells.

Rare-Earth Doped Iron Oxide Nanostructures for Cancer Theranostics: Magnetic Hyperthermia and Magnetic Resonance Imaging

Superparamagnetic iron oxide nanoparticles (SPIONs) have been extensively investigated during the last couple of decades because of their potential applications across various disciplines ranging from spintronics to nanotheranostics. However, pure iron oxide nanoparticles cannot meet the requirement for practical applications. Doping is considered as one of the most prominent and simplest techniques to achieve optimized multifunctional properties in nanomaterials. Doped iron oxides, particularly, rare-earth (RE) doped nanostructures have shown much-improved performance for a wide range of biomedical applications, including magnetic hyperthermia and magnetic resonance imaging (MRI), compared to pure iron oxide. Extensive investigations have revealed that bigger-sized RE ions possessing high magnetic moment and strong spin-orbit coupling can serve as promising dopants to significantly regulate the properties of iron oxides for advanced biomedical applications. This review provides a detailed investigation on the role of RE ions as primary dopants for engineering the structural and magnetic properties of Fe₃ O₄ nanoparticles to carefully introspect and correlate their impact on cancer theranostics with a special focus on magnetic hyperthermia and MRI. In addition, prospects for achieving high-performance magnetic hyperthermia and MRI are thoroughly discussed. Finally, suggestions on future work in these two areas are also proposed.

SPIONs self-assembly and magnetic sedimentation in quadrupole magnets: Gaining insight into the separation mechanisms

Superparamagnetic iron oxide nanoparticles (SPIONs) are currently popular materials experiencing rapid development with potential application value, especially in biomedical and chemical engineering fields. Examples include wastewater management, bio-detection, biological imaging, targeted drug delivery and biosensing. While not exclusive, magnetically driven isolation methods are typically required to separate the desired entity from the media in specific applications and in their manufacture and/or quality control. However, due to the nano-size of SPIONs, their magnetic manipulation is affected by Brownian motion, adding considerable complexities. The two most common methods for SPION magnetic separation are high and low gradient magnetic separation (HGMS and LGMS, respectively). Nevertheless, the effect of specific magnetic energy fields on SPIONs, such as horizontal (perpendicular to gravity), high fields and gradients (higher than LGMS) on the horizontal magnetophoresis and vertical sedimentation of SPIONs has only recently been suggested as a way to separate very small particles (5 nm). In this work, we continue those studies on the magnetic separation of 5-30 nm SPIONs by applying fields and gradients perpendicular to gravity. The magnetic field was generated by permanent magnets arranged in quadrupolar configurations (QMS). Different conditions were studied, and multiple variables were evaluated, including the particle size, the initial SPIONs concentration, the temperature, the magnetic field gradient and the magnetic exposure time. Our experimental data show that particles are subjected to horizontal magnetic forces, to particle agglomeration due to dipole-dipole interactions, and to vertical sedimentation due to gravity. The particle size and the type of separator employed (i.e. different gradient and field distribution acting on the particle suspension) have significant effects on the phenomena involved in the separation, whereas the temperature and particle concentration affect the separation to a lesser extent. Finally, the separation process was observed to occur in less than 3 mins for our experimental conditions, which is encouraging considering the long operation time (up to days) necessary to separate particles of similar sizes in LGMS columns that also employ permanent magnets.

Highly efficient and recyclable polyolefin-based magnetic sorbent for oils and organic solvents spill cleanup

The oil dispersants have been applied in a broad oil pollution area, but the dispersed oil caused environmental problems during sedimentation. Unlike oil dispersants, flake type polyolefin-based oil absorbent (PA) is not emulsified and shows excellent swelling characteristic for oil removal. However, the sprayed PA flakes cannot be fully collected due to its tiny architectures, the uncollected flakes can cause unintentional secondary pollution. In this study, we develop a kind of flake type polyolefin-based magnetic absorbent (PMA) hybridized with magnetic nanoparticle, to facilitate the collection process. The magnetic nanoparticle is uniformly dispersed in PMA due to the hydrophobic functionalization of iron oxide nanoparticle. This enables the convenient collection of isolated sorbent flakes even when they were placed in the marine system and show a desirable oil recovery performance up to about 37 times for organic solvent. Moreover, oil-soaked PMA flakes can be fully converted into refined oil via a pyrolysis process. After pyrolysis, the thermally undecomposed compounds, which comprise of carbon residue and magnetic nanoparticle, can be also separated by a magnet. The as-prepared flake type PMA possesses good oil recovery performance, fast magnetic response, and efficient oil recycling, thus representing an environmentally promising method for oil spill cleanup.

Potential Use of DMSA-Containing Iron Oxide Nanoparticles as Magnetic Vehicles against the COVID-19 Disease

Iron oxide magnetic nanoparticles have been employed as potential vehicles for a large number of biomedical applications, such as drug delivery. This article describes the synthesis, characterization and in vitro cytotoxic in COVID-19 cells evaluation of DMSA superparamagnetic iron oxide magnetic nanoparticles. Magnetite (Fe3O4) nanoparticles were synthesized by co-precipitation of iron salts and coated with meso-2,3-dimercaptosuccinic acid (DMSA) molecule. Structural and morphological characterizations were performed by X-ray diffraction (XRD), Fourier transformed infrared (FT-IR), magnetic measurements (SQUID), transmission electron microscopy (TEM), and dynamic light scattering (DLS). Our results demonstrate that the nanoparticles have a mean diameter of 12 nm in the solid-state and are superparamagnetic at room temperature. There is no toxicity of SPIONS-DMSA under the cells of patients with COVID-19. Taken together the results show that DMSA- Fe3O4 are good candidates as nanocarriers in the alternative treatment of studied cells.

1,2,3-Triazole framework: a strategic structure for C-H⋯X hydrogen bonding and practical design of an effective Pd-catalyst for carbonylation and carbon-carbon bond formation

1,2,3-Triazole is an interesting N-heterocyclic framework which can act as both a hydrogen bond donor and metal chelator. In the present study, C-H hydrogen bonding of the 1,2,3-triazole ring was surveyed theoretically and the results showed a good agreement with the experimental observations. The click-modified magnetic nanocatalyst Pd@click-Fe₃O₄/chitosan was successfully prepared, in which the triazole moiety plays a dual role as both a strong linker and an excellent ligand and immobilizes the palladium species in the catalyst matrix. This nanostructure was well characterized and found to be an efficient catalyst for the CO gas-free formylation of aryl halides using formic acid (HCOOH) as the most convenient, inexpensive and environmentally friendly CO source. Here, the aryl halides are selectively converted to the corresponding aromatic aldehydes under mild reaction conditions and low Pd loading. The activity of this catalyst was also excellent in the Suzuki cross-coupling reaction of various aryl halides with phenylboronic acids in EtOH/H₂O (1 : 1) at room temperature. In addition, this catalyst was stable in the reaction media and could be magnetically separated and recovered several times.

Inulin-Coated Iron Oxide Nanoparticles: A Theranostic Platform for Contrast-Enhanced MR Imaging of Acute Hepatic Failure

The present study introduces a superparamagnetic nanocomposite, Fe-Si-In, as a T2 magnetic resonance imaging (MRI) contrast agent with a core of iron oxide nanoparticles and a nonporous silica inner shell/carboxymethyl inulin outer shell. Due to its core/shell properties, the structure characterization, biocompatibility, and performance in MRI, as well as its potential as a drug delivery system, were thoroughly evaluated. The results have shown that the synthesized nanocomposite possesses excellent biocompatibility and acceptable magnetization (M_s = 20 emu g^-1). It also has the potential to be a nanocarrier for drug delivery purposes, as evidenced by the results of curcumin administration studies. The developed nanocomposite has shown excellent performance in MRI, while the in vitro relaxivity measurements reveal a stronger T2 relaxivity (r₂ = 223.2 ms) compared to the commercial samples available in the market. Furthermore, the in vivo MRI studies demonstrate an excellent contrast between injured livers and normal ones in rats which again upholds the high performance of Fe-Si-In in MRI diagnostics.

Magnetic nanoparticles applied in targeted therapy and magnetic resonance imaging: crucial preparation parameters, indispensable pre-treatments, updated research advancements and future perspectives

Magnetic nanoparticles (MNPs) have attracted much attention in cancer treatment as carriers for drug delivery and imaging contrast agents due to their distinctive performances based on their magnetic properties and nanoscale structure. In this review, we aim to comprehensively dissect how the applications of MNPs in targeted therapy and magnetic resonance imaging are achieved and their specificities by focusing on the following aspects: (1) several important preparation parameters (pH, temperature, ratio of the reactive substances, etc.) that have crucial effects on the properties of MNPs, (2) indispensable treatments to improve the biocompatibility, stability, and targeting ability of MNPs and prolong their circulation time for biomedical applications, (3) the mechanism for MNPs to deliver and release medicine to the desired sites and be applied in magnetic hyperthermia as well as related updated research advancements, (4) comparatively promising research directions of MNPs in magnetic resonance imaging, and (5) perspectives in the further optimization of their preparations, pre-treatments and applications in cancer diagnosis and therapy.

Catalytic Enhancement of Inductively Heated Fe3 O4 Nanoparticles by Removal of Surface Ligands

Heat management in catalysis is limited by each material's heat transfer efficiencies, resulting in energy losses despite current thermal engineering strategies. In contrast, induction heating of magnetic nanoparticles (NPs) generates heat at the surface of the catalyst where the reaction occurs, reducing waste heat via dissipation. However, the synthesis of magnetic NPs with optimal heat generation requires interfacial ligands, such as oleic acid, which act as heat sinks. Surface treatments using tetramethylammonium hydroxide (TMAOH) or pyridine are used to remove these ligands before applications in hydrophilic media. In this study, Fe₃ O₄ NPs are surface treated to study the effect of induction heating on the catalytic oxidation of 1-octanol. Whereas TMAOH was unsuccessful in removing oleic acid, pyridine treatment resulted in a roughly 2.5-fold increase in heat generation and product yield. Therefore, efficient surfactant removal has profound implications in induction heating catalysis by increasing the heat transfer and available surface sites.

Geogenic arsenic removal through core-shell based functionalized nanoparticles: Groundwater in-situ treatment perspective in the post-COVID anthropocene

Groundwater, one of the significant potable water resources of the geological epoch is certainly contaminated with class I human carcinogenic metalloid of pnictogen family which delimiting its usability for human consumption. Hence, this study concerns with the elimination of arsenate (As(V)) from groundwater using bilayer-oleic coated iron-oxide nanoparticles (bilayer-OA@FeO NPs). The functionalized (with high-affinity carboxyl groups) adsorbent was characterized using the state-of-the-art techniques in order to understand the structural arrangement. The major emphasis was to examine the effects of pH (5.0-13), contact times (0-120 min), initial concentrations (10-150 μg L^-1), adsorbent dosages (0.1-3 g L^-1), and co-existing anions in order to understand the optimal experimental conditions for the effective removal process. The adsorbent had better adsorption efficiency (∼ 32.8 μg g^-1, after 2 h) for As(V) at neutral pH. Adsorption process mainly followed pseudo-second-order kinetics and Freundlich isotherm models (R²∼0.90) and was facilitated by coulombic, charge-dipole and surface complexation interactions. The regeneration (upto five cycles with 0.1 M NaOH) and competition studies (with binary and cocktail mixture of co-anions) supported the potential field application of the proposed adsorbent.

Anticancer potential of docetaxel-loaded cobalt ferrite nanocarrier: an in vitro study on MCF-7 and MDA-MB-231 cell lines

AIM

To develop a biocompatible cobalt ferrite (CF-NP) nanodrug formulation using oleic acid and poly (d,l-lactide-co-glycolic) acid (PLGA) for the delivery of docetaxel (DTX) specifically to breast cancer cells.

METHODS

The CF-NP were synthesised by hydrothermal method and conjugated with DTX in a PLGA matrix and were systematically characterised using XRD, FE-SEM, TEM, DLS, FTIR, TGA, SQUID etc. The drug loading, in vitro drug release, cellular uptake, cytotoxicity were evaluated and haemolytic effect was studied.

RESULTS

The CF-NP showed good crystallinity with an average particle size of 21 nm and ferromagnetic nature. The DTX-loaded CF-NP (DCF-NP) showed 8.4% (w/w) drug loading with 81.8% loading efficiency with a sustained DTX release over time. An effective internalisation and anti-proliferative efficiency was observed in MCF-7 and MDA-MB-231 breast cancer cells and negligible haemolytic effect.

CONCLUSION

The DCF-NP can have the potential for the effective delivery of DTX for breast cancer treatment.

Comparable antibacterial effects and action mechanisms of silver and iron oxide nanoparticles on Escherichia coli and Salmonella typhimurium

The current research reports the antibacterial effects of silver (Ag) and citric acid coated iron oxide (Fe₃O₄) NPs on Escherichia coli wild type and kanamycin-resistant strains, as well as on Salmonella typhimurium MDC1759. NPs demonstrated significant antibacterial activity against these bacteria, but antibacterial effect of Ag NPs is more pronounced at low concentrations. Ag NPs inhibited 60–90% of S. typhimurium and drug-resistant E. coli. The latter is more sensitive to Fe₃O₄ NPs than wild type strain: the number of bacterial colonies is decreased ~ 4-fold. To explain possible mechanisms of NPs action, H⁺-fluxes through the bacterial membrane and the H⁺-translocating F_OF₁-ATPase activity of bacterial membrane vesicles were studied. N,N′-Dicyclohexylcarbodiimide (DCCD)-sensitive ATPase activity was increased up to ~ 1.5-fold in the presence of Fe₃O₄ NPs. ATPase activity was not detected by Ag NPs even in the presence of DCCD, which confirms the bactericidal effect of these NPs. The H⁺-fluxes were changed by NPs and by addition of DCCD. H₂ yield was inhibited by NPs; the inhibition by Ag NPs is stronger than by Fe₃O₄ NPs. NPs showed antibacterial effect in bacteria studied in concentration-dependent manner by changing in membrane permeability and membrane-bound enzyme activity. The F_OF₁-ATPase is suggested might be a target for NPs.

Antitumor activity associated with hyperthermia and 4-nitrochalcone loaded in superparamagnetic poly(thioether-ester) nanoparticles

The combination of hyperthermia and chemotherapy has a potential synergic effect in antitumor activity. The development of new biocompatible and biodegradable polymers to simultaneously encapsulate magnetic nanoparticles (MNPs) and antitumoral drugs offer new cancer treatment opportunities. Here, biodegradable and biocompatible poly(thioether-ester) (PTEe) was used to encapsulate MNPs and 4-nitrochalcone (4NC) using miniemulsification and solvent evaporation. The resulting hybrid particles (MNPs-4NC-PTEe) had nanometer-scale diameters, spherical morphology, negative surface charge, high encapsulation efficiency, and superparamagnetic properties. Results showed that 4NC release occurred through diffusion. Free 4NC and MNPs + 4NC-PTEe did not have any cytotoxic effect on erythrocytes and mouse embryonic fibroblast (NIH3T3) cells. 4NC antitumor activity was verified on human cervical cancer (HeLa) and melanoma (B16F10) cells. Cellular uptake of MNPs + 4NC-PTEe nanoparticles was higher in HeLa cells compared to B16F10 and NIH3T3 cells. The hyperthermia application (115 kHz-500 Oe) potentiated the 4NC effects on HeLa and B16F10 cells when MNPs + 4NC-PTEe nanoparticles were used, indicating more effective antitumor activity. We concluded that the use of MNPs + 4NC-PTEe nanoparticles associated with hyperthermia is a promising form of treatment for some types of cancers.

Surface-Functionalized Superparamagnetic Nanoparticles (SPNs) for Enhanced Oil Recovery: Effects of Surface Modifiers and Their Architectures

Superparamagnetic nanoparticles (SPNs) have been considered as one of the most studied nanomaterials for subsurface applications, including in enhanced oil recovery (EOR), due to their unique physicochemical properties. However, a comprehensive understanding of the effect of surface functionalization on the ability of the nanoparticles to improve secondary and tertiary oil recoveries remains unclear. Therefore, investigations on the application of bare and surface-functionalized SPNs in EOR using a sand pack were carried out in this study. Here, the as-prepared SPNs were functionalized using oleic acid (OA) and polyacrylamide (PAM) to obtain several types of nanostructure architectures such as OA-SPN, core-shell SPN@PAM, and SPN-PAM. Based on the result, it is found that both the viscosity and mobility of the nanofluids were significantly affected by not only the concentration of the nanoparticles but also the type and architecture of the surface modifier, which dictated particle hydrophilicity. According to the sand pack tests, the nanofluid containing SPN-PAM was able to recover as much as 19.28% of additional oil in a relatively low concentration (0.9% w/v). The high oil recovery enhancement was presumably due to the ability of suspended SPN-PAM to act as a mobility control and wettability alteration agent and facilitate the formation of a Pickering emulsion and disjoining pressure.

Evaluation of in vitro cytotoxicity of superparamagnetic poly(thioether-ester) nanoparticles on erythrocytes, non-tumor (NIH3T3), tumor (HeLa) cells and hyperthermia studies

Magnetic nanoparticles encapsulated in biocompatible and biodegradable polymeric matrices are promising materials for biomedical applications, such as transport of antitumoral drugs and cancer treatment by hyperthermia. In this study, biobased poly(thioether-ester), PTEe, was obtained by thiol-ene polymerization and superparamagnetic nanoparticles, MNPs, were successfully incorporated in PTEe nanoparticles by miniemulsification followed by solvent evaporation. MNPs-PTEe nanoparticles with average diameter around 150 nm presented superparamagnetic behavior as confirmed by magnetization curves analysis. MNPs-PTEe nanoparticles did not present hemolytic damage on human red blood cells when incubated for 24 h. According to the cell viability assays, nanoparticles did not present any cytotoxic effect on murine fibroblast cell (NIH3T3) and human cervical cancer (HeLa). Hyperthermia assays were applied, demonstrating that AC magnetic field application (110 KHz-500 Oe) for 20 min significantly reduced the cells viability. The morphology evaluation of HeLa showed a hypoxia region one hour after hyperthermia application. Therefore, the results indicated that the superparamagnetic poly(thioether-ester) nanoparticles can be an excellent alternative for the targeted delivery of antitumor drugs and cancer treatment for hyperthermia.

Low intensity sonosynthesis of iron carbide@iron oxide core-shell nanoparticles

Here we demonstrate a simple method for the organic sonosynthesis of stable Iron Carbide@Iron Oxide core-shell nanoparticles (ICIONPs) stabilized by oleic acid surface modification. This robust synthesis route is based on the sonochemistry reaction of organometallic precursor like Fe(CO)₅ in octanol using low intensity ultrasonic bath. As obtained, nanoparticles diameter sizes were measured around 6.38 nm ± 1.34 with a hydrodynamic diameter around 25 nm and an estimated polydispersity of 0.27. Core-Shell structure of nanoparticles was confirmed using HR-TEM and XPS characterization tools in which a core made up of iron carbide (Fe₃C) and a shell of magnetite (γ-Fe₂O₃) was found. The overall nanoparticle presented ferromagnetic behavior at 4 K by SQUID. With these characteristics, the ICIONPs can be potentially used in various applications such as theranostic agent due to their properties obtained from the iron oxides and iron carbide phases.

Surface Modification of Magnetic Iron Oxide Nanoparticles

Functionalized iron oxide nanoparticles (IONPs) are of great interest due to wide range applications, especially in nanomedicine. However, they face challenges preventing their further applications such as rapid agglomeration, oxidation, etc. Appropriate surface modification of IONPs can conquer these barriers with improved physicochemical properties. This review summarizes recent advances in the surface modification of IONPs with small organic molecules, polymers and inorganic materials. The preparation methods, mechanisms and applications of surface-modified IONPs with different materials are discussed. Finally, the technical barriers of IONPs and their limitations in practical applications are pointed out, and the development trends and prospects are discussed.

Surface-initiated atom transfer radical polymerization of cationic corona on iron oxide nanoparticles for magnetic sorting of macrophages

Ovalbumin-incorporated antigen carriers were prepared by surface-initiated atom transfer radical polymerization (SI-ATRP) of iron oxide nanoparticles for magnetic sorting of antigen-presenting cells. Iron oxide nanoparticles were surface-decorated with cationic shells by SI-ATRP, and the primary amines on the surface were further tri-methylated. Surface decoration of the nanoparticles was characterized by Fourier transform infrared spectroscopy, matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, and transmission electron microscopy with energy-dispersive spectrometry. Ovalbumin-loaded nanoparticles showed higher incorporation in comparison to non-decorated nanoparticles, and the loaded ovalbumin was released faster at low pH than at neutral pH. Ovalbumin-loaded nanoparticles were endocytosed by macrophages, and macrophages with nanoparticles were easily harvested by magnetic separation. Magnetically sorted macrophages showed higher release of cytokines including TNF-α, MIP-1α, and IL-1β than unsorted macrophages. These results suggest that ovalbumin-loaded nanoparticles can potentially increase the efficiency of immune therapy during the antigen-presenting pathway.

Comprehensive cytotoxicity studies of superparamagnetic iron oxide nanoparticles

Recently lots of efforts have been taken to develop superparamagnetic iron oxide nanoparticles (SPIONs) for biomedical applications. So it is utmost necessary to have in depth knowledge of the toxicity occurred by this material. This article is designed in such way that it covers all the associated toxicity issues of SPIONs. It mainly emphasis on toxicity occurred at different levels including cellular alterations in the form of damage to nucleic acids due to oxidative stress and altered cellular response. In addition focus is been devoted for in vitro and in vivo toxicity of SPIONs, so that a better therapeutics can be designed. At the end the time dependent nature of toxicity and its ultimate faith inside the body is being discussed.

Superparamagnetic iron oxide nanocargoes for combined cancer thermotherapy and MRI applications

Nanoparticle-based cancer diagnosis-therapy integrative systems (cancer theranostics) represent an emerging approach in oncology. To address this issue in the present work iron oxide (γ-Fe2O3-maghemite) nanoparticles (IONPs) were encapsulated within the matrix of (bis(p-sulfonatophenyl)phenylphosphine)-methoxypolyethylene glycol-thiol (mPEG) polymer vesicles using a two-step process for active chemotherapeutic cargo loading in cancer theranostics. This formation method gives simple access to highly reactive surface groups present on IONPs together with good control over the vesicle size (50-100 nm). The simultaneous loading of a chemotherapeutic drug cargo (doxorubicin) and its in vitro release in cancer cells was achieved. The feasibility of controlled drug release under different pH conditions was demonstrated in the case of encapsulated doxorubicin molecules, showing the viability of the concept of stimulated drug delivery for magneto-chemotherapy. These polymer-magnetic nanocargoes (PMNCs) exhibit enhanced contrast properties that open potential applications for magnetic resonance imaging. These self-assembled magnetic polymersomes can be used as efficient multifunctional nanocarriers for combined therapy and imaging.

Nonsacrificial Template Synthesis of Magnetic-Based Yolk-Shell Nanostructures for the Removal of Acetaminophen in Fenton-like Systems

Recently, yolk-shell structured materials with active metal cores have received considerable attention in heterogeneous Fenton-like systems, which have excellent catalytic performance. In this study, we initially attempted the nonsacrificial template synthesis of yolk-shell structured nanoparticles with magnetite cores encapsulated in a mesoporous silica shell (Fe₃O₄@SiO₂) via a modified sol-gel process and then evaluated their catalytic activity for acetaminophen degradation in Fenton-like systems. Second, copper nanoparticles were decorated on the surface of the Fe₃O₄@SiO₂ microspheres (Fe₃O₄@SiO₂@Cu) to enhance the catalytic activity. The morphological, structural, and physicochemical properties of the prepared materials were characterized via X-ray diffraction, X-ray photoelectron spectroscopy, field emission scanning electron microscopy, field emission transmission electron microscopy, nitrogen adsorption-desorption isotherms, specific surface area, ζ-potential, magnetic properties, and Fourier transform infrared spectroscopy. The results demonstrated a successful fabrication of the targeted materials. The yolk-shell structured materials possess a spherical morphology with an active core, protective shell, and hollow void. The Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂@Cu variants showed acetaminophen removal rates significantly higher compared to those of their counterparts, i.e., the Fe₃O₄ and Fe₃O₄@Cu core-shell structures. Fe₃O₄@SiO₂@Cu showed that the copper nanoparticles were firmly immobilized on the mesoporous silica shell, dramatically improving the catalytic performance. Both the yolk-shell structured Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂@Cu exhibited good separation and satisfactory regeneration properties, which could be recycled six times without any obvious decline in catalytic activity. Overall, the results of this study suggested that Fe₃O₄@SiO₂ and Fe₃O₄@SiO₂@Cu yolk-shell nanostructures could be promising catalysts for a heterogeneous Fenton-like system by which the removal of emerging contaminants can be greatly improved.

Magnetite and cobalt ferrite nanoparticles used as seeds for acid mine drainage treatment

In this study, magnetite and cobalt ferrite nanoparticles were used as seeds for acid mine drainage (AMD) treatment at pH of 7.05±0.35. Duplicate samples of AMD, one without heating and another with heating at 60°C was treated under continuous stirring for 1h. The filtrate analysis results from ICP-OES have shown complete removal of Al, Mg, and Mn, while for Fe, Ni and Zn over 90% removals were recorded. Particularly, settling time has significant effect on the removal of Mg, Ca and Na. The results from SQUID have shown superparamagnetic properties of the synthesised magnetic nanoparticles and ferrite sludge. The recovered nanoparticles from AMD are economically important and reduce the cost of waste disposal.

Biocompatible Colloidal Suspensions Based on Magnetic Iron Oxide Nanoparticles: Synthesis, Characterization and Toxicological Profile

The use of magnetic iron oxide nanoparticles in biomedicine has evolved intensely in the recent years due to the multiple applications of these nanomaterials, mainly in domains like cancer. The aim of the present study was: (i) to develop biocompatible colloidal suspensions based on magnetic iron oxide nanoparticles as future theranostic tools for skin pathology and (ii) to test their effects in vitro on human keratinocytes (HaCat cells) and in vivo by employing an animal model of acute dermal toxicity. Biocompatible colloidal suspensions were obtained by coating the magnetic iron oxide nanoparticles resulted during the solution combustion synthesis with a double layer of oleic acid, as innovative procedure in increasing bioavailability. The colloidal suspensions were characterized in terms of dynamic light scattering (DLS) and transmission electron microscopy (TEM). The in vitro effects of these suspensions were tested by means of Alamar blue assay and the noxious effects at skin level were measured using non-invasive methods. The in vitro results indicated a lack of toxicity on normal human cells induced by the iron oxide nanoparticles colloidal suspensions after an exposure of 24 h to different concentrations (5, 10, and 25 μg·mL⁻¹). The dermal acute toxicity test showed that the topical applications of the colloidal suspensions on female and male SKH-1 hairless mice were not associated with significant changes in the quality of barrier skin function.

A novel-green adsorbent based on betaine-modified magnetic nanoparticles for removal of methyl blue

A potential adsorbent based on betaine-modified magnetic iron oxide nanoparticles (BMNPs) was successfully synthesized by facile method, characterized and applied for methyl blue (MB) removal from aqueous solution. The characterization results of FTIR, transmission electron microscopy (TEM), X-ray diffraction (XRD) and vibrating sample magnetometer (VSM) showed that the prepared nanoparticles could be well dispersed in water and exhibited excellent superparamagnetism. These properties imply the potential to recycle BMNPs from wastewater through magnetic field. In the adsorption process, the effects of main experimental parameters such as pH of MB solution, initial concentration of MB, contact time, and adsorption capacity for MB were studied and optimized. These results demonstrated that large amounts of quaternary ammonium groups existing on the surface of BMNPs could promote absorption of MB via electrostatic forces. Additionally, the adsorption kinetics of MB was found to follow a pseudo-second-order kinetic model and the adsorption equilibrium data fitted very closely to the Langmuir adsorption isotherm model. The maximum adsorption capacity for MB was calculated to be 136mgg^-1 at room temperature. Moreover, the BMNPs showed good reusability with 73.33% MB adsorption in the 5th cycle.

Studies on enhanced colloidal stability and heating ability of glycine functionalized LSMO nanoparticles for cancer hyperthermia therapy

The heating ability of glycine functionalized LSMO nanoparticles for cancer hyperthermia is measured in different physiological media.

Highly stable water-soluble magnetic nanoparticles synthesized through combined co-precipitation, surface-modification, and decomposition of a hybrid hydrogel

The synthesized magnetic nanoparticles were stable not only in aqueous media but also in mixtures of water and hydrophilic organic solvents.

Multi-modal MR imaging and magnetic hyperthermia study of Gd doped Fe3O4 nanoparticles for integrative cancer therapy

Gadolinium (Gd) doped iron oxide nano-mediator in cancer theranostics are one of the most promising candidates in combining diagnostics (imaging) and therapeutics (molecular therapy) functions in a single, multimodal platform.

Magnetic Control of Fe₃O₄ Nanomaterial for Fat Ablation in Microchannel

In this study, surface modification of iron (II, III) oxide Fe₃O₄ nanoparticles by oleic acid (OA) coating is investigated for the microablation of fat in a microchannel. The nanoparticles are synthesized by the co-precipitation method and then dispersed in organic solvent prior to mixing with the OA. The magnetization, agglomeration, and particle size distribution properties of the OA-coated Fe₃O₄ nanoparticles are characterized. The surface modification of the Fe₃O₄ nanoparticles reveals that upon injection into a microchannel, the lipophilicity of the OA coating influences the movement of the nanoparticles across an oil-phase barrier. The motion of the nanoparticles is controlled using an AC magnetic field to induce magnetic torque and a static gradient field to control linear translation. The fat microablation process in a microchannel is demonstrated using an oscillating driving field of less than 1200 Am^-1.

Simultaneous Phase Transfer and Surface Modification of TiO₂ Nanoparticles Using Alkylphosphonic Acids: Optimization and Structure of the Organosols

An original protocol of simultaneous surface modification and transfer from aqueous to organic phases of anatase TiO2 nanoparticles (NPs) using alkylphosphonic acids (PAs) is studied. The influence of the solvent, the nature and concentration of the PA, and the size, concentration, and aggregation state of the TiO2 NPs was investigated. Complete transfer was observed for linear alkyl chains (5, 8, 12, and 18 C atoms), even at very high sol concentrations. After transfer, the grafted NPs were characterized by (31)P solid-state MAS NMR. The dispersion state of NPs before and after phase transfer was monitored by dynamic light scattering (DLS). Small-angle neutron scattering (SANS) was used to characterize the structure of PA-grafted NPs in the organic solvent. Using a quantitative core-shell model cross-checked under different contrast conditions, it is found that the primary particles making up the NPs are homogeneously grafted with a solvated PA-layer. The nanometric thickness of the latter is shown to increase with the length of the linear carbon chain of the PA, independent of the size of the primary TiO2 NP. Interestingly, a reversible temperature-dependent aggregation was evidenced visually for C18PA, and confirmed by DLS and SANS: heating the sample induces the breakup of aggregates, which reassemble upon cooling. Finally, in the case of NPs agglomerated by playing with the pH or the salt concentration of the sols, the phase transfer with PA is capable of redispersing the agglomerates. This new and highly versatile method of NP surface modification with PAs and simultaneous transfer is thus well suited for obtaining well-dispersed grafted NPs.

Innovative Developments in Bacterial Detection with Magnetic Nanoparticles

It has been seen from the last decade that many bacterial strains are becoming insensitive to conventional detection techniques and it has its own limitations. Current developments in nanoscience and nanotechnology have expanded the ability to design and construct nanomaterials with targeting, therapeutic, and diagnostic functions. These multifunctional nanomaterials have attracted researchers, to be used as the promising tool for selective bacterial sensing applications. An important advantage of using magnetic nanoparticles to capture bacteria is the simple separation of bacteria from biological samples using magnets. This review includes significance of magnetic nanoparticles in bacterial detection. Relevant to topic, properties, designing strategies for magnetic nanoparticle, and innovative techniques used for detection are discussed. This review provides the readers how magnetic properties of nanoparticles can be utilized systematically for bacterial identification.