Magnetic Composite Nanoparticles Research Articles

Improving enzyme immobilization: A new carrier-based magnetic polymer for enhanced covalent binding of laccase enzyme

In the quest for effective enzyme immobilization methods, this study focuses on synthesizing carrier-based magnetic polymer to enhance the covalent binding of T. versicolor laccase. Utilizing chitosan (CS) and alginate (ALG) composites, modified with Fe3O4 magnetic nanoparticles (MNPs), we aimed to improve the enzyme's stability, reusability, and performance under varying conditions. The ionic gelation method was employed to prepare CS-ALG and CS-ALG-Fe3O4 MNPs composites, resulting in an 84 % and 91 % immobilization efficiency. The immobilized enzyme demonstrated superior thermal stability, retaining 48 % activity for CS-ALG-laccase and 67 % for CS-ALG-Fe3O4 MNPs-laccase at 70 °C, compared to 29 % for the free enzyme. Scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy were used to characterize the composites, revealing significant morphological changes and successful enzyme integration. Kinetic studies indicated that immobilization increased the Vmax to 141 μmol/min for CS-ALG-laccase and 111 μmol/min for CS-ALG-Fe3O4 MNPs-laccase, while slightly reducing substrate affinity (Km) to 1.42 mM−1 and 1.32 mM−1, respectively. The immobilized laccase retained higher activity after ten reaction cycles (81 % activity for CS-ALG-Fe3O4 MNPs-laccase) and during prolonged storage (75 % activity retention), showcasing its potential for industrial applications. Additionally, the enzyme exhibited increased resistance to various organic solvents, enhancing its practical utility.

Synthesis of magnetic zirconium oxide-iron oxide nanoparticles composite using chemical precipitation process for Pb (II) adsorption

The exploration and utilization of natural raw zircon minerals in Indonesia, particularly in Central Kalimantan, remain largely untapped in their potential as high-tech and commercially valuable substances with eco-friendly properties, particularly in water and industrial wastewater treatment. The primary objective of this research is to enhance the development and synthesis of natural raw zircon minerals by converting them into zirconium oxide and integrating them with magnetic nanoparticles. The magnetic nanoparticle composite material for zirconium oxide (MNP@ZrO2) was synthesized using the chemical co-precipitation method. Zirconium and its oxides have gained significant application in water and wastewater treatment in recent years. Through chemical co-precipitation processes (MNP@ZrO2), the natural raw zircon minerals were transformed into zirconium oxides and combined with magnetic nanoparticles due to their exceptional potential as effective adsorbents for anions and cations in water and industrial treatment processes. In the utilization of Scanning Electron Microscopy (SEM), magnetic nanoparticles with a diameter of less than 50 nm emerged on the surface of the zirconium crystals within the magnetic nanoparticle composites. X-ray diffraction (X-RD) analysis indicated that the treatment of zirconium minerals resulted in 11.19% decrease in the Crystallinity Index and a significant reduction of 98% in silica content. By maintaining a pH level of approximately 7 ± 0.2 over 360 min with a stirring rate of 150 rpm, and at ambient temperature, the optimal conditions for Pb (II) adsorption were achieved with the adsorption capacity of 68.98 mg/g using MNP@ZrO2 as adsorbent. The successful synthesis of magnetic zirconium oxide-iron oxide nanoparticles at various pH levels using the chemical co-precipitation process has facilitated a comprehensive assessment of their performance in Pb (II) adsorption.

Design and application of environmentally friendly composite magnetic particles for microplastic extraction from water media

The widespread presence of microplastic particles in aquatic environments requires methods of their extraction from water for counting and analysis and for water purification technologies. In this study, new magnetic composite nanoparticles (FNP) were designed, characterized and explored to be used as magnetic seeds for extracting polyethylene terephthalate microparticles (MPET, 5–30 μm) from water by magnetic sedimentation. The engineered seeds have a complex morphology, with magnetic cores of Fe3O4 dispersed in an environmentally compatible polymer matrix of silicon dioxide, chitosan or gelatine. Mechanisms of the heteroaggregation of FNP and MPET are considered and the main influencing factors (particles concentrations, major ions, duration of the preliminary exposure and of the sedimentation) are studied. The heteroaggregates are removed from water using a gradient magnetic field (Bzmax = 0.44 T) generated by a system of permanent magnets. The mass concentration of magnetic nanoseeds for more than 98 % capture of PET particles in pure and in salted water after 0.5 hour of magnetic sedimentation was detected to be 0.002 g/L. It is two orders of magnitude lower than that reported for uncovered magnetite-based particles. Using magnetic composite seeds with ecofriendly coatings allows to perform a high efficient magnetic separation of microplastic particles from water both for analytical purpose and for potential water cleaning technologies, while strongly reducing the synthetic flocculant sludge volume.

Efficiency enhancement of organic light-emitting diodes with multifunctional magnetic composite nanoparticles of Fe3O4@Au@SiO2

Multifunctional nanomaterials have been widely utilized to optimize the performances of optoelectronic devices. In this work, magnetic composite nanoparticles (NPs) of Fe3O4@Au@SiO2 are used as dopants to improve the quantum efficiency of electroluminescence of the tris-(8-hydroxyquinoline) aluminum-based organic light emitting devices (OLEDs). As a result, the performances of doped OLED (Von = 2.8 V, L = 23,400 cd/m2, EQE = 1.55) are obviously boosted as compared to the control device (Von = 2.9 V, L = 19,780 cd/m2, EQE = 1.27). Especially, the current efficiency of fluorescent green OLEDs can be 22.5 % enhanced by simply mixing the magnetic Fe3O4@Au@SiO2 (0.5 wt‰) NPs into poly(3,4-ethylenedioxythiophene):poly(styrene sulfonate) (PEDOT:PSS), yielding the maximum value of 4.62 cd/A. The efficiency enhancement could be attributed to the collective effects of light-scattering, localized surface plasmon resonance (LSPR) and magnetic effect induced by magnetic composite NPs.

Impact of CoFe2O4 Magnetic Nanoparticles on the Physical and Mechanical Properties and Shape Memory Effect of Polylactide

The acceleration in advancements of smart materials and non-contact controlled devices in the field of 4D printing is facilitated by the use of magnetically responsive shape memory polymer (SMP) composites. This study is dedicated to the development of promising shape memory materials based on polylactic acid (PLA) and cobalt ferrite (CoFe2O4) nanoparticles. The activation of the shape memory effect (SME) in magnetic nanoparticle composites was achieved by applying a high-frequency alternating magnetic field (HFAMF). The PLA/CoFe2O4 composites exhibited a remarkable shape recovery ratio (>84%) and underwent rapid heating when exposed to HFAMF. The interaction of these composites with mouse adipose-derived mesenchymal stem cells demonstrated adequate cytocompatibility. The rapid magnetosensitive behavior and high shape recovery characteristics of PLA/CoFe2O4 composites make them promising candidates for biomedical applications.

Chloromethylated magnetic polystyrene composite nanoparticles prepared via RAFT-mediated surfactant-free emulsion polymerization

Polystyrene-based magnetic composite nanoparticles with well-defined core-shell morphology, customizable surface functionalization, and adjustable magnetic properties are promising catalyst support materials. In this work, chloromethylated magnetic polystyrene composite nanoparticles are successfully prepared through RAFT-mediated surfactant-free emulsion polymerization. A comprehensive investigation is carried out to explore the influence of copolymer monomer ratios and polymerization degrees on emulsion polymerization conversion and encapsulation efficiency. The results unveil the critical importance of moderately adjusting the hydrophobic/hydrophilic properties of the macroRAFT agents in achieving an effective encapsulation process. Excessive monomer addition is found to disrupt the conditions necessary for emulsion polymerization by causing the detachment of macroRAFT agents from the surface of the modified Fe3O4 nanoclusters. These results are instructive for the future rational design and synthesis of high-performance catalysts.

Co-encapsulation of organic polymers and inorganic superparamagnetic iron oxide colloidal crystals requires matched diffusion time scales.

Nanoparticles (NPs) that contain both organic molecules and inorganic metal or metal oxide colloids in the same NP core are "composite nanoparticles" which are of interest in many applications, particularly in biomedicine as "theranostics" for the combined delivery of colloidal diagnostic imaging agents with therapeutic drugs. The rapid precipitation technique Flash NanoPrecipitation (FNP) enables continuous and scalable production of composite nanoparticles with hydrodynamic diameters between 40-200 nanometers (nm) that contain hydrophobic superparamagnetic iron oxide primary colloids. Composite NPs co-encapsulate these primary colloids (diameters of 6 nm, 15 nm, or 29 nm), a fluorescent dye (600 Daltons), and poly(styrene) homopolymer (1800, 50 000, or 200 000 Daltons) with NPs stabilized by a poly(styrene)-block-poly(ethylene glycol) (1600 Da-b-5000 Da) block copolymer. Nanoparticle assembly in FNP occurs by diffusion limited aggregation of the hydrophobic core components followed by adsorption of the hydrophobic block of the stabilizing polymer. The hydrodynamic diameter mismatch between the collapsed organic species and the primary colloids (0.5-5 nm versus 6-29 nm) creates a diffusion-aggregation time scale mismatch between components that can lead to nonstoichiometric co-encapsulation in the final nanoparticles; some nanoparticles are composites with primary colloids co-encapsulated alongside organics while others are devoid of the primary colloids and contain only organic species. We use a magnetic capture process to separate magnetic composite nanoparticles from organic-only nanoparticles and quantify the amount of iron oxide colloids and hydrophobic fluorescent dye (as a proxy for total hydrophobic polymer content) in the magnetic and nonmagnetic fractions of each formulation. Analysis of the microstructure in over 1100 individual nanoparticles by TEM imaging and composition measurements identifies the conditions that produce nonstoichiometric composite NP populations without co-encapsulated magnetic iron oxide colloids. Stoichiometric magnetically responsive composite NPs are produced when the ratio of characteristic diffusion-aggregation time scales between the inorganic primary colloid and the organic core component is less than 30 and all NPs in a dispersion contain organic and inorganic species in approximately the same ratio. These rules for assembly of colloids and organic components into homogeneous composite nanoparticles are broadly applicable.

Ferroptosis-enhanced chemotherapy for triple-negative breast cancer with magnetic composite nanoparticles

Triple-negative breast cancer (TNBC) causes great suffering to patients because of its heterogeneity, poor prognosis, and chemotherapy resistance. Ferroptosis is characterized by iron-dependent oxidative damage by accumulating intracellular lipid peroxides to lethal levels, and plays a vital role in the treatment of TNBC based on its intrinsic characteristics. To identify the relationship between chemotherapy resistance and ferroptosis in TNBC, we analyzed the single cell RNA-sequencing public dataset of GSE205551. It was found that the expression of Gpx4 in DOX-resistant TNBC cells was significantly higher than that in DOX-sensitive TNBC cells. Based on this finding, we hypothesize that inducing ferroptosis by inhibiting the expression of Gpx4 can reduce the resistance of TNBC to DOX and enhance the therapeutic effect of chemotherapy on TNBC. Herein, dihydroartemisinin (DHA)-loaded polyglutamic acid-stabilized Fe3O4 magnetic nanoparticles (Fe3O4-PGA-DHA) was combined with DOX-loaded polyaspartic acid-stabilized Fe3O4 magnetic nanoparticles (Fe3O4-PASP-DOX) for ferroptosis-enhanced chemotherapy of TNBC. Compared with Fe3O4-PASP-DOX, Fe3O4-PGA-DHA + Fe3O4-PASP-DOX demonstrated significantly stronger cytotoxicity against different TNBC cell lines and achieved significantly more intracellular accumulation of reactive oxygen species and lipid peroxides. Furthermore, transcriptomic analyses demonstrated that Fe3O4-PASP-DOX-induced apoptosis could be enhanced by Fe3O4-PGA-DHA-induced ferroptosis and Fe3O4-PGA-DHA + Fe3O4-PASP-DOX might trigger ferroptosis in MDA-MB-231 cells by inhibiting the PI3K/AKT/mTOR/GPX4 pathway. Fe3O4-PGA-DHA + Fe3O4-PASP-DOX showed superior anti-tumor efficacy on MDA-MB-231 tumor-bearing mice, providing great potential for improving the therapeutic effect of TNBC.

Review on the Use of Magnetic Nanoparticles in the Detection of Environmental Pollutants

Magnetic nanomaterials (MNPs) have been widely used in the detection of pollutants in the environment because of their excellent nano effect and magnetic properties. These intrinsic properties of MNPs have diversified their application in environmental contaminant detection. In this paper, the research status quo of the use of MNPs in detecting organic and inorganic contaminants from wastewater and soil is reviewed. The preparation method and modification technology of magnetic nanoparticles are also described in detail. The application prospect of magnetic nanoparticle composites in the detection of contaminants in water and soil is discussed. Compared with traditional detection methods, MNPs are more accurate and efficient in pollutant enrichment. Moreover, the biological synthesis of MNPs was proven to be eco-friendly and aided in sustainable development. The study shows that MNPs have good application prospects in soil pollution detection, but the mechanism still needs to be investigated to realize their popularization and application.

Therapeutic Potential of Methotrexate-Loaded Superparamagnetic Iron Oxide Nanoparticles Coated with Poly(lactic-co-glycolic acid) and Polyethylene Glycol against Breast Cancer: Development, Characterization, and Comprehensive In Vitro Investigation.

Novel superparamagnetic iron oxide nanoparticles (SPIONs) of Methotrexate (MTX) were developed using supercritical liquid technology and optimized with a Box-Behnken design in order to assess its potential as a candidate for the treatment of breast cancer. MTX-SPIONs coated with poly(lactic-co-glycolic acid)-polyethylene glycol 400 had an aggregate size of 500 nm and an encapsulation efficiency of 46.8 ± 3.9%. The Fourier-transformed infrared spectroscopy analysis revealed a shift in the main bands due to intermolecular hydrogen bonds, whereas the differential scanning calorimetry analysis revealed the absence of the MTX melting endotherm, indicating complete encapsulation with oxide nanoparticles. The zeta potential results indicated a value of 4.98 mV, whereas the in vitro release study revealed an initial burst release followed by a considerable release of 35.1 ± 2.78% after 12 h. Using flow cytometry, control, MTX, and MTX-SPIONs were evaluated for apoptosis, with MTX-SPIONs exhibiting greater apoptosis than the control group and MTX. In addition, MTX-SPIONs inhibited cell division and content organization while substantially increasing the proportion of cells in the G1 and G2 phases relative to the control group. MTX-SPIONs exhibited prolonged anticancer effects against MCF-7 cell lines compared to MTX alone, indicating that SPION-delivered chemotherapeutics may increase cytotoxicity. The medication was stable with low encapsulated drug loss, suggesting that the supercritical liquid technology-based method is a promising way for generating drug-polymer magnetic composite nanoparticles for cancer treatment.

Synthesis of magnetic nanoparticles coated zirconia using one-pot solvothermal processes as adsorbent for Pb(II) and Cd(II) removal

Indonesia, notably in Central Kalimantan, has the potential for raw zirconia mineral, but it has not been successfully developed as a material that has ecologically friendly, high economic and technical value. The magnetic nanoparticles coated zirconia mineral was synthesized by using one-pot solvothermal processes, and then was used as adsorbent for water and wastewater treatment in adsorption process. Zirconia minerals are turned into composites with magnetic nanoparticles with the addition of hexane diamine to create the composite with amino groups (MH@ZrO2). It was then utilized as adsorbent to adsorb lead and cadmium metal in an artificial solution, and lower the metal content of lead/ (Pb(II)) and cadmium (Cd(II)) in it. The first stage was to determine the equilibrium of contact time (30, 60, 120, 240, and 360 min) of the adsorbent in binding Pb(II) and Cd(II) ions. The variations of pH 3, 5, 7, and 9 in the solution during adsorption were also examined to establish appropriate conditions for the adsorption process. The observations of magnetic nanoparticles composites based on a Scanning Electron Microscopy (SEM) analysis showed that magnetic nanoparticles with the diameter of 30–50 nm were generated on the face of zirconia minerals. X-Ray Diffraction (X-RD) analysis revealed that zirconia minerals treatment lowered the Crystallinity Index by 11.19% and the silica content by 98%. A Fourier Transform Infra-Red (FT-IR) spectrometer showed an adsorption peak of 590 cm−1 for the Fe-O bond on Fe3O4. Meanwhile, the optimum condition for Pb(II) and Cd(II) adsorption with pHe around 7 ± 0.2 for 360 min resulted in an adsorption density of 117.67 mg/g and 24.19 mg/g, respectively. The MH@ZrO2 led to development for high potential adsorbent due to stable material and easy separation, and capable for absorbing Pb(II) and Cd(II) ions from an aqueous solution.

SiCNFe Ceramics as Soft Magnetic Material for MEMS Magnetic Devices: A Mössbauer Study.

Polymer-derived SiCNFe ceramics is a prospective material that can be used as soft magnets in MEMS magnetic applications. The optimal synthesis process and low-cost appropriate microfabrication should be developed for best result. Homogeneous and uniform magnetic material is required for developing such MEMS devices. Therefore, the knowledge of exact composition of SiCNFe ceramics is very important for the microfabrication of magnetic MEMS devices. The Mössbauer spectrum of SiCN ceramics, doped with Fe (III) ions, and annealed at 1100 °C, was investigated at room temperature to accurately establish the phase composition of Fe-containing magnetic nanoparticles, which were formed in this material at pyrolysis and which determine their magnetic properties. The analysis of Mössbauer data shows the formation of several Fe-containing magnetic nanoparticles in SiCN/Fe ceramics, such as α-Fe, FexSiyCz, traces of Fe-N and paramagnetic Fe3+ with octahedral oxygen environment. The presence of iron nitride and paramagnetic Fe3+ ions shows that the pyrolysis process was not completed in SiCNFe ceramics annealed at 1100 °C. These new observations confirm the formation of different Fe-containing nanoparticles with complex composition in SiCNFe ceramic composite.

Polyethylenimine–Silica–Magnetic Nanoparticle Composites for Efficient Extraction of Dissolved Copper from Aqueous Solutions and Multiphase Mixtures

Design of micro/nanoadsorbents developed for effective copper extraction should consider methods of their retrieval from relevant copper-rich environments, which are commonly complex multiphase mixtures, such as slurries of polluted soils and sediments, copper minerals including low-grade ores, and industrial and mining wastes. This work reports integration of copper-chelating polyethylenimine (PEI) with a robust silica network and highly magnetic magnetite nanoparticles, resulting in magnetic PEI–silica nanocomposite microparticles that enable efficient binding of copper ions in both aqueous solutions and complex, multiphase mixtures with subsequent retrieval using magnetic force. Produced via simple emulsion templating, these nanocomposite particles can withstand highly acidic conditions and multiple copper extraction cycles, without loss of efficiency after five consecutive cycles of copper extraction. PEI–silica–magnetic nanoparticles composites effectively bind all copper ions leached into an aqueous phase and allow their rapid magnetically induced separation from aqueous solutions and mixtures of both coarse and fine solid particles, demonstrating promising results for progress toward more sustainable copper extraction techniques.

Magnetic Composite Lignin Colloids Prepared with a Convenient Patching Method for Generally Treating Heterogeneous Oily Wastewater

AbstractThe key to the efficient use of biomass resources is the rational design and preparation of lignin‐based fine chemicals. In this investigation, the colloidal self‐assembly structure formed by lignin in good solvents is used as the module, magnetic Fe3O4 nanoparticles are taken as the carrier, and magnetic composite lignin nanoparticles are prepared in batches by a rapid and convenient surficial grafting (patching) process. The varying amphiphilicity and wettability of lignin are influenced by the various types of wetting solvents. Its wetting behavior can be regulated to achieve oil–water separation in different adsorption or/and emulsification processes. This study provides a novel tool for industrial oil–water separation and, thus, general oily wastewater treatment.

Direct continuous synthesis of macroRAFT-grafted Fe3O4 nanoclusters for the preparation of magnetic nanocomposites

A new method for synthesizing magnetic nanocomposite latex particles with a significant magnetic response and high coating rate is reported herein. Based on a micro-flow platform, Fe3O4 nanoclusters grafted with macroRAFT agents were continuously synthesized within 90 s. The obtained clusters present high mono-dispersity, narrow size distribution, and excellent saturation magnetization. Moreover, the macroRAFT polymer chains grafted on the surface of the nanoclusters can be reactivated for polymerizing hydrophobic monomers without using any surfactant, to achieve the coating of magnetic particles. The resulting polymer shell can protect the magnetic core and maintain a substantial magnetic response. Furthermore, by optimising the reaction conditions, the encapsulation efficiency can be significantly improved for the efficient preparation of magnetic nanocomposites.

The State of the Art of Natural Polymer Functionalized Fe3O4 Magnetic Nanoparticle Composites for Drug Delivery Applications: A Review.

Natural polymers have received a great deal of interest for their potential use in the encapsulation and transportation of pharmaceuticals and other bioactive compounds for disease treatment. In this perspective, the drug delivery systems (DDS) constructed by representative natural polymers from animals (gelatin and hyaluronic acid), plants (pectin and starch), and microbes (Xanthan gum and Dextran) are provided. In order to enhance the efficiency of polymers in DDS by delivering the medicine to the right location, reducing the medication's adverse effects on neighboring organs or tissues, and controlling the medication's release to stop the cycle of over- and under-dosing, the incorporation of Fe3O4 magnetic nanoparticles with the polymers has engaged the most consideration due to their rare characteristics, such as easy separation, superparamagnetism, and high surface area. This review is designed to report the recent progress of natural polymeric Fe3O4 magnetic nanoparticles in drug delivery applications, based on different polymers' origins.

Tailored design and preparation of magnetic nanocomposite particles for the isolation of exosomes

Here, we prepared a magnetic nanocomposite system composed of a cluster of magnetite nanoparticles coated with silica shell (MSNPs) with an average diameter of 140 ± 20 nm and conjugated with CD9 antibody (AntiCD9) using different strategies including adsorption or chemical conjugation of antibody molecules to either aminated MSNPs (AMSNPs) or carboxylated MSNPs (CMSNPs). Then, MSNPs were employed to isolate exosomes from ultracentrifuge-enriched solution, PC3 cell-culture medium, or exosome-spiked simulated plasma samples. Quantitative tests using nanoparticle-tracking analysis confirmed antibody-covalently conjugated MSNPs, i.e. the AntiCD9-AMSNPs and AntiCD9-CMSNPs enabled >90% recovery of exosomes. Additionally, the exosomes isolated with AntiCD9-CMSNPs showed higher recovery efficiency compared to the AntiCD9-AMSNPs. For both nanoadsorbents, lower protein impurities amounts were obtained as compared to that of exosomes isolated by ultracentrifugation and Exocib kit. The mean diameter assessment of the isolated exosomes indicates that particles isolated by using AntiCD9-AMSNPs and AntiCD9-CMSNPs have smaller sizes (136 ± 2.64 nm and 113 ± 11.53 nm, respectively) than those obtained by UC-enriched exosomes (140.9 ± 1.6 nm) and Exocib kit (167 ± 10.53 nm). Such promising results obtained in the isolation of exosomes recommend magnetic nanocomposite as an efficient tool for the simple and fast isolation of exosomes for diagnosis applications.

Magnetic Hydroxyapatite Composite Nanoparticles for Augmented Differentiation of MC3T3-E1 Cells for Bone Tissue Engineering.

Progressive aging harms bone tissue structure and function and, thus, requires effective therapies focusing on permanent tissue regeneration rather than partial cure, beginning with regenerative medicine. Due to advances in tissue engineering, stimulating osteogenesis with biomimetic nanoparticles to create a regenerative niche has gained attention for its efficacy and cost-effectiveness. In particular, hydroxyapatite (HAP, Ca10(PO4)6(OH)2) has gained significant interest in orthopedic applications as a major inorganic mineral of native bone. Recently, magnetic nanoparticles (MNPs) have also been noted for their multifunctional potential for hyperthermia, MRI contrast agents, drug delivery, and mechanosensitive receptor manipulation to induce cell differentiation, etc. Thus, the present study synthesizes HAP-decorated MNPs (MHAP NPs) via the wet chemical co-precipitation method. Synthesized MHAP NPs were evaluated against the preosteoblast MC3T3-E1 cells towards concentration-dependent cytotoxicity, proliferation, morphology staining, ROS generation, and osteogenic differentiation. The result evidenced that MHAP NPs concentration up to 10 µg/mL was non-toxic even with the time-dependent proliferation studies. As nanoparticle concentration increased, FACS apoptosis assay and ROS data showed a significant rise in apoptosis and ROS generation. The MC3T3-E1 cells cocultured with 5 µg/mL MHAP NPs showed significant osteogenic differentiation potential. Thus, MHAP NPs synthesized with simple wet chemistry could be employed in bone regenerative therapy.

Application of Biobased Substances in the Synthesis of Nanostructured Magnetic Core-Shell Materials

We propose here a novel green synthesis route of core-shell magnetic nanomaterials based on the polyol method, which uses bio-based substances (BBS) derived from biowaste, as stabilizer and directing agent. First, we studied the effect of BBS concentration on the size, morphology, and composition of magnetic iron oxides nanoparticles obtained in the presence of BBS via the polyol synthesis method (MBBS). Then, as a proof of concept, we further coated MBBS with mesoporous silica (MBBS@mSiO2) or titanium dioxide (MBBS@TiO2) to obtain magnetic nanostructured core-shell materials. All the materials were deeply characterized with diverse physicochemical techniques. Results showed that both the size of the nanocrystals and their aggregation strongly depend on the BBS concentration used in the synthesis: the higher the concentration of BBS, the smaller the sizes of the iron oxide nanoparticles. On the other hand, the as-prepared magnetic core-shell nanomaterials were applied with good performance in different systems. In particular, MBBS@SiO2 showed to be an excellent nanocarrier of ibuprofen and successful adsorbent of methylene blue (MB) from aqueous solution. MBBS@TiO2 was capable of degrading MB with the same efficiency of pristine TiO2. These excellent results encourage the use of bio-based substances in different types of synthesis methods since they could reduce the fabrication costs and the environmental impact.

Removal of As(V) from aqueous solution using modified Fe3O4 nanoparticles.

The removal of arsenic contamination from the aqueous environment is of great importance in the conservation of the Earth's water resources, and surfactants are a promising material used to modify magnetic nanoparticles to improve adsorption properties. Therefore, it is important to develop efficient and selective adsorbents for arsenic. Surface modification of Fe3O4 was carried out using anionic, cationic and zwitterionic surfactants to obtain composite Fe3O4@SDS, Fe3O4@CTAB, Fe3O4@SNC 16 and Fe3O4@NPC 16 (collectively referred to as Fe3O4@surfactants). The synthesized composite Fe3O4@surfactants magnetic nanoparticles were characterized by XRD, TEM and FTIR. The As(V) removal characteristics of the composite magnetic nanoparticles from the aqueous solution were evaluated by adsorption batch experiments which indicated the possibility of effective application of the surfactant-modified Fe3O4 magnetic nanoparticles for the removal of As(V) from aqueous solution. The adsorption equilibrium of the composites was reached in 30 min and the kinetic data followed the pseudo-second-order model. Langmuir equation could represent the adsorption isotherm data very well. Moreover, under the identical conditions, Fe3O4@CTAB showed maximum capacity of adsorption for As(V) (55.671 mg g-1), with its removal efficiency being much higher than that of the other composites. In addition, the Fe3O4@surfactants composite magnetic nanoparticles retained 93.5% of its initial arsenic removal efficiency even after re-using it five times. The mechanism of arsenic adsorption by Fe3O4@surfactants composite magnetic nanoparticles was proved to be complexation via electrostatic attraction, which was mainly innersphere in nature.