Ultrasmall Fe3O4 Nanoparticles Research Articles

Construct of Carbon Nanotube-Supported Fe2O3 Hybrid Nanozyme by Atomic Layer Deposition for Highly Efficient Dopamine Sensing.

The Fe2O3 nanozyme has been identified as the most promising alternative for the Fe3O4 nanozyme due to its relatively low toxic risk and good chemical stability. However, its enzyme-like activity is relatively low enough to meet specific application requirements. Furthermore, previous synthesis approaches have difficulties in fabricating ultra-small Fe2O3 nanoparticles with tunable size and suffer from agglomeration problems. In this study, atomic layer deposition (ALD) was used to deposit Fe2O3 on surfaces of carbon nanotubes to form hybrid nanozymes (Fe2O3/CNTs). ALD enables the preparation of ultrafine Fe2O3 nanoparticles with precise size control <1 nm, while CNTs could be served as promising support for good dispersibility and as an effective activity activator. Hence, the formed Fe2O3/CNTs exhibit excellent peroxidase-like activity with a specific peroxidase activity of 24.5 U mg−1. A colorimetric method for sensing dopamine (DA) was established and presented good sensitivity with a limit of detection (LOD) as low as 0.11 μM. These results demonstrated that, in virtue of meticulous engineering methods like ALD, carbon nanomaterial-based hybrids can be developed as talented enzyme mimetic, thus paving a way for nanozyme design with desired activity and broadening their applications in biosensing and other fields.

The Use of Ultra-Small Fe3O4 Magnetic Nanoparticles for Hydrothermal Synthesis of Fe3+-Doped Titanate Nanotubes.

A method of the hydrothermal synthesis of Fe3+-doped titanate nanotubes (TNT) is reported in which the ultra-small Fe3O4 nanoparticles are used as the sources of Fe3+ ions. The magnetic nanoparticles with a diameter of about 2 nm are added during the washing stage of the hydrothermal procedure. During washing, they gradually degrade and at the same time, the titanate product is transformed into nanotubes. The obtained nanotubes were characterized by structural and magnetic measurements. It was found that, depending on the value of the external magnetic field, they may show the property of room temperature ferromagnetism, paramagnetism or they may be diamagnetic. It was also shown that the modified TNTs have greater photocatalytic activity compared to unmodified TNTs.

One-step synthesis of ultra-small Fe2O3 nanoparticles on carbon nanotubes at a low temperature as a high-performance anode for supercapacitors

The composites of Fe2O3 nanoparticles and carbon nanotubes (CNTs) can be applied in many fields including energy storage. The synthesis of Fe2O3/CNTs composite is usually carried out under high temperatures with complicated processes. To solve these problems, we report a novel one-step chemical bath deposition method to synthesize it at a very low temperature in this work. With DMF as a complex agent, ferrous cations can be well combined with the external surface of CNTs to form small Fe2O3 nanoparticles just at 70 °C for 2-h reaction. XRD, SEM, and TEM analyses confirm that as-prepared Fe2O3 nanoparticles are ultra-small, well crystallized, and highly dispersed onto the surface of CNTs. When being used as an electrode material for supercapacitor, the composite has a specific capacitance of 942 F g−1 at 2 A g−1 and 645 F g−1 at 15 A g−1, exhibiting a higher specific capacitance than previously reported Fe2O3/CNTs composites due to its smaller size.

Synergistic inhibitory effect of ultralight CNTs-COOH@Fe3O4 modified separator on polysulfides shuttling for high-performance lithium–sulfur batteries

Lithium-sulfur (Li–S) battery has attracted widespread research interest owing to its broad application prospects in high-density energy storage. However, the notorious “shuttle effect” is still the biggest obstacle to its practical application. In this work, the synergistic inhibitory effect on polysulfides shuttling has proposed by introducing a coating of ultrasmall Fe3O4 nanoparticles modified carboxylated carbon nanotubes (CNTs-COOH@Fe3O4) on a commercial separator. The carboxylated carbon nanotube networks can act as both physical barrier and ion shielding layer, preventing the migration of polysulfides. Meanwhile, the ultrasmall Fe3O4 nanoparticles can act as polysulfide-trapping centers to anchor polysulfides via robust chemical adsorption. In addition, the highly conductive CNTs-COOH@Fe3O4 coating can act as “upper current collector”, promoting the kinetic conversion reaction of sulfur species and facilitating the reutilization of active materials. The synergistic effect of the ultralight separator coating (areal weight 1.79 g m−2) enables the Li–S batteries showing outstanding cycle stability (the capacity decay is as low as 0.032% per cycle at 1 C over 2000 cycles), excellent rate performance and superior anti-self-discharge capability. The proposed combination strategy paves the way to the simple and scalable preparation of advanced separators.

Ultra-small Fe3O4 nanoparticles for nuclei targeting drug delivery and photothermal therapy

The aim of this study is to investigate the size-dependent behaviors of the Fe3O4 nanoparticles. We synthesize Fe3O4 nanoparticles with average diameters of 2.1, 4.3 and 9.5 nm then systematically study their photothermal effects and biological behaviors as drug carriers in MCF-7 cells. The results indicate that the Fe3O4 nanoparticles with size below 5 nm can enter the nuclei, while larger ones (9.5 nm) are only located in the cytoplasm. All nanoparticles exhibit favorable photothermal effect and can trigger the release of doxorubicin (DOX) that loaded on the nanoparticles to kill the cancer cells. 2.1 nm and 4.3 nm Fe3O4 nanoparticles demonstrate superior toxicity to 9.5 nm nanoparticles due to the outstanding nuclei targeting ability. This work presents a strategy for the drug carrier design to enhance the therapeutic effect.

Anchoring ultrasmall FeIII-based nanoparticles on silica and titania mesostructures for syngas H2S purification

Abstract Mesostructured titania (Anatase) and silica (MCM-41) were proposed as supports to design highly active, selective, and regenerable FeIII-based nanostructured sorbents for mid-temperature H2S removal in a model sour syngas. The resulting sorbents (Fe–SiO2 and Fe–TiO2) were tested as H2S removers at 300 °C and exhibited high reactivity and regenerability over repeated sulfidation cycles, with the best sorption performances achieved by the silica-based sorbent. Specifically, Fe–SiO2 showed a constant sorption capacity of 19 ± 1 mgS gsorbent−1 after the first sulfidation cycle. Meanwhile, a lower sorption capacity of 10 ± 1 mgS gsorbent−1 was found for the Fe–TiO2 composite. As evidenced by combining 57Fe Mossbauer spectroscopy with DC magnetometry, the nature (amorphous or crystalline) and composition (SiO2 or TiO2) of the inorganic mesostructures played a crucial role in the formation of the ultrasmall FeIII-active phase: maghemite (γ-Fe2O3) and pseudobrookite (Fe2TiO5) in the case of silica and titania, respectively. Therefore, the performance can be mainly justified in the light of the different reactivity of the active phases (Fe2O3 vs Fe2TiO5). FeIII-active phase in the form of ultrasmall Fe2O3 nanoparticles (about 2 nm) homogeneously dispersed in a highly stable mesostructured silica support assured high reactivity (85%–100% of the active phase involvement) and regenerability in the mid-temperature range as for the sulfidation run during the repeated sulfidation cycles (steady performances) avoiding the common drawbacks of unsupported sorbents (unreacted core and sintering phenomena causing loss of activity).

Three Dimensional Carbon Supported Ultrasmall Fe2O3 Nanoparticles as Anode Material for Lithium Ion Batteries

In this article, carbon nanotubes were grown on free standing multi-layer graphene sheet to form three dimensional carbon (3D-carbon) materials, and then used as support of Fe2O3 nanoparticles. Ultrasmall Fe2O3 nanoparticles were uniformly deposited on the surface of the 3D-carbon. Due to the synergistic effect of Fe2O3 nanoparticles and 3D-carbon, the electrochemical properties are higher than that of bare Fe2O3 material and multi-layer graphene sheet supported Fe2O3. Reversible capacity 528 mAh g-1 is maintained at a high current density of 500 mA g−1 after 50 cycles. This composite shows a stable cycling and high rate performance.

Fe/N-doped hollow porous carbon spheres for oxygen reduction reaction

Herein, we design a dual-template-assisted pyrolysis method to prepare ultra-small Fe3O4 nanoparticles anchored on Fe/N-doped hollow porous carbon spheres (0.010-Fe/NHPCS-800) for oxygen reduction reaction (ORR). The synthesized SiO2 nanospheres, which are selected as the hard template, contribute to forming macroporous structure. Pluronic ® F127 is employed to fabricate mesopores through high-temperature pyrolysis as a soft template. In this way, the 0.010-Fe/NHPCS-800 architecture represents an ordered hierarchically porous property with a large BET surface area (1812 m2 g−1), which can facilitate the mass transport of reactants and increase the electrochemically active area. The Fe3O4 nanoparticles wrapped by graphitic carbon layers provide more active sites, and the synergistic interaction between Fe3O4 nanoparticles and doping N has a positive effect on ORR performance. The 0.010-Fe/NHPCS-800 catalyst outperforms the most effective ORR activities among a series of Fe/NHPCS samples with onset potential of 0.95 V (versus reversible hydrogen potential) and half-wave potential of 0.81 V, which is almost the same as the commercial Pt/C (0.96 and 0.81 V, correspondingly) in 0.10 M KOH. However, both the stability and durability of 0.010-Fe/NHPCS-800 surpass those of commercial Pt/C. Given all these advantages, 0.010-Fe/NHPCS-800 is a promising candidate to take the place of Pt-based electrocatalysts for ORR in the future.

Light-Addressable Nanoclusters of Ultrasmall Iron Oxide Nanoparticles for Enhanced and Dynamic Magnetic Resonance Imaging of Arthritis.

Design of novel nanoplatforms with single imaging elements for dynamic and enhanced T 1/T 2‐weighted magnetic resonance (MR) imaging of diseases still remains significantly challenging. Here, a facile strategy to synthesize light‐addressable ultrasmall Fe3O4 nanoparticles (NPs) that can form nanoclusters (NCs) under laser irradiation for enhanced and dynamic T 1/T 2‐weighted MR imaging of inflammatory arthritis is reported. Citric acid‐stabilized ultrasmall Fe3O4 NPs synthesized via a solvothermal approach are linked with both the arthritis targeting ligand folic acid (FA) and light‐addressable unit diazirine (DA) via polyethylene glycol (PEG) spacer. The formed ultrasmall Fe3O4‐PEG‐(DA)‐FA NPs are cytocompatible, display FA‐mediated targeting specificity to arthritis‐associated macrophage cells, and can form NCs upon laser irradiation to have tunable r 1 and r 2 relaxivities by varying the laser irradiation duration. With these properties owned, the designed Fe3O4‐PEG‐(DA)‐FA NPs can be used for T 1‐weighted MR imaging of arthritis without lasers and enhanced dual‐mode T 1/T 2‐weighted MR imaging of arthritis under laser irradiation due to the formation of NCs that have extended accumulation within the arthritis region and limited intravasation back to the blood circulation. The designed light‐addressable Fe3O4‐PEG‐(DA)‐FA NPs may be used as a promising platform for dynamic and precision T 1/T 2‐weighted MR imaging of other diseases.

2D Fe2O3 nanosheets with bi-continuous pores inherited from Fe-MOF precursors: an advanced anode material for Li-ion half/full batteries

Two-dimensional (2D) materials are appealing for energy storage devices due to their intriguing chemical and physical properties. Herein, a promising anode material for both half/full cells is well prepared by constructing bi-continuous porous structure in Fe2O3 nanosheets (bp-Fe2O3) through a target construction method. Notably, the obtained bp-Fe2O3 exhibits a unique wrinkled layer structure composed by ultrasmall Fe2O3 nanoparticles, which can well shorten the charge diffusion pathway. Furthermore, the wrinkled layer structure and the presence of pores in the bp-Fe2O3 sample are able to accommodate the volume variation during deep lithiation–delithiation processes, and enable electrolyte easy penetration to the whole electrode, thus significantly improving the electrochemical performance. Benefiting from the favorable electrode framing together with fast lithiation dynamics, the prepared bp-Fe2O3 exhibits considerably better electrochemical performance in half/full cells for lithium ion batteries (LIBs), as well as superior low temperature (low-T) performance. In detail, when cycled at 1.5 A g−1, 2D bp-Fe2O3 electrode displays a reversible capacity up to 818.7 mAh g−1 for 350 cycles. Even at a stern temperature of 0 °C and −25 °C, the as-prepared bp-Fe2O3 still presents a capacity of 840.3 and 635.6 mAh g−1 at 0.5 A g−1, respectively, suggesting the normal operation of LIBs under low temperature condition. More competitively, the full cell fabricated by bp-Fe2O3 anode and LiFePO4 cathode gives excellent electrochemical performance (421.2 mAh g−1 after 80 cycles at 0.1 A g−1) between 0.4 and 3.4 V and high energy density of 247.03 Wh kg−1.

Fabrication of a dual T1 and T2 contrast agent for magnetic resonance imaging using cellulose nanocrystals/Fe3O4 nanocomposite

A dual T1-T2 contrast agent for magnetic resonance imaging was developed based on ultrasmall superparamagnetic Fe3O4 nanoparticles. The magnetite nanoparticles were synthesized with thermal decomposition method, then loaded on hydrophilic cellulose nanocrystals-poly citric acid nanoplatform. The high saturation magnetization value (52.2 emu g−1), considerable relaxivity parameters r1 (13.8 mM−1 s−1), r2 (96.2 mM−1 s−1), and appropriate r2/r1 (7.0) at 3.0 T demonstrated the significant enhancement effect of nanocomposite as a dual positive and negative contrast agent. In vitro cellular uptake study using inductively coupled plasma optical emission spectroscopy, in vitro cytotoxicity up to 200 μg mL−1 Fe with HeLa cell lines and colloidal stability investigations revealed that the sufficient cellular uptake, excellent biocompatibility and low toxicity of nanocomposite which is promising for its biomedical applications.

Fe3O4 Nanoparticles Functionalized with Polymer Ligand for T1-Weighted MRI In Vitro and In Vivo.

Magnetic resonance imaging (MRI) has gained wide interest in early accurate diagnoses due to the high resolution and low toxicity of magnetic nanoparticles. In order to develop potential alternatives of toxic Gd- or Mn-based chelating agents, we report the synthesis of water soluble ultra-small Fe3O4 nanoparticles by a modified co-precipitation method as T1-weighted positive contrast agents. The magnetic iron oxide nanoparticles (MIONs) were functionalized by polymer ligand dodecanthiol-polymethacrylic acid (DDT-PMAA) to enhance their colloidal stability. These MIONs have high longitudinal relaxivity (r1 = 8.18 mM−1·S−1) and exhibited good results in the in vitro and in vivo MR imaging. No toxicity was observed in cytotoxicity assay and histology toxicity analysis. The MIONs@DDT-PMAA(magnetic iron oxide nanoparticles @ dodecanthiol-polymethacrylic acid) present great potential as positive contrast agents for tumor diagnosis.

Fabrication, optimization, and characterization of ultra-small superparamagnetic Fe3O4 and biocompatible Fe3O4@ZnS core/shell magnetic nanoparticles: Ready for biomedicine applications

Magnetic nanoparticles that preferred for biomedical applications are required to be biocompatible, nanosized and superparamagnetic. In this research, ultra-small superparamagnetic Fe3O4 nanoparticles and novel superparamagnetic Fe3O4@ZnS core/shell nanocomposites were fabricated using biocompatible ethylenediaminetetraacetic acid (EDTA) as a capping agent by a facile refluxing assisted co-precipitation method at optimum condition. The Fe3O4 and Fe3O4@ZnS nanoparticles were investigated using X-ray diffraction (XRD), scanning and transmission electron microscopy (SEM and TEM), UV–Vis spectroscopy, vibrating sample magnetometer (VSM) and Dynamic Light Scattering (DLS). The VSM results indicated that all of the samples have superparamagnetic behavior. The particle size of the Fe3O4 and Fe3O4@ZnS nanoparticles were obtained at about 10 and 22 nm, respectively.

Polydopamine-coated magnetic mesoporous silica nanoparticles for multimodal cancer theranostics.

Polydopamine-coated magnetic mesoporous silica nanoparticles have been designed by loading ultrasmall iron oxide nanoparticles within hollow mesoporous silica nanopartricles and then coating polydopamine onto the particle surface. The developed nanoplatform displayed improved colloidal stability, enhanced r1 relaxivity and near infrared absorption feature, affording their use for multimodal cancer theranostics.

Facile synthesis of ultrasmall Fe3O4 nanoparticles on MXenes for high microwave absorption performance

Although two dimensional (2D) materials have already been studied as promising microwave absorption materials due to fascinating layered structure, it is hard to achieve both thin coating and excellent absorbing capability. Herein, 2D hierarchical composites of nano-sized Fe3O4 particles on MXenes (TiO2/Ti3C2Tx/Fe3O4) with different [TiO2/Ti3C2Tx]/[Fe3O4] ratios were synthesized by using a moderate chemical hydrothermal reaction. Scanning electron microscope and transmission electron microscope techniques indicated that the surfaces of MXenes were densely covered with Fe3O4 nanoparticles of ∼4.9 nm in diameter and TiO2 particles. By tuning the ratio of [TiO2/Ti3C2Tx]/[Fe3O4], microwave absorption capabilities in terms of the maximum reflection loss (RL) value and absorber thickness could be readily optimized. Specifically, the sample TiO2/Ti3C2Tx/Fe3O4-5 exhibited a remarkable absorption performance, with a maximum reflectivity of −57.3 dB at 10.1 GHz and a band range below −10 dB to over 9.1–11.1 GHz at a thickness of 1.9 mm. Therefore, our 2D MXene composites are expected to be promising candidates as ultrathin and lightweight absorbing materials.

Development of tailored SPION-PNIPAM nanoparticles by ATRP for dually responsive doxorubicin delivery and MR imaging.

Biocompatible, colloidally stable and ultra-small Fe3O4 nanoparticles (SPIONs) coated with poly(N-isopropylacrylamide) (PNIPAM) were synthesized via surface-initiated ATRP (atom transfer radical polymerization) to prevent excessive aggregation of magnetic cores and interparticle crosslinking, and to provide control over polymer content. These SPION-PNIPAM nanoparticles (NPs) have a hydrodynamic size between 8 and 60 nm depending on the PNIPAM content, and hence are ultrasmall in size and have an LCST around 38 °C. They had a high drug-loading capacity reaching 9.6 wt% doxorubicin in the final composition. The Dox release studies revealed pH and temperature-dependent release, which was not reported for PNIPAM before. Release of Dox under physiological conditions was below 20%, but around 90% at 42 °C and pH 5. This dually responsive nature is very advantageous to increase the drug efficacy and reduce side-effects, simultaneously. The cytocompatability of the SPION-PNIPAM NPs and the influence of Dox delivery to cells were investigated via in vitro cell viability, apoptosis, DNA-damage and confocal microscopy studies. The NPs were shown to be highly cytocompatible and induce significant cell death due to Dox when loaded with the drug. Besides, it was seen that the polymeric content can be used as an additional factor in tuning the release kinetics. Lastly, these nanoparticles reduced the signal intensity significantly in the T2 mode, acting as a potential SPION-based contrast agent. Overall, here, we demonstrate the design of small, smart theranostic nanoparticles with high drug-loading capacity and pH-dependent temperature-sensitive release characteristics with the ability to generate contrast in MRI.

Tumor-selective catalytic nanomedicine by nanocatalyst delivery

Tumor cells metabolize in distinct pathways compared with most normal tissue cells. The resulting tumor microenvironment would provide characteristic physiochemical conditions for selective tumor modalities. Here we introduce a concept of sequential catalytic nanomedicine for efficient tumor therapy by designing and delivering biocompatible nanocatalysts into tumor sites. Natural glucose oxidase (GOD, enzyme catalyst) and ultrasmall Fe3O4 nanoparticles (inorganic nanozyme, Fenton reaction catalyst) have been integrated into the large pore-sized and biodegradable dendritic silica nanoparticles to fabricate the sequential nanocatalyst. GOD in sequential nanocatalyst could effectively deplete glucose in tumor cells, and meanwhile produce a considerable amount of H2O2 for subsequent Fenton-like reaction catalyzed by Fe3O4 nanoparticles in response to mild acidic tumor microenvironment. Highly toxic hydroxyl radicals are generated through these sequential catalytic reactions to trigger the apoptosis and death of tumor cells. The current work manifests a proof of concept of catalytic nanomedicine by approaching selectivity and efficiency concurrently for tumor therapeutics.

Labeling adipose derived stem cell sheet by ultrasmall super-paramagnetic Fe3O4 nanoparticles and magnetic resonance tracking in vivo

Cell sheet therapy has emerged as a potential therapeutic option for reparation and reconstruction of damaged tissues and organs. However, an effective means to assess the fate and distribution of transplanted cell sheets in a serial and noninvasive manner is still lacking. To investigate the feasibility of tracking Adipose derived stem cells (ADSCs) sheet in vivo using ultrasmall super-paramagnetic Fe3O4 nanoparticles (USPIO), canine ADSCs were cultured and incubated with USPIO and 0.75 μg/ml Poly-L-Lysine (PLL) for 12 h. Labeling efficiency, cell viability, apoptotic cell rate were assessed to screen the optimum concentrations of USPIO for best labeling ADSCs. The results showed ADSCs were labeled by USPIO at an iron dose of 50 μg/ml for a 12 h incubation time, which can most efficiently mark cells and did not impair the cell survival, self-renewal, and proliferation capacity. USPIO-labeled ADSCs sheets can be easily and clearly detected in vivo and have persisted for at least 12 weeks. Our experiment confirmed USPIO was feasible for in vivo labeling of the ADSCs sheets with the optimal concentration of 50 μg Fe/ml and the tracing time is no less than 12 weeks.

Ultrasmall Fe2O3 nanoparticles/MoS2 nanosheets composite as high-performance anode material for lithium ion batteries

Coupling ultrasmall Fe2O3 particles (~4.0 nm) with the MoS2 nanosheets is achieved by a facile method for high-performance anode material for Li-ion battery. MoS2 nanosheets in the composite can serve as scaffolds, efficiently buffering the large volume change of Fe2O3 during charge/discharge process, whereas the ultrasmall Fe2O3 nanoparticles mainly provide the specific capacity. Due to bigger surface area and larger pore volume as well as strong coupling between Fe2O3 particles and MoS2 nanosheets, the composite exhibits superior electrochemical properties to MoS2, Fe2O3 and the physical mixture Fe2O3+MoS2. Typically, after 140 cycles the reversible capacity of the composite does not decay, but increases from 829 mA h g−1 to 864 mA h g−1 at a high current density of 2 A g−1. Thus, the present facile strategy could open a way for development of cost-efficient anode material with high-performance for large-scale energy conversion and storage systems.

Fe3O4 nanoparticle-coated boron nitride nanospheres: Synthesis, magnetic property and biocompatibility study

Hybrid nanocomposites consisting of uniform Fe3O4 nanoparticles and boron nitride (BN) nanospheres were synthesized via an ethanol-thermal reaction method. The spherical BN nanoparticles (BNNSs) with average diameter 150nm have been uniformly coated with dense ultra-small Fe3O4 nanoparticles (with average diameter of 10nm), forming novel Fe3O4@BNNS nanocomposites. Magnetic measurement by using vibrating sample magnetometer (VSM) indicates that the Fe3O4 coating is superparamagnetic, and the nanocomposites can be physically manipulated at a low magnetic field. Preliminary biocompatibility study has also been performed to evaluate the toxicity of the nanocomposites. The nanocomposites show cytocompatibility at low concentration and have little effect on cell viability of MCF-7, MCF-10 and Hela cell lines. The Fe3O4@BNNS nanocomposites may find a wide range of potential applications including water treatment, catalysts, carriers for boron neutron capture therapy and magnetic-targeted drug delivery.