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Fe <sub/>3</sub> O <sub/>4</sub> nanoparticles as the saturable absorber for a mode-locked fiber laser at 1558 nm
摘要： We demonstrated a mode-locked erbium doped fiber laser (EDFL) operating at 1558 nm by exploiting ferroferric-oxide nanoparticles (FONPs) as the saturable absorber (SA) material. FONPs, with an average diameter of ~20 nm, were prepared by a thermal decomposition method, then mixed with sodium carboxymethylcelluose to form an FONP film. The FONP SA was fabricated through a sandwiched FONP film between two fiber connectors. By inserting the FONPs SA into an EDFL cavity pumped by a 980 nm laser diode, stable passive mode-locking was achieved with a threshold pump power of ~120 mW. The obtained mode-locked laser had a central wavelength of ~1558 nm, a spectral bandwidth of ~0.8 nm, a pulse width of ~4.35 ns, and a repetition rate of ~37.32 MHz. Furthermore, a maximum average power of ~17 mW was obtained for a pump power of 340 mW. To the best of our knowledge, this is the first time that it has been demonstrated that FONPs can be used for constructing mode-locked fiber lasers.
关键词： mode-locked,fibre laser,Fe3O4 nanoparticles,saturable absorber (SA)
更新于2025-11-28 14:23:57
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Ultraviolet light assisted heterogeneous Fenton degradation of tetracycline based on polyhedral Fe3O4 nanoparticles with exposed high-energy {110} facets
摘要： Polyhedral Fe3O4 nanoparticles (NPs) with exposed high-energy {110} facets were synthesized by hydro-thermal method using ferrous sulfate and sodium thiosulfate as precursor at 140 °C. The as-synthesized catalysts were characterized via X-ray powder diffraction (XRD), electro impedance spectra (EIS), scanning electron microscope (SEM), transmission electron microscope (TEM) and vibrating sample magnetometer (VSM) at room temperature. The well-defined Fe3O4 NPs with exposed high-energy {110} facets distributed a wide size, and the percentage of {110} facets was approximately 38.5% for single Fe3O4 NPs crystal. The synergistic effect of UV irradiation and the polyhedral Fe3O4 NPs improved the photodegradation efficiency of tetracycline (TC). The degradation efficiency of polyhedral Fe3O4 NPs catalyzing UV-Fenton system reached 96.7% after 60 min reaction, which was more substantial than polyhedral Fe3O4/H2O2 system (40%) and spherical Fe3O4 NPs catalyzing UV-Fenton system (28%) after 60 min reaction. The TOC degradation efficiency reached 56.5% for polyhedral Fe3O4 NPs catalyzing UV-Fenton after 120 min reaction, while UV/H2O2 system and spherical Fe3O4 NPs catalyzing UV-Fenton was 36.0% and 22.1% respectively after 120 min reaction. Moreover, polyhedral Fe3O4 NPs catalyzing UV-Fenton system exhibited an extremely wide pH range (from 3.0 to 9.0) for efficient degradation of TC. Simultaneously, the extraordinary high degradation efficiency was based on 10 mM H2O2 concentration, which had low requirement for H2O2. Further, the polyhedral Fe3O4 NPs could be reused for five consecutive cycles while still achieving at 91.7% of its original degradation efficiency and recycled under a magnetic field along with excellent chemical stability. Ultraviolet light assisted heterogeneous Fenton in the polyhedral Fe3O4 NPs system improved the ?OH and O2?- production efficiency and Fe(III)/Fe(II) redox cycle, which consequently achieved an excellent degradation efficiency.
关键词： heterogeneous UV-Fenton,Polyhedral Fe3O4 nanoparticles,high-energy {110} facets,tetracycline degradation
更新于2025-11-14 17:03:37
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A magnetic and carbon dot based molecularly imprinted composite for fluorometric detection of 2,4,6-trinitrophenol
摘要： A magnetic molecularly imprinted composite was prepared by reverse microemulsion using carbon dots (CDs), Fe3O4 as the co-nucleus, and a molecularly imprinted polymer (MIP; with 2,4,6-trinitrophenol as the template) acting as recognition sites. The composite of type CD/Fe3O4@MIPs was characterized by transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FT-IR), zeta potentiometric analysis, X-ray diffraction (XRD) and vibrating sample magnetometry (VSM). The results showed that the composite MIP has a spherical shape with average diameter of 200 nm. They also showed that the composite contains core-shell structures with several Fe3O4 nanoparticles and CDs embedded in each of the microsphere. The composite can extract 2,4,6-trinitrophenol (TNP) and has an imprinting factor of 3.6. It has high selectivity and sensitivity for TNP which acts as a quencher of the fluorescence of the CDs (with excitation/emission maxima at 370/470 nm). The limit of detection of this fluorometric TNP assay is 0.5 nM. The method was successfully applied to the determination of TNP in spiked tap water and river water samples, and recoveries ranged from 89.4% to 108.5% (with an RSD of <6%).
关键词： Fluorescence quenching,Fe3O4 nanoparticles,Stern-Volmer plot,Environmental pollutants,Reverse microemulsion method,Selective recognition,Molecularly imprinting
更新于2025-09-23 15:23:52
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Microtubule network as a potential candidate for targeting by gold nanoparticle-assisted photothermal therapy
摘要： Photothermal therapy is achieving ever-increasing attention as a promising method for killing cancer cells. Although, gold nanoparticles are regarded as one of the most effective photothermal therapy agents, the mechanisms underlying their action have to be addressed. Moreover, studies have showed that gold nanoparticles induce apoptosis in treated cultures. Hence, in this study, we investigated the interaction of folic acid functionalized gold nanoparticles and gold-shelled Fe3O4 nanoparticles with microtubule and microtubule associated protein tau in order to introduce intracellular targets of these nanoparticles and provide a holistic view about the mechanism of action of gold nanoparticles used in photothermal therapy. Various spectroscopic methods were used to find gold nanoparticles interaction with Tubulin and Tau. Our results indicated that these gold nanoparticles interact with both Tau and Tubulin and their affinity increases as temperature rises. Also, the results illustrated that quenching mechanism for gold nanoparticles interaction with Tubulin and Tau was static. The hydrophobic interaction was determined as driving force for gold nanoparticles binding to Tubulin and Tau. Moreover, it was showed that both type of gold nanoparticles stabilize microtubule polymers. These results suggest Tau and Tubulin as intracellular target of gold nanoparticles and propose that microtubule network is at the heart of apoptosis mechanisms initiated by photothermal therapy.
关键词： Gold-shelled Fe3O4 nanoparticles,Tubulin,Gold nanoparticles,Tau protein,Photothermal therapy
更新于2025-09-19 17:15:36
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Synthesis and Photocatalytic Activity of Fe3O4–WO3–CQD Multifunctional System
摘要： In this work, superparamagnetic Fe3O4 nanocrystalline was prepared by using citric acid as an additive and co-precipitation method. The Fe3O4–WO3–carbon quantum dot (CQD) metal oxide porous structure was constructed, characterized and analyzed. When the amount of citric acid added was 22.7 wt%, the specific saturation magnetization of Fe3O4 nanocrystals was 52.567 emu/g, and the Fe3O4–WO3 composite structure was agglomerated into spheroids having a diameter of about 200 nm. The constructed Fe3O4–WO3–CQD metal oxide porous structure has a specific surface area of 166.78 m2/g. In the experiment of adsorption and degradation of rhodamine B solution (20 mg/L), the decolorization rate of the dye by Fe3O4–WO3–CQD system was 54.42% after 60 min of dark treatment. After 240 min of photocatalysis, the dye decolorization rate increased by 14.17% to 65.56%. This shows that the photocatalytic performance of the sample was improved after the compounding process. The results provided that Fe3O4–WO3–CQD composite structure has great application potential in the field of photo-catalytic degradation of organic pollutants.
关键词： Photocatalytic,Fe3O4 nanoparticles,Carbon quantum dot (CQD),WO3
更新于2025-09-19 17:15:36
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Core-shell nanocomposite of superparamagnetic Fe3O4 nanoparticles with poly(m-aminobenzenesulfonic acid) for polymer solar cells
摘要： Superparamagnetic Fe3O4 nanoparticles play a significant role in enhancing the performance and efficiency of polymer-based solar cells using nanocomposites. For the first time in this study, a novel superparamagnetic core-shell nanocomposite of poly(m-aminobenzenesulfonic acid) (PABS) and Fe3O4 was synthesized by in-situ polymerization of m-ABS as a monomer in the presence of FeCl3.6H2O as oxidant under solid-state conditions. The poly(m-aminobenzenesulfonic acid) (PABS)-Fe3O4 nanocomposite (NCPABS-Fe3O4) was characterized using scanning electron microscopy (SEM) and transmission electron microscopy (TEM) that revealed a core-shell morphology. Under simulated solar irradiation, the photovoltaic cell characteristics were measured. Based on our results, the polymer-hybrid solar cell was fabricated using FTO/TiO2/NCPABS-Fe3O4/Al and demonstrated a power conversion efficiency (PCE or η) 4.24% that was approximately 660% higher than those obtained from FTO/TiO2/(PABS)/Al. We have also proposed a new mechanism for the 660% enhanced efficiency. To the best of our knowledge, this is the highest enhancement reported in the literature. Our results showed that the polymer-hybrid solar cell was completely efficient with a high η in comparison with similar ones reported in literature, and also had less fabrication costs using green synthesis conditions with a simple structure and displayed resistance to oxidation with high stability.
关键词： conductive polymers,Fe3O4 nanoparticles,Solar cell,photovoltaics,core-shell nanocomposite
更新于2025-09-16 10:30:52
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Magneto-fluorescent microbeads for bacteria detection constructed from superparamagnetic Fe <sub/>3</sub> O <sub/>4</sub> nanoparticles and AIS/ZnS quantum dots
摘要： The efficient and sensitive detection of pathogenic microorganisms in aqueous environments such as water used in medical applications, drinking water, and cooling water of industrial plants requires simple and fast methods suitable for multiplexed detection such as flow cytometry (FCM) with optically encoded carrier beads. For this purpose, we combine fluorescent Cd-free Ag-In-S ternary quantum dots (t-QDs) with fluorescence lifetimes (LTs) of several hundred nanoseconds and superparamagnetic Fe3O4 nanoparticles (SPIONs) with mesoporous CaCO3 microbeads to a magneto-fluorescent bead platform that can be surface-functionalized with bioligands such as antibodies. This inorganic bead platform enables immuno-magnetic separation, target enrichment, and target quantification with optical readout. The beads can be detected with steady-state and time-resolved fluorescence microscopy and flow cytometry (FCM). Moreover, they are suited for readout by time gated emission. In the following, the preparation of these magneto-fluorescent CaCO3 beads, their spectroscopic and analytic characterization, and their conjugation with bacteria-specific antibodies are presented as well as proof-of-concept measurements with Legionella pneumophila including cell cultivation and plating experiments for bacteria quantification. Additionally, the possibility to discriminate between the long-lived emission of the LT-encoded capture and carrier CaCO3 beads and the short-lived emission of the dye-stained bacteria with time-resolved fluorescence techniques and single wavelength excitation is demonstrated.
关键词： AIS/ZnS quantum dots,flow cytometry,magneto-fluorescent microbeads,time-resolved fluorescence,superparamagnetic Fe3O4 nanoparticles,bacteria detection
更新于2025-09-11 14:15:04
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Preyssler-based nanocomposite as a magnetic photocatalyst: synthesis, characterisation and its photocatalytic activity for decolourisation of rhodamine B
摘要： In this work, the authors prepared a novel magnetic photocatalyst by grafting of Preyssler-type polyoxometalate, H14 [NaP5 W30 O110] onto Fe3O4 nanoparticles via an internal layer of silver nanoparticles. The obtained nanocomposite has been characterised by electron dispersive X-ray, transmission electron microscopy and scanning electron microscopy. The activity of the synthesised nanomagnetic photocatalyst was tested by the photocatalytic decolourisation of rhodamine B under UV light irradiation in the study’s designed reactor. It was found that, compared to pure Preyssler, decolourisation of rhodamine B was occurred four times faster using the synthesised magnetic nanocomposite with easy separation. The magnetic nanocatalyst was separated after ending the reaction and recycled. It just showed 2–3% decrease in catalytic activity after four recycling.
关键词： Preyssler-type polyoxometalate,Fe3O4 nanoparticles,photocatalytic decolourisation,rhodamine B,magnetic photocatalyst,silver nanoparticles
更新于2025-09-09 09:28:46
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Preparation of High Performance Conductive Polyaniline Magnetite (PANI/Fe3O4) Nanocomposites by Sol-Gel Method
摘要： The conductivities of polyaniline magnetite (PANI/Fe3O4) nanocomposites prepared by sol-gel method were measured by standard van der Pauw DC 4-point probe method. PANI/Fe3O4 conductivity was measured as a function of wt % (5, 10, 15, 20 and 25 wt %) of Fe3O4 nanoparticles. It was observed that the conductivity of polyaniline containing certain percentage of Fe3O4 nanoparticles is slightly lower than the bulk PANI nanotubes and drastically decreases with increase of wt % Fe3O4 nanoparticles. The high conductivities of PANI/Fe3O4 nanocomposites was observed due to high concentration of dopant (oxidants) used in the polymerization process and the optimization of these composites allows this being use as a parameter for the production of nanofibers. Fourier transform infrared spectra, field emission scanning electron microscope, X-ray diffraction and ultraviolet-visible absorption spectra are used to characterize the phase structure, morphologies and functional group of the PANI/Fe3O4 composites samples. Fourier transform infrared analysis indicates the presence of PANI containing Fe3O4 nanoparticles and the field emission scanning electron microscope (FESEM) results has proven that the formation of nanofibers in the PANI/Fe3O4 nanocomposites. The crystalline phase of PANI/Fe3O4 nanocomposites studied by X-ray diffraction indicated that the Fe3O4 nanoparticles was present in the PANI matrices.
关键词： Polyaniline,Fe3O4 nanoparticles,FESEM,Conductivity,Composites
更新于2025-09-09 09:28:46
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Synthesis of Si-based KH560/RGO@Fe3O4 composite for improving electromagnetic properties in 2–18?GHz frequency range
摘要： Silicon coupling reagent is regarded as a common additive on surface treatment of polymer due to its high bonding strength and low cost. In this paper, a series of γ-(2, 3-epoxypropoxy) propyltrimethoxysilane (KH560)-based reduced graphene oxide (RGO)@Fe3O4 (KH560/RGO@Fe3O4) composites with different ratio of Fe3O4 nanoparticles (NPs) are synthesized by a facile hydrothermal method. It is confirmed that the silicon reagent KH560, as a hopeful candidate for increasing the RGO lattice defects, is favorable to improve the electromagnetic wave absorption. Meanwhile, the microwave attenuation mechanism of KH560/RGO@Fe3O4 composite suggests that the dielectric loss mainly causes by multiple Debye dipolar relaxation and its magnetic loss comes from the eddy-current effect of Fe3O4 NPs over the high frequency range. In consequence, the KH560/RGO@Fe3O4 composite endows the excellent absorption performance, the reflection loss (RL) value is optimized to ? 25 dB at 14.1 GHz with a thickness of 3 mm and the maximum frequency bandwidth for RL < ? 10 dB is 4.1 GHz with a thickness of 4 mm.
关键词： Electromagnetic wave absorption,Fe3O4 nanoparticles,Reduced graphene oxide,Hydrothermal method,Silicon coupling reagent
更新于2025-09-04 15:30:14