Loaded Fe3O4 Nanoparticles Research Articles

Synthesis of CS/Fe3O4/TiO2@MXene nanocomposite photocatalyst with excellent degradation and bacteriostatic properties by one-step hydrothermal method

With the rapid development of global economy and industrialization, the management and protection of water resources have become increasingly important. In this paper, a novel three-dimensional Chitosan/Fe3O4/TiO2@MXene photocatalyst with excellent degradation and bacterial inhibition properties was prepared by a simple one-step hydrothermal method using FeCl3·6H2O, Chitosan (CS) and MXene (Ti3C2) as main raw materials. TiO2 was generated in-situ on the surface of Ti3C2 nanosheets and modified by loading Fe3O4 nanoparticles and CS films. The conformations and band gaps of the composites were modified, and then photocatalytic mechanisms, phase compositions, morphological structures, magnetic properties and photoelectrochemical properties of the photocatalysts were systematically analyzed. The degradation efficiency of the CS/Fe3O4/TiO2@Ti3C2 composite photocatalyst can reach 95.9 % when the ration of CS to FeCl3·6H2O is 1:3 and the hydrothermal temperature is 180 °C, which showing excellent photocatalytic performance. Meanwhile, the inhibition rate of Staphylococcus aureus (S. aureus) is close to 98.91 % under the light condition. This study further reveals that visible light is a cost-effective way to treat pollution in terms of degradation and bacteriostatic inhibition, and the composite photocatalysts can be efficiently recycled and reused under the action of a magnetic field.

Efficient construction of self-assembled starch colloidosomes for controlled-release of pesticides

Biodegradable colloidosomes have attracted increasing attention for their applications to enhance the efficacy and reduce wastage of pesticides in agriculture. In this study, we present a continuous and highly efficient method for production of starch colloidosomes. The starch particles with an average particle size of 230.2 nm and good dispersibility were prepared using surface modification technology, and then used as environment-friendly shell materials to form self-assembled starch colloidosomes using spray drying technology. The influences of inlet temperature, feed rate and air flow rate on the morphologies of colloidosomes were also studied. This strategy enables the construction of starch colloidosomes with uniform spherical morphology and controllable pore sizes under different pH, and can be used for pesticide encapsulation. After loading pyraclostrobin (PYR), the regular spherical colloidosomes not only achieve a small mean diameter of 2.35 µm, but also realize a high encapsulation efficiency of 82 %. The release performance of PYR has an obvious pH response and follows the segmented Ritger-Pepapes model of sustained-release. The colloidosomes were used to prevent the photodegradation of pesticides. The PYR loaded colloidosomes exhibit excellent UV resistance with a retention rate of 72.7 %. In addition, the loading of Fe3O4 nanoparticles and the embedding of carbon dots were also explored.

A Magnetic Reduced Graphene Oxide Nanocomposite: Synthesis, Characterization, and Application for High-Efficiency Detoxification of Aflatoxin B1.

(1) Background: Safety problems associated with aflatoxin B1 (AFB1) contamination have always been a major threat to human health. Removing AFB1 through adsorption is considered an attractive remediation technique. (2) Methods: To produce an adsorbent with a high AFB1 adsorption efficiency, a magnetic reduced graphene oxide composite (Fe3O4@rGO) was synthesized using one-step hydrothermal fabrication. Then, the adsorbent was characterized using a series of techniques, such as SEM, TEM, XRD, FT-IR, VSM, and nitrogen adsorption-desorption analysis. Finally, the effects of this nanocomposite on the nutritional components of treated foods, such as vegetable oil and peanut milk, were also examined. (3) Results: The optimal synthesis conditions for Fe3O4@rGO were determined to be 200 °C for 6 h. The synthesis temperature significantly affected the adsorption properties of the prepared material due to its effect on the layered structure of graphene and the loading of Fe3O4 nanoparticles. The results of various characterizations illustrated that the surface of Fe3O4@rGO had a two-dimensional layered nanostructure with many folds and that Fe3O4 nanoparticles were distributed uniformly on the surface of the composite material. Moreover, the results of isotherm, kinetic, and thermodynamic analyses indicated that the adsorption of AFB1 by Fe3O4@rGO conformed to the Langmuir model, with a maximum adsorption capacity of 82.64 mg·g-1; the rapid and efficient adsorption of AFB1 occurred mainly through chemical adsorption via a spontaneous endothermic process. When applied to treat vegetable oil and peanut milk, the prepared material minimized the loss of nutrients and thus preserved food quality. (4) Conclusions: The above findings reveal a promising adsorbent, Fe3O4@rGO, with favorable properties for AFB1 adsorption and potential for food safety applications.

A Glucose Metabolic Intervention Nanoplatform for Enhanced Chemodynamic Therapy and Sensitized Photothermal Therapy of Hepatocellular Carcinoma

Traditional treatments for hepatocellular carcinoma (HCC) still lack effectiveness. Recently, the combined mode of chemodynamic therapy (CDT) and photothermal therapy (PTT) has shown great potential against HCC. However, insufficient Fenton reaction rates and hyperthermia-induced heat shock responses greatly impair their efficiency, hindering their further clinical application. Here, we constructed a cascade-amplified PTT/CDT nanoplatform by coating an IR780-embedded red blood cell membrane on glucose oxidase (GOx)-loaded Fe3O4 nanoparticles for effective HCC treatment. On the one hand, the nanoplatform interfered with glucose metabolism through the action of GOx to reduce the synthesis of ATP, which reduced the expression of heat shock proteins, thereby sensitizing the IR780-mediated PTT. On the other hand, hydrogen peroxide generated during GOx catalysis and the thermal effect of PTT accelerated the Fe3O4-mediated Fenton reaction, realizing enhanced CDT. Consequently, the sensitized PTT and enhanced CDT for HCC management could be simultaneously achieved by interfering with glucose metabolism, providing an alternative strategy for the effective treatment of tumors.

Dual-Loading of Fe3O4 and Pd Nanoparticles on g-C3N4 Nanosheets Toward a Magnetic Nanoplatform with Enhanced Peroxidase-like Activity for Loading Various Enzymes for Visual Detection of Small Molecules.

Enzyme mimics now play a significant role in biochemistry. Especially, peroxidase mimics have been widely used for developing colorimetric sensors of blood glucose. The peroxidase mimics previously reported could not be recycled for reusing and may generate scattering to cause unwanted optical interference when it was used for fabricating colorimetric sensors. We herein prepared a broad-applicable and reusable magnetic enzyme-loading nanoplatform with enhanced peroxidase-like activity by simultaneously loading Fe3O4 nanoparticles (Fe3O4NPs) and palladium nanoparticles (PdNPs) on graphitic carbon nitride (g-C3N4) nanosheets (Fe3O4NPs/PdNPs/g-C3N4). The prepared Fe3O4NPs/PdNPs/g-C3N4 possesses stable and enhanced peroxidase-like activity and good enzyme-loading capacity and can be used to load various natural enzymes to form highly-efficient and stable double-active nanozyme for fabricating colorimetric sensors for the visual detection of small molecules. Especially, the magnetic feature facilitates the magnetic separation of Fe3O4NPs/PdNPs/g-C3N4 from sample solution, which is in favor of recycling and eliminating the optical interference caused by nanozyme in colorimetric sensors. The prepared Fe3O4NPs/PdNPs/g-C3N4 has been successfully used to load glucose oxidase (GOx) and cholesterol oxidase (Chox) to form magnetic peroxidase-GOx and peroxidase-Chox double-active nanozymes, which can be used to fabricate colorimetric methods for the detection of glucose and cholesterol, respectively, with a visual detection limit of 15 μM and a spectrometry detection limit of 1.0 μM. With the developed glucose and cholesterol detection methods, we have successfully detected glucose and cholesterol in serum with a recovery of 98-104% and a RSD (n = 5) < 5%. With high peroxidase-like activity, good stability, reusable features, and broad applicability of loading enzyme, the developed magnetic Fe3O4NPs/PdNPs/g-C3N4 provided a promising approach for fabricating cost-effective, sensitive, and simple colorimetric sensors for the visual detection of various small molecules.

Loading Fe3O4 nanoparticles on N, S co-doped graphene suppressing polysulfides conversion toward high-performance Li–S batteries

Loading Fe3O4 nanoparticles on N, S co-doped graphene suppressing polysulfides conversion toward high-performance Li–S batteries

A mechanothermal approach for the synthesis of Fe3O4 nanoparticles as dopant on mesoporous TiO2 for electrochemical determination of catechol

The subject of water contamination and how it gets defiled to the society and humans is confabulating from the past decades. Phenolic compounds widely exist in the water sources and it is emergent to determine the toxicity in natural and drinking water, because it is hazardous to the humans. Among these compounds, catechol has sought a strong concern because of its rapid occurrence in nature and its potential toxicity to humans. The present work aims to develop an effective electrochemical sensing of catechol using mesoporous structure of Fe3O4–TiO2 decorated on glassy carbon (GC) electrode. The creation of pure TiO2 using the sol-gel technique was the first step in the synthesis protocol for binary nanocomposite, which was then followed by the loading of Fe3O4 nanoparticles on the surface of TiO2 using the thermal decomposition method. The resultant Fe3O4–TiO2 based nanocomposite exhibited mesoporous structure and the cavities were occupied with highly active magnetite nanoparticles (Fe3O4) with high specific surface area (90.63 m2/g). When compared to pure TiO2, catechol showed a more prominent electrochemical response for Fe3O4–TiO2, with a significant increase in anodic peak current at a lower oxidation potential (0.387 V) with a detection limit of 45 μM. Therefore, the prepared magnetite binary nanocomposite can serve as an efficient electroactive material for sensing of catechol, which could also act as a promising electrocatalyst for various electrocatalytic applications.

Tailoring carboxylatopillar[5]arene-modified magnetic graphene oxide nanocomposites for the efficient removal of cationic dyes.

A carboxylatopillar[5]arene-embellished (CP5) magnetic graphene oxide nanocomposite (MGO@CP5) was smoothly constructed via a mild layer-by-layer method. The morphology, structure, and surface characteristics of this nanocomposite was investigated by field-emission scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectroscopy, Raman spectroscopy, zeta potential, and other techniques. Benefiting from a high capture ability for small molecules of CP5 as a supramolecular host molecule, along with a negative surface charge and large surface area of MGO@CP5, this nanocomposite exhibits an ultrafast, efficient adsorption property for representative cationic dyes: methylene blue (MB) and basic fuchsin (BF). The removal efficiency of MB and BF can reach nearly 99% within 3 min, while the maximum adsorption capacity of the two dyes reaches 240 mg g-1 for MB and 132 mg g-1 for BF. Furthermore, owing to excellent magnetic responsiveness from the tight loading of Fe3O4 nanoparticles on graphene oxide, MGO@CP5 could be easily and magnetically separated, regenerated, and reused four times without an evident reduction in the removal efficiency (>95%). Impressively, the adsorption property of MGO@CP5 reveals a strong tolerance to pH changes and ionic strength interference, which renders it a promising adsorbent in the field of water treatment.

Poly (hydroxyethyl methacrylate - acrylic acid) microspheres loaded with magnetically responsive Fe3O4 nanoparticles for arterial embolization, drug loading and MRI detection

In recent decades, transcatheter arterial embolization (TAE) has been attached great importance in the noninvasive vascular interventional therapy for treating various diseases. In this study, a novel magnetic embolic agent of Fe3O4-loaded hydrophilic poly (hydroxyethyl methacrylate - acrylic acid) microspheres (FPHA-Ms) was constructed using inverse suspension polymerization and sequential in situ co-precipitation method. The loading of Fe3O4 nanoparticles in FPHA-Ms was verified by infrared spectrum, vibrating sample magnetometer, X-ray diffraction and X-ray photoelectron spectroscopy, respectively. The weight percentage of iron content in lyophilized FPHA-Ms was measured by inductive coupled plasma emission spectrometer. The morphology, particle size distribution, equilibrium water content, elasticity, drug loading & eluting capacity, biosafety, magnetic resonance imaging (MRI) detectability and embolic efficacy of FPHA-Ms were systematically evaluated, respectively. FPHA-Ms possessed many merits including spherical shape, uniform and wide size range, considerable water content, high drug loading, sustained drug release and good elasticity and biocompatibility. The in vivo experiments showed FPHA-Ms could effectively block the blood supply and could be detected by MRI device. All the results proved that FPHA-Ms could serve as a novel MRI-visible multi-functional embolic agent for clinical vessel embolization, drug loading and MRI tracing in the near future.

The construction of high efficient visible-light-driven 3D porous g-C3N4/Fe3O4 photocatalyst: A new photo-induced bacterial inactivation material enhanced by cascade photo-Fenton reaction

Photocatalytic disinfection is considered a promising method for eliminating the hazards of pathogenic bacteria. Graphitic carbon nitride (g-C3N4) is an ideal photocatalytic bacterial inactivation material for its advantage of tunable band structure, good stability and easy preparation. This work has constructed a novel defective 3D porous g-C3N4 by cyanamide carbonation using dendritic mesoporous silica template. The direct loading of Fe3O4 nanoparticles provided an excellent pg–C3N4–Fe3O4 photocatalyst suitable for water disinfection. Compared to pristine g-C3N4, the prepared 3D porous defective g–C3N4–Fe3O4 exhibited the enhanced visible light absorbance as indicated by the band gap decreasing of 0.66 eV, and about 3 and 10 fold increase of photo-induced current response and O2 adsorption respectively. The pg–C3N4–Fe3O4 showed excellent visible-light-driven photocatalytic bactericidal activity. It could kill 1 × 107 cfu mL−1Escherichia coli completely within 1 h under visible-light illumination (100 mW cm−2) with good reusability, its logarithmic bacterial inactivation efficiency was about 2.5 fold higher than pg-C3N4. The enhanced bactericidal performance is mainly ascribed to the Fe3O4 involved cascade photo-Fenton reaction.

Promoting the electromagnetic interference shielding of Ti3C2T flakes by loading Fe3O4 nanoparticles: Insights into the performance of oligo-layers exposed to microwave interferences

This study aims to provide insights into the absorption and shielding performances of Fe 3 O 4 modified oligo-layered Ti 3 C 2 T x towards microwave electromagnetic interference. Oligo-layered Ti 3 C 2 T x was modified by Fe 3 O 4 nanoparticles (60 nm) via a facile electrostatic assembly approach at different loading rates. This composite was shown to have high dielectric constant and high permeability compared with oligo-layered Ti 3 C 2 T x . The microwave electromagnetic absorbing and shielding performances were monitored through a vector network instrument with focuses on the EMI performance. The sample Ti 3 C 2 T x /Fe 3 O 4 with a 5:1 mass ratio of Ti 3 C 2 T x to Fe 3 O 4 displayed the optimized EMI shielding performance. The average SE value was 62.19 dB, and the maximum value was 68.72 dB at 18 GHz with a 2.6 mm thickness. The EMI shielding mechanism was understood based on the conductive loss, magnetic loss, dipole polarization, and multiple scattering. Results suggests that Ti 3 C 2 T x /Fe 3 O 4 composites are expected to be superior EMI shielding material.

Magnetic MXene-NH2 decorated with persimmon tannin for highly efficient elimination of U(VI) and Cr(VI) from aquatic environment

Herein, a magnetic MXenes based composite (Fe3O4@Ti3C2-NH2-PT) was constructed by loading Fe3O4 nano-particles into the interlamellar spacing of persimmon tannin-functionalized Ti3C2-NH2. The structure, morphology and physicochemical properties of the as-prepared adsorbents were probed by advanced spectroscopy techniques, while the impact of various experimental conditions like pH values, amount of adsorbent and contact time on the removal trend were examined by batch experiments. The elimination results revealed that Fe3O4@Ti3C2-NH2-PT could be applied in a wide range of initial concentrations, and exhibited outstanding removal efficiency for U(VI) (104.9 mg/g, pH = 5.0) and Cr(VI) (83.8 mg/g, pH = 2.0). Meanwhile, the adsorption process was described well with the Langmuir isotherm and Pseudo-second-order kinetics models, which indicated that the monolayer chemical adsorption occurred during elimination of the two contaminants. The spectral analysis results manifested that elimination of U(VI) followed an inner-sphere configuration, whereas uptake of Cr(VI) was determined by electrostatic interaction and adsorption-reduction process. This work opened a new opportunity in designing MXenes based adsorbents in the application for environmental remediation.

Tailored design of MXene-like 2D MOF derived carbon/Fe3O4 Fenton-like catalysts towards effective removal of contaminants via size-exclusion effect

The development of high-performance heterogeneous Fenton-like catalysts boosts their practical application under different scenario requirements. Herein, we put forward a MXene-like 2D MOF-derived carbon loaded Fe3O4 nanoparticles strategy to assemble NSC@Fe3O4 catalyst, which achieved effective removal of target pollutant via size-exclusion effect of 2D intervals. Under humic acid and tetracycline (TTCH) coexist condition, the degradation rate of target pollutant tetracycline presented negligible impact. To confirm the possible size-exclusion effect, Fe3O4 nanoparticles and unloaded NSC were also prepared to remove tetracycline. By quenching experiments, fluorescence detection, and EPR analysis, a non-radical mechanism dominated by 1O2 and electron transfer was hypothesized. The degradation products were analyzed by 3D EEM fluorescence and LC-MS, and the possible degradation pathways were inferred. Further toxicity analysis of intermediates and E. coli culture indicated that the toxicity of TTCH was reduced under NSC@Fe3O4/PMS system. Overall, this research proposes a novel method for selective and effective removal of target pollutants in complex water bodies using 2D MOF-derived carbon compounds.

Self-Adaptive Flask-like Nanomotors Based on Fe3O4 Nanoparticles to a Physiological pH.

In living bodies, pH values, which are precisely regulated and closely associated with diseased cells, can act as an efficient biologically intrinsic indicator for future intelligent biomedicine microsystems. In this work, we have developed flask-like carbonaceous nanomotors (FCNMs), via loading Fe3O4 nanoparticles (NPs) into a cavity, which exhibit a self-adaptive feature to a specific physiological pH by virtue of the pH-dependent dual enzyme-like activities of Fe3O4 NPs. Specifically, the peroxidase-like activity of Fe3O4 NPs in an acidic pH range, and the catalase-like activity in a near neutral and alkaline pH range, determine the products in the motion system (•OH, ions and O2), whose diffusions from the inner to the outside of the flask result in fluid movement providing the driving force for the movement of the FCNMs. Correspondingly, changes of the product concentrations and species in the physiological pH range (4.4–7.4) result, firstly, in velocity decrease and, then, with increase in pH, increase of the FCNMs occurs. Thanks to the non-linear velocity responsiveness, the FCNMs show intriguing pH taxis towards 6.8 (generally corresponding to the physiological pH in tumor microenvironments), where a maximum velocity appears. Furthermore, the superparamagnetic feature of the Fe3O4 NPs simultaneously endows the FCNMs with the abilities to be magnetic-oriented and easily separated. This work could significantly increase the possibility of nanomotors for targeted therapy of tumors and next-generation biotechnological applications.

Fe3O4–Mg(OH)2 nanocomposite as a scavenger for silver nanoparticles: Rational design, facile synthesis, and enhanced performance

Silver nanoparticles (AgNPs) are considered as emerging contaminants because of their high toxicity and increasing environmental impact. Removal of discharged AgNPs from water is crucial for mitigating the health and environmental risks. However, developing facile, economical, and environment-friendly approaches remains challenging. Herein, an Fe3O4–Mg(OH)2 nanocomposite, as a novel magnetic scavenger for AgNPs, was prepared by loading Fe3O4 nanoparticles on Mg(OH)2 nanoplates in a one-pot synthesis. Batch removal experiments revealed that the maximum removal capacities for the two model AgNPs (citrate- or polyvinylpyrrolidone-coated AgNPs) were 476 and 442 mg/g, respectively, corresponding to partition coefficients 8.03 and 4.89 mg/g/μM. Removal feasibilities over a wide pH range of 5–11 and in real water matrices and scavenger reusability with five cycles were also confirmed. Both Fe3O4 and Mg(OH)2 components contributed to the removal; however, their nanocomposites exhibited an enhanced performance because of the high specific surface area and pore volume. Chemical adsorption and electrostatic attraction between the coatings on the AgNPs and the two components in the nanocomposite was considered to be responsible for the removal. Overall, the facile synthesis, convenient magnetic separation, and high removal performance highlight the great potential of the Fe3O4–Mg(OH)2 nanocomposite for practical applications.

Achieving high out-of-plane thermal conductivity for boron nitride nano sheets/epoxy composite films by magnetic orientation

The preparation of boron nitride nanosheet (BNNS)/polymer composite films with high out-of-plane thermal conductivity (K) remains a challenge. Here, we obtained BNNS/epoxy (EP) resin composite films with well aligned BNNSs exhibiting a high K in the out-of-plane direction through the careful optimization of the magnetic field strength. Firstly, magnetically responsive BNNSs (m-BNNSs) with a large surface area were prepared by loading Fe3O4 nanoparticles via in situ co-precipitation. Secondly, m-BNNSs were incorporated into EP to prepare well aligned m-BNNS/EP composites by controlling the intensity and direction of the magnetic field. The results show that the BNNSs are well oriented in the out-of-plane direction, resulting in a K as high as 14.55 Wm−1K−1 for 30.0- wt% BNNS loading, which is 4.5 times higher than that of unoriented films and 70 times higher than that of pure EP. This strategy can be extrapolated to obtain polymer composite films filled with other two-dimensional materials.

Removal of aqueous pharmaceuticals by magnetically functionalized Zr-MOFs: Adsorption Kinetics, Isotherms, and regeneration

The functionalization of metal–organic frameworks (MOFs) is imperative and challenging for the development of practical MOF-based materials. Herein, a magnetically functionalized Zr-MOF (Fe3O4@MOF-525) was synthesized via secondary-growth approach to obtain an easily-separated and recyclable adsorbent for the removal of pharmaceuticals (tetracycline (TC) and diclofenac sodium (DF)). After loading Fe3O4 nanoparticles (NPs), due to the increase of micropore volume and specific surface area caused by defects, the adsorption performance of Fe3O4@MOF-525 was improved. The kinetics could be described by the pseudo-second-order kinetic model. The different adsorption capacity and initial rate were attributed to the properties of the pharmaceuticals, including the molecular size and hydrophobicity/hydrophilicity. In isotherm experiments, the maximum adsorption capacities of DF and TC on Fe3O4@MOF-525 calculated by Sips model reached 745 and 277 mg·g−1, respectively. The thermodynamic studies indicated the adsorption was endothermic and spontaneous. The effect of pH suggested that electrostatic interaction, π-π interaction, anion-π interaction, and H-bonding were possibly involved in the adsorption process. The adsorbent was separated by magnetic and regenerated. Washed with ethanol, Fe3O4@MOF-525 remained about 80% adsorption capacity after four cycles. In-situ photo-regeneration under visible-light irradiation was another attractive method, where > 95% TC was degraded in 4 h. The reaction with scavengers revealed that 1O2 was the dominant reactive species in our system, indicating the occurrence of Type II photosensitization. The separability, excellent adsorption performance, and recyclability of Fe3O4@MOF-525 may lead to its beneficial applications in water treatment.

A Multifunctional Magnetic Red Blood Cell-Mimetic Micromotor for Drug Delivery and Image-Guided Therapy.

Inspired by nature, innovative devices have been made to imitate the morphology and functions of natural red blood cells (RBCs). Here, we report a red blood cell-mimetic micromotor (RBCM), which was fabricated based on a layer-by-layer assembly method and precisely controlled by an external rotating uniform magnetic field. The main framework of the RBCM was constructed by the natural protein zein and finally camouflaged with the RBC membrane. Functional cargos such as Fe3O4 nanoparticles and the chemotherapeutic agent doxorubicin were loaded within the wall part of the RBCM for tumor therapy. Due to the massive loading of Fe3O4 nanoparticles, the RBCM can be precisely navigated by an external rotating uniform magnetic field and be used as a magnetic resonance imaging contrast agent for tumor imaging. The RBCM has been proven to be biocompatible, biodegradable, magnetically manipulated, and imageable, which are key requisites to take micromotors from the chalkboard to clinics. We expect the RBC-inspired biohybrid device to achieve wide potential applications.

Electrospun Fe3O4-Sn@Carbon Nanofibers Composite as Efficient Anode Material for Li-Ion Batteries.

Nanoscale Fe3O4-Sn@CNFs was prepared by loading Fe3O4 and Sn nanoparticles onto CNFs synthesized via electrostatic spinning and subsequent thermal treatment by solvothermal reaction, and were used as anode materials for lithium-ion batteries. The prepared anode delivers an excellent reversible specific capacity of 1120 mAh·g−1 at a current density of 100 mA·g−1 at the 50th cycle. The recovery rate of the specific capacity (99%) proves the better cycle stability. Fe3O4 nanoparticles are uniformly dispersed on the surface of nanofibers with high density, effectively increasing the electrochemical reaction sites, and improving the electrochemical performance of the active material. The rate and cycling performance of the fabricated electrodes were significantly improved because of Sn and Fe3O4 loading on CNFs with high electrical conductivity and elasticity.

Flexible fabrication of lipophilic-hydrophilic micromotors by off-chip photopolymerization of three-phase immiscible flow induced Janus droplet templates

Self-propelled microparticles are promising for lots of applications ranging from analytical detection to water treatment. Herein, we present an effective approach to fabricate lipophilic-hydrophilic micromotors via the photocuring of three-phase immiscible flow induced droplet templates. In the microfluidic system, two immiscible inner fluids, the lipophilic 1, 6-Hexanediol diacrylate (HDDA), and the hydrophilic poly (ethylene glycol) diacrylate (PEGDA), are simultaneously injected into a theta-shaped cylindrical capillary from two separate inlets, and they are emulsified into Janus drops when encountering the outer immiscible silicone oil. Because of the immiscible feature of droplet templates, off-chip photopolymerization strategy has been used, which can significantly decrease the blocking chance of microdevice. And also, the lipophilic-hydrophilic structure of droplets is convenient for the loading of cargos with different characteristics. More importantly, the size and configuration of droplet templates can be flexibly regulated by changing the flow rates of three different phases. Accordingly, multifunctional micromotors can be fabricated by adding different nanoparticles and materials into the HDDA or PEGDA phase first and then photocuring the droplets. Taking the bubble-propelled micromotors for example, we prepare microswimmers by loading Ag, TiO2 and Fe3O4 nanoparticles into the PEGDA phase. The swimming behaviors of micromotors in H2O2 solution are systematically investigated, finding that the proportion of PEGDA phase and the concentration of H2O2 both positively affect the moving speed. Furthermore, the applicability of motor particles on water treatment is successfully demonstrated by using neutral red solution as the model pollutant. And the micromotors can be recycled using magnets after the catalytic degradation process. Therefore, this micromotor generation technique and this kind of micromotor can be attractive for many applications.