Ag Fe3O4 Research Articles

A cell targeting and sorting approach based on the magnetophoretic capturing for early prognostics of metastatic cervical cancer cells

HeLa cervical cancer cells are immortal with telomerase activity and metastatic characteristics similar to circulating tumor cells (CTCs). Here, we report aptamer-modified multilayered magnetic beads (Apt@MBs) that efficiently targeted and captured HeLa cells up to a low concentration of freshly prepared cell suspension (500 cells/mL). Apt@MBs were functionalized with fluorophore-conjugated AS1411-aptamer on an outer layer made up of molybdenum disulfide (MoS2) to target nucleolin on the cell surface of captured HeLa cells. Moreover, this outer MoS2 layer of MBs was nanoporous and could load anticancer drugs inside its porous cavities with the possibility of killing the captured and metastatic CTCs in vivo. An internal core layer of Apt@MBs consisting of Ag–Fe3O4 magnetic particles (MPs) was designed for magnetic manifestations and cell sorting with the possibility of screening CTCs (in the patient's blood samples) for early diagnosis of metastatic cancers. The Apt@MBs after cell capture gave rise to the heavier HeLa-MBs composites to get settled down under gravitational/inertial forces to the bottom of the tube quicker than the free cells (within 10 min). The gravitational settling of HeLa-MBs was further coupled with exposing a magnetic field to effectively capture and enrich the cells at the bottom of the tube (from 91 to 98 % cells). While the fluid containing dead, non-cancerous, or uncaptured cells in the supernatant layers were easily removed by pipetting. The HeLa-MBs after sorting out were resuspended into a fresh culture medium for further incubation or cellular analysis. Moreover, both cisplatin (CP) and epirubicin (EP) loaded Apt@MBs showed the killing of about 50 % of the captured cells. Therefore, we are confident that Apt@MBs can contribute to enumerating patients' blood samples for screening CTCs to timely and efficiently detect metastatic cancers along with the ability to effectively perform prognosis, and treatment of metastatic cancers.

Synthesis and characterization of magnetic Ag–Fe3O4@polymer hybrid nanocomposite systems with promising antibacterial application

Introduction Bacterial infections caused by different strains of bacteria still one of the most important disorders affecting humans worldwide. Polymers nanocomposite systems could be considered as an alternative to conventional antibiotics to eradicate bacterial infections. Significance In an attempt to enhance the antibacterial performance of silver and iron oxide nanoparticles, decrease their aggregation and toxicity, a polymeric hybrid nanocomposite system combining both nanoparticles is produced. Methods Magnetic Ag–Fe3O4@polymer hybrid nanocomposites prepared using different polymers, namely polyethylene glycol 4000, ethyl cellulose, and chitosan were synthesized via wet impregnation and ball-milling techniques. The produced nanocomposites were tested for their physical properties and antibacterial activities. Results XRD, FT-IR, VSM, and TEM results confirmed the successful preparation of hybrid nanocomposites. Hybrid nanocomposites have average crystallite sizes in the following order Ag–Fe3O4@CS (8.9 nm) < Ag–Fe3O4@EC (9.0 nm) < Ag–Fe3O4@PEG4000 (9.4 nm) and active surface area of this trend Ag–Fe3O4@CS (130.4 m2g−1) > Ag–Fe3O4@EC (128.9 m2g−1) > Ag–Fe3O4@PEG4000 (123.4 m2g−1). In addition, they have a saturation magnetization in this order: Ag–Fe3O4@PEG4000 (44.82 emu/g) > Ag–Fe3O4@EC (40.14 emu/g) > Ag–Fe3O4@CS (22.90 emu/g). Hybrid nanocomposites have a pronounced antibacterial action against Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa, and Staphylococcus intermedius compared to iron oxide nanoparticles and positive antibacterial drug. In addition, both Ag–Fe3O4@EC and Ag–Fe3O4@CS have a lower MIC values compared to Ag–Fe3O4@PEG and positive control. Conclusion Magnetic Ag–Fe3O4 hybrid nanocomposites could be promising antibacterial nanomaterials and could pave the way for the development of new materials with even more unique properties and applications.

The CCLW collagen biocomposite consisting Ag–Fe3O4 nanoparticles as a novel biomaterial with a view to facile green approach

The CCLW collagen biocomposite consisting Ag–Fe3O4 nanoparticles as a novel biomaterial with a view to facile green approach

Comprehensive investigations of (Au-Ag/Blood and Cu-Fe3O4/Blood) hybrid nanofluid over two rotating disks: Numerical and computational approach

The purpose of this work is to investigate the Darcy-Forchheimer flow of a hybrid nanofluid within two parallel discs. We combine gold Au, silver Ag, copper Cu, and iron oxide Fe3O4 nanoparticles with base fluid blood in this framework. An appropriate similarity variables technique is implemented to transform partial differential systems into ordinary systems. In the results validation section, the numerical result is evaluated using a higher-order precise algorithm (bvp4c), and determined to the analytical result is by making use of the firing approach. Pictorial judgments revealed the estimates of several physical variables that arise over the momentum distribution and thermal distribution profiles. As compared to nanofluid, hybrid nanofluid significantly improves heat transfer rate. The thermal profile is improved when the Brinkman number increases in value. As the porosity parameter is increased, the velocity profile decreases. As the amplitude of the rotation parameter increases, so does the pressure profile. The Darcy-Forchheimer medium investigation of a hybrid nano-fluid streaming through the middle of two parallel disks is addressed, taking into account viscous dissipation and heat radiation for various nanoparticles. Additionally, enough agreement is observed when the numerical findings are compared to previously reported and analytical data. As compared to simple nanofluids, hybrid nanofluids have shown higher thermal properties and stability, making them attractive candidates for thermal applications such as solar thermal systems, automotive cooling systems, heat sinks, engineering, medical fields, or thermal energy storage.

Rational design of trimetallic AgPt–Fe3O4 nanozyme for catalyst poisoning-mediated CO colorimetric detection

Carbon monoxide (CO) is not only a highly poisonous gas that brings great health risk, but also a significant signaling molecule in body. However, it is still challengeable for development of alternative colorimetric probes to traditional organic chromophores for simple, sensitive and convenient CO sensing. Here, for the first time, we rationally design a novel hydrophilic AgPt–Fe3O4 nanozyme with a unique heterodimeric nanostructure for colorimetric sensing of CO based on the excellent peroxidase-like catalytic activity as well as highly poisonous effect of CO on the nanozyme's catalytic activity. Both experimental evidence and theoretical calculations reveal the trimetallic AgPt–Fe3O4 nanozyme is susceptible to poisoning with the strongest affinity towards CO compared to individual Fe3O4 or Ag–Fe3O4, which is attributed to the adequate exposure of the active metallic sites and efficient interfacial synergy of unique heterodimeric nanostructure. Accordingly, a novel nanozyme-based colorimetric strategy is developed for CO detection with a low detection limit of 5.6 ppb in solution. Furthermore, the probe can be prepared as very convenient test strips and integrated with the portable smartphone platforms for detecting CO gas samples with a low detection limit of 8.9 ppm. Overall, our work proposes guidelines for the rational design of metallic heterogeneous nanostructure to expand the analytical application of nanozyme.

Green synthesis and characterization of Ag and Ag/Fe3O4 nanocomposites for antimicrobial effect and rhodamine- B dye degradation

We used a simple two-stage tactic to design and synthesize a magnetically separable catalyst (MSC) Ag/Fe3O4 by combining independently synthesized Fe3O4 and Jatropha curcas root functionalized Ag nanoparticles (NPs) at room temperature. The phase composition of Ag/Fe3O4 NCs was revealed by morphological and structural assessment. The derived Ag/Fe3O4 nanocomposites demonstrated outstanding antimicrobial activity against Gram-negative Pseudomonas aeruginosa comparing to Gram-positive Bacillus subtilis which was determined by the agar well diffusion method. This is due to positively charged surface of metal oxide NPs that may bind to cell membrane. Interestingly, Ag–Fe3O4 NCs demonstrated good photocatalytic activity for organic dye degradation. According to a kinetic study, Ag/Fe3O4 MSC removed 99% of Rhodamine B at a rate constant of 1.89 min−1. The photoelectron could perhaps ultimately collide only with dissolved solids in the substrate to form superoxides, which can damage the dye. Notably, the MSCs reusability was tested using magnetic detachment without sacrificing photocatalytic efficiency. This finding represents a significant breakthrough in the domain of wastewater treatment and biomedicine.

Highly Dispersed Ag and G-C3n4 Quantum Dots Co-Decorated 3d Hierarchical Fe3o4 Hollow Microspheres for Solar-Light-Driven Pharmaceutical Pollutants Degradation in Natural Water Matrix

Highly Dispersed Ag and G-C3n4 Quantum Dots Co-Decorated 3d Hierarchical Fe3o4 Hollow Microspheres for Solar-Light-Driven Pharmaceutical Pollutants Degradation in Natural Water Matrix

Investigation of Ag and magnetite nanoparticle effect on the membrane fouling in membrane bioreactor

In this study, Ag nanoparticles (Ag NPs) as antibacterial substance and Fe3O4 nanoparticles (Fe3O4 NPs) as magnetic material were synthesized and then utilized in the MBR system (Ag NPs-MBR/Fe3O4 NPs-MBR), and for synthetic petrochemical wastewater treatment, their effect on biomass characteristics and consequently effect on membrane fouling was evaluated. Chemical oxygen demand (COD), extracellular polymeric substance (EPS), soluble microbial product (SMP), flux, membrane fouling resistance, as well as particle size distribution, Fourier transform infra-red (FTIR) spectroscopy, and scanning electron microscope (SEM) analysis were performed for performance evaluation. The average particle size of Fe3O4 NPs and Ag NPs was 2 and 10 nm, respectively. It was observed that overall, the application of nanoparticles results in better removal of organic matter in the system. Control-MBR, Ag NPs-MBR, and Fe3O4 NPs-MBR reduce COD by 80, 96.64, and 95.35%, respectively. Besides, improvement in flux rate by 41% and 32% for Ag NPs-MBR and Fe3O4 NPs-MBR was observed, respectively. EPS in Ag NPs-MBR and Fe3O4 NPs-MBR decreased by 49% and 38%, while SMP decreased by 66% and 54%, respectively. The FTIR analysis also confirmed the reduction in EPS and SMP. SEM images revealed that the cake layer on the membrane in the Ag NPs-MBR system has more porosity. Based on the results, the application of NPs in MBR systems leads to significantly improved performance and reduced membrane fouling.

Microwave assisted fast fabrication of zinc/iron oxides based polymeric nanocomposites and evaluation on equine fibroblasts

We aimed to provide a tissue repair material, which can be synthesized rapidly, using polymers mimicking the natural environment in the extra-cellular matrix and metals/minerals. The components should have the potential to be used in tissue repair and simultaneously, reducing the side-effects of the incorporated molecules. It is challenging to manage the dispersibility of ZnO NPs in common solutions like water. Here, we report a novel method for preparing highly dispersible suspensions of ZnO NPs. In contrast to those synthesized by conventional methods, microwave assisted method allowed synthesis of dispersible ZnO NPs and the incorporation of zinc/Iron oxides NPs within alginate and gum matrix (AG) in a short span of time providing high yield of the product. The nanoformulations were characterized for size, morphology, interaction of various chemicals used during their synthesis by transmissible electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy and energy dispersive X ray Spectrum. It was also evaluated for cytotoxicity and their effect on equine fibroblast cells. Microwave-assisted fabrication of zinc/iron oxides nanoparticles provided flowerlike morphology with good dispersibility and high yield in a short span of time. Our results revealed that ZnO NPs were more cytotoxic than AG ZnO NPs and doped AG Fe3O4 doped ZnO NPs at higher concentrations. Further metal nanoparticles capped with alginate/acacia with size range less than 100 nm demonstrated high stability, good biocompatibility, re-epithelization and enhanced mineralization in horse fibroblast cells.

Phospholipids modifications in human hepatoma cell lines (HepG2) exposed to silver and iron oxide nanoparticles

Metallic nanoparticles such as silver (Ag NPs) and iron oxide (Fe3O4 NPs) nanoparticles are high production volume materials due to their applications in various consumer products, and in nanomedicine. However, their inherent toxicities to human cells remain a challenge. The present study was aimed at combining lipidomics data with common phenotypically-based toxicological assays to gain better understanding into cellular response to Ag NPs and Fe3O4 NPs exposure. HepG2 cells were exposed to different concentrations (3.125, 6.25, 12.5, 25, 50 and 100µg/ml) of the nanoparticles for 24h, after which they were assayed for toxic effects using toxicological assays like cytotoxicity, mutagenicity, apoptosis and oxidative stress. The cell membrane phospholipid profile of the cells was also performed using shotgun tandem mass spectrometry. The results showed that nanoparticles exposure resulted in concentration-dependent cytotoxicity as well as reduced cytokinesis-block proliferation index (CBPI). Also, there was an increase in the production of ROS and superoxide anions in exposed cells compared to the negative control. The lipidomics data revealed that nanoparticles exposure caused a modulation of the phospholipidome of the cells. A total of 155 lipid species were identified, out of which the fold changes of 23 were significant. The high number of differentially changed phosphatidylcholine species could be an indication that inflammation is one of the major mechanisms of toxicity of the nanoparticles to the cells.

Coupled graphene oxide with hybrid metallic nanoparticles as potential electrochemical biosensors for precise detection of ascorbic acid within blood

Ascorbic acid (AA) as an essential biological molecule for proper performance of body can act as a biological metric for precise detection of various kinds of disease through measuring the level of oxidative stress; thus its precise/dividable detection is an urgent requirement for development of advanced biosensors. To address this requirement, we decorated well-exfoliated graphene oxide (GO) with Ag and hybrid Ag–Fe3O4 metallic nanoparticles toward precise, real-time and repeatable detection of AA within the blood plasma samples via electrochemical approaches that led to the development of a retrievable biosensor. Outcome of performed evaluations showed that modification of glassy carbon electrode (GCE) with selected additives significantly improved its sensitivity/selectivity. In this matter, the modified GCE with GO-Ag-Fe3O4 showed limit of detection and sensitivity of 74 nM and 1146.8 μA mM−1 cm−2, respectively, within the concentration range of 0.2–60 μM. Additionally, the modified electrode kept 91.23% of its total performance after 15 days of performance and detected the oxidation peak of AA even with present of 50 fold of annoying contents which highlighting its superior stability/selectivity. More importantly, the developed electrode showed recovery range between 96.0 and 104.4% within the human blood plasma samples that confirmed the ideal capability of developed platform for accurate detection of AA within biological fluids.

Heterostructured Nanocomposites of Ag Doped Fe3O4 Embedded in ZnO for Antibacterial Applications and Catalytic Conversion of Hazardous Wastes

Heterostructured ternary nanocomposites of silver doped magnetites with ZnO (Z), namely Ag/ZnO (AZ), Ag/Fe3O4 (AF), ZnO/Fe3O4 (ZF) and Ag/ZnO/Fe3O4 (AZF) were synthesized. X-ray diffraction studies indicated the formation of wurtzite hexagonal phase for ZnO, cubic structure for Fe3O4 and FCC structure for silver nanocomposites. Field emission scanning electron microscopy revealed the uniform distribution of granules of AZF. Fourier transform infrared spectroscopic studies confirmed the presence of M–O bonds. The ultra violet-visible diffuse reflectance spectroscopy and photoluminescence studies indicated the higher photo degradation activity of silver doped nanocomposites. Thermogravimetric analysis point towards the enhanced thermal stability of doped and coupled nanocomposites. Hydrogenation of 4-nitrophenol to 4-aminophenol showed that AZ, AF & AZF completed the reaction within 3, 4 & 2 min respectively while Z and ZF are ineffective. The photo catalytic activity of the nano composites was investigated by studying the degradation of malachite green (MG) & methylene blue (MB) under UV irradiation. Hetero structured and Ag doped nano composites exhibited better degradation efficiency of MG & MB. Using well diffusion method antibacterial activity of the as-prepared nanoparticles was tested against gram-positive bacteria Staphylococus aureus and gram negative bacteria Escherichia coli. AF & AZF nanocomposites exhibited strong antibacterial activity with greater inhibition zones due to the synergistic effect of silver and magnetite nanoparticles.

Physicochemical and antimicrobial photodynamic chemotherapy (against E. coli) by indium phthalocyanines in the presence of silver–iron bimetallic nanoparticles

In this work, Schiff base indium phthalocyanines: In–Cl tetrakis N,N-dimethyl-4-(methylimino) phthalocyanine (complex 1b) and In–Cl tetrakis phenoxy N,N-dimethyl-4-(methylimino) phthalocyanine (complex 2b) are synthesized from tetra amino and tetra phenoxy amino phthalocyanines, respectively. These complexes were further quartenised with 1,3-propanesultone to form zwitterionic complexes 1 and 2, respectively. Silver–iron dimers (Ag–Fe3O4) and silver-iron core shell (Ag@Fe3O4) nanoparticles (NPs) were linked to the synthesised complexes. The photophysical and photochemical behaviour of the complexes and their conjugates with NPs were investigated in dimethyl sulfoxide. Complexes 2 and 2b and their conjugates were then used for photodynamic antimicrobial chemotherapy on Escherichia coli. The zwitter ionic photosensitiser 2 and its conjugates showed better efficiency for photodynamic antimicrobial chemotherapy compared to their neutral counterparts.

Rotating Ag-Fe3O4-Au Nanograin by Optical Torque with a Monochromatic Light Beam

Optical torques of asymmetrical Ag–Fe3O4–Au nanograins were investigated by the method of discrete dipole approximation (DDA). The results show that surface plasmon resonance (SPR) causes the optical torques which can keep the nanograins rotating clockwise or counterclockwise. When the power density of optical radiation is I = 109 W/m2, the angular velocities of the hybrid sphere and cube heterotrimers can reach to about 104 rad/s in the ranges of 360–374 nm and 403–426 nm, which is ten times larger than that of Brownian rotation. The peak widths at half height of angular velocity curves for two kinds of grains are in the ranges of 31–47 nm and 54–70 nm, respectively. When light radiation force offers a regular driving force, such grains can serve as potential nanoscale optical wrench or microscopic mixers. In addition, the influences of Brownian rotation and photophoresis were discussed.

Strategies to tailor the architecture of dual Ag/Fe-oxide nano-heterocrystals—interfacial and morphology effects on the magnetic behavior

Bifunctional nanostructured architectures have shown appealing properties, since a single entity can combine the diverse properties of its individual constituents. Particularly, by growing Fe-oxide domains over Ag nanoparticles, the plasmonic and superparamagnetic properties can be combined in a single particle. Beyond the multifunctionality of this system, there are several properties that emerge from intrinsic factors, such as: interface and/or morphology. In this study, we present the synthesis protocols to obtain two sets of heterocrystals, each one with different morphology: dimer and flower-like. In addition, the magnetization behavior of these hybrid nano-heterocrystals is investigated and discussed. These nanomaterials were built by a seed assisted heterogeneous nucleation process, carried out in organic solvents of high boiling point, using the same batch of silver nanoparticles with a mean size of 6 nm as seeds, and tuning the electron-donor capacity of the reaction environment at the thermal decomposition of the iron precursor. Ag/Fe3O4 heterocrystals with dimer and flower-like morphologies were obtained. The synthesis protocols for generating these types of nanomaterials are discussed step-by-step. Structural and morphological properties were determined by transmission electron microscopy, x-ray diffraction and x-ray absorption fine structure. DC magnetization results suggest that the silver/magnetite coupling generates an increase of the blocking temperature in comparison to those obtained from pure magnetite. This behavior could be linked to a possible increase in the magnetic anisotropy produced by an additional disorder at the Ag–Fe3O4 interface. The higher interface area of the Ag/Fe3O4 heterocrystals with flower-like architecture leads to a higher blocking temperature and a stronger magnetic anisotropy. These results are supported by AC susceptibility data.

Synthesis of Ag–Fe3O4 nanoparticles supported on polydopamine-functionalized porous cellulose acetate microspheres: catalytic and antibacterial applications

Polydopamine (PDA)—decorated porous cellulose acetate microspheres (PCA/PDA) were synthesized and employed as support for Ag–Fe3O4 NPs (SFNPs) by an in situ one pot method without additional reductants. Different PCA/SFNPs have been studied using various characterization techniques. The as-prepared PCA/PDA/SFNPs exhibited excellent catalytic property for the reduction of 4-nitrophenol within 10 min and strong bactericidal activity against E. coli. Interestingly, the corresponding rate constant increased with the increase of SFNPs amount in PCA/PDA and PCA/PDA/SFNPs showed significantly higher catalytic activity as compared to those exhibited by SFNPs deposited on deacetylated porous cellulose acetate/SFNPs microspheres (DPCA/SFNPs). The enhanced catalytic performance may be attributed to the improved adsorbability and dispersity of SFNPs via the introduction of abundant amine and catechol groups of PDA onto the PCA nanoporous structure. This work has demonstrated the PCA/PDA/SFNPs may hold application potentials in various fields.

Gap-plasmon of Fe3O4@Ag core-shell nanostructures for highly enhanced fluorescence detection of Rhodamine B

A novel gap-plasmon of Fe3O4@Ag core-shell nanoparticles for surface enhanced fluorescence detection of Rhodamine B (RB) was developed. Fe3O4@Ag core-shell nanostructures with Ag shell and Fe3O4 core were synthetized by self-assembled method with the assistance of 3-mercaptopropyl trimethoxy silane (MPTS). To study the RB fluorescence enhanced by gap-plasmon, the fluorescence properties of RB on the substrates with different nanogap densities were systematically investigated, and the results showed that the fluorescence intensity of RB on Fe3O4@Ag core-shell NPs substrate was much stronger than that on bare glass substrate, and the fluorescence intensity was further improved by using multilayer Fe3O4@Ag core-shell NPs substrate which had higher nanogap density. Different from the mechanism that is based on the maximum overlap of the surface plasmon resonance (SPR) band and emission band, the mechanism of the fluorescence enhancement in our work is based on the localized surface plasmon (LSP) and the gap plasmon near-field coupling with the Fe3O4@Ag core-shell NPs. Besides, the detection limit obtained was as low as 1×10-7 mol/L, and the Fe3O4@Ag core-shell NPs substrate had high selectivity for RB fluorophores. It was demonstrated that the Fe3O4@Ag core-shell NPs substrate had activity, good stability, and selectivity for fluorescence detection of RB. And the detection of RB by the surface plasmon enhanced fluorescence was more convenient and rapid than the traditional detection methods in previous works.

Tunable and enhanced SERS activity of magneto-plasmonic Ag–Fe3O4 nanocomposites with one pot synthesize method

In this paper, we report the tunable and enhanced SERS activity of magneto-plasmonic Ag–Fe3O4 nanocomposites that are synthesized by a one pot method. Crystal violet (CV), rhodamine 6 G (R6G) and 4-mercaptobenzoic acid (4-MBA) molecules are used to investigate the SERS optical activity of Ag–Fe3O4 nanocomposites under different external magnetic fields (1500, 2000, 2500, 3500 and 5000 gauss). The experimental results demonstrate the enhanced Raman effects that can be obtained by increasing the magnitude of external magnetic field. This is because the electromagnetic hot spots located between the neighboring Ag–Fe3O4 nanocomposites can be tuned by utilizing the external magnetic field. The bigger density of the hot-spots and amplitude of the electric field in the hot-spot are responsible for the enhanced SERS effect. The detection limit of CV molecule can be at least down to 10−9 M. The spectra measurements of hemoglobin adsorbed on the Ag−Fe3O4 nanocomposites under different external magnetic fields are also performed to explore its bio-applications. Finite element method (FEM) is used to simulate the local electromagnetic field distribution in Ag–Fe3O4 nanocomposites, revealing the SERS enhanced mechanism is determined mainly by the near field enhanced electromagnetic field. Due to its tunable and enhanced properties, Ag–Fe3O4 nanocomposites are expected to be promising SERS substrates for chemical and biological sensing applications.

Silk Fiber as the Support and Reductant for the Facile Synthesis of Ag-Fe₃O₄ Nanocomposites and Its Antibacterial Properties.

We report a facile and environmentally friendly approach to prepare Ag–Fe3O4–silk fiber nanocomposites. The Ag–Fe3O4–silk fiber acts as: (i) a biocompatible support for the silver nanoparticles; and (ii) a reducing agent for the silver ions. Neither additional reducing agents nor toxic organic solvents were used during the preparation process. The Ag–Fe3O4–silk fiber nanocomposites can be actuated by a small household magnet and have high antibacterial activities against both Escherichia coli and Staphylococcus aureus. These nanocomposites could be easily recycled without a decrease in their antibacterial activities due to the synergistic effects between the Ag NPs and Fe3O4 NPs with large amounts of active sites.

Synthesis, characterization, and application of Fe3O4/Ag magnetic composites for mercury removal from water

Engineered nanocomposites (NCs) have recently emerged as materials of great scientific and technological interest. In these materials, different components are combined to yield a nanoentity with desired properties not afforded by the constituent materials. Designing novel NCs and synthetic routes that enable controlling the size and functionalities remains an active area of research. Here, we present a two-step method of synthesizing Ag–Fe3O4 NCs with tunable sizes. Unlike previously reported structures, the prepared NCs do not have a familiar core–shell architecture. Instead, small Fe3O4 nanoparticles (NPs) are embedded in a larger silver matrix. The superparamagnetic Fe3O4 NPs endow the NC with magnetic properties, enabling easy separation from solution. The degree of the NC response to an external magnetic field can be controlled by varying the concentration of Fe3O4 NPs during the synthesis. The Ag matrix serves to protect the embedded Fe3O4 NPs from degradation and can be used for further functionalization of the NCs with different sulfhydryl containing linkers. To demonstrate utility, we show how decorating the outer layer of the Ag NC with diphenyl-4,4′-dithiol transforms the NCs into a water purifying system capable of sequestering highly toxic Hg2+ ions from solution magnetically.