Magnetic Nanospheres Research Articles

The use of iron oxide magnetic nanospheres and nanocubes for targeted doxorubicin delivery into 4t1 mouse breast carcinoma cells

Магнитные наночастицы (МНЧ) привлекают все больше внимания в качестве перспективного материала для разработки эффективных систем противоопухолевой терапии и диагностики. В данной работе исследовано влияние формы магнитного ядра наночастиц (НЧ) оксида железа на эффективность доставки доксорубицина в клетки линии 4T1. НЧ сферической и кубической формы синтезировали методом термического разложения, что позволило эффективно контролировать их форму и размер. После гидрофилизирования с помощью Pluronic F-127 в полученные средства доставки загружали доксорубицин (15,22% для сферических и 15,44% для кубических НЧ). Для незагруженного доксорубицина IC50 достигала 1 мкМ, в то время как для сферических и кубических НЧ с препаратом ― 6,4 мкМ и 5,5 мкМ соответственно. В протестированном диапазоне концентраций (1,77–227,2 мг/л) цитотоксичность у наночастиц без препарата не выявлена. Согласно данным динамики накопления доксорубицина, в клетках 4T1 активнее всего накапливается свободный доксорубицин и локализуется в клеточном ядре. Препарат, загруженный в НЧ, накапливается менее интенсивно и первоначально локализуется в везикулах вокруг ядра, обнаруживаясь в самом ядре лишь через 2 ч совместной инкубации. Доставка противоопухолевого препарата на кубических НЧ несколько более выражена на ранних сроках инкубации с клетками по сравнению со сферическими частицами, однако данная разница не существенна.

Engineering of rich nitrogen-doped and magnetic mesoporous carbon nanospheres with predictable size uniformity for acid dye molecules adsorption

Abstract The fabrication of monodispersed N-doped mesoporous carbon nanospheres (NMCNs) with a high N content remains a formidable challenge due to the decomposition of N-containing frameworks during the pyrolysis and the weak self-assembly ability between carbon precursors and templates. Herein, we demonstrated a strong hydrogen-bonding interaction driving self-assembly method to fabricate uniform NMCNs with rich N content. In this route, phloroglucinol-formaldehyde (PF) not only acted as a rigid phenolic resin framework to prevent N-containing framework from decompose during carbonization, but also provided greater driving force for the self-assembly interaction with F127 through enhanced hydrogen-bonding interaction. The nitrogen doping level, particle size and uniformity of the formed NMCNs could be facilely tuned by adjusting the concentrations of ethylenediamine (EDA). Interestingly, the NMCNs possess high N content (up to ∼ 13.2 wt%), high surface area (556 m2g−1) and large pore volumes (∼0.50 cm3/g). By engineering the compositional diversity inside the single nanoparticles, Fe3O4 nanoparticles can be introduced into the NMCNs. The resultant Fe-NMCNs showed efficient adsorption (283 mg g−1) and magnetic separation property for acid red 57. The feasibility of the fabrication strategy may provide a new insight into the understanding of preparing functionalized carbon nanomaterials with mesoporous structure.

Novel Approach for the Decoration of Magnetic Carbon Nanospheres with Platinum Nanoparticles and Their Enhanced Peroxidase Activity for the Colorimetric Detection of H2O2

Pt/Fe3O4-DIB-DETA-CNS(PFDDC) nanocomposite(DIB=2,4-dihydroxybenzaldehyde; DETA=diethylene-triamine; CNS=carbon nanosphere) was synthesized by dispersing Pt nanoparticles on magnetic carbon nanospheres. The structure, morphology and composition of the nanocomposite were studied by X-ray diffraction(XRD), transmission electron microscopy(TEM), energy-dispersive X-ray spectroscopy(EDX) and X-ray photoelectron spectroscopy(XPS). In addition, the nanocomposite showed superior peroxidase-like activity towards 3,3′,5,5′-tetramethylbenzidine(TMB) with a visual color change in the presence of hydrogen peroxide(H2O2). Therefore, the PFDDC nanocomposite provides a sensing platform for the colorimetric detection of H2O2 with high sensitivity and selectivity. Furthermore, the nano-composite can be conveniently preserved and separated. These features enable the nanocomposite to colorimetrically detect H2O2 for potential pharmaceutical, environmental and industrial applications.

La(OH)3 loaded magnetic mesoporous nanospheres with highly efficient phosphate removal properties and superior pH stability

It is of key importance to remove the excessive phosphate in a water body to prevent the occurrence of eutrophication. Lanthanum (La)-based materials have shown great potential for phosphate removal due to the strong affinity between La and phosphate. In this study, we report the first example of loading La in magnetic ordered mesoporous silica nanoparticles for the removal of phosphate in water. Our optimum sample Mag-MSNs-42%La exhibited a fast adsorption kinetics and a high Langmuir maximum adsorption capacity of 54.2 mg P/g. Remarkably, this sample demonstrated ultrahigh stability within the pH range 4.0–11.0, broader than many other La-based adsorbents reported previously. Our sample also showed high adsorption selectivity to phosphate in the presence of competing anions and humic acid, and efficient P removal from real contaminated water. With more merits of easy separation though magnetic force and easy reproduction, our sample could be an ideal candidate as an effective phosphate adsorbent.

Facile synthesis of silver-decorated magnetic nanospheres used as effective and recyclable antibacterial agents

The development of a highly effective and recyclable antibacterial agent is of great interest. In this work, magnetic Fe3O4/Ag antibacterial nanoagent was successfully fabricated through a facile surface functionalization approach. Utilizing the strong interaction between silver and the amino groups on the surface of Fe3O4 nanospheres, the nanosized silver particles were tightly bonded on the Fe3O4 nanospheres' surface, improving silver nanoparticalsʼ antibacterial activity by preventing agglomeration of silver nanoparticles. Our antibacterial tests showed that the as-synthesized Fe3O4/Ag nanospheres presented high antibacterial performance against Gram-negative and Gram-positive bacteria. Moreover, these antibacterial nanohybrids can be easily recycled from water solution by applying an external magnetic field. Overall, taking into consideration the facile preparation method, excellent antibacterial activity and high magnetic recycling property, the as-synthesized Fe3O4/Ag nanospheres have great potential applications in medicine and water disinfection.

The use of magnetic targeting for drug delivery into cardiac myocytes

Abstract With the continuous technological advancements being made in the medical field every day, the ability to improve drug delivery uptake in cardiac research is a prominent topic of discussion. Nanoparticles provide the opportunity to improve the efficiency of drug therapy while minimizing chemotherapy side effects through controllably releasing the encapsulated drug at the target site. Mono-disperse Fe3O4 nanoparticles/polystyrene composite nanospheres with a large volume fraction of trapped magnetite and fluorophores were used in an in vivo experiment. In this study, magnetic nanoparticles were successfully delivered into the heart by utilizing magnetic targeting. Magnetic targeting allowed the mono-disperse Fe3O4 nanospheres to be dramatically localized in the heart myocardium. This increased the quantity of delivery to the cardiac myocytes in comparison to magnetic nanospheres without magnetic targeting.

Multiplex On-Bead Isotope Dimethyl Labeling Coupled with Liquid Chromatography-High-Resolution Mass Spectrometry for Quantitative Analysis of Sulfonamides in Estuarine Ice.

A multiplex-on-bead-isotope-dimethyl-labeling method was developed for the quantitative analysis of sulfonamides (SAs) in environmental water samples by liquid chromatography-high-resolution mass spectrometry (LC-HRMS). In this method, five samples could be labeled in parallel with different isotope reagents and quantified in a single LC-HRMS analysis. Magnetic solid-phase extraction (MSPE) was employed in the sample preparation to concentrate the trace-level analytes by using lab-synthesized magnetic carbon nanospheres (MCNSs). After the analytes were captured on the MCNSs, the isotope labeling was performed directly by dispersing the MCNSs in the reaction buffer (on-bead labeling). The experimental conditions for MSPE and labeling were systematically investigated. For the tested 12 SAs, a labeling efficiency of over 99% could be achieved within 20 min. The LC-HRMS separation, including equilibration, could be achieved in 6 min. By combining MSPE (enriched 200-fold), multiplex on-bead dimethyl labeling, and LC-HRMS, all the tested SAs could be reliably quantified with limits of detection (LODs) of 0.1-5 ng/L. This method was verified using fortified pond water spiked with 12 SAs (0.01-5 μg/L), and accuracies of 81-106% were achieved with good reproducibility (RSD < 10%, n = 3), which confirmed its applicability in real-sample analysis. With this method, ice samples collected at the estuary of the Daliao River in northeast China were analyzed; nine SAs (sulfanilamide, sulfapyridine, sulfamethazine, sulfamethizole, sulfachloropyridazine, sulfamethoxypyridazine, sulfameter, sulfathiazole, and sulfisoxazole) were detected at concentrations of 0-85 ng/L, and the total concentrations were in the range of 185-402 ng/L with a median value of 274 ng/L.

Magnetic mesoporous nanospheres supported phosphomolybdate-based ionic liquid for aerobic oxidative desulfurization of fuel

Phosphomolybdate-based ionic liquid [(C8H17)3NCH3]3PMo12O40 was prepared and supported on a magnetic mesoporous silica (γ-Fe2O3@SiO2@mSiO2) to obtain a magnetic mesoporous catalyst. The morphology and components of the catalyst were characterized by FT-IR, XRD, XPS, SEM, TEM, nitrogen adsorption-desorption isotherms, and VSM. With air as oxidant, the catalyst showed perfect desulfurization performance in oxidation of dibenzothiophene (DBT). The removal of DBT from model oil could reach 100% within 5 h at 120 °C. After reaction, the catalyst could be separated by a magnet and recycled at least four times without obvious decrease in the catalytic performance.

Chip-Assisted Single-Cell Biomarker Profiling of Heterogeneous Circulating Tumor Cells Using Multifunctional Nanospheres.

Profiling the heterogeneous phenotypes of individual circulating tumor cells (CTCs) from patients is a very challenging task, but it paves new ways for cancer management, especially personalized anticancer therapy. Herein, we propose a chip-assisted multifunctional-nanosphere system for efficient and reliable biomarker phenotype analysis of individual heterogeneous CTCs. Red fluorescent magnetic biotargeting multifunctional nanospheres and green fluorescent biotargeting nanospheres targeting to two kinds of CTC biomarkers are used for convenient dual-fluorescence labeling of CTCs along with magnetic tags. By integrating magnetic enrichment with a size-selective single-cell-trapping microfluidic chip (SCT-chip), over 90% of CTCs, even when the concentrations is as low as 10 CTCs per milliliter of blood, can be individually trapped at highly ordered micropillars, spatially separated from the minimal residual blood cells. Such single CTCs offer easy-readout fluorescence signals, facilitating efficient identification and reliable phenotype analysis in accordance with their biomarker expressions. Therefore, the phenotypes of breasttumor cells in terms of the expression level of human epidermal-growth-factor receptor 2, an important target of clinical anticancer drugs, are accurately assessed, and over 82% of them can be classified into corresponding cell subpopulations. Furthermore, this system demonstrates successful detection and subpopulation analysis of heterogeneous CTCs from seven breast cancer patients, which provides a promising new means for single-cell profiling of CTC-biomarker phenotypes and guiding of personalized anticancer therapy.

Functional mesoporous carbon nanospheres: Effects of adding magnetic source during different stage

To solve the challenge of preparing magnetic mesoporous carbon nanospheres (MMCNs) with uniform and disperse particles, a series of MMCNs are achieved by a self-assembly procedure in one-pot aqueous solution. Impacts of magnetic source on the morphology and textural property of the as-synthesized MMCNs are systematically investigated by altering their adding time. An extended “two-stage dispersion polymerization” mechanism is employed to explain the formation of MMCNs. Interestingly, adding Fe3+ during the particle growing stage can obtain MMCNs-2, exhibiting uniform particle size, large specific surface area, high adsorption capacity and magnetic properties for improving the release of water-insoluble drugs such as Lovastatin (LOV).

Self-Assembling Hydrophilic Magnetic Covalent Organic Framework Nanospheres as a Novel Matrix for Phthalate Ester Recognition.

The development of covalent organic framework (COF)-derived materials with additional functions and applications is highly desired. In this work, a unique COF-functionalized hydrophilic magnetic nanosphere (Fe3O4@PDA@TbBd) with Fe3O4 as a magnetic core, polydopamine (PDA) as a hydrophilic middle layer, and TbBd as an outer COF shell was facilely prepared as a novel hydrophilic platform for efficient detection of phthalic acid esters (PAEs). The resultant Fe3O4@PDA@TbBd nanosphere displayed strong magnetic response, high surface area, and good hydrophilicity. Accordingly, the newly synthesized COF exhibited great potential in phthalate analysis with a wide linearity (50-8000 ng/mL), good recovery (92.3-98.9%), a low limit of detection (0.0025-0.01 ng/mL), and a small relative standard deviation (for intraday less than 4.6% and for interday less than 6.8%). More excitingly, the new COF was applied to analyze nine PAEs in the human plasma sample. This work opens up new avenues for the development and application of functionalized COF-derived materials.

Spatial Isolation of Carbon and Silica in a Single Janus Mesoporous Nanoparticle with Tunable Amphiphilicity.

Like surfactants with tunable hydrocarbon chain length, Janus nanoparticles also possess the ability to stabilize emulsions. The volume ratio between the hydrophilic and hydrophobic domains in a single Janus nanoparticle is very important for the stabilization of emulsions, which is still a great challenge. Herein, dual-mesoporous Fe3O4@mC&mSiO2 Janus nanoparticles with spatial isolation of hydrophobic carbon and hydrophilic silica at the single-particle level have successfully been synthesized for the first time by using a novel surface-charge-mediated selective encapsulation approach. The obtained dual-mesoporous Fe3O4@mC&mSiO2 Janus nanoparticles are made up of a pure one-dimensional mesoporous SiO2 nanorod with tunable length (50-400 nm), ∼100 nm wide and ∼2.7 nm mesopores and a closely connected mesoporous Fe3O4@mC magnetic nanosphere (∼150 nm diameter, ∼10 nm mesopores). As a magnetic "solid amphiphilic surfactant", the hydrophilic/hydrophobic ratio can be precisely adjusted by varying the volume ratio between silica and carbon domains, endowing the Janus nanoparticles surfactant-like emulsion stabilization ability and recyclability under a magnetic field. Owing to the total spatial separation of carbon and silica, the Janus nanoparticles with an optimized hydrophilic/hydrophobic ratio show spectacular emulsion stabilizing ability, which is crucial for improving the biphasic catalysis efficiency. By selectively anchoring catalytic active sites into different domains, the fabricated Janus nanoparticles show outstanding performances in biphasic reduction of 4-nitroanisole with 100% conversion efficiency and 700 h-1 high turnover frequency for biphasic cascade synthesis of cinnamic acid.

Polyoxometalate-Coated Magnetic Nanospheres for Highly Selective Isolation of Immunoglobulin G.

Polyoxometalate [{a-PW11O39Zr(μ-OH)(H2O)}2]8- (POM1) is first prepared by sandwiching ZrIV among 2 mono-lacunary α-Keggin polyoxometalates, and then novel magnetic nanoparticles (NPs), Fe3O4@polyethyleneimine (PEI)@POM1, are fabricated by coating POM1 onto the surface of magnetic Fe3O4@PEI NPs under electrostatic interaction. The obtained Fe3O4@PEI@POM1 NPs are characterized by Fourier transform infrared, zeta potential, vibrating sample magnetometer, transmission electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction. Ascribed to the hydrogen-bonding and electrostatic interactions, the NPs exhibit high adsorption selectivity toward IgG, and the adsorption capacity is high up to 304 mg g-1 under optimal adsorption conditions. By using 0.01% cetyl trimethylammonium bromide to strip the adsorbed protein species, an elution efficiency of 95% is achieved. The feasibility of Fe3O4@PEI@POM1 NPs in real-world sample assay has been demonstrated by the selective isolation of IgG heavy chain and light chain from human serum, as confirmed by the sodium dodecyl sulfate polyacrylamide gel electrophoresis assay.

Photo-Fenton Degradation of Organic Dyes Based on a Fe₃O₄ Nanospheres/Biomass Composite Loaded Column.

In order to deal with pollution of organic dyes, magnetic Fe3O4 nanospheres (NPs) with an average diameter of 202 ± 0.5 nm were synthesized by a solvothermal method at 200 °C, and they can efficiently degrade organic dyes (methylene blue (MB), rhodamine B (RhB) and xylenol orange (XO)) aqueous solutions (20 mg/L) within 1 min. Based on this Fenton reagent, Fe3O4 NPs/biomass composite degradation column was made using sawdust as substrate, and it can efficiently degrade organic dyes continually. More importantly, the composite can be regenerated just by an ultrasonic treatment, and its degradation performance almost remains the same.

Near-Infrared Fluorescent Ag2S Nanodot-Based Signal Amplification for Efficient Detection of Circulating Tumor Cells.

The level of circulating tumor cells (CTCs) plays a critical role in tumor metastasis and personalized therapy, but it is challenging for highly efficient capture and detection of CTCs because of the extremely low concentration in peripheral blood. Herein, we report near-infrared fluorescent Ag2S nanodot-based signal amplification combing with immune-magnetic spheres (IMNs) for highly efficient magnetic capture and ultrasensitive fluorescence labeling of CTCs. The near-infrared fluorescent Ag2S nanoprobe has been successfully constructed through hybridization chain reactions using aptamer-modified Ag2S nanodots, which can extremely improve the imaging sensitivity and reduce background signal of blood samples. Moreover, the antiepithelial-cell-adhesion-molecule (EpCAM) antibody-labeled magnetic nanospheres have been used for highly capture rare tumor cells in whole blood. The near-infrared nanoprobe with signal amplification and IMNs platform exhibits excellent performance in efficient capture and detection of CTCs, which shows great potential in cancer diagnostics and therapeutics.

Ruthenium-based metal organic framework (Ru-MOF)-derived novel Faraday-cage electrochemiluminescence biosensor for ultrasensitive detection of miRNA-141

A novel Faraday-cage electrochemiluminescence (ECL) biosensor for the sensitive detection of miRNA-141 was constructed. The capture unit was prepared by immobilizing the capture DNA (cDNA) on the functionalized magnetic nanospheres nanoFe3O4@SiO2@Au, while the signal unit was ruthenium-based metal organic framework Ru-MOF labeled by signal DNA (sDNA). The recognition scaffold was as follows: the capture unit was immobilized onto the magnetic electrode surface; the target miRNA-141 was caught; the signal unit was further hybridized; the Faraday-cage biosensor structure was formed finally. In this case, the signal unit became part of the electrode surface, the outer Helmholtz plane (OHP) of the proposed electrode was extended, all electrochemiluminophores in the signal unit could take part in the electrode reaction, and thus then the detection sensitivity was greatly improved. Taking advantage of the proposed Faraday-cage cascade, the ECL intensity was found to increase with the logarithm of miRNA-141 concentration. The linear range was wide from 1 fM to 10 pM with a limit of detection 0.3 fM. The selectivity, stability, reproducibility, precision and application of this biosensor were validated. This proposed Faraday-cage ECL biosensor has a potential prospect for clinical miRNA detection.

Preparation of iron oxide silica particles for Zika viral RNA extraction

In this work, a robust synthetic pathway for magnetic core preparation and silica surface coating of magnetic microparticles is presented. Silica-coated magnetic particles are widely used to extract DNA and RNA from various biological samples. We present a novel route for the synthesis of iron oxide silica particles (Fe3O4@Silica) and demonstrate their performance for extracting ZIKA viral RNA from serum. The iron (II, III) oxide (Fe3O4), magnetite core is first prepared by ammonia neutralization of ferrous and ferric chloride aqueous solution under argon, followed by the addition of citrate salt to stabilize the surface of the resultant magnetic nanospheres. After this one-pot, two-step synthesis, the magnetic nanospheres are consumed during silica coating by hydrolysis of tetraethoxysilane (TEOS) under alkaline condition. The final product is a sphere-like magnetic aggregate with a size range of 1–2 micron. By simply suspending the magnetic aggregates in guanidinium chloride solution, the silica surface can be prepared for RNA binding. The RNA extraction efficiency was evaluated by extracting ZIKA viral RNA from serum followed by a PCR-based assay. The data indicate excellent recovery of target RNA and removal of PCR inhibitors. This manufacturing procedure for the silica coated microparticles provides a low-cost, effective and ready for scale-up method whose performance is equivalent to commercial alternatives such as magnetic silica surface particles for DNA and RNA sample preparations. The cost of the clinical assays could be largely decreased due to the 100 fold reduction in cost by replacing the commercially available magnetic particles with the developed material for RNA extraction.

Functionalized Magnetic PLGA Nanospheres for Targeting and Bioimaging of Breast Cancer.

Superparamagnetic iron oxide nanoparticles (SPIONs) are actively used as highly sensitive imaging probes to provide contrast in MRI. In this study, we propose the use of SPIONs encapsulated with antibody-conjugated poly(lactic-co-glycolic acid) (PLGA) as a potent theragnostic agent. The SPIONs were synthesized by a chemical co-precipitation method of ferric and ferrous ions, and subsequently encapsulated with PLGA by using an emulsification-diffusion method. Herceptin was chemically conjugated to the SPION-encapsulating PLGA nanoparticles to target the human epidermal growth factor receptor 2 (Her2/neu) overexpressing breast cancers. FACS and MR molecular imaging revealed that the Her2/neu overexpressing cell line showed a stronger contrast enhancement than the Her2/neu non-expressing cell lines, and the signal intensity of in vivo MR imaging decreased as the concentration of Herceptin increased. This strategy of encapsulating SPIONs with PLGA will be highly useful in functionalizing magnetic nanoparticles and improving the diagnostic and therapeutic efficacy of a wide array of cancer treatments.

Porphyrin-based magnetic nanocomposites for efficient extraction of polycyclic aromatic hydrocarbons from water samples

Stable and reusable porphyrin-based magnetic nanocomposites were successfully synthesized for efficient extraction of polycyclic aromatic hydrocarbons (PAHs) from environmental water samples. Meso-Tetra (4-carboxyphenyl) porphyrin (TCPP), a kind of porphyrin, can connect the copolymer after amidation and was linked to Fe3O4@SiO2 magnetic nanospheres via cross-coupling. Several characteristic techniques such as field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, Fourier transform infrared spectrometry, vibrating sample magnetometry and a tensiometer were used to characterize the as-synthesized materials. The structure of the copolymer was similar to that of graphene, possessing sp2-conjugated carbon rings, but with an appropriate amount of delocalized π-electrons giving rise to the higher extraction efficiency for heavy PAHs without sacrificing the performance in the extraction of light PAHs. Six extraction parameters, including the TCPP:Fe3O4@SiO2 (m:m) ratio, the amount of adsorbents, the type of desorption solvent, the desorption solvent volume, the adsorption time and the desorption time, were investigated. After the optimization of extraction conditions, a comparison of the extraction efficiency of Fe3O4@SiO2-TCPP and Fe3O4@SiO2@GO was carried out. The adsorption mechanism of TCPP to PAHs was studied by first-principles density functional theory (DFT) calculations. Combining experimental and calculated results, it was shown that the π-π stacking interaction was the main adsorption mechanism of TCPP for PAHs and that the amount of delocalized π-electrons plays an important role in the elution process. Under the optimal conditions, Fe3O4@SiO2-porphyrin showed good precision in intra-day (<8.9%) and inter-day (<13.0%) detection, low method detection limits (2–10 ng L−1), and wide linearity (10–10000 ng L−1). The method was applied to simultaneous analysis of 15 PAHs with acceptable recoveries, which were 71.1%-106.0% for ground water samples and 73.7%–107.1% for Yangtze River water samples, respectively.

Porous Co nanospheres supported on nitrogen-doped graphene as high-efficiency electromagnetic wave absorbers with thin thickness

The design of magnetic/dielectric composites with rational nanostructures can greatly determine the electromagnetic wave absorption performance of absorbers. Herein, the porous magnetic Co nanospheres supported on lightweight dielectric nitrogen-doped graphene (N-GN) were prepared through a simple one-pot solvothermal method as enhanced synergistic electromagnetic wave absorbers. The Co nanocrystals show porous spherical shape with hexagonal phase, which are supported uniformly on the crumpled N-GN without conglomeration. Even powerful ultrasound treatment cannot separate the Co nanospheres from N-GN, suggesting that the porous Co nanospheres are in-situ anchored on N-GN. Taking the combined advantages of magnetic porous Co nanospheres and dielectric lightweight N-GN, the Co/N-GN nanocomposites perform improved electromagnetic wave absorption abilities, such as high-efficiency absorption performance, thin matching thickness and broad effective absorption bandwidth. When the absorber thickness of nanocomposites is only 1.3 mm, the maximum reflection loss (RL) value can reach −24.3 dB at 17.7 GHz. And the effective absorption frequency with RL < −10 dB is ranging from 3.6 to 18 GHz, when the thickness of nanocomposites absorber is 1.2–4.0 mm. However, in the entire frequency range, the bare Co nanocrystals cannot exceed −10 dB. The improved absorption abilities for the Co/N-GN nanocomposites are mainly due to the combined effect of excellent magnetic and dielectric loss, which may result in better impedance matching condition and improved attenuation capacity. These results suggest that the porous Co/N-GN nanocomposites are attractive absorbents for electromagnetic wave absorption. Besides, decorating magnetic nanocrystals with nitrogen-doped graphene is believed to be a promising kind of magnetic/dielectric composites for high-efficiency electromagnetic wave absorption.