In this report, Fe3O4 nanoparticles are modified for the first time with graphene quantum dots (GQD) and used for the stabilization of PdCu bimetallic nanoparticles. The new magnetic compound, ...PdCu@GQD@Fe3O4, is characterized by different methods such as SEM, high‐resolution (HR)‐TEM, energy‐dispersive X‐ray spectroscopy (EDS) mapping, XRD, and X‐ray photoelectron spectroscopy (XPS). This material is applied as an efficient catalyst for the Sonogashira reaction of aryl iodides, bromides, and chlorides in toluene or N,N‐dimethylacetamide at 60–110 °C in very high yields with 0.3 mol % of Pd loading. According to different tests, such as polyvinylpyridine poisoning, hot filtration, and kinetic studies, this catalyst works under heterogeneous conditions. By magnetic separation of the catalyst, it can be recycled for six consecutive runs with only a small decrease in activity without appreciable structural modification of the reused catalyst, which is characterized by TEM and XPS.
Going dotty: Fe3O4 nanoparticles modified with graphene quantum dots (GQD) are used for the stabilization of PdCu bimetallic nanoparticles. This material is applied as an efficient catalyst for the Sonogashira reaction of aryl iodides, bromides, and chlorides in toluene or N,N‐dimethylacetamide at 60–110 °C in very high yields with 0.3 mol % of Pd loading.
Pathogenic bacteria contamination poses a major threat to human health. The detection of low-abundance bacteria in complex samples has always been a knotty problem, and high-sensitivity bacterial ...detection remains challenging. In this work, a novel magnetic platform with high enrichment efficiency for L. monocytogenes was developed. The magnetic platform was designed by branched polyglutamic acid-mediated indirect coupling of cefepime on magnetic nanoparticles (Cefe-PGA-MNPs), and the specific enrichment of low-abundance L. monocytogenes in real samples was achieved by an external magnet, with a capture efficiency over 90%. A controllable and highly active platinum-palladium nanozyme was synthesized and further introduced in the magnetic nanoplatform for the construction of enzymatic colorimetric biosensor. The total detection time for L. monocytogenes was within 100 min. The colorimetric signals generated by labelled nanozyme were corresponding to different concentrations of L. monocytogenes, with a limit of detection (LOD) of 3.1 × 101 CFU/mL, and high reliability and accuracy (with a recovery rate ranging from 96.5% to 116.4%) in the test of real samples. The concept of the developed method is applicable to various fields of biosensing that rely on magnetic separation platforms.
Display omitted
•Broom-like magnetic platform captured > 90% of L. monocytogenes in real samples.•Size-controlled PdPt nanozyme demonstrated superior catalytic activity than HRP.•A signal acquisition and analysis system based on smartphone was established.•The LOD of L. monocytogenes was 3.1 × 101 CFU/mL.
Display omitted
•A new method was established to encapsulate silicon onto magnetic nanoparticles.•The silicon layer has better surface morphology, stronger acid resistance.•The purification result ...leaded to better results in comparison with commercial kit.
A new method was developed for preparing monodisperse Fe3O4@SiO2 magnetic core-shell nanoparticles via three steps. The obtained nanoparticles exhibit high saturation magnetization, good surface topography and dispersion as characterized by FTIR, SEM and VSM. The experimental results of hydrochloric acid treatment show that the obtained nanoparticles have excellent acid resistance and stable and compact silicon coating. The magnetic core-shell nanoparticles were further tested for purification of plasmid DNA from E. coli DH5a cells. The result of purification leaded to better adsorption, elution and purity results in comparison with isolated commercial extraction kit.
Recent advances in development of potential magnetic nanoparticles for magnetic fluid hyperthermia are summarized. This review covers relation between various size dependent physical properties and ...their applications subject to modification in synthesis methods. Brief discussion on different heating mechanism of magnetic nanoparticles is provided. This review covers recent progress of various magnetic nanoparticles including core shell type for in vitro, in vivo and pre-clinical trials. The highlight of this review is to build up a bridge between synthesis, surface modification and in vivo- pre-clinical in magnetic fluid hyperthermia.
The bioavailability and ecotoxicity of pollutants are important for urban ecological systems and human health, particularly at contaminated urban sites. Therefore, whole-cell bioreporters are used in ...many studies to assess the risks of priority chemicals; however, their application is restricted by low throughput for specific compounds and complicated operations for field tests. In this study, an assembly technology for manufacturing Acinetobacter-based biosensor arrays using magnetic nanoparticle functionalization was developed to solve this problem. The bioreporter cells maintained high viability, sensitivity, and specificity in sensing 28 priority chemicals, seven heavy metals, and seven inorganic compounds in a high-throughput manner, and their performance remained acceptable for at least 20 d. We also tested the performance by assessing 22 real environmental soil samples from urban areas in China, and our results showed positive correlations between the biosensor estimation and chemical analysis. Our findings prove the feasibility of the magnetic nanoparticle-functionalized biosensor array to recognize the types and toxicities of multiple contaminants for online environmental monitoring at contaminated sites.
Display omitted
•First MNPs functionalized biosensor array for contaminated soil measurement.•Toxicity assessment and simulation of 28 priority chemicals.•Novel biosensor array for contaminated soil in situ monitoring and assessment.•Evaluation of bioavailability and ecotoxicity in various contaminated soils.
•Label-free aptamer was immobilized on the surface of MNPs via hybridization with capture probe.•A simple and universal aptamer-based fluorescent assay is described for allergen detection.•The ...magnetic-assisted aptamer-based sensing system showed desired sensitivity and selectivity for tropomyosin detection.•The proposed aptamer-based assay presented a low detection limit of 77 ng mL−1.
Herein, a facile and versatile label-free aptamer-based fluorescent assay for simple and sensitive detection of food allergen in food matrix is developed based on the functionalized magnetic nanoparticles (MNPs) as separation carrier and commercially available OliGreen dye as signal probe. First, the aptamer hybridized with capture probe that was conjugated on the surface of MNPs to form aptamer-MNPs complexes as detection probes, which undergo conformational change upon interaction with target analytes, resulting in the release of aptamer from the surface of MNPs. So the released aptamer in the supernatant produced a significant fluorescence enhancement signal by introducing the OliGreen dye based on its ultrasensitive and specific fluorescence enhancement upon binding to ssDNA. As proof-of concept, this proposed strategy was applied to quantitative detection of tropomyosin, one of the major allergen found in shellfish. Under optimal conditions, the linear range was from 0.4 to 5 μg mL−1 (R2 = 0.996) with a low limit of detection calculated to be 77 ng mL−1. Moreover, the aptamer-based assay had remarkable selectivity and was successfully applied in the detection of tropomyosin in food matrix. Due to its simple design, easy operation and high sensitivity and selectivity, the proposed aptamer assay could expect to expand applications in various allergens detection by changing corresponding aptamers on the detection probe.
Thermal fluctuations play an increasingly important role in micromagnetic research relevant for various biomedical and other technological applications. Until now, it was deemed necessary to use a ...time stepping algorithm with a fixed time step in order to perform micromagnetic simulations at nonzero temperatures. However, Berkov and Gorn have shown in D. Berkov and N. Gorn, J. Phys.: Condens. Matter, 14, L281, 2002 that the drift term which generally appears when solving stochastic differential equations can only influence the length of the magnetization. This quantity is however fixed in the case of the stochastic Landau-Lifshitz-Gilbert equation. In this paper, we exploit this fact to straightforwardly extend existing high order solvers with an adaptive time stepping algorithm. We implemented the presented methods in the freely available GPU-accelerated micromagnetic software package MuMax(3) and used it to extensively validate the presented methods. Next to the advantage of having control over the error tolerance, we report a twenty fold speedup without a loss of accuracy, when using the presented methods as compared to the hereto best practice of using Heun's solver with a small fixed time step. (c) 2017 Author(s).
In this study, magnetic sporopollenin supported cyanocalixarene (MSP-CyCalix) nanocomposite was synthesized and introduced as an adsorbent material for the removal of pesticides from aqueous media. ...MSP-CyCalix was characterized by different analytical techniques FTIR, SEM, EDX, BET, VSMand TEM. Chlorpyrifos and hexaconazole pesticides were chosen as model analytes solutions for testing the adsorption efficiency of MSP-CyCalix adsorbent. The adsorption results showed that the incorporated cyano functional groups significantly increased the chemical reactivity and adsorption capacity for pesticides. To obtain the highest possible performance, experimental parameters such as pH, salt, dosage and time were optimized. Adsorption kinetics and isotherms models showed that pesticide adsorption process was well fitted with the pseudo-second-order and Langmuir models with a maximum adsorption capacity of 13.88 mg g−1 and 12.34 mg g−1 and a removal efficiency of >90% for both pesticides. Lastly, MSP-CyCalix maintained a removal efficiency of >80% for ten cycles and 60% after the eleventh cycles of usage. The results proved that MSP-CyCalix nanocomposite can be used as an efficient adsorbent for the removal of pesticide residues from water.
•Synthesis and characterizations of new green and honey-comb like cyno-substituted calix-based magnetic sporopollenin.•Removal behavior investigations of the new magnetic adsorbent for pesticides.•Optimization of parameters to evaluate removal performance of the MSP-CyCalix.•Pesticides adsorption on nanocomposite was fitted by Langmuir model.
The physicochemical properties of spinel oxide magnetic nanoparticles depend critically on both their size and shape. In particular, spinel oxide nanocrystals with cubic morphology have shown ...superior properties in comparison to their spherical counterparts in a variety of fields, like, for example, biomedicine. Therefore, having an accurate control over the nanoparticle shape and size, while preserving the crystallinity, becomes crucial for many applications. However, despite the increasing interest in spinel oxide nanocubes there are relatively few studies on this morphology due to the difficulty to synthesize perfectly defined cubic nanostructures, especially below 20 nm. Here we present a rationally designed synthesis pathway based on the thermal decomposition of iron(III) acetylacetonate to obtain high quality nanocubes over a wide range of sizes. This pathway enables the synthesis of monodisperse Fe3O4 nanocubes with edge length in the 9–80 nm range, with excellent cubic morphology and high crystallinity by only minor adjustments in the synthesis parameters. The accurate size control provides evidence that even 1–2 nm size variations can be critical in determining the functional properties, for example, for improved nuclear magnetic resonance T 2 contrast or enhanced magnetic hyperthermia. The rationale behind the changes introduced in the synthesis procedure (e.g., the use of three solvents or adding Na-oleate) is carefully discussed. The versatility of this synthesis route is demonstrated by expanding its capability to grow other spinel oxides such as Co-ferrites, Mn-ferrites, and Mn3O4 of different sizes. The simplicity and adaptability of this synthesis scheme may ease the development of complex oxide nanocubes for a wide variety of applications.
PDF
