Impact of magnetite nanoparticle incorporation on optical and electrical properties of nanocomposite LbL assemblies
Alexey M. YashchenokDmitry A. GorinM. BadylevichAlexey A. SerdobintsevMatthieu F. BédardYanina FedorenkoGennady B. KhomutovDmitri O. GrigorievHelmuth Möhwald
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Optical and electrical properties of polyelectrolyte/iron oxide nanocomposite planar films on silicon substrates were investigated for different amount of iron oxide nanoparticles incorporated in the films. The nanocomposite assemblies prepared by the layer-by-layer assembly technique were characterized by ellipsometry, atomic force microscopy, and secondary ion mass-spectrometry. Absorption spectra of the films reveal a shift of the optical absorption edge to higher energy when the number of deposited layers decreases. Capacitance-voltage and current-voltage measurements were applied to study the electrical properties of metal-oxide-semiconductor structures prepared by thermal evaporation of gold electrodes on nanocomposite films. The capacitance-voltage measurements show that the dielectric constant of the film increases with the number of deposited layers and the fixed charge and the trapped charge densities have a negative sign.Keywords:
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Nanosized magnetite is a highly toxic material due to its strong ability to generate reactive oxygen species in vivo, and the presence of magnetite NPs in the brain has been linked with aging and neurodegenerative diseases such as Alzheimer's disease. Recently, magnetite pollution nanoparticles (NPs) were found to be present in the human brain, heart, and blood, which raises great concerns about the health risks of airborne magnetite NPs. Here, we report the abundant presence and chemical multifingerprints (including high-resolution structural and elemental fingerprints) of magnetite NPs in the urban atmosphere. We establish a methodology for high-efficiency retrieving and accurate quantification of airborne magnetite NPs. We report the occurrence levels (annual mean concentration 75.5 ± 33.2 ng m–3 in Beijing with clear season variations) and the pollution characteristics of airborne magnetite NPs. Based on the chemical multifingerprints of the NPs, we identify and estimate the contributions of the major emission sources for airborne magnetite NPs. We also give an assessment of human exposure risks of airborne magnetite NPs. Our findings support the identification of airborne magnetite NPs as a threat to human health.
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Magnetite nanoparticles exhibit clear technological potential for biomedical applications. The objectives of this study were to synthesize magnetite-organic complex nanoparticles through the use of metal-reducing bacteria and characterize the mineralogical and surface chemical properties of these nanoparticles as well as to test their potential applications in biomedical technology with regards to their protein immobilization capacity. The microbially formed magnetite nanoparticles had a size of around 10 nm with a spherical shape and were coated with organics containing an abundance of reactive carboxyl groups without any chemical process for functionalizing them. These microbial processes may lead to a simple preparation of functional magnetite-organic complex nanoparticles which have benefits for biomedical applications.
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Pyrrole is polymerised in the presence of ultrafine silica-coated magnetite particles; the resulting colloidal poly(pyrrole)–silica–magnetite nanocomposites have a conducting polymer content of 75 mass% and exhibit superparamagnetism.
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Magnetite nanoparticles were used extensively for various applications. In the present study, magnetite nanoparticles were synthesized and characterized by atomic force microscopy (AFM). AFM images showed that the obtained particles were perfectly spherical. Functionality is afforded to these magnetite nanoparticles by adding biocompatible polymer chitosan during the synthesis. AFM phase image clearly showed that the magnetite core is encapsulated with the polymeric shell. Fourier-transform infrared spectroscopy (FTIR) study showed the chitosan absorption on Fe2O3 nanoparticle surface. The drug sulphamethoxazole was loaded over magnetite nanoparticles and the encapsulation efficiency of drug was calculated at different concentrations of magnetite. The encapsulation efficiency increases with increase in the concentration of magnetite. Thus, an attempt was made in synthesizing drug loaded biopolymer magnetite nanoparticles suitable for targeted drug delivery.
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A promising avenue of research in materials science is to follow the strategies used by Mother Nature to fabricate ornate hierarchical structures as exemplified by organisms such as diatoms, sponges and magnetotactic bacteria. Some of the strategies used in the biological world to create functional inorganic materials may well have practical implications in the world of nanomaterials. The aim of our work is to examine the synthetic of magnetite nanoparticles under different conditions to show the influence in magnetic properties of magnetite nanoparticles. Magnetospirillum strain AMB-1 was used in this study in order to produce magnetite nanoparticles. Magnetite nanoparticles of average size~47 nm were obtained. The magnetic properties of magnetite nanoparticles under different incubation temperature were examined and a small influence in magnetic properties of magnetite nanoparticles was indicated.
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В статье представлены результаты по изучению размеров и сорбционной емкости наночастиц магнетита, полученных на основе метода соосаждения. С использованием метода светодинамического рассеяния определен гидродинамический диаметр образцов магнетита, который для МУС-2М составил 20 ± 5 нм. Показано, что наночастицы магнетита имеют высокую сорбционную емкость к альбумину 34,4 ± 4.1 мг/г, превышающую сорбционную емкость известных угольных гемосорбентов. Полученные наночастицы магнетита могут быть рекомендованы для создания на их основе магнитных иммуноадсорбентов для очистки биологических жидкостей от токсинов. The paper presents the results of investigating the sizes and sorption capacity of the magnetite nanoparticles obtained by the coprecipitation method. A hydrodynamic diameter of the magnetite samples was determined by the SDR method and equals 20 ± 5 nm for MUS-2M. It has been shown that magnetite MUS-2M has the highest sorption capacity to albumin equaling 34.4 ± 4.1 mg/g, which exceeds that of the known hemosorbents. The obtained magnetite nanoparticles can be recommended for creating on their basis magnetic immunoadsorbents to clean biological liquids from toxins.
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In order to protect the magnetite nano-particles from agglomeration and environmental concerns because of their inherent hydrophobicity, magnetite nano-particles need to be encapsulated by some less reactive material that could again be used as a template for subsequent functionalization. Magnetite nano-particles can then be utilized in practical applications. Present work comprises of preparing silica wrapped magnetite nanoparticles (Fe3O4@SiO2) using a two-step synthetic approach through modified Stöber method, involving ultrasonic generator. It has been demonstrated that maintaining an optimum silica wrapping is needed to balance between the required size and conductivity of the magnetite nano-particles, simultaneously attaining minimum micro-strain within their silica encapsulated configuration, for efficient applications.
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