Synthesis and Properties of Magnetic Nanoparticles

The uniform mesoporous SBA-15 consisting of SiO2 with long-range channels Offers an excellent host material to synthesize or assemble the magnetic nanocomposites, such as Fe, Ni. In this paper, highly dispersed and uniform iron nanoparticles were incorporated into the pore channels of SBA-15 through a newly developed strategy in which some kinds of coupling agents were used to entrap the nanoparticles into the silica framework. The X-ray diffraction （XRD）, fourier transmission infrared spectroscopy （FTIR）, high-resolution transmission electronic microscopy （HRTEM） and energy dispersive X-ray spectroscopy （EDX） were performed to further identify the successful incorporation and grafting of iron. Compared with other ordinary non-assembled magnetic nanoparticles, the assembled Fe nanoparticles with the diameter even in the size range of 5～6 nm still have better magnetic properties.     

Advances in the Application of Magnetic Nanoparticles for Sensing

Magnetic nanoparticles (MNPs) are of high significance in sensing as they provide viable solutions to the enduring challenges related to lower detection limits and nonspecific effects. The rapid expansion in the applications of MNPs creates a need to overview the current state of the field of MNPs for sensing applications. In this review, the trends and concepts in the literature are critically appraised in terms of the opportunities and limitations of MNPs used for the most advanced sensing applications. The latest progress in MNP sensor technologies is overviewed with a focus on MNP structures and properties, as well as the strategies of incorporating these MNPs into devices. By looking at recent synthetic advancements, and the key challenges that face nanoparticle‐based sensors, this review aims to outline how to design, synthesize, and use MNPs to make the most effective and sensitive sensors.     

铁纳米粉体的磁性能研究

为了研究铁纳米粉体材料与常规材料在磁性能方面的不同,采用阳极弧放电等离子体方法制备了铁纳米粉体。利用X射线衍射(XRD)、透射电子显微镜(TEM)和振动样品磁强计(VSM)等测试手段对样品的形貌、晶体结构、粒度、磁性能进行表征,并对振动样品磁强计测量静态磁特性的原理进行了分析。测试结果表明,样品呈规则的球形链状分布,表面光洁,平均粒径为39nm,粒径范围分布区间窄,晶体结构为bcc结构的晶态;纳米结构材料与常规材料在磁结构上有差别,铁纳米粉体的饱和磁化强度Ms为53emu/g,剩余磁化强度Mr为1.5emu/g,矫顽力Hc为32.2Oe。     

Low-Temperature Magnetic Properties of Vanadium-Doped ZnO Nanoparticles

Low-temperature magnetic study of transition metal-doped ZnO nanoparticles tends to spring ambiguities of magnetic phases due to defect states, environment of doped ions, and anisotropy. Interestingly, vanadium doping in ZnO brings out versatile magnetic ordering which offers more room for basic understanding of the underlying mechanism. Vanadium-doped ZnO nanoparticles are prepared using a simple cost-effective approach of solution combustion method. Macroscopic and microscopic aspects of the samples have been unraveled using structural and morphological studies with the implications on the exhibited magnetic behavior. Development of antiferromagnetic, ferromagnetic, and ferrimagnetic interactions in the material illustrated by low-temperature magnetic measurements preludes the possible interplay of dopant-initiated defect correlation and morphological and interfacial secondary phases. The grain boundary reformation due to vanadium in the ZnO nanograins is exploited through a systematic correlation of structural and morphological studies in order to gain more insight into the portrayed magnetic signatures.     

Bacterial Ferrihydrite Nanoparticles: Preparation,Magnetic Properties,and Application in Medicine

Nanoparticles of antiferromagnetically ordered materials acquire the uncompensated magnetic moment caused by defects and surface effects. A bright example of such a nano-antiferromagnet is nanoferrihydrite consisting of particles 2–5 nm in size, the magnetic moment of which amounts to hundreds of Bohr magnetons per particle. We present a brief review of the studies on magnetic properties of ferrihydrite produced by bacteria. Special attention is focused on the aspects of possible biomedical applications of this material, i.e., the particle elimination, toxicity, and possible use for targeted drug delivery.     

Magnetic Properties of Mechanically Alloyed Cobalt-Zinc Ferrite Nanoparticles

In this work, the physical and the magnetic properties of cobalt-zinc ferrite nanoparticles, synthesized via high-energy ball milling (HEBM), were examined. X-Ray diffraction (XRD), field emission scanning electron microscopy (FeSEM), and scanning transmission electron microscopy (STEM) were used to study changes of the powder structure and morphology analyses. Hysteresis and permeability measurement were carried out using a BH hysteresisgraph system and an impedance analyzer, respectively. The results suggested improved magnetic properties of Co_0.5Zn_0.5Fe₂O₄ with increasing sintering temperature from 950 °C up to 1200 °C. However, the variations of the magnetic responses were consistent with the varying volume concentration of the ferrite composites. Unlike the highly crystalline pure ferrite which showed magnetic resonance within the measured frequency, the crystallineamorphous composites showed no visible resonance peak. This proved that the resonance peak shifted to higher frequency as a result of the single domain spin behavior in the absence of domain walls movement.     

New results on Magnetic Properties of Tin-Ferrite Nanoparticles

This paper presents new physical properties of nanocrystalline SnFe₂O₄ ferrites, synthesized by co-precipitation method. Magnetization measurement indicates superparamagnetic behavior; the blocking temperature is about 300?K. We performed X-ray diffraction, infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), Energy Dispersive Spectroscopy (EDS), UV-visible measurement, superconducting quantum interference device (SQUID) and zero-field-cooled (ZFC)/field-cooled (FC) measurements. TEM images show the high crystallinity and grain size of ferrite nanocrystals. The refinement result showed that the type of the cationic distribution over the tetrahedral and octahedral sites in the nanocrystalline lattice is a partially inverse spinel. The obtained UV?Cvis data were used to calculate the energy band gap (3.82?eV) of nanocrystalline SnFe₂O₄. On the other hand the magnetic properties of the samples; saturation magnetization (M _s ) and coercive field (H _c ) were determined using a superconducting quantum interference device (SQUID).     

多肽自组装及其在生物医学中的应用

多肽自组装广泛存在于自然界中。自组装多肽分子成分简单,生物相容性良好,自组装过程受多方面因素的影响,在生物医学材料方面具有巨大的应用前景。介绍了多肽分子自组装技术的概念和多肽自组装过程中的影响因素(氨基酸的组成和序列、温度、pH值、离子强度、多肽浓度、超声波),综述了多肽自组装系统的种类和多肽自组装技术在创伤修复、药物释放载体以及组织工程支架方面的应用。     

One‐Dimensional Assemblies of Nanoparticles: Preparation,Properties, and Promise

Nanoparticle (NP) assemblies are of considerable interest for both fundamental research and applications, since they provide direct bridges between nanometer‐scale objects and the macroscale world. Unlike two‐dimensional or three‐dimensional NP assemblies, which have been extensively studied and reviewed, reports on one‐dimensional (1D) NP assemblies are rather rare, even though these assemblies are likely to play critical roles in the improvement of the efficiencies of various electronic, optoelectronic, magnetic, and other devices based on single NPs or their composites. Additionally, 1D assemblies of NPs, i.e., chains, can significantly help in the understanding of a number of biological processes and fundamental quantum mechanics of nanometer‐scale systems. The difficulties are very evident when one wants to realize anisotropic 1D assemblies from presumably isotropic, zero‐dimensional NPs. In this context, the authors present a systemic review of current research on 1D NP assemblies. Their preparation methods are classified and novel characteristics of NP chains, such as collective properties and directional transfer of photons, electrons, spins, etc., are elucidated. Current problems underlying the fundamental research and practical applications of 1D NP assemblies are also addressed.     

单相钡铁氧体磁性材料的制备及磁性能研究

以硝酸钡、硝酸铁和柠檬酸为原料,采用溶胶-凝胶法制备了单相钡铁氧体(BaFe12O19)纳米粉体,并进一步研究了n(Fe)/n(Ba)、热处理温度对产物组成、形貌以及磁性能的影响。用X射线衍射仪(XRD)、扫描电子显微镜(SEM)和振动样品磁强计(VSM)分别对样品的组成、形貌和磁性能进行了表征。实验结果表明,当煅烧温度不变时,样品的晶粒尺寸随着n(Fe)/n(Ba)的增大而变大,磁性能随n(Fe)/n(Ba)的增大而增强;当n(Fe)/n(Ba)不变时,样品的晶粒尺寸随着煅烧温度的升高而变大。当n(Fe)/n(Ba)=12时,在800℃煅烧2h得到单一晶型的钡铁氧体粉体。1000℃时样品的磁性能最佳,饱和磁化强度(Ms)为70.88A.m2/kg,矫顽力(Hc)为372.89kA/m。     

纳米技术在生物医学上的应用

分别论述了纳米技术在生物学和医药学上的应用，以及纳米生物技术与医学结合在诊断技术和治疗技术方面的应用，并列举了一些生物医学上应用的先进的纳米生物技术和纳米生物材料。     

Structural, Optical and Magnetic Properties of Mn-doped CdS Diluted Magnetic Semiconductor Nanoparticles

Diluted magnetic CdS:Mn nanoparticles were synthesized by the aqueous solution method with different manganese (Mn²⁺) concentrations (x=7?C10?atom?%) at room temperature in nitrogen atmosphere and capped with Thiogelycerol. The X-ray diffraction patterns of CdS nanoparticles with different Mn doping concentration indicated that samples have hexagonal structure at room temperature. Energy dispersive X-ray spectroscopy confirmed incorporative of Mn ions in CdS nanoparticles. UV-Visible spectroscopy is used to investigate optical absorption of Mn-doped CdS. From photoluminescence measurement it was found that the intensity of the luminescence spectra decreases by increasing Mn²⁺ dopant ions at high precursor concentration. Also, the room temperature ferromagnetic behavior of Mn-doped CdS nanoparticles is discussed by using hysteresis measurement results.     

纳米技术在生物医学上的应用

分别论述了纳米技术在生物学和医药学上的应用,以及纳米生物技术与医学结合在诊断技术和治疗技术方面的应用,并列举了一些生物医学上应用的先进的纳米生物技术和纳米生物材料.     

Magnetic Properties of Zinc Ferrite Nanoparticles Synthesized by Coprecipitation Method

The influence of the precipitant and ferric concentration on the magnetic properties of coprecipitated zinc ferrite nanoparticles has been investigated. The nanoparticles were characterized using X-ray diffraction, scanning and transmission electron microscope, and vibrating sample magnetometer techniques. The results showed that the single-phase zinc ferrite with partially inverse spinel structures can be formed at high concentrations. The inversion coefficient calculated by the Rietveld method decreases with increasing of the concentrations, may be due to the crystal growth. The magnetic measurements exhibited that the coprecipitated zinc ferrite nanoparticles were superparamagnet and magnetization decreases with increasing of the concentrations through decreasing of inversion coefficient.     

Synthesis and Magnetic Properties of Fe3O4 Nanoparticles

Magnetic Fe₃O₄ nanoparticles with size below 10 nm have been prepared by the aqueous phase coprecipitation method. The Fe₃O₄ nanoparticles show typical superparamagnetism. Comparison is made between the dispersed sample and the powder sample, and the results are discussed.     

Synthesis and Magnetic Properties of Mn-Doped and SnO2 Nanoparticles

This paper reports the synthesis of Sn_1?x Mn _x O₂ (for x=0, 0.01, 0.05 and 0.10) nanoparticles using the co-precipitation method. X-ray diffraction (XRD) results show that all samples are single phase with tetragonal crystalline structure. Rietveld refinements from XRD patterns show that the samples present particle average sizes of 4–30 nm confirmed by scanning electron microscopy. Magnetization results for SnO₂ nanoparticles at 5% and 10% of Mn synthesized at 800?°C exhibit a ferromagnetic behavior at room temperature and an increasing of the magnetization for increasing doping concentration. On the other hand, samples synthesized at 300?°C are paramagnetic.