Synthesis,functionalization, and nanomedical applications of functional magnetic nanoparticles

This review summarizes the current synthesis of magnetic nanoparticles (MNPs) preparation, functionalization and stabilization methods. And furthermore it highlights some actual case analyses of these MNPs for disease therapy, drug delivery, hyperthermia, bioseparation and bioimaging applications.     

Magnetic nanoparticles: synthesis, protection, functionalization, and application

This review focuses on the synthesis, protection, functionalization, and application of magnetic nanoparticles, as well as the magnetic properties of nanostructured systems. Substantial progress in the size and shape control of magnetic nanoparticles has been made by developing methods such as co-precipitation, thermal decomposition and/or reduction, micelle synthesis, and hydrothermal synthesis. A major challenge still is protection against corrosion, and therefore suitable protection strategies will be emphasized, for example, surfactant/polymer coating, silica coating and carbon coating of magnetic nanoparticles or embedding them in a matrix/support. Properly protected magnetic nanoparticles can be used as building blocks for the fabrication of various functional systems, and their application in catalysis and biotechnology will be briefly reviewed. Finally, some future trends and perspectives in these research areas will be outlined.     

磁粒子成像示踪剂的研究进展

磁粒子成像是基于功能和断层影像技术检测磁性纳米粒子空间分布的示踪方法, 具有正向的对比信号、 较低的组织背景、 无限的组织穿透深度、 非侵入性成像以及无电离辐射等优点, 是近年来一种很有前途的生物医学成像技术. 磁粒子成像信号是通过在无场点切换磁性纳米粒子的磁自旋矢量来产生的. 磁粒子成像的灵敏度和空间分辨率都高度依赖于作为磁粒子成像示踪剂的磁性纳米粒子本身的磁性能, 因此目前的研究主要集中在磁性纳米粒子的设计和合成上. 本文重点介绍了磁粒子成像示踪剂的最新研究进展, 总结了可作为磁粒子成像示踪剂的磁性纳米粒子的种类、 合成方法、 性能以及生物医学应用, 以期为磁粒子成像的未来研究提供参考.     

Chemical Synthesis of Magnetic Nanoparticles for Permanent Magnet Applications

Permanent magnets are a class of critical materials for information storage, energy storage, and other magneto-electronic applications. Compared with conventional bulk magnets, magnetic nanoparticles (MNPs) show unique size-dependent magnetic properties, which make it possible to control and optimize their magnetic performance for specific applications. The synthesis of MNPs has been intensively explored in recent years. Among different methods developed thus far, chemical synthesis based on solution-phase reactions has attracted much attention owing to its potential to achieve the desired size, morphology, structure, and magnetic controls. This Minireview focuses on the recent chemical syntheses of strongly ferromagnetic MNPs (H_c>10 kOe) of rare-earth metals and FePt intermetallic alloys. It further discusses the potential of enhancing the magnetic performance of MNP composites by assembly of hard and soft MNPs into exchange-coupled nanocomposites. High-performance nanocomposites are key to fabricating super-strong permanent magnets for magnetic, electronic, and energy applications.     

Magnetic nanoparticles for the manipulation of proteins and cells

In the rapidly developing areas of nanobiotechnology, magnetic nanoparticles (MNPs) are one type of the most well-established nanomaterials because of their biocompatibility and the potential applications as alternative contrast enhancing agents for magnetic resonance imaging (MRI). While the development of MNPs as alternative contrast agents for MRI application has moved quickly to testing in animal models and clinical trials, other applications of biofunctional MNPs have been explored extensively at the stage of qualitative or conceptual demonstration. In this critical review, we summarize the development of two straightforward applications of biofunctional MNPs--manipulating proteins and manipulating cells--in the last five years or so and hope to provide a relatively comprehensive assessment that may help the future developments. Specifically, we start with the examination of the strategy for the surface functionalization of MNPs because the applications of MNPs essentially depend on the molecular interactions between the functional molecules on the MNPs and the intended biological targets. Then, we discuss the use of MNPs for manipulating proteins since protein interactions are critical for biological functions. Afterwards, we evaluate the development of the use of MNPs to manipulate cells because the response of MNPs to a magnetic field offers a unique way to modulate cellular behavior in a non-contact or "remote" mode (i.e. the magnet exerts force on the cells without direct contact). Finally, we provide a perspective on the future directions and challenges in the development of MNPs for these two applications. By reviewing the examples of the design and applications of biofunctional MNPs, we hope that this article will provide a reference point for the future development of MNPs that address the present challenges and lead to new opportunities in nanomedicine and nanobiotechnology (137 references).     

过渡金属掺杂磁性纳米粒子在生物医学领域中的研究进展

在过去50多年中,磁性纳米粒子(MNPs)由于其可协调的磁性、非侵入性、易操控性和良好的生物相容性等优点得到了广泛的关注.从具有复合结构或不同形状的MNPs的合成方法到与MNPs相关的大量表征技术,其应用领域也与我们的生活紧密相关.然而,MNPs的复杂磁行为受到多种参量的影响,包括粒径、成分、形状和结构等.基于此,通过...     

高性能磁性纳米粒子的有机相制备与生物应用的研究进展

磁性纳米粒子(MNPs)的合成开发在基础科学研究和技术应用方面得到了深入的发展。与大块的磁性材料不同,MNPs展现出了独特的磁性,并且可以通过系统的纳米尺寸工程调控它们的性能。本文首先简要介绍了MNPs的基本特征,总结了不同MNPs的制备方法,包括金属、合金、金属氧化物和多功能的MNPs;重点关注了可精确控制MNPs尺寸、形状、组成和结构的有机相合成方法;最后讨论了这些MNPs在生物方面的应用。     

用于富集低分子量糖蛋白的多功能磁性纳米材料的制备

低分子量糖蛋白被认为是发现疾病生物标志物的宝库。特异性的萃取吸附剂对这一类化合物的萃取和富集是必不可少的。硼亲和材料在近年来取得了很大的发展,但专门用于选择性富集低分子量糖蛋白的硼亲和材料目前鲜有报道。该文提出了具有多种功能的磁性纳米颗粒(MNPs),用于低分子量糖蛋白的选择性捕获。该多功能磁性纳米颗粒是用硼酸功能化聚合物网络包裹的磁性纳米复合物。该多功能磁性纳米材料是利用磁性的纳米颗粒内核通过在其表面修饰苯硼酸功能团的聚丙烯酸高分子网络链制备得到。该材料不仅具有常规磁性材料在磁分离方面的基本优势,还能提供三重预先设计的先进功能:1)尺寸排阻效应,去除高分子量蛋白质的干扰;2)对低分子量糖蛋白的选择性萃取;3)保护捕获到的低分子量糖蛋白不被降解和污染。该材料的选择性萃取功能来自于硼酸配基与糖蛋白的顺式二醇部分的亲和性,而尺寸限制效应和保护功能则依赖于磁性纳米颗粒表面修饰的聚合物网络,允许低分子量化合物选择性通过。通过实验验证了这些预设的功能,且通过改变聚合物链长可以调节限径效应的阈值。这种多功能磁性纳米复合物可以进一步发展成有前景的纳米探针,不仅可以选择性捕获低分子量糖蛋白,还可以选择性捕获核苷和聚糖等其他具有重要生物学意义的顺式二醇分子。因此,该文报道的材料制备策略为从复杂样品中选择性萃取靶标化合物的多功能吸附剂的设计和合成提供了新思路。     

非接触式原子力显微镜在分子几何结构解析中的应用进展

具有化学键分辨的非接触式原子力显微（nc-AFM）表征展现出了优异的分子结构解析能力,是近十年来显微表征领域里的代表性进展,成为表面分子相关研究的重要工具。本文首先介绍了化学键分辨的非接触式原子力显微镜的核心部件: qPlus传感器,以及实现化学键分辨所必须的针尖修饰技术。围绕该表征方法在分子几何结构成像上的功能,重点介绍了nc-AFM在天然产物结构确定以及表面在位反应研究上的最新进展。     

Resolving the structure of ligands bound to the surface of superparamagnetic iron oxide nanoparticles by high-resolution magic-angle spinning NMR spectroscopy

A major challenge in magnetic nanoparticle synthesis and (bio)functionalization concerns the precise characterization of the nanoparticle surface ligands. We report the first analytical NMR investigation of organic ligands stably anchored on the surface of superparamagnetic nanoparticles (MNPs) through the development of a new experimental application of high-resolution magic-angle spinning (HRMAS). The conceptual advance here is that the HRMAS technique, already being used for MAS NMR analysis of gels and semisolid matrixes, enables the fine-structure-resolved characterization of even complex organic molecules bound to paramagnetic nanocrystals, such as nanosized iron oxides, by strongly decreasing the effects of paramagnetic disturbances. This method led to detail-rich, well-resolved (1)H NMR spectra, often with highly structured first-order couplings, essential in the interpretation of the data. This HRMAS application was first evaluated and optimized using simple ligands widely used as surfactants in MNP synthesis and conjugation. Next, the methodology was assessed through the structure determination of complex molecular architectures, such as those involved in MNP3 and MNP4. The comparison with conventional probes evidences that HRMAS makes it possible to work with considerably higher concentrations, thus avoiding the loss of structural information. Consistent 2D homonuclear (1)H- (1)H and (1)H- (13)C heteronuclear single-quantum coherence correlation spectra were also obtained, providing reliable elements on proton signal assignments and carbon characterization and opening the way to (13)C NMR determination. Notably, combining the experimental evidence from HRMAS (1)H NMR and diffusion-ordered spectroscopy performed on the hybrid nanoparticle dispersion confirmed that the ligands were tightly bound to the particle surface when they were dispersed in a ligand-free solvent, while they rapidly exchanged when an excess of free ligand was present in solution. In addition to HRMAS NMR, matrix-assisted laser desorption ionization time-of-flight MS analysis of modified MNPs proved very valuable in ligand mass identification, thus giving a sound support to NMR characterization achievements.     

Biogenic synthesis of gold and silver nanoparticles used in environmental applications: A review

Due to their physical, chemical, optical, and mechanical properties, metallic nanoparticles (MNPs) are increasingly being used, with an emphasis on silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs). In recent years, green synthesis has gained prominence for exploring the use of naturally available biological sources for the obtention of metallic nanoparticles. Among these, algae and plants stand out due to the presence of polysaccharides, proteins, polyphenols, and vitamins (among others) in their composition, which can act in the reduction and stabilisation of MNPs, and these biogenic materials have been characterised mainly by spectrometric and microscopic techniques. In addition, due to the numerous advantages of nanoparticles (NPs) synthetize from biogenic source, such as their simplicity and cost benefits, they have been used in the development of sensors applied in the determination of contaminants present in environmental samples and in the catalytic reduction of organic and inorganic contaminants. Therefore, this review describes the synthesis, mechanisms, characterization, and environmental analytical applications of NPs obtained by biogenic synthesis as well as the perspectives and challenges of these NPs.     

Synthetization and Functionalization of Natural,Polymer, and Quantum-Based Carbon Nanodots and Their Application in Biomedicine

Carbon nanodots (CNDs) are a developing branch of nanomaterials and nanoscience. This has generated much more interest in the field and class of biomedicine science by way of unique particular properties, such as high stability, great photoluminescence, easy green synthesis, and simple surface modification. Numerous applications, such as bioimaging, biosensing, and treatment, have made use of CNDs. This review describes the most recent developments in CND research and talks about major changes in the understanding of CNDs and their prospects as biomedical tools. The importance of this work lies in the ability of CNDs to overcome many of the limitations associated with traditional materials used in biomedicine, such as toxicity, poor biocompatibility, and limited functionality. Furthermore, the use of CNDs as drug carriers, imaging agents, and sensors has shown great potential in improving the diagnosis and treatment of various diseases. The novelty of this work lies in the diversity of approaches used in the synthesis and functionalization of CNDs, and the unique properties of CNDs that make them versatile tools for biomedicine. In particular, the ability to tune the size, shape, and surface chemistry of CNDs allows for the creation of tailored materials with specific biomedical applications. The review also discusses the challenges and future prospects of CNDs in biomedicine, including the need for standardization and optimization of CND synthesis, functionalization, and characterization protocols.     

Synthesis of Small‐Sized,Porous, and Low‐Toxic Magnetite Nanoparticles by Thin POSS Silica Coating

In this communication, we report the synthesis of small‐sized (<10 nm), water‐soluble, magnetic nanoparticles (MNPs) coated with polyhedral oligomeric silsesquioxanes (POSS), which contain either polyethylene glycol (PEG) or octa(tetramethylammonium) (OctaTMA) as functional groups. The POSS‐coated MNPs exhibit superparamagnetic behavior with saturation magnetic moments (51–53 emu g^?1) comparable to silica‐coated MNPs. They also provide good colloidal stability at different pH and salt concentrations, and low cytotoxicity to MCF‐7 human breast epithelial cells. The relaxivity data and magnetic resonance (MR) phantom images demonstrate the potential application of these MNPs in bioimaging.     

Polysaccharide-modified iron oxide nanoparticles as an effective magnetic affinity adsorbent for bovine serum albumin

The magnetic separation technique based on magnetic iron oxide nanoparticles (MNPs) has potential applications in protein adsorption and purification, enzyme immobilization, cell sorting, nucleic acid detachment, and drug release. However, the naked MNPs are often insufficient for their hydrophilicity, colloidal stability, and further functionalization. To overcome these limitations, chitosan was firstly carboxymethylated and then covalently conjugated on the surface of the MNPs ranging in size from about 5 to 15 nm, which were prepared by co-precipitating iron (II) and iron (III) in alkaline solution and then treating under hydrothermal conditions. It was found that such modification did not result in the phase change of the MNPs, and the resultant modified nanoparticles were still superparamagnetic. In particular, the colloidal stability of MNPs in aqueous suspension was improved after the surface modification. By investigating the adsorption of bovine serum albumin (BSA) on the modified MNPs, it was observed that the adsorption capacity of the BSA on the modified MNPs increased rapidly within several minutes and then reached the maximum value at about 10 min. The adsorption equilibrium isotherm could be fitted well by the Langmuir model. The medium pH affected greatly the adsorption of the BSA. The maximum adsorption of the BSA occurred at the pH value close to the isoelectric point of the BSA, with a saturation adsorption amount of 94.45 mg/g (25 °C). For the BSA feed concentration of 1.017 mg/ml, a high desorption percentage of 91.5% could be achieved under an alkaline condition (pH 9.4).     

Synthesis,Characterization and Evaluation of Peptide Nanostructures for Biomedical Applications

There is a challenging need for the development of new alternative nanostructures that can allow the coupling and/or encapsulation of therapeutic/diagnostic molecules while reducing their toxicity and improving their circulation and in-vivo targeting. Among the new materials using natural building blocks, peptides have attracted significant interest because of their simple structure, relative chemical and physical stability, diversity of sequences and forms, their easy functionalization with (bio)molecules and the possibility of synthesizing them in large quantities. A number of them have the ability to self-assemble into nanotubes, -spheres, -vesicles or -rods under mild conditions, which opens up new applications in biology and nanomedicine due to their intrinsic biocompatibility and biodegradability as well as their surface chemical reactivity via amino- and carboxyl groups. In order to obtain nanostructures suitable for biomedical applications, the structure, size, shape and surface chemistry of these nanoplatforms must be optimized. These properties depend directly on the nature and sequence of the amino acids that constitute them. It is therefore essential to control the order in which the amino acids are introduced during the synthesis of short peptide chains and to evaluate their in-vitro and in-vivo physico-chemical properties before testing them for biomedical applications. This review therefore focuses on the synthesis, functionalization and characterization of peptide sequences that can self-assemble to form nanostructures. The synthesis in batch or with new continuous flow and microflow techniques will be described and compared in terms of amino acids sequence, purification processes, functionalization or encapsulation of targeting ligands, imaging probes as well as therapeutic molecules. Their chemical and biological characterization will be presented to evaluate their purity, toxicity, biocompatibility and biodistribution, and some therapeutic properties in vitro and in vivo. Finally, their main applications in the biomedical field will be presented so as to highlight their importance and advantages over classical nanostructures.     

Sulfamic acid heterogenized on functionalized magnetic Fe3O4 nanoparticles with diaminoglyoxime as a green,efficient and reusable catalyst for one‐pot synthesis of substituted pyrroles in aqueous phase

Surface functionalization of magnetic nanoparticles is an elegant way to bridge the gap between heterogeneous and homogeneous catalysis. We have conveniently loaded sulfonic acid groups on amino‐functionalized Fe₃O₄ nanoparticles affording sulfamic acid‐functionalized magnetic Fe₃O₄ nanoparticles (MNPs/DAG‐SO₃H) as an active and stable magnetically separable acidic nanocatalyst, which was characterized using X‐ray diffraction, Fourier transform infrared and energy‐dispersive X‐ray spectroscopies, scanning and transmission electron microscopies, vibrating sample magnetometry and elemental analysis. The catalytic activity of MNPs/DAG‐SO₃H was probed through one‐pot synthesis of N‐substituted pyrroles from γ‐diketones and primary amines in aqueous phase at room temperature. The heterogeneous catalyst could be recovered easily by applying an external magnet device and reused many times without significant loss of its catalytic activity. Copyright © 2014 John Wiley & Sons, Ltd.     

Anisotropic janus magnetic polymeric nanoparticles prepared via miniemulsion polymerization

Anisotropic Janus magnetic polymeric nanoparticles are prepared via the miniemulsion polymerization of styrene and acrylic acid monomers in the presence of oleic acid‐coated magnetic nanoparticles (MNPs). The controllable phase separation between the polymer matrix and the encapsulated MNPs is a key success factor to produce Janus morphology. The effects of MNPs, 2,2′‐azobis(2‐isobutyronitrile) and sodium dodecyl sulfate contents, on the morphology, chemical composition and colloidal stability of the prepared Janus hybrid particles are investigated. Besides the determination of polymerization conversion, zeta potential, size analysis, TGA, and TEM are applied for characterization of the anisotropic particles. The results show the stable spherical Janus particles containing MNPs (15 wt % magnetic content) located on one side of each polymer particle. The anisotropic submicron Janus magnetic polymeric particles (250 nm) can be easily separated by an external magnet. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 4779–4785     

功能化磁性纳米粒子在乳状液制备及破乳中的应用及作用机制

功能化磁性纳米粒子因其独特的理化性质,在乳状液制备与破乳领域的应用受到广泛关注。本文归纳了功能化磁性纳米粒子的制备方法、合成结构与特征性质,阐述了其在乳状液制备及破乳中的应用过程,重点分析了磁性纳米粒子在溶液中良好分散、稳定吸附于油水界面排布为膜结构的作用行为,尤其是磁性纳米粒子的磁响应特征对乳状液中界面性质、液滴形貌及运动状态的影响,并进一步总结出其表面性质及作用行为对稳定乳状液或使乳状液破乳的规律。针对磁性纳米粒子对乳状液稳定性影响规律的探究可为其在应用领域提供理论支持。最后本文就功能化磁性纳米粒子研究中亟待解决的新问题作出展望。     

磁性纳米粒子负载钯催化剂在C-C键偶联反应中的应用

磁性纳米粒子(MNPs)负载钯催化剂因具有高的催化活性及易于原位磁分离回收等优点而得到快速发展,成为一类具有广泛应用前景的纳米催化剂,在学术及工业领域均受到广泛的关注。 本文对近年来MNPs负载钯催化剂在Suzuki、Heck等C-C偶联反应中的应用研究进行简要阐述,并对其发展前景进行了展望。     

Synthesis,characterization, and catalytic application of Fe3O4‐Si‐[CH2]3‐N=CH‐aryl for the efficient synthesis of novel poly‐substituted pyridines

Fe₃O₄ magnetic nanoparticles (MNPs) were functionalized by aminopropylsilane and reacted with aromatic aldehyde, and Fe₃O₄‐Si‐[CH₂]₃‐N=CH‐Aryl and Fe₃O₄‐Si‐(CH₂)₃‐NH‐CH₂‐Aryl MNPs were prepared as novel magnetic nanocatalysts. Fourier transform infrared (FT‐IR), X‐ray diffraction (XRD), and scanning and transmission electron microscopy (SEM and TEM) were used to identify the MNPs. The catalytic activity of the MNPs was evaluated in the one‐pot synthesis of some novel poly‐substituted pyridine derivatives.