Controlling transport and chemical functionality of magnetic nanoparticles

Composite Sorbents Based on Chitosan Polymer Matrix and Derivatives of 4-Amino-N'-hydroxy-1,2,5-oxadiazole-3-carboximidamide for Uranium Removal from Liquid Mineralized Media

Composite adsorbents based on a natural biopolymer matrix of chitosan, to which 4-amino-N'-hydroxy-1,2,5-oxadiazole-3-carboximidamide and its Se derivative were attached, were synthesized. A complex of physicochemical analysis methods indicates that the direct introduction of a matrix with high ionic permeability into the reaction mixture contributes to the formation of homogeneous particles of composite with developed surface morphology, which enhances the kinetic and capacitive parameters of uranium sorption in liquid media. It has been established that the direct introduction of a matrix with high ionic permeability into the reaction mixture contributes to the formation of homogeneous particles with a developed surface morphology, which enhances the kinetic and capacitive parameters of uranium sorption in liquid media. The synthesized materials had increased sorption-selective properties towards uranium in the pH range from 4 to 9 under static sorption conditions. The formation of the Se derivative of amidoxime during its attachment to the polymer matrix (Se-chit) contributes to the creation of a more chemically stable and highly effective adsorbent, compared to the direct binding of 4-amino-N'-hydroxy-1,2,5-oxadiazole-3-carboximidamide with chitosan (43AF-chit). The optimal parameters for the synthesis of materials were established. It was demonstrated that the ratio of amidoxime to chitosan should be within the range of 2:1 to 1:2. As the mass content of chitosan increases, the material gradually dissolves and transforms into a gel, resulting in the formation of liquid radioactive waste with a complex chemical composition. It was found that the kinetic sorption parameters of composite materials increase 2-10 times compared to those of non-composite materials. The sorption capacity of uranium in solutions with pH 6 and pH 8 can reach approximately 400-450 mg g-1. Under dynamic sorption conditions, the effective filtration cycle values (before uranium slips into the filtrate ≥ 50%) improve significantly when transitioning from a non-composite adsorbent to a composite one: increasing from 50 to 800 b.v. for pH 6 and from 2700 to 4000 b.v. for pH 8. These results indicate that the synthesized sorbents are promising materials for uranium removal from liquid media, suitable for both purification and the recovery of radionuclides as valuable raw materials.

Composite Sorbents Based on Polymeric Se-Derivative of Amidoximes and SiO2 for the Uranium Removal from Liquid Mineralized Media

A new composite material with enhanced sorption-selective properties for uranium recovery from liquid media has been obtained. Sorbents were synthesized through a polycondensation reaction of a mixture of 4-amino-N'-hydroxy-1,2,5-oxadiazole-3-carboximidamide (hereinafter referred to as amidoxime) and SiO2 in an environment of organic solvents (acetic acid, dioxane) and highly porous SiO2. To establish optimal conditions for forming the polymer sorption-active part and the synthesis as a whole, a series of composite adsorbents were synthesized with varying amidoxime/matrix ratios (35/65, 50/50, 65/35). The samples were characterized with FT-IR, XRD, SEM, EDX, XRFES spectroscopy and TGA. Under static conditions of uranium sorption, the dependence of the efficiency of radionuclide recovery from mineralized solutions of various acidities on the ratio of the initial components was established. In the pH range from 4 to 8 (inclusive), the uranium removal efficiency exceeds 95%, while the values of the distribution coefficients (Kd) exceed 104 cm3g-1. It was demonstrated that an increase in the surface development of the sorbents enhances such kinetic parameters of uranium sorption as diffusion rate by 10-20 times compared to non-porous materials. The values of the maximum static capacity exceed 700 mg g-1. The enhanced availability of adsorption centers, achieved through the use of a porous SiO2 matrix, significantly improves the kinetic parameters of the adsorbents. A composite with optimal physicochemical and sorption properties (amidoxime/matrix ratio of 50/50) was examined under dynamic conditions of uranium sorption. It was found that the maximum dynamic sorption capacity of porous materials is four times greater compared to that of a non-porous adsorbent Se-init. The effective filter cycle exceeds 3200 column volumes-twice that of an adsorbent with a monolithic surface. These results indicate the promising potential of the developed materials for uranium sorption from liquid mineralized media under dynamic conditions across a wide pH range.

Progress in Core-Shell Magnetic Mesoporous Materials for Enriching Post-Translationally Modified Peptides

Endogenous peptides, particularly those with post-translational modifications, are increasingly being studied as biomarkers for diagnosing various diseases. However, they are weakly ionizable, have a low abundance in biological samples, and may be interfered with by high levels of proteins, peptides, and other macromolecular impurities, resulting in a high limit of detection and insufficient amounts of post-translationally modified peptides in real biological samples to be examined. Therefore, separation and enrichment are necessary before analyzing these biomarkers using mass spectrometry. Mesoporous materials have regular adjustable pores that can eliminate large proteins and impurities, and their large specific surface area can bind more target peptides, but this may result in the partial loss or destruction of target peptides during centrifugal separation. On the other hand, magnetic mesoporous materials can be used to separate the target using an external magnetic field, which improves the separation efficiency and yield. Core-shell magnetic mesoporous materials are widely utilized for peptide separation and enrichment due to their biocompatibility, efficient enrichment capability, and excellent recoverability. This paper provides a review of the latest progress in core-shell magnetic mesoporous materials for enriching glycopeptides and phosphopeptides and compares their enrichment performance with different types of functionalization methods.

Design, synthesis and application of a magnetic H-bond catalyst in the preparation of new nicotinonitriles via cooperative vinylogous anomeric-based oxidation

Herein, we designed and synthesized a new H-bond magnetic catalyst with 2-tosyl-N-(3-(triethoxysilyl)propyl)hydrazine-1-carboxamide as a sensitive H-bond donor/acceptor. We created an organic structure with a urea moiety on the magnetic nanoparticles, which can function as a hydrogen bond catalyst. Hydrogen bond catalysts serve as multi-donor/-acceptor sites. Additionally, we utilized magnetic nanoparticles in the production of the target catalyst, giving it the ability to be recycled and easily separated from the reaction medium with an external magnet. We evaluated the catalytic application of Fe3O4@SiO2@tosyl-carboxamide as a new magnetic H-bond catalyst in the synthesis of new nicotinonitrile compounds through a multicomponent reaction under solvent-free and green conditions with high yields (50-73%). We confirmed the structure of Fe3O4@SiO2@tosyl-carboxamide using various techniques. In addition, the structures of the desired nicotinonitriles were confirmed using melting point, 1H-NMR, 13C-NMR and HR-mass spectrometry analysis. The final step of the reaction mechanism was preceded via cooperative vinylogous anomeric-based oxidation (CVABO).

Asymmetric imaging through engineered Janus particle obscurants using a Monte Carlo approach for highly asymmetric scattering media

The advancement of imaging systems has significantly ameliorated various technologies, including Intelligence Surveillance Reconnaissance Systems and Guidance Systems, by enhancing target detection, recognition, identification, positioning, and tracking capabilities. These systems can be countered by deploying obscurants like smoke, dust, or fog to hinder visibility and communication. However, these counter-systems affect the visibility of both sides of the cloud. In this sense, this manuscript introduces a new concept of a smoke cloud composed of engineered Janus particles to conceal the target image on one side while providing clear vision from the other. The proposed method exploits the unique scattering properties of Janus particles, which selectively interact with photons from different directions to open up the possibility of asymmetric imaging. This approach employs a model that combines a genetic algorithm with Discrete Dipole Approximation to optimize the Janus particles' geometrical parameters for the desired scattering properties. Moreover, we propose a Monte Carlo-based approach to calculate the image formed as photons pass through the cloud, considering highly asymmetric particles, such as Janus particles. The effectiveness of the cloud in disguising a target is evaluated by calculating the Probability of Detection (PD) and the Probability of Identification (PID) based on the constructed image. The optimized Janus particles can produce a cloud where it is possible to identify a target more than 50% of the time from one side (PID > 50%) while the target is not detected more than 50% of the time from the other side (PD < 50%). The results demonstrate that the Janus particle-engineered smoke enables asymmetric imaging with simultaneous concealment from one side and clear visualization from the other. This research opens intriguing possibilities for modern obscurant design and imaging systems through highly asymmetric and inhomogeneous particles besides target detection and identification capabilities in challenging environments.

Efficient cyanide sensing using plasmonic Ag/Fe3O4 nanoparticles

In the line of our previous studies, we have reported a developed sensitive and selective probe for cyanide detection based on Ag/Fe3O4 nanoparticles (NPs) with an extremely low limit of detection at the level of ng per milliliter. Herein, we report the improvement of the easy-to-make magnetic silver nanoparticle-based sensor system for cyanide determination in an extended calibration range with higher selectivity and precision. As far as our knowledge is concerned, the detectable linear range from 1.0 nM to 160 μM (0.026 ng mL-1 to 4.16 μg mL-1) of the improved simple highly precise technique represents the widest assay that has been reported so far. The method is based on strong enhancement of scattered light of the plasmonic nanoparticles and simultaneously cyanide fluorescence quenching. Although the fluorescence of cyanide is highly selective and precise, its intensity is poor. On the other hand, the strongly enhanced Rayleigh signal has a low repeatability. We proposed a method to remove the interference and obtained an effective factor that is directly proportional to cyanide concentration utilizing both above signals simultaneously. In this work, Ag/Fe3O4 NPs have been synthesized easily using a green preparation method and the NPs were consequently characterized using powder XRD, UV-Vis absorption spectroscopy, transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX). A combination of absorption, Rayleigh and fluorescence characteristics were used for detection of cyanide in real samples and an overview of recently reported sensors for cyanide was also provided.

Nickel substituted polyoxometalates in layered double hydroxides as metal-based nanomaterial of POM-LDH for green catalysis effects

Three nickel substituted Keggin-type polyoxometalates, α-[SiW₉O₃₇{Ni(H₂O)}₃]^-10 (denoted as SiW₉Ni₃), was intercalated into Zn₃Al based Layered Double Hydroxide (Zn₃Al-LDH) by the selective ion-exchange technique. The as-synthesized nanocomposite, SiW₉Ni₃@Zn₃Al, was used as heterogeneous nanoreactor to promote the synthesis of drug-like aminoimidazopyridine small molecule skeletons via the well-known Ugi-type Groebke-Blackburn-Bienaymé reaction (GBB 3-CRs) in the absence of any acid/additive and under mild and solvent-free conditions. A synergistic catalytic effect between SiW₉Ni₃ polyoxometalate and Zn₃Al-LDH precursors is evidenced by a higher catalytic property of the SiW₉Ni₃@Zn₃Al composite compared to the individual constituents separately. Lewis/Bronsted acidity of the SiW₉Ni₃ polyoxometalate and Zn₃Al-LDH precursors appear to be essential for the catalytic performance of the composite. Furthermore, the catalytic performance of SiW₉Ni₃@Zn₃Al was also tested in GBB 3-CRs synthesis of amino imidazothiazole under mild and solvent-free conditions.

Synthesis and characterization of an Fe-MOF@Fe3O4 nanocatalyst and its application as an organic nanocatalyst for one-pot synthesis of dihydropyrano[2,3-c]chromenes

In this study, the recyclable heterogeneous cluster bud Fe-MOF@Fe₃O₄ 'nanoflower' composite (CB Fe-MOF@Fe₃O₄ NFC) was successfully synthesized using Fe(NO₃)₃·9H₂O, 8-hydroxyquinoline sulfate monohydrate, and Fe₃O₄ nanoparticles by microwave irradiation. The as-prepared CB Fe-MOF@Fe₃O₄ NFC was characterized by X-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), vibrational sampling magnetometry (VSM), and Fourier transform infrared spectroscopy (FTIR). The CB Fe-MOF@Fe₃O₄ NFC samples proved to have excellent catalytic activity. The activity of the CB Fe-MOF@Fe₃O₄ NFC nanocatalyst was explored in the synthesis of dihydropyrano[3, 2-c]chromene derivatives via a three-component reaction of 4-hydroxycoumarin, malononitrile, and a wide range of aromatic aldehyde compounds. Optimized reaction conditions had several advantages, including the use of water as a green solvent, environmental compatibility, simple work-up, reusability of the catalyst, low catalyst loading, faster reaction time, and higher yields.

Surface Dissociation Effect on Phosphonic Acid Self-Assembled Monolayer Formation on ZnO Nanowires

Understanding the formation process of self-assembled monolayers (SAMs) of organophosphonic acids on ZnO surfaces is essential to designing their various applications, including solar cells, heterogeneous catalysts, and molecular sensors. Here, we report the significant effect of surface dissociation on SAM formation of organophosphonic acids on single-crystalline ZnO nanowire surfaces using infrared spectroscopy. When employing the most conventional solvent-methanol (relative permittivity ε_r = 32.6), the production of undesired byproducts (layered zinc compounds) on the surface was identified by infrared spectral data and microscopy. On the other hand, a well-defined SAM structure with a tridentate coordination of phosphonic acids on the surface was confirmed when employing toluene (ε_r = 2.379) or tert-butyl alcohol (ε_r = 11.22-11.50). The observation of layered zinc compounds as byproducts highlights that the degree of Zn²⁺ dissociation from the ZnO solid surface into a solvent significantly affects the surface coordination of phosphonic acids during the SAM formation process. Although the ZnO nanowire surface (m-plane) is hydrophilic, the present results suggest that a weaker solvent polarity is preferred to form well-defined phosphonic acid SAMs on ZnO nanowire surfaces without detrimental surface byproducts.

Recovery of Uranium by Se-Derivatives of Amidoximes and Composites Based on Them

An Se-derivative of amidoxime was synthesized for the first time as a result of the reaction of oxidative polycondensation of N’-hydroxy-1,2,5-oxadiazole-3-carboximidamide with SeO₂: its elementary units are linked to each other due to the formation of strong diselenide bridges. The element composition of the material was established, and the structure of the elementary unit was suggested. The sorption-selective properties were evaluated, and it was found that the adsorbent can be used for the selective recovery of U (VI) from liquid media with a pH of 6–9. The effect of some anions and cations on the efficiency of recovery of U (VI) was estimated. Composite materials were fabricated, in which silica gel with a content of 35, 50, and 65 wt.% was used as a matrix to be applied in sorption columns. The maximum values of adsorption of U (VI) calculated using the Langmuir equation were 620–760 mg g⁻¹ and 370 mg g⁻¹ for the composite and non-composite adsorbents, respectively. The increase in the kinetic parameters of adsorption in comparison with those of the non-porous material was revealed, along with the increase in the specific surface area of the composite adsorbents. In particular, the maximum sorption capacity and the rate of absorption of uranium from the solution increased two-fold.

Effect of coverage on the magnetic properties of -COOH, -SH, and -NH2 ligand-protected cobalt nanoparticles

Implementation of magnetic nanoparticles in biomedicine requires their passivation, which often comes at a cost of diminished magnetic properties. For the design of nano-agents with targeted magnetic behaviour, it is important to distinguish between ligands which can improve desired performance, and those that reduce it. Carboxylic acid-, thiol-, and amine-protected cobalt nanoparticles were studied by density functional theory calculations to model the impact of ligand coverage on the magnetic properties. The simulations show that the functional group, arrangement, and coverage density of the ligand coating control both the total magnetic moment and magnetic anisotropy energy of the nanoparticle, as well as the distribution of local spin magnetic moments across the metallic core. Captured effects of ligand binding on the orbital moments of cobalt atoms were insignificant. Out of the three ligand families, only carboxylic acid coatings increased the magnetic moments of cobalt nanoparticles, while amines and thiols quenched them. Calculated anisotropy energies of protected nanoparticles consistently increased with the growing ligand density, reaching the highest values for a 100% coverage of both carboxylic acid and thiol coatings. However, the binding nature of the two functional groups showed opposite impacts on the d-states of interacting cobalt atoms. This study has thus established important principles for the design of biocompatible magnetic nanocomposites, highlighting different routes to achieve desired magnetic behaviour.

Tearable and Fillable Composite Sponges Capable of Heat Generation and Drug Release in Response to Alternating Magnetic Field

Tearable and fillable implants are used to facilitate surgery. The use of implants that can generate heat and release a drug in response to an exogenous trigger, such as an alternating magnetic field (AMF), can facilitate on-demand combined thermal treatment and chemotherapy via remote operation. In this study, we fabricated tearable sponges composed of collagen, magnetite nanoparticles, and anticancer drugs. Crosslinking of the sponges by heating for 6 h completely suppressed undesirable drug release in saline at 37 °C but allowed drug release at 45 °C. The sponges generated heat immediately after AMF application and raised the cell culture medium temperature from 37 to 45 °C within 15 min. Heat generation was controlled by switching the AMF on and off. Furthermore, in response to heat generation, drug release from the sponges could be induced and moderated. Thus, remote-controlled heat generation and drug release were achieved by switching the AMF on and off. The sponges destroyed tumor cells when AMF was applied for 15 min but not when AMF was absent. The tearing and filling properties of the sponges may be useful for the surgical repair of bone and tissue defects. Moreover, these sponges, along with AMF application, can facilitate combined thermal therapy and chemotherapy.

Multifunctional magnetic iron oxide nanoparticles: an advanced platform for cancer theranostics

Multifunctional magnetic nanoparticles and derivative nanocomposites have aroused great concern for multimode imaging and cancer synergistic therapies in recent years. Among the rest, functional magnetic iron oxide nanoparticles (Fe3O4 NPs) have shown great potential as an advanced platform because of their inherent magnetic resonance imaging (MRI), biocatalytic activity (nanozyme), magnetic hyperthermia treatment (MHT), photo-responsive therapy and drug delivery for chemotherapy and gene therapy. Magnetic Fe3O4 NPs can be synthesized through several methods and easily surface modified with biocompatible materials or active targeting moieties. The MRI capacity could be appropriately modulated to induce response between T1 and T2 modes by controlling the size distribution of Fe3O4 NPs. Besides, small-size nanoparticles are also desired due to the enhanced permeation and retention (EPR) effect, thus the imaging and therapeutic efficiency of Fe3O4 NP-based platforms can be further improved. Here, we firstly retrospect the typical synthesis and surface modification methods of magnetic Fe3O4 NPs. Then, the latest biomedical application including responsive MRI, multimodal imaging, nanozyme, MHT, photo-responsive therapy and drug delivery, the mechanism of corresponding treatments and cooperation therapeutics of multifunctional Fe3O4 NPs are also be explained. Finally, we also outline a brief discussion and perspective on the possibility of further clinical translations of these multifunctional nanomaterials. This review would provide a comprehensive reference for readers to understand the multifunctional Fe3O4 NPs in cancer diagnosis and treatment.

Independent control over size, valence, and elemental composition in the synthesis of DNA-nanoparticle conjugates

DNA–nanoparticle conjugates have found widespread use in sensing, imaging, and as components of devices. However, their synthesis remains relatively complicated and empirically based, often requiring specialized protocols for conjugates of different size, valence, and elemental composition. Here we report a novel, bottom-up approach for the synthesis of DNA–nanoparticle conjugates, based on ring-opening metathesis polymerization (ROMP), intramolecular crosslinking, and template synthesis. Using size, valence, and elemental composition as three independent synthetic parameters, various conjugates can be obtained using a facile and universal procedure. Examples are given to show the usefulness of these conjugates as sensing probes, building blocks for self-assembly, and as model particles for structure–property relationship studies.

DNA–nanoparticle conjugates can be synthesized with independent control over size, valence and elemental composition using a template-based strategy.

Low-temperature wet chemistry synthetic approaches towards ferrites

Solution chemistry allows the crystallisation of range of iron oxides, including MFe₂O₄ spinels, MFeO₃ perovskites and hexaferrites, such as BaFe₁₂O₁₉, with nanoscale crystallinity and properties suitable for fields such as catalysis and electronics.

Multifunctional magnetic iron oxide nanoparticles: diverse synthetic approaches, surface modifications, cytotoxicity towards biomedical and industrial applications

Magnetic iron oxide nanoparticles (MIONPs) play a major role in the emerging fields of nanotechnology to facilitate rapid advancements in biomedical and industrial platforms. The superparamagnetic properties of MIONPs and their environment friendly synthetic methods with well-defined particle size have become indispensable to obtain their full potential in a variety of applications ranging from cellular to diverse areas of biomedical science. Thus, the broadened scope and need for MIONPs in their demanding fields of applications required to be highlighted for a comprehensive understanding of their state-of-the-art. Many synthetic methods, however, do not entirely abolish their undesired cytotoxic effects caused by free radical production and high iron dosage. In addition, the agglomeration of MIONPs has also been a major problem. To alleviate these issues, suitable surface modification strategies adaptive to MIONPs has been suggested not only for the effective cytotoxicity control but also to minimize their agglomeration. The surface modification using inorganic and organic polymeric materials would represent an efficient strategy to utilize the diagnostic and therapeutic potentials of MIONPs in various human diseases including cancer. This review article elaborates the structural and magnetic properties of MIONPs, specifically magnetite, maghemite and hematite, followed by the important synthetic methods that can be exploited for biomedical approaches. The in vivo cytotoxic effects and the possible surface modifications employed to eliminate the cytotoxicity thereby enhancing the nanoparticle efficacy are also critically discussed. The roles and applications of surface modified MIONPs in medical and industrial platforms have been described for the benefits of global well-being.

Magnetic Particles-Based Analytical Platforms for Food Safety Monitoring

Magnetic nanoparticles (MNPs) have attracted growing interest as versatile materials for the development of analytical detection and separation platforms for food safety monitoring. This review discusses recent advances in the synthesis, functionalization and applications of MNPs in bioanalysis. A special emphasis is given to the use of MNPs as an immobilization support for biomolecules and as a target capture and pre-concentration to increase selectivity and sensitivity of analytical platforms for the monitoring of food contaminants. General principles and examples of MNP-based platforms for separation, amplification and detection of analytes of interest in food, including organic and inorganic constituents are discussed.

Quaternary ferrites by batch and continuous flow hydrothermal synthesis: a comparison

Crystalline spinel quaternary ferrites M_xZn_1−xFe₂O₄ (M = Co, Ni) were synthesised through two synthetic routes: conventional batch and continuous flow hydrothermal synthesis.

A Critical Review on Selected External Physical Cues and Modulation of Cell Behavior: Magnetic Nanoparticles, Non-thermal Plasma and Lasers

Physics-based biomedical approaches have proved their importance for the advancement of medical sciences and especially in medical diagnostics and treatments. Thus, the expectations regarding development of novel promising physics-based technologies and tools are very high. This review describes the latest research advances in biomedical applications of external physical cues. We overview three distinct topics: using high-gradient magnetic fields in nanoparticle-mediated cell responses; non-thermal plasma as a novel bactericidal agent; highlights in understanding of cellular mechanisms of laser irradiation. Furthermore, we summarize the progress, challenges and opportunities in those directions. We also discuss some of the fundamental physical principles involved in the application of each cue. Considerable technological success has been achieved in those fields. However, for the successful clinical translation we have to understand the limitations of technologies. Importantly, we identify the misconceptions pervasive in the discussed fields.

Recent Modifications and Validation of QuEChERS-dSPE Coupled to LC-MS and GC-MS Instruments for Determination of Pesticide/Agrochemical Residues in Fruits and Vegetables: Review

Fruits and vegetables constitute a major type of food consumed daily apart from whole grains. Unfortunately, the residual deposits of pesticides in these products are becoming a major health concern for human consumption. Consequently, the outcome of the long-term accumulation of pesticide residues has posed many health issues to both humans and animals in the environment. However, the residues have previously been determined using conventionally known techniques, which include liquid-liquid extraction, solid-phase extraction (SPE) and the recently used liquid-phase microextraction techniques. Despite the positive technological effects of these methods, their limitations include; time-consuming, operational difficulty, use of toxic organic solvents, low selective property and expensive extraction setups, with shorter lifespan of instrumental performances. Thus, the potential and maximum use of these methods for pesticides residue determination has resulted in the urgent need for better techniques that will overcome the highlighted drawbacks. Alternatively, attention has been drawn recently towards the use of quick, easy, cheap, effective, rugged and safe technique (QuEChERS) coupled with dispersive solid-phase extraction (dSPE) to overcome the setback challenges experienced by the previous technologies. Conclusively, the reviewed QuEChERS-dSPE techniques and the recent cleanup modifications justifiably prove to be reliable for routine determination and monitoring the concentration levels of pesticide residues using advanced instruments such as high-performance liquid chromatography, liquid chromatography-mass spectrometry and gas chromatography-mass spectrometry.

Perspective: Outstanding theoretical questions in polymer-nanoparticle hybrids

This topical review discusses the theoretical progress made in the field of polymer nanocomposites, i.e., hybrid materials created by mixing (typically inorganic) nanoparticles (NPs) with organic polymers. It primarily focuses on the outstanding issues in this field and is structured around five separate topics: (i) the synthesis of functionalized nanoparticles; (ii) their phase behavior when mixed with a homopolymer matrix and their assembly into well-defined superstructures; (iii) the role of processing on the structures realized by these hybrid materials and the role of the mobilities of the different constituents; (iv) the role of external fields (electric, magnetic) in the active assembly of the NPs; and (v) the engineering properties that result and the factors that control them. While the most is known about topic (ii), we believe that significant progress needs to be made in the other four topics before the practical promise offered by these materials can be realized. This review delineates the most pressing issues on these topics and poses specific questions that we believe need to be addressed in the immediate future.

Cooperative Assembly of Magneto-Nanovesicles with Tunable Wall Thickness and Permeability for MRI-Guided Drug Delivery

This article describes the fabrication of nanosized magneto-vesicles (MVs) comprising tunable layers of densely packed superparamagnetic iron oxide nanoparticles (SPIONs) in membranes via cooperative assembly of polymer-tethered SPIONs and free poly(styrene)- b-poly(acrylic acid) (PS- b-PAA). The membrane thickness of MVs could be well controlled from 9.8 to 93.2 nm by varying the weight ratio of PS- b-PAA to SPIONs. The increase in membrane thickness was accompanied by the transition from monolayer MVs, to double-layered MVs and to multilayered MVs (MuMVs). This can be attributed to the variation in the hydrophobic/hydrophilic balance of polymer-grafted SPIONs upon the insertion and binding of PS- b-PAA onto the surface of nanoparticles. Therapeutic agents can be efficiently encapsulated in the hollow cavity of MVs and the release of payload can be tuned by varying the membrane thickness of nanovesicles. Due to the high packing density of SPIONs, the MuMVs showed the highest magnetization and transverse relaxivity rate ( r₂) in magnetic resonance imaging (MRI) among these MVs and individual SPIONs. Upon intravenous injection, doxorubicin-loaded MuMVs conjugated with RGD peptides could be effectively enriched at tumor sites due to synergetic effect of magnetic and active targeting. As a result, they exhibited drastically enhanced signal in MRI, improved tumor delivery efficiency of drugs as well as enhanced antitumor efficacy, compared with groups with only magnetic or active targeting strategy. The unique nanoplatform may find applications in effective disease control by delivering imaging and therapy to organs/tissues that are not readily accessible by conventional delivery vehicles.

Synthesis of platinum nanoparticles templated by dendrimers terminated with alkyl chains

A new approach to synthesize platinum nanoparticles templated by dendrimers terminated with alkyl chains was developed using hydrogen as a reducing agent.

Light and Magnetic Dual-Responsive Pickering Emulsion Micro-Reactors

Emulsion droplets can serve as ideal compartments for reactions. In fact, in many cases, the chemical reactions are supposed to be triggered at a desired position and time without change of the system environment. Here, we present a type of light and magnetic dual-responsive Pickering emulsion microreactor by coadsorption of light-sensitive titania (TiO₂) and super paramagnetic iron oxide (Fe₃O₄) nanoparticles at the oil-water interface of emulsion droplets. The droplets encapsulating different reactants in advance can be driven close to each other by an external magnetic field, and then the chemical reaction is triggered by UV illumination due to the contact of the isolated reactants as a result of droplet coalescence. An insight into the incorporation of hydrophobic TiO₂ and hydrophilic Fe₃O₄ nanoparticles simultaneously at the emulsion interface is achieved. On the basis of that, an account is given of the coalescence mechanism of the Pickering emulsion microreactors. Our work not only provides a novel Pickering emulsion microreactor platform for triggering chemical reactions in a nonintrusive and well-controlled way but also opens a promising avenue to construct multifunctional Pickering emulsions by assembly of versatile building block nanoparticles at the interface of emulsion droplets.

Magnetic separation: its application in mining, waste purification, medicine, biochemistry and chemistry

The use of strong magnetic field gradients and high magnetic fields generated by permanent magnets or superconducting coils has found applications in many fields such as mining, solid state chemistry, biochemistry and medical research.