Ultrafast hydrothermal synthesis of high quality magnetic core phenol-formaldehyde shell composite microspheres using the microwave method

Rational Design of Coordination Polymers Composited Hollow Multishelled Structures for Drug Delivery

Multifunctional drug delivery systems (DDS) are in high demand for effectively targeting specific cells, necessitating excellent biocompatibility, precise release mechanisms, and sustained release capabilities. The hollow multishelled structure (HoMS) presents a promising solution, integrating structural and compositional design for efficient DDS development amidst complex cellular environments. Herein, starting from a Fe-based metal-organic framework (MOF), amorphous coordination polymers (CP) composited HoMS with controlled shell numbers are fabricated by balancing the rate of MOF decomposition and shell formation. Fe-CP HoMS loaded with DOX is utilized for synergistic chemotherapy and chemodynamic therapy, offering excellent responsive drug release capability (excellent pH-triggered drug release 82% within 72 h at pH 5.0 solution with doxorubicin (DOX) loading capacity of 284 mg g-1). In addition to its potent chemotherapy attributes, Fe-CP-HoMS possesses chemodynamic therapy potential by continuously catalyzing H2O2 to generate ·OH species within cancer cells, thus effectively inhibiting cancer cell proliferation. DOX@3S-Fe-CP-HoMS, at a concentration of 12.5 µg mL-1, demonstrates significant inhibitory effects on cancer cells while maintaining minimal cytotoxicity toward normal cells. It is envisioned that CP-HoMS could serve as an effective and biocompatible platform for the advancement of intelligent drug delivery systems in the realm of cancer therapy.

Magnetically stabilized bed packed with synthesized magnetic silicone loaded with ionic liquid particles for efficient enrichment of flavonoids from tree peony petals

In this work, synthesized magnetic silicone loaded with ionic liquid (Fe₃O₄@SiO₂@IL) particles combined with gas-liquid-solid magnetically stabilized bed (GLS-MSB) were applied to enrich flavonoids from tree peony petal extraction solution. The magnetic core (Fe₃O₄) encased in silica was conducive to its rapid and efficient separation, and the modification of silica with ionic liquids (ILs) could provide the functional groups for selective adsorption of flavonoids. Furthermore, the magnetic materials were evenly dispersed in the GLS-MSB system, realizing the adequate contact and causing the positive influence on the result. After physicochemical characterization, the prepared Fe₃O₄@SiO₂@IL (IL=VBimBr) particles were validated in the enrichment performance of flavonoids, including the type of ionic liquid loaded, desorption solution, adsorption and desorption kinetics. The adsorption kinetics obeyed the pseudo-second-order model, the adsorption isotherms were consistent with the Langmuir equation, and the adsorption process was spontaneous and exothermic. Additionally, the dynamic processes using GLS-MSB packed with Fe₃O₄@SiO₂@IL particles were evaluated systematically, deriving the optimum conditions (5 mL/min liquid flow rate, 130 mL Loading amount and 42.55 Oe magnetic field intensity) and improving the purity of flavonoids. After enrichment, the Fe₃O₄@SiO₂@IL particles were successfully recycled and reused. Overall, the developed method offers a great potential for the enrichment of flavonoids from natural materials.

C@Fe3O4 nanoparticles anchored on carbon nanotubes with enhanced reversible lithium storage

Porous CNT@Fe₃O₄@C was synthesized by a microwave-assisted method, which achieved the double fixation of nanoparticles and exhibited favorable electrochemical performances.

Nanoengineering Carbon Spheres as Nanoreactors for Sustainable Energy Applications

Colloidal carbon sphere nanoreactors have been explored extensively as a class of versatile materials for various applications in energy storage, electrochemical conversion, and catalysis, due to their unique properties such as excellent electrical conductivity, high specific surface area, controlled porosity and permeability, and surface functionality. Here, the latest updated research on colloidal carbon sphere nanoreactor, in terms of both their synthesis and applications, is summarized. Various synthetic strategies are first discussed, including the hard template method, the soft template method, hydrothermal carbonization, the microemulsion polymerization method, and extension of the Stöber method. Then, the functionalization of colloidal carbon sphere nanoreactors, including the nanoengineering of compositions and the surface features, is discussed. Afterward, recent progress in the major applications of colloidal carbon sphere nanoreactors, in the areas of energy storage, electrochemical conversion, and catalysis, is presented. Finally, the perspectives and challenges for future developments are discussed in terms of controlled synthesis and functionalization of the colloidal carbon sphere nanoreactors with tunable structure, and the composition and properties that are desirable for practical applications.

Complexes of magnetic nanospheres with amphiprotic polymer-Zn systems for the selective isolation of lactoferrin

Amphiprotic polymer-Zn complex magnetic nanospheres, termed Fe₃O₄@PCL-CMC-Zn, are designed and prepared via a step-wise synthetic strategy. Hydrophobic polycaprolactone (PCL) is firstly coated onto the magnetic Fe₃O₄ nanospheres, and then hydrophilic carboxymethylcellulose (CMC) is grafted onto the hydrophobic PCL blocks via an esterification reaction, followed by finally chelating with Zn²⁺ ions. The homogeneous core-shell structure and fastened amphiprotic polymer layer provide the as-prepared Fe₃O₄@PCL-CMC-Zn magnetic nanospheres with improved protein binding behavior, and the chelated Zn²⁺ offers the nanospheres favorable adsorption selectivity towards apo-lactoferrin. The adsorption capacity of apo-lactoferrin is high, up to 615.3 mg g^-1. The exploitation of FeCl₃ as a stripping reagent not only provides efficient recovery of the adsorbed apo-lactoferrin, i.e. a recovery of 83.2%, but also achieves the restoration of the lactoferrin structure. The Fe₃O₄@PCL-CMC-Zn magnetic nanospheres are then employed as a sorbent for the selective isolation of lactoferrin from human colostrum samples, obtaining high-purity lactoferrin as demonstrated by SDS-PAGE and Q-TOF LC-MS assays.

Synthesis of multifunctional Fe3O4@PLGA-PEG nano-niosomes as a targeting carrier for treatment of cervical cancer

A new folic acid (FA)-conjugated poly (lactic-co-glycolicacid) (PLGA)-polyethylene glycol (PEG) nano-noisome was prepared. The noisome was employed as a drug delivery system to load curcumin (Cur) as a model drug and fluorescent probe for cervical cancer therapy and cell imaging. The Fe₃O₄@PLGA-PEG@FA noisomes were prepared through facile emulsion solvent evaporation and conjugation chemistry method, possessing the properties of high rapid magnetic separation and targeting character. X-ray photoelectron spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), dynamic light scattering (DLS), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM) were adopted to characterize the chemical structure and properties of these niosomes. MTT assay revealed that the blank noisomes exhibited excellent biocompatibility. The in vitro drug loading and release behavior studier showed the as prepared nano-noisome presented ultrahigh performance as drug carrier. The confocal laser scanning microscopy (CLSM) and flow cytometry (FCM) experiments demonstrated that Cur-loaded Fe₃O₄@PLGA-PEG@FA niosomes achieved significantly high targeting efficiency for cervical cancer. Additionally, the FA-targeted niosomes exhibited higher antitumor efficiency than free Cur. Cell morphology, the mitochondrial membrane potential and cell cycle changes indicated that Cur-loaded niosomes induced HeLa229 cells to apoptosis by destroying mitochondrion of cervical tumor cells, simultaneously changing nuclear morphology and blocking tumor cell proliferation. These results demonstrate that Fe₃O₄@PLGA-PEG@FA noisomes have promising applications as targeted drug delivery system for sustained drug release in cancer treatment.

One-Step Carbon Coating and Polyacrylamide Functionalization of Fe₃O₄ Nanoparticles for Enhancing Magnetic Adsorptive-Remediation of Heavy Metals

Magnetic nanoparticles are used in adsorptive removal of heavy metals from polluted wastewater. However, their poor stability in an acidic medium necessitates their protection with a coating layer. Coating magnetic nanoparticles with carbon showed proper protection but the heavy metal removal efficiency was slightly weak. However, to boost the removal efficiencies of surface functionalization, polyacrylamide was applied to carbon-coated Fe₃O₄ nanoparticles. In this paper, to facilitate the synthesis process, one-step carbon coating and polyacrylamide functionalization were conducted using the hydrothermal technique with the aim of enhancing the adsorptive removal capacity of Fe₃O₄ nanoparticles towards some heavy metals such as Cu(II), Ni(II), Co(II), and Cd(II). The results showed that the one-step process succeeded in developing a carbon coating layer and polyacrylamide functionality on Fe₃O₄ nanoparticles. The stability of the magnetic Fe₃O₄ nanoparticles as an adsorbent in an acidic medium was improved due to its resistance to the dissolution that was gained during carbon coating and surface functionalization with polyacrylamide. The adsorptive removal process was investigated in relation to various parameters such as pH, time of contact, metal ion concentrations, adsorbent dose, and temperature. The polyacrylamide functionalized Fe₃O₄ showed an improvement in the adsorption capacity as compared with the unfunctionalized one. The conditions for superior adsorption were obtained at pH 6; time of contact, 90 min; metal solution concentration, 200 mg/L; adsorbent dose, 0.3 g/L. The modeling of the adsorption data was found to be consistent with the pseudo-second-order kinetic model, which suggests a fast adsorption process. However, the equilibrium data modeling was consistent with both the Langmuir and Freundlich isotherms. Furthermore, the thermodynamic parameters of the adsorptive removal process, including ΔG°, ΔH°, and ΔS°, indicated a spontaneous and endothermic sorption process. The developed adsorbent can be utilized further for industrial-based applications.

Sandwich-Like CNT@Fe3O4@C Coaxial Nanocables with Enhanced Lithium-Storage Capability

Through the combined method of a low-temperature reflux and calcination, porous sandwich-like CNT@Fe₃O₄@C coaxial nanocables were cleverly constructed, which exhibited a favorable specific capacity of 724.8 mA h g^-1 at 1000 mA g^-1, a satisfying rate performance and admirable Coulombic efficiency (ca. 100%) for anodes of lithium-ion batteries. Due to the enlarged contact surface area, shortened Li⁺ diffusion distance, hierarchical porosity, reasonable structural design and good structural stability, the electrochemical performance of the CNT@Fe₃O₄@C nanocomposites was greatly enhanced in comparison with the traditional iron oxide anodes. So, it is a good candidate for anode materials with high performance.

Magnetic hollow carbon microspheres as a reusable adsorbent for rhodamine B removal

Porous magnetic hollow carbon microspheres (MHCMs) were fabricated with a high surface area and superior adsorption performance for reusable RB removal.

Monodisperse Mesoporous Carbon Nanoparticles from Polymer/Silica Self-Aggregates and Their Electrocatalytic Activities

In our quest to make various chemical processes sustainable, the development of facile synthetic routes and inexpensive catalysts can play a central role. Herein we report the synthesis of monodisperse, polyaniline (PANI)-derived mesoporous carbon nanoparticles (PAMCs) that can serve as efficient metal-free electrocatalysts for the hydrogen peroxide reduction reaction (HPRR) as well as the oxygen reduction reaction (ORR) in fuel cells. The materials are synthesized by polymerization of aniline with the aid of (NH4)2S2O8 as oxidant and colloidal silica nanoparticles as templates, then carbonization of the resulting PANI/silica composite material at different high temperatures, and finally removal of the silica templates from the carbonized products. The PAMC materials that are synthesized under optimized synthetic conditions possess monodisperse mesoporous carbon nanoparticles with an average size of 128 ± 12 nm and an average pore size of ca. 12 nm. Compared with Co3O4, a commonly used electrocatalyst for HPRR, these materials show much better catalytic activity for this reaction. In addition, unlike Co3O4, the PAMCs remain relatively stable during the reaction, under both basic and acidic conditions. The nanoparticles also show good electrocatalytic activity toward ORR. Based on the experimental results, PAMCs' excellent electrocatalytic activity is attributed partly to their heteroatom dopants and/or intrinsic defect sites created by vacancies in their structures and partly to their high porosity and surface area. The reported synthetic method is equally applicable to other polymeric precursors (e.g., polypyrrole (PPY)), which also produces monodisperse, mesoporous carbon nanoparticles in the same way. The resulting materials are potentially useful not only for electrocatalysis of HPRR and ORR in fuel cells but also for other applications where high surface area, small sized, nanostructured carbon materials are generally useful for (e.g., adsorption, supercapacitors, etc.).

Facile preparation of biphasic-induced magnetic icariin-loaded composite microcapsules by automated in situ click technology

This research aims to prepare the biphasic-induced magnetic composite microcapsules (BIMCM) as a promising environmental stimuli-responsive delivery vehicle to dispose the problem of drug burst effect. The paper presented a novel automated in situ click technology of magnetic chitosan/nano hydroxyapatite (CS/nHA) microcapsules. Fe3O4 magnetic nanoparticles (MNP) and nHA were simultaneously in situ crystallized by one-step process. Icariin (ICA), a plant-derived flavonol glycoside, was combined to study drug release properties of BIMCM. BIMCM were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and Thermal gravimetric analysis/Differential Scanning Calorimetry(TGA/DSC) in order to reveal their component and surface morphology as well as the role of the in situ generated Fe3O4 MNP and nHA. The magnetic test showed the BIMCM were super-paramagnetic. Both in situ generated Fe3O4 MNP and nHA serve as stable inorganic crosslinkers in BIMCM to form many intermolecular crosslinkages for the movability of the CS chains. This makes ICA loaded microcapsules take on a sustained release behavior and results in the self-adjusting of surface morphology, decreasing of swelling and degradation rates. In addition, in vitro tests were systematically carried out to examine the biocompatibility of the microcapsules by MTT test, Wright-Giemsa dying assay and AO/EB fluorescent staining method. These results demonstrated that successful introduction of the in situ click Fe3O4 MNP provided an alternative strategy because of magnetic sensitivity and sustained release. As such, the novel ICA loaded biphasic-induced magnetic CS/nHA/MNP microcapsules are expected to find potential applications in drug delivery system for bone repair.

Core-Shell Ferromagnetic Nanorod Based on Amine Polymer Composite (Fe3O4@DAPF) for Fast Removal of Pb(II) from Aqueous Solutions

Heavy metal ion removal from wastewater constitutes an important issue in the water treatment industry. Although a variety of nanomaterials have been developed for heavy metal removal via adsorption, the adsorption capacity, removal efficiency, and material recyclability still remain a challenge. Here, we present novel Fe3O4@DAPF core-shell ferromagnetic nanorods (CSFMNRs) for the removal of Pb(II) from aqueous solutions; they were prepared by the facile surface modification of twin-like ferromagnetic Fe3O4 nanorods using a 2,3-diaminophenol and formaldehyde (DAPF)-based polymer. The crystallinity and structure of the Fe3O4 nanorods were confirmed via X-ray diffraction (XRD). Transmission electron microscopy (TEM) and X-ray photoelectron spectroscopy (XPS) revealed the core-shell morphology and composition of the materials. Pb(II) removal using the prepared Fe3O4@DAPF CSFMNRs was assessed, and comparable adsorption capacities (83.3 mg g(-1)) to the largest value were demonstrated. A thermodynamic study of the adsorption clearly indicated that the adsorption was exothermic and spontaneous. Due to the ferromagnetic properties with a high saturation magnetization value (56.1 emu g(-1)) of the nanorods, the nanorods exhibited excellent reusability with one of the fastest recovery times (25 s) among reported materials. Therefore, the Fe3O4@DAPF CSFMNRs can serve as recyclable adsorbent materials and as an alternative to commonly used sorbent materials for the rapid removal of heavy metals from aqueous solutions.

Molecular-based design and emerging applications of nanoporous carbon spheres

Over the past decade, considerable progress has been made in the synthesis and applications of nanoporous carbon spheres ranging in size from nanometres to micrometres. This Review presents the primary techniques for preparing nanoporous carbon spheres and the seminal research that has inspired their development, presented potential applications and uncovered future challenges. First we provide an overview of the synthesis techniques, including the Stöber method and those based on templating, self-assembly, emulsion and hydrothermal carbonization, with special emphasis on the design and functionalization of nanoporous carbon spheres at the molecular level. Next, we cover the key applications of these spheres, including adsorption, catalysis, separation, energy storage and biomedicine — all of which might benefit from the regular geometry, good liquidity, tunable porosity and controllable particle-size distribution offered by nanoporous carbon spheres. Finally, we present the current challenges and opportunities in the development and commercial applications of nanoporous carbon spheres.

Recent progress on magnetic iron oxide nanoparticles: synthesis, surface functional strategies and biomedical applications

This review focuses on the recent development and various strategies in the preparation, microstructure, and magnetic properties of bare and surface functionalized iron oxide nanoparticles (IONPs); their corresponding biological application was also discussed. In order to implement the practical in vivo or in vitro applications, the IONPs must have combined properties of high magnetic saturation, stability, biocompatibility, and interactive functions at the surface. Moreover, the surface of IONPs could be modified by organic materials or inorganic materials, such as polymers, biomolecules, silica, metals, etc. The new functionalized strategies, problems and major challenges, along with the current directions for the synthesis, surface functionalization and bioapplication of IONPs, are considered. Finally, some future trends and the prospects in these research areas are also discussed.

Ultrasmall single micelle@resin core–shell nanocarriers as efficient cargo loading vehicles for in vivo biomedical applications

Ultrasmall core–shell nanocarriers (NCs) are believed to be ideal candidates for biological applications, as proved by silica-based core–shell NCs fabricated using a single micelle as a template.

Recent advances in carbon nanospheres: synthetic routes and applications

Various strategies to carbon nanospheres together with a brief introduction of applications are presented in this feature article.

Selective detection of ferric ions by blue-green photoluminescent nitrogen-doped phenol formaldehyde resin polymer

The smaller, the more fluorescent: The hydrothermal reaction of phenol with hexamethylenetetramine (HMT) leads to two morphologies of phenol formaldehyde resin (PFR), namely, bigger nanoparticles with feeble green fluorescence and smaller amorphous polymers with strong blue-green fluorescence. It reveals that both of them are doped with nitrogen, and the blue-green photoluminescent polymer is confirmed to sense ferric ion (Fe(3+) ) with high selectivity.

Movable magnetic porous cores enclosed within carbon microcapsules: structure-controlled synthesis and promoted carbon-based applications

Rattle-type porous carbon microcapsules (RPCMs) were deliberately designed to combine multiple functions with the aim of improving the applicability of amorphous carbon in a synergistic fashion. A movable Fe3O4 nanocluster coated with porous carbon is encapsulated in the cavity of a carbon microcapsule with an eggshell-like characteristic, allowing for storage, adsorption, and exchange of matters through the mesoporous channels of the carbon layer. The synthetic strategy of RPCMs is flexible and universal, involving the constitution and carbonization of Fe3O4@PF@PS@PF template particles. This results in a double carbon shell and a sandwiched hollow cavity with a movable magnetic core. There is evidence that RPCMs possess large surface areas, hierarchical pore sizes, hydrophobicity, and magnetic responsiveness. Hence, diverse applications have been investigated. It is proved that RPCMs exhibit excellent performance in the effective enrichment of peptides/proteins. The detection limit toward peptides could reach as low as 10 nM, and the enrichment capacity toward MYO protein is as high as 410 mg/g (protein/beads). Furthermore, RPCMs are able to harvest proteins in complex real samples such as fetal bovine serum and rabbit blood. In addition, RPCMs could be fabricated in a supercapacitor electrode and display outstanding energy-storage performance. The electrochemical measurements demonstrate that RPCM-based electrodes have a specific capacitance of as high as 216 F/g (0.1 A/g), long-term cycling stability with a capacitance retention of 92.4% over 1000 cycles (0.2 A/g), and good electronic conductivity.

Shell thickness-dependent microwave absorption of core-shell Fe3O4@C composites

Core-shell composites, Fe3O4@C, with 500 nm Fe3O4 microspheres as cores have been successfully prepared through in situ polymerization of phenolic resin on the Fe3O4 surface and subsequent high-temperature carbonization. The thickness of carbon shell, from 20 to 70 nm, can be well controlled by modulating the weight ratio of resorcinol and Fe3O4 microspheres. Carbothermic reduction has not been triggered at present conditions, thus the crystalline phase and magnetic property of Fe3O4 micropsheres can be well preserved during the carbonization process. Although carbon shells display amorphous nature, Raman spectra reveal that the presence of Fe3O4 micropsheres can promote their graphitization degree to a certain extent. Coating Fe3O4 microspheres with carbon shells will not only increase the complex permittivity but also improve characteristic impedance, leading to multiple relaxation processes in these composites, thus the microwave absorption properties of these composites are greatly enhanced. Very interestingly, a critical thickness of carbon shells leads to an unusual dielectric behavior of the core-shell structure, which endows these composites with strong reflection loss, especially in the high frequency range. By considering good chemical homogeneity and microwave absorption, we believe the as-fabricated Fe3O4@C composites can be promising candidates as highly effective microwave absorbers.

Recent advances in superparamagnetic iron oxide nanoparticles for cellular imaging and targeted therapy research

Advances of nanotechnology have led to the development of nanomaterials with both potential diagnostic and therapeutic applications. Among them, superparamagnetic iron oxide (SPIO) nanoparticles have received particular attention. Over the past decade, various SPIOs with unique physicochemical and biological properties have been designed by modifying the particle structure, size and coating. This article reviews the recent advances in preparing SPIOs with novel properties, the way these physicochemical properties of SPIOs influence their interaction with cells, and the development of SPIOs in liver and lymph nodes magnetic resonance imaging (MRI) contrast. Cellular uptake of SPIO can be exploited in a variety of potential clinical applications, including stem cell and inflammation cell tracking and intra-cellular drug delivery to cancerous cells which offers higher intra-cellular concentration. When SPIOs are used as carrier vehicle, additional advantages can be achieved including magnetic targeting and hyperthermia options, as well as monitoring with MRI. Other potential applications of SPIO include magnetofection and gene delivery, targeted retention of labeled stem cells, sentinel lymph nodes mapping, and magnetic force targeting and cell orientation for tissue engineering.

Magnetic colloidal supraparticles: design, fabrication and biomedical applications

Magnetic nanoparticles (MNPs) bear many intriguing properties such as superparamagnetism, high specific surface area, remarkable colloidal stability and biocompatibility, which evoke great interest and desire of exploration in biomedical applications. For the use in the complicated physiological environment, MNPs are still being developed to have the enhanced performances and down-to-earth practicality. Engineering of MNPs into hierarchical structures is thus proposed to create a new family of magnetic materials, magnetic colloidal supraparticles (MCSPs), which exhibit collective properties and unique nanomaterial characters. From a biomedical point of view, applicability of MCSPs is somewhat more distinctive in contrast to their primary MNPs, because MCSPs are amenable to modulation of secondary structure, promotion of magnetic responsiveness and ease of function design. As a result, MCSPs have been subject to intense researches in recent years, with the aim to develop outstanding composite materials for biomedical applications. In this review, we embark on an overview of foundational topics that detail the design and fabrication of MCSPs by evaporation-induced emulsion and solvothermal techniques, and continue with a guideline for modification of MCSPs with inorganic oxides and organic polymers. Particular focus is then placed on the biomedical applications of modified MCSPs. Many examples illustrate the latest progress in design of MCSP-based microspheres for magnetic resonance imaging, targeted drug delivery, sensing, and harvesting of peptides/proteins. After these detailed accounts, the current challenges and future development of researches and applications are discussed as a conclusion to the review.