Black Titania Janus Mesoporous Nanomotor for Enhanced Tumor Penetration and Near-Infrared Light-Triggered Photodynamic Therapy.

Thanks to their excellent photoelectric characteristics to generate cytotoxic reactive oxygen species (ROS) under the light-activation process, TiO2 nanomaterials have shown significant potential in photodynamic therapy (PDT) for solid tumors. Nevertheless, the limited penetration depth of TiO2-based photosensitizers and excitation sources (UV/visible light) for PDT remains a formidable challenge when confronted with complex tumor microenvironments (TMEs). Here, we present a H2O2-driven black TiO2 mesoporous nanomotor with near-infrared (NIR) light absorption capability and autonomous navigation ability, which effectively enhances solid tumor penetration in NIR light-triggered PDT. The nanomotor was rationally designed and fabricated based on the Janus mesoporous nanostructure, which consists of a NIR light-responsive black TiO2 nanosphere and an enzyme-modified periodic mesoporous organosilica (PMO) nanorod that wraps around the TiO2 nanosphere. The overexpressed H2O2 can drive the nanomotor in the TME under catalysis of catalase in the PMO domain. By precisely controlling the ratio of TiO2 and PMO compartments in the Janus nanostructure, TiO2&PMO nanomotors can achieve optimal self-propulsive directionality and velocity, enhancing cellular uptake and facilitating deep tumor penetration. Additionally, by the decomposition of endogenous H2O2 within solid tumors, these nanomotors can continuously supply oxygen to enable highly efficient ROS production under the NIR photocatalysis of black TiO2, leading to intensified PDT effects and effective tumor inhibition.

Camouflaged Virus-Like-Nanocarrier with a Transformable Rough Surface for Boosting Drug Delivery.

Due to non-specific strong nano-bio interactions, it is difficult for nanocarriers with permanent rough surface to cross multiple biological barriers to realize efficient drug delivery. Herein, a camouflaged virus-like-nanocarrier with a transformable rough surface is reported, which is composed by an interior virus-like mesoporous SiO2 nanoparticle with a rough surface (vSiO2 ) and an exterior acid-responsive polymer. Under normal physiological pH condition, the spikes on vSiO2 are hidden by the polymer shell, and the non-specific strong nano-bio interactions are effectively inhibited. While in the acidic tumor microenvironment, the nanocarrier sheds the polymer camouflage to re-expose its rough surface. So, the retention ability and endocytosis efficiency of the nanocarrier are great improved. Owing to it's the dynamically variable rough surface, the rationally designed nanocarrier exhibits extended blood-circulation-time and enhanced tumor accumulation.

Versatile synthesis of dendritic mesoporous rare earth-based nanoparticles.

Rare earth-based nanomaterials that have abundant optical, magnetic, and catalytic characteristics have many applications. The controllable introduction of mesoporous channels can further enhance its performance, such as exposing more active sites of rare earth and improving the loading capacity, yet remains a challenge. Here, we report a universal viscosity-mediated assembly strategy and successfully endowed rare earth-based nanoparticles with central divergent dendritic mesopores. More than 40 kinds of dendritic mesoporous rare earth-based (DM-REX) nanoparticles with desired composition (single or multiple rare earth elements, high-entropy compounds, etc.), particle diameter (80 to 500 nanometers), pore size (3 to 20 nanometers), phase (amorphous hydroxides, crystalline oxides, and fluorides), and architecture were synthesized. Theoretically, a DM-REX nanoparticle library with 393,213 kinds of possible combinations can be constructed on the basis of this versatile method, which provides a very broad platform for the application of rare earth-based nanomaterials with rational designed functions and structures.

MXene (Ti3C2Tx)/Cellulose Acetate Mixed-Matrix Membrane Enhances Fouling Resistance and Rejection in the Crossflow Filtration Process.

Obstacles in the membrane-based separation field are mainly related to membrane fouling. This study involved the synthesis and utilization of covalently crosslinked MXene/cellulose acetate mixed matrix membranes with MXene at different concentrations (CCAM-0% to CCAM-12%) for water purification applications. The membranes' water flux, dye, and protein rejection performances were compared using dead-end (DE) and crossflow (CF) filtration. The fabricated membranes, especially CCAM-10%, exhibited high hydrophilicity, good surface roughness, significantly high water flux, high water uptake, and high porosity. A significantly higher flux was observed in CF filtration relative to DE filtration. Moreover, in CF filtration, the CCAM-10% membrane exhibited 96.60% and 99.49% rejection of methyl green (MG) and bovine serum albumin (BSA), respectively, while maintaining a flux recovery ratio of 67.30% and an irreversible fouling ratio at (Rir) of 32.70, indicating good antifouling performance. Hence, this study suggests that covalent modification of cellulose acetate membranes with MXene significantly improves the performance and fouling resistance of membranes for water filtration in CF mode relative to DE mode.

Enzyme-Based Mesoporous Nanomotors with Near-Infrared Optical Brakes.

As one of the most important parameters of the nanomotors' motion, precise speed control of enzyme-based nanomotors is highly desirable in many bioapplications. However, owing to the stable physiological environment, it is still very difficult to in situ manipulate the motion of the enzyme-based nanomotors. Herein, inspired by the brakes on vehicles, the near-infrared (NIR) "optical brakes" are introduced in the glucose-driven enzyme-based mesoporous nanomotors to realize remote speed regulation for the first time. The novel nanomotors are rationally designed and fabricated based on the Janus mesoporous nanostructure, which consists of the SiO2@Au core@shell nanospheres and the enzymes-modified periodic mesoporous organosilicas (PMOs). The nanomotor can be driven by the biofuel of glucose under the catalysis of enzymes (glucose oxidase/catalase) on the PMO domain. Meanwhile, the Au nanoshell at the SiO2@Au domain enables the generation of the local thermal gradient under the NIR light irradiation, driving the nanomotor by thermophoresis. Taking advantage of the unique Janus nanostructure, the directions of the driving force induced by enzyme catalysis and the thermophoretic force induced by NIR photothermal effect are opposite. Therefore, with the NIR optical speed regulators, the glucose-driven nanomotors can achieve remote speed manipulation from 3.46 to 6.49 µm/s (9.9-18.5 body-length/s) at the fixed glucose concentration, even after covering with a biological tissue. As a proof of concept, the cellar uptake of the such mesoporous nanomotors can be remotely regulated (57.5-109 µg/mg), which offers great potential for designing smart active drug delivery systems based on the mesoporous frameworks of this novel nanomotor.

Streamlined Mesoporous Silica Nanoparticles with Tunable Curvature from Interfacial Dynamic-Migration Strategy for Nanomotors.

Streamlined architectures with a low fluid-resistance coefficient have been receiving great attention in various fields. However, it is still a great challenge to synthesize streamlined architecture with tunable surface curvature at the nanoscale. Herein, we report a facile interfacial dynamic migration strategy for the synthesis of streamlined mesoporous nanotadpoles with varied architectures. These tadpole-like nanoparticles possess a big streamlined head and a slender tail, which exhibit large inner cavities (75-170 nm), high surface areas (424-488 m2 g-1), and uniform mesopore sizes (2.4-3.2 nm). The head curvature of the streamlined mesoporous nanoparticles can be well-tuned from ∼2.96 × 10-2 to ∼5.56 × 10-2 nm-1, and the tail length can also be regulated from ∼30 to ∼650 nm. By selectively loading the Fe3O4 catalyst in the cavity of the streamlined silica nanotadpoles, the H2O2-driven mesoporous nanomotors were designed. The mesoporous nanomotors with optimized structural parameters exhibit outstanding directionality and a diffusion coefficient of 8.15 µm2 s-1.

A comprehensive review summarizing the recent biomedical applications of functionalized carbon nanofibers.

Since the discovery and fabrication of carbon nanofibers (CNFs) over a decade ago, scientists foster to discover novel myriad potential applications for this material in both biomedicine and industry. The unique economic viability, mechanical, electrical, optical, thermal, and structural properties of CNFs led to their rapid emergence. CNFs become an artificial intelligence platform for different uses, including a wide range of biomedical applications. Furthermore, CNFs have exceptionally large surface areas that make them flexible for tailoring and functionalization on demand. This review highlights the recent progress and achievements of CNFs in a wide range of biomedical fields, including cancer therapy, biosensing, tissue engineering, and wound dressing. Besides the synthetic techniques of CNFs, their potential toxicity and limitations, as biomaterials in real clinical settings, will be presented. This review discusses CNF's future investigations in other biomedical fields, including gene delivery and bioimaging and CNFs risk assessment.

Unveiling One-Pot Template-Free Fabrication of Exquisite Multidimensional PtNi Multicube Nanoarchitectonics for the Efficient Electrochemical Oxidation of Ethanol and Methanol with a Great Tolerance for CO.

Multidimensional bimetallic Pt-based nanoarchitectonics are highly promising in electrochemical energy conversion technologies because of their fancy structural merits and accessible active sites; however, hitherto their precise template-free fabrication remains a great challenge. We report a template-free solvothermal one-pot approach for the rational design of cocentric PtNi multicube nanoarchitectonics via adjusting the oleylamine/oleic acid ratio with curcumin. The obtained multidimensional PtNi multicubes comprise multiple small interlace-stacked nanocube subunits assembled in spatially porous branched nanoarchitectonics and bound by high-index facets. The synthetic mechanism is driven by spontaneous isolation among prompt nucleation and oriented attachment epitaxial growth. These inimitable architectural and compositional merits of PtNi multicubes endowed the ethanol oxidation mass and specific activity by 5.6 and 9.03 times than the Pt/C catalyst, respectively, along with the enhancement of methanol oxidation mass activity by 2.3 times. Moreover, PtNi multicubes showed superior durability and a higher tolerance for CO poisoning than the Pt/C catalyst. This work may pave the way for tailored preparation of Pt-based nanoarchitectonics for myriad catalytic reactions.

Interface Coassembly and Polymerization on Magnetic Colloids: Toward Core-Shell Functional Mesoporous Polymer Microspheres and Their Carbon Derivatives.

Core-shell structured magnetic mesoporous polymer or carbon-based microspheres not only possess the combined merits of magnetic particles and stable mesoporous shell but also provide various organic functional groups for further modification and immobilization of active sites, thus opening up more possibility for various applications. Herein, a bottom-up soft-templating strategy is developed to controllably synthesize core-shell magnetic mesoporous polydopamine microspheres (MMP) and their derivative magnetic mesoporous carbon (MMC) microspheres via an amphiphilic block copolymer-directed interface assembly and polymerization (denoted as abc-DIAP) approach. The obtained uniform MMP microspheres have a well-defined structure consisting of magnetic core, silica middle layer and mesoporous PDA shell, uniform mesopores of 11.9 nm, high specific surface areas (235.6 m2 g-1) and rich functional groups. They show fast magnetic separation speed and superior performance in selective adsorption of Cyt.C from complex biosample solutions. Moreover, they can be in situ converted into core-shell magnetic mesoporous carbon (MMC) for efficient in-pore immobilization of ultrafine Au nanoparticles for high-efficiency catalytic epoxidation of styrene with high conversion (88.6%) and selectivity (90.1%) toward styrene oxide.

Synthesis of Podlike Magnetic Mesoporous Silica Nanochains for Use as Enzyme Support and Nanostirrer in Biocatalysis.

Magnetic mesoporous materials have attracted great interest due to their combined property of magnetic nanomaterials and mesoporous materials as well as their potential applications in catalysis, bioenrichment, drug delivery, nanoreactors, etc. In this study, one-dimensional (1D) podlike magnetic mesoporous silica nanochains with tunable hollow space (Fe3O4@nSiO2@void@mSiO2 nanochain named as podlike 1D magnetic mesoporous silica (PL-MMS) nanochain) are rationally synthesized for the first time through a controlled magnetic-induced interface coassembly approach. The obtained PL-MMS possesses a tunable diameter (300-500 nm), large and perpendicular mesopores (8.2 nm) in the outer shell, a silica-protected magnetic-responsive core, and a high surface area (325 m2/g). Benefiting from the large voids and unique mesopores, these mesoporous nanochains exhibit superior performance in enzyme (lipase with a size of 4.0 nm) immobilization with a high loading capacity of 223 µg/mg, and the immobilized lipase demonstrates enhanced catalytic activity in different pH values and temperatures as well as excellent tolerance of organic solvent.

Highly dispersed Pt nanoparticles on ultrasmall EMT zeolite: A peroxidase-mimic nanoenzyme for detection of H2O2 or glucose.

In past decade, Pt-based nanomaterials as peroxidase mimics have attracted much attention for H2O2 and glucose detection. However, easy aggregation of Pt nanoparticles (Pt NPs) greatly decreases their peroxidase-like activity. In this work, novel Pt/EMT nanocomposites were prepared by uniformly loading Pt NPs (5-8 nm) onto the support of ultrasmall EMT zeolite (15-20 nm), a kind of low-silica microporous aluminosilicate material. The hybrid Pt/EMT nanomaterials could be well dispersed in water to form a homogeneous suspension, and were then utilized as a superior peroxidase-like catalyst for oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) in the presence of hydrogen peroxide (H2O2). The optimal catalyst of 2.6Pt/EMT nanocomposite exhibited excellent catalytic performance toward H2O2 and TMB than natural enzyme of horseradish peroxidase (HRP) by using a steady-state kinetic analysis based on the typical Michaelis-Menten kinetics theory. The peroxidase-like catalyst showed a promising activity in a wide pH and temperature range as well as the long-term stability. A facile and reliable colorimetric assay based on the peroxidase mimic of Pt/EMT nanocomposite was constructed for precise detection of H2O2 and glucose in a wide linear range, with low limits of detection of 1.1 µM and 13.2 µM, respectively. Due to high selectivity to glucose against other sugars on the catalyst, the method was demonstrated to accurately measure the concentration of glucose in real samples including human blood serum and fruit juices, indicating a potential application of the Pt/EMT nanocomposites as a robust peroxidase mimic and a reliable biosensor in the fields of clinical diagnosis, pharmaceutical, food research and so on.

Sequential Chemistry Toward Core-Shell Structured Metal Sulfides as Stable and Highly Efficient Visible-Light Photocatalysts.

A universal sequential synthesis strategy in aqueous solution is presented for highly uniform core-shell structured photocatalysts, which consist of a metal sulfide light absorber core and a metal sulfide co-catalyst shell. We show that the sequential chemistry can drive the formation of unique core-shell structures controlled by the constant of solubility product of metal sulfides. A variety of metal sulfide core-shell structures have been demonstrated, including CdS@CoSx , CdS@MnSx , CdS@NiSx , CdS@ZnSx , CuS@CdS, and more complexed CdS@ZnSx @CoSx . The obtained strawberry-like CdS@CoSx core-shell structures exhibit a high photocatalytic H2 production activity of 3.92 mmol h-1 and an impressive apparent quantum efficiency of 67.3 % at 420 nm, which is much better than that of pure CdS nanoballs (0.28 mmol h-1 ), CdS/CoSx composites (0.57 mmol h-1 ), and 5 %wt Pt-loaded CdS photocatalysts (1.84 mmol h-1 ).

Plasmonic MXene-based nanocomposites exhibiting photothermal therapeutic effects with lower acute toxicity than pure MXene.

Purpose: Here, we fabricated two plasmonic 2D Ti3C2Tx-based nanocomposites (Au/MXene and Au/Fe3O4/MXene) with similarly high anti-cancer photothermal therapy (PTT) capabilities, but with less in vivo toxicity than a pure MXene. Methods: Au/MXene was synthesized by in situ reduction of tetrachloroauric acid using NaBH4 on Ti3C2Tx flakes. For targeted PTT, magnetic Au/Fe3O4/MXene was synthesized via a reaction between freshly prepared magnetite Fe3O4 NPs and MXene solution, followed by in situ integration of gold nanoparticles (AuNPs). Results: Morphological characterization by XRD, SEM, and TEM revealed the successful synthesis of Au/MXene and Au/Fe3O4/MXene. Both new composites exhibited a significant in vitro dose-dependent PTT effect against human breast cancer cells MCF7. Interestingly, in vivo acute toxicity assays using zebrafish embryos indicated that Au/MXene and Au/Fe3O4/MXene had less embryonic mortality (LC50 ≫ 1000 µg/mL) than pure MXene (LC50=257.46 µg/mL). Conclusion: Our new Au/MXene and Au/Fe3O4/MXene nanocomposites could be safer and more suitable than the pure MXene for biomedical applications, especially when targeted PTT is warranted.

Molecular Design Strategy for Ordered Mesoporous Stoichiometric Metal Oxide.

A molecular design strategy is used to construct ordered mesoporous Ti3+ -doped Li4 Ti5 O12 nanocrystal frameworks (OM-Ti3+ -Li4 Ti5 O12 ) by the stoichiometric cationic coordination assembly process. Ti4+ /Li+ -citrate chelate is designed as a new molecular precursor, in which the citrate can not only stoichiometrically coordinate Ti4+ with Li+ homogeneously at the atomic scale, but also interact strongly with the PEO segments in the Pluronic F127. These features make the co-assembly and crystallization process more controllable, thus benefiting for the formation of the ordered mesostructures. The resultant OM-Ti3+ -Li4 Ti5 O12 shows excellent rate (143 mAh g-1 at 30 C) and cycling performances (<0.005 % fading per cycle). This work could open a facile avenue to constructing stoichiometric ordered mesoporous oxides or minerals with highly crystalline frameworks.

Melt Electrospinning Designs for Nanofiber Fabrication for Different Applications.

Nanofibers have been attracting growing attention owing to their outstanding physicochemical and structural properties as well as diverse and intriguing applications. Electrospinning has been known as a simple, flexible, and multipurpose technique for the fabrication of submicro scale fibers. Throughout the last two decades, numerous investigations have focused on the employment of electrospinning techniques to improve the characteristics of fabricated fibers. This review highlights the state of the art of melt electrospinning and clarifies the major categories based on multitemperature control, gas assist, laser melt, coaxial, and needleless designs. In addition, we represent the effect of melt electrospinning process parameters on the properties of produced fibers. Finally, this review summarizes the challenges and obstacles connected to the melt electrospinning technique.

A perspective on magnetic core-shell carriers for responsive and targeted drug delivery systems.

Magnetic core-shell nanocarriers have been attracting growing interest owing to their physicochemical and structural properties. The main principles of magnetic nanoparticles (MNPs) are localized treatment and stability under the effect of external magnetic fields. Furthermore, these MNPs can be coated or functionalized to gain a responsive property to a specific trigger, such as pH, heat, or even enzymes. Current investigations have been focused on the employment of this concept in cancer therapies. The evaluation of magnetic core-shell materials includes their magnetization properties, toxicity, and efficacy in drug uptake and release. This review discusses some categories of magnetic core-shell drug carriers based on Fe2O3 and Fe3O4 as the core, and different shells such as poly(lactic-co-glycolic acid), poly(vinylpyrrolidone), chitosan, silica, calcium silicate, metal, and lipids. In addition, the review addresses their recent potential applications for cancer treatment.

Core-Shell Magnetic Mesoporous Silica Microspheres with Large Mesopores for Enzyme Immobilization in Biocatalysis.

Magnetic mesoporous silica microspheres with core-shell structure and large pores are highly desired in macromolecules delivery and biocatalysis, biospeparation, and adsorption. In this work, a controllable solvent evaporation induced solution-phase interface co-assembly approach was developed to synthesize core-shell structural magnetic mesoporous silica microspheres with ultralarge mesopore size (denoted as LP-MMS). The synthesis was achieved by employing large-molecular-weight amphiphilic block copolymers poly(ethylene oxide)- block-poly(methyl methacrylate) (PEO- b-PMMA) and small surfactant cetyltrimethylammonium bromide as co-templates, which can co-assemble with silica source in tetrahydrofuran/water solutions. The obtained LP-MMS microspheres possess uniform rasberry-like morphology with a diameter of 600 nm, large primary spherical mesopores (ca. 36 nm), large specific surface area (348 m2/g), high specific pore volume (0.59 cm3/g), and fast magnetic responsivity with high magnetization (15.9 emu/g). The mesopore morphology can be transformed from spherical to cylindrical through introducing a shearing force during the interfacial co-assembly in the synthesis system. The designed LP-MMS microspheres turn out to be good carriers for enzyme (trypsin) immobilization with a high loading capacity of 80 µg/mg and demonstrate excellent biocatalysis efficiency up to 99.1% for protein digestion within 30 min and good recycling stability with negligible decay in digestion efficiency after reuse for five times.

Rational design of a stable peroxidase mimic for colorimetric detection of H2O2 and glucose: A synergistic CeO2/Zeolite Y nanocomposite.

Owing to the high costs and instability of natural enzymes, the development of enzyme mimics based on inorganic nanomaterials has attracted a wide concern in recent years. In this work, a stable nanocomposite composed of highly dispersed CeO2 nanoparticles decorated on zeolite Y as support (CeO2/Y) was synthesized by a facile wet impregnation method, and the CeO2/Y nanocomposite was firstly proposed as an efficient peroxidase-mimicking nanozyme for accurate detection of H2O2 and glucose. The best catalyst was the nanocomposite with CeO2 to zeolite Y mass ratio of 0.20 (denoted as 20CeO2/Y), showing a better affinity and higher catalytic constant to the substrate of H2O2 and 3,3',5,5'-tetramethylbenzidine (TMB) than horseradish peroxidase (HRP) enzymes by the steady-state kinetic analysis. The enzyme-mimicking catalyst could be used over a wider range of pH and temperature for a long-time reuse in TMB oxidation. A facile colorimetric assay was set up for the accurate detection of H2O2 and glucose, with the detection limits of 0.323 µM and 35.4 µM, respectively. The CeO2/Y-based peroxidase mimic was used to precisely detect the glucose concentration in real blood serum samples, exhibiting a great potential to be constructed as a reliable biosensor for glucose detection in some complex systems. The superior peroxidase-mimicking performance of CeO2/Y nanocomposite is attributed to the synergistic effects of outstanding activity of highly dispersed CeO2 nanoparticles (5-10 nm) and adsorption properties of zeolite Y with large surface area (517 m2·g-1) and pore volume (0.329 cm3·g-1).

PVA/Chitosan/Silver Nanoparticles Electrospun Nanocomposites: Molecular Relaxations Investigated by Modern Broadband Dielectric Spectroscopy.

In this study, we used broadband dielectric spectroscopy to analyze polymer nanofibers of poly(vinyl alcohol)/chitosan/silver nanoparticles. We also studied the effect of incorporating silver nanoparticles in the polymeric mat, on the chain motion dynamics and their interactions with chitosan nanofibers, and we calculated the activation energies of the sub-Tg relaxation processes. Results revealed the existence of two sub-Tg relaxations, the first gets activated at very low temperature (-90 °C) and accounts for motions of the side groups within the repeating unit such as ⁻NH2, ⁻OH, and ⁻CH2OH in chitosan and poly(vinyl alcohol). The second process gets activated around -10 °C and it is thought to be related to the local main chain segments' motions that are facilitated by fluctuations within the glycosidic bonds of chitosan. The activation energy for the chitosan/PVA/AgNPs nanocomposite nanofibers is much higher than that of the chitosan control film due to the presence of strong interactions between the amine groups and the silver nanoparticles. Kramers⁻Krönig integral transformation of the ε'' vs. f spectra in the region of the chitosan Tg helped resolve this relaxation and displayed the progress of its maxima with increasing temperature in the regular manner.

A Magnetic-Field Guided Interface Coassembly Approach to Magnetic Mesoporous Silica Nanochains for Osteoclast-Targeted Inhibition and Heterogeneous Nanocatalysis.

1D core-shell magnetic materials with mesopores in shell are highly desired for biocatalysis, magnetic bioseparation, and bioenrichment and biosensing because of their unique microstructure and morphology. In this study, 1D magnetic mesoporous silica nanochains (Fe3 O4 @nSiO2 @mSiO2 nanochain, Magn-MSNCs named as FDUcs-17C) are facilely synthesized via a novel magnetic-field-guided interface coassembly approach in two steps. Fe3 O4 particles are coated with nonporous silica in a magnetic field to form 1D Fe3 O4 @nSiO2 nanochains. A further interface coassembly of cetyltrimethylammonium bromide and silica source in water/n-hexane biliquid system leads to 1D Magn-MSNCs with core-shell-shell structure, uniform diameter (≈310 nm), large and perpendicular mesopores (7.3 nm), high surface area (317 m2 g-1 ), and high magnetization (34.9 emu g-1 ). Under a rotating magnetic field, the nanochains with loaded zoledronate (a medication for treating bone diseases) in the mesopores, show an interesting suppression effect of osteoclasts differentiation, due to their 1D nanostructure that provides a shearing force in dynamic magnetic field to induce sufficient and effective reactions in cells. Moreover, by loading Au nanoparticles in the mesopores, the 1D Fe3 O4 @nSiO2 @mSiO2 -Au nanochains can service as a catalytically active magnetic nanostirrer for hydrogenation of 4-nitrophenol with high catalytic performance and good magnetic recyclability.