Electrostatic Self‐Assembly of Au Nanoparticles onto Thermosensitive Magnetic Core‐Shell Microgels for Thermally Tunable and Magnetically Recyclable Catalysis

A facile route to fabricate a nanocomposite of Fe₃O₄@poly[N‐isopropylacrylamide (NIPAM)‐co‐2‐(dimethylamino)ethyl methacrylate (DMAEMA)]@Au (Fe₃O₄@PND@Au) is developed for magnetically recyclable and thermally tunable catalysis. The negatively charged Au nanoparticles with an average diameter of 10 nm are homogeneously loaded onto positively charged thermoresponsive magnetic core‐shell microgels of Fe₃O₄@poly(NIPAM‐co‐DMAEMA) (Fe₃O₄@PND) through electrostatic self‐assembly. This type of attachment offers perspectives for using charged polymeric shell on a broad variety of nanoparticles to immobilize the opposite‐charged nanoparticles. The thermosensitive PND shell with swollen or collapsed properties can be as a retractable Au carrier, thereby tuning the aggregation or dispersion of Au nanoparticles, which leads to an increase or decrease of catalytic activity. Therefore, the catalytic activity of Fe₃O₄@PND@Au can be modulated by the volume transition of thermosensitive microgel shells. Importantly, the mode of tuning the aggregation or dispersion of Au nanoparticles using a thermosensitive carrier offers a novel strategy to adjust and control the catalytic activity, which is completely different with the traditional regulation mode of controlling the diffusion of reactants toward the catalytic Au core using the thermosensitive poly(N‐isopropylacrylamide) network as a nanogate. Concurrent with the thermally tunable catalysis, the magnetic susceptibility of magnetic cores enables the Fe₃O₄@PND@Au nanocomposites to be capable of serving as smart nanoreactors for thermally tunable and magnetically recyclable catalysis.     

Amphiphilic Block Copolymers Directed Interface Coassembly to Construct Multifunctional Microspheres with Magnetic Core and Monolayer Mesoporous Aluminosilicate Shell

Core–shell magnetic porous microspheres have wide applications in drug delivery, catalysis and bioseparation, and so on. However, it is great challenge to controllably synthesize magnetic porous microspheres with uniform well‐aligned accessible large mesopores (>10 nm) which are highly desired for applications involving immobilization or adsorption of large guest molecules or nanoobjects. In this study, a facile and general amphiphilic block copolymer directed interfacial coassembly strategy is developed to synthesize core–shell magnetic mesoporous microspheres with a monolayer of mesoporous shell of different composition (FDUcs‐17D), such as core–shell magnetic mesoporous aluminosilicate (CS‐MMAS), silica (CS‐MMS), and zirconia‐silica (CS‐MMZS), open and large pores by employing polystyrene‐block‐poly (4‐vinylpyridine) (PS‐b‐P4VP) as an interface structure directing agent and aluminum acetylacetonate (Al(acac)₃), zirconium acetylacetonate, and tetraethyl orthosilicate as shell precursors. The obtained CS‐MMAS microspheres possess magnetic core, perpendicular mesopores (20–32 nm) in the shell, high surface area (244.7 m² g^?1), and abundant acid sites (0.44 mmol g^?1), and as a result, they exhibit superior performance in removal of organophosphorus pesticides (fenthion) with a fast adsorption dynamics and high adsorption capacity. CS‐MMAS microspheres loaded with Au nanoparticles (≈3.5 nm) behavior as a highly active heterogeneous nanocatalyst for N‐alkylation reaction for producing N‐phenylbenzylamine with a selectivity and yields of over 90% and good magnetic recyclability.     

Fabrication and characterization of 1 D Fe<Subscript>3</Subscript>O<Subscript>4</Subscript>/P(NIPAM–MAA–MBA) nanochains with thermo- and pH-responsive shell for controlled release for phenolphthalein

One-dimensional (1D) Fe₃O₄/poly(N-isopropylacrylamide-methacrylic acid-N,N′ -methylenebisacrylamide)(Fe₃O₄/P(NIPAM–MAA–MBA)) peapod-like nanochains have been successfully synthesized by magnetic field-induced precipitation polymerization. Fe₃O₄ microspheres modified with vinyl groups can be arranged with the direction of the external magnetic field in a line and linked permanently via P(NIPAM–MAA–MBA) coating during precipitation polymerization. The properties of 1D Fe₃O₄/P(NIPAM–MAA–MBA) were characterized by transmission electron microscopy, X-ray diffraction, thermogravimetric analysis (TGA), vibrating sample magnetometry, X-ray photoelectron spectroscopy, and UV–Vis spectrophotometer. Magnetic measurement revealed that these 1D peapod-like nanochains showed highly magnetic sensitivity. The thermal- and pH- response of 1D magnetic Fe₃O₄/P(NIPAM–MAA–MBA) nanochains was investigated by the temperature/pH dependence of hydrodynamic radius of Fe₃O₄/P(NIPAM–MAA–MBA) microspheres. The release behavior of phenolphthalein from 1D magnetic Fe₃O₄/P(NIPAM–MAA–MBA) nanochains could be effectively controlled by changing the temperature/pH values.     

Nonsacrificial Self‐Template Synthesis of Colloidal Magnetic Yolk–Shell Mesoporous Organosilicas for Efficient Oil/Water Interface Catalysis

Using interfacial reaction systems for biphasic catalytic reactions is attracting more and more attention due to their simple reaction process and low environmental pollution. Yolk–shell structured materials have broad applications in biomedicine, catalysis, and environmental remediation owing to their open channels and large space for guest molecules. Conventional methods to obtain yolk–shell mesoporous materials rely on costly and complex hard‐template strategies. In this study, a mild and convenient nonsacrificial self‐template strategy is developed to construct yolk–shell magnetic periodic mesoporous organosilica (YS‐mPMO) particles by using the unique swelling–deswelling property of low‐crosslinking density resorcinol formaldehyde (RF). The obtained YS‐mPMO microspheres possess an amphiphilic outer shell, high surface area (393 m² g^?1), uniform mesopores (2.58 nm), a tunable middle hollow space (50–156 nm), and high superparamagnetism (34.4–37.1 emu g^?1). By tuning the synthesis conditions, heterojunction structured yolk–shell Fe₃O₄@RF@void@PMO particles with different morphologies can be produced. Owing to the amphipathy of PMO framworks, the YS‐mPMO particles show great emulsion stabilization ability and recyclability under a magnetic field. YS‐mPMO microspheres with immobilized Au nanoparticles (≈3 nm) act as both solid emulsifier for dispersing styrene (St) in water and interface catalysts for selective conversion of St into styrene oxide with a high selectivity of 86%, and yields of over 97%.     

Multifunctional Magnetic Gd3+‐Based Coordination Polymer Nanoparticles: Combination of Magnetic Resonance and Multispectral Optoacoustic Detections for Tumor‐Targeted Imaging in vivo

To overcome traditional barriers in optical imaging and microscopy, optoacoustic‐imaging has been changed to combine the accuracy of spectroscopy with the depth resolution of ultrasound, achieving a novel modality with powerful in vivo imaging. However, magnetic resonance imaging provides better spatial and anatomical resolution. Thus, a single hybrid nanoprobe that allows for simultaneous multimodal imaging is significant not only for cutting edge research in imaging science, but also for accurate clinical diagnosis. A core‐shell‐structured coordination polymer composite microsphere has been designed for in vivo multimodality imaging. It consists of a Fe₃O₄ nanocluster core, a carbon sandwiched layer, and a carbocyanine‐Gd^III (Cy‐Gd^III) coordination polymer outer shell (Fe₃O₄@C@Cy‐Gd^III). Folic acid‐conjugated poly(ethylene glycol) chains are embedded within the coordination polymer shell to achieve extended circulation and targeted delivery of probe particles in vivo. Control of Fe₃O₄ core grain sizes results in optimal r₂ relaxivity (224.5 × 10^–3 m ⁻¹ s^‐1) for T₂‐weighted magnetic resonance imaging. Cy‐Gd^III coordination polymers are also regulated to obtain a maximum 25.1% of Cy ligands and 5.2% of Gd^III ions for near‐infrared fluorescence and T₁‐weighted magnetic resonance imaging, respectively. The results demonstrate their impressive abilities for targeted, multimodal, and reliable imaging.     

Fabrication of superparamagnetic hydroxyapatite with highly ordered three-dimensional pores

Hydroxyapatite (HA) with highly ordered three-dimensional pores, whose size is about 300 nm, was prepared by colloidal template method. The effect of the surface modification of silica spheres on the order degree of porous structure was investigated by field emission scanning electron microscopy (FESEM). Then, superparamagnetic Fe₃O₄ nanoparticles were fabricated via redox reaction, followed by coating with silica via a sol–gel process, in which a certain amount of TEOS was used in order to control the thickness of the silica shell. X-ray diffraction (XRD), transmission electron microscopy (TEM), and magnetometry were applied to characterize the properties. Finally, Fe₃O₄ magnetic nanoparticles coated with silica were adsorbed in the mesopores of HA with highly ordered three-dimensional pores by capillarity. The influence of dispersing agent on the adsorption results has been studied. Magnetometry was applied to characterize the magnetic properties of superparamagnetic HA. The quantities of adsorbed SiO₂/Fe₃O₄ nanoparticles with core–shell have been compared by variation of saturation magnetization before and after adsorption.     

Giant Magnetic Heat Induction of Magnesium‐Doped γ‐Fe2O3 Superparamagnetic Nanoparticles for Completely Killing Tumors

Magnetic fluid hyperthermia has been recently considered as a Renaissance of cancer treatment modality due to its remarkably low side effects and high treatment efficacy compared to conventional chemotheraphy or radiotheraphy. However, insufficient AC induction heating power at a biological safe range of AC magnetic field (H_appl·f_appl < 3.0–5.0 × 10⁹ A m^?1 s^?1), and highly required biocompatibility of superparamagnetic nanoparticle (SPNP) hyperthermia agents are still remained as critical challenges for successful clinical hyperthermia applications. Here, newly developed highly biocompatible magnesium shallow doped γ‐Fe₂O₃ (Mg_0.13‐γFe₂O₃) SPNPs with exceptionally high intrinsic loss power (ILP) in a range of 14 nH m² kg^?1, which is an ≈100 times higher than that of commercial Fe₃O₄ (Feridex, ILP = 0.15 nH m² kg^?1) at H_appl·f_appl = 1.23 × 10⁹ A m^?1 s^?1 are reported. The significantly enhanced heat induction characteristics of Mg_0.13‐γFe₂O₃ are primarily due to the dramatically enhanced out‐of‐phase magnetic susceptibility and magnetically tailored AC/DC magnetic softness resulted from the systematically controlled Mg²⁺ cations distribution and concentrations in octahedral site Fe vacancies of γ‐Fe₂O₃ instead of well‐known Fe₃O₄ SPNPs. In vitro and in vivo magnetic hyperthermia studies using Mg_0.13‐γFe₂O₃ nanofluids are conducted to estimate bioavailability and biofeasibility. Mg_0.13‐γFe₂O₃ nanofluids show promising hyperthermia effects to completely kill the tumors.     

Immobilization of ALA‐ZnII Coordination Polymer Pro‐photosensitizers on Magnetite Colloidal Supraparticles for Target Photodynamic Therapy of Bladder Cancer

5‐Aminolevulinic acid (ALA) is a widely used photodynamic therapy (PDT) prodrug in the clinic. It can be metalized to the photosensitizer PpIX, which produces toxic singlet oxygen to kill cancer cells upon visible light irradiation. Herein, a core/shell‐structured vehicle is designed to comprise magnetite colloidal supraparticles (MCSPs) as cores and ALA‐Zn^II coordination polymers as shells (Fe₃O₄@ALA‐Zn^II) for target pro‐photosensitizer delivery. The coordination polymers with 2D layered structures are locally deposited on the MCSPs by the complexation of the ALA and Zn^II ions, and are readily controlled by varying the feed precursors and reaction temperatures. The maximum conjugated ALA amount is up to 17%. The Fe₃O₄@ALA‐Zn^II microspheres exhibit pH‐sensitive release of ALA in acidic environment and rapid magnetic responsiveness. Cytotoxicity results demonstrate that Fe₃O₄@ALA‐Zn^II shows a significant inhibitory effect to T24 cells and is nontoxic to 293T normal cells as exposed to the 630 nm visible light for a very short time, which may due to the selective accumulation of ALA‐induced PpIX in T24 cancer cells. Compared to the ALA used alone, the coordination polymer form is more efficient because of the bioactivity of incorporated Zn ions despite underlying the same apoptosis mechanism as ALA agent.     

Platelet Membrane‐Camouflaged Magnetic Nanoparticles for Ferroptosis‐Enhanced Cancer Immunotherapy

Although cancer immunotherapy has emerged as a tremendously promising cancer therapy method, it remains effective only for several cancers. Photoimmunotherapy (e.g., photodynamic/photothermal therapy) could synergistically enhance the immune response of immunotherapy. However, excessively generated immunogenicity will cause serious inflammatory response syndrome. Herein, biomimetic magnetic nanoparticles, Fe₃O₄‐SAS @ PLT, are reported as a novel approach to sensitize effective ferroptosis and generate mild immunogenicity, enhancing the response rate of non‐inflamed tumors for cancer immunotherapy. Fe₃O₄‐SAS@PLT are built from sulfasalazine (SAS)‐loaded mesoporous magnetic nanoparticles (Fe₃O₄) and platelet (PLT) membrane camouflage and triggered a ferroptotic cell death via inhibiting the glutamate‐cystine antiporter system X_c^? pathway. Fe₃O₄‐SAS @ PLT‐mediated ferroptosis significantly improves the efficacy of programmed cell death 1 immune checkpoint blockade therapy and achieves a continuous tumor elimination in a mouse model of 4T1 metastatic tumors. Proteomics studies reveal that Fe₃O₄‐SAS @ PLT‐mediated ferroptosis could not only induce tumor‐specific immune response but also efficiently repolarize macrophages from immunosuppressive M2 phenotype to antitumor M1 phenotype. Therefore, the concomitant of Fe₃O₄‐SAS @ PLT‐mediated ferroptosis with immunotherapy are expected to provide great potential in the clinical treatment of tumor metastasis.     

Patterning Graphene Surfaces with Iron‐Oxide‐Embedded Mesoporous Polypyrrole and Derived N‐Doped Carbon of Tunable Pore Size

This study develops a novel strategy, based on block copolymer self‐assembly in solution, for preparing two‐dimensional (2D) graphene‐based mesoporous nanohybrids with well‐defined large pores of tunable sizes, by employing polystyrene‐block‐poly(ethylene oxide) (PS‐b‐PEO) spherical micelles as the pore‐creating template. The resultant 2D nanohybrids possess a sandwich‐like structure with Fe₂O₃ nanoparticle‐embedded mesoporous polypyrrole (PPy) monolayers grown on both sides of reduced graphene oxide (rGO) nanosheets (denoted as mPPy‐Fe₂O₃@rGO). Serving as supercapacitor electrode materials, the 2D ternary nanohybrids exhibit controllable capacitive performance depending on the pore size, with high capacitance (up to 1006 F/g at 1 A/g), good rate performance (750 F/g at 20 A/g) and excellent cycling stability. Furthermore, the pyrolysis of mPPy‐Fe₂O₃@rGO at 800 °C yields 2D sandwich‐like mesoporous nitrogen‐doped carbon/Fe₃O₄/rGO (mNC‐Fe₃O₄@rGO). The mNC‐Fe₃O₄@rGO nanohybrids with a mean pore size of 12 nm show excellent electrocatalytic activity as an oxygen reduction reaction (ORR) catalyst with a four‐electron transfer nature, a high half‐wave‐potential of +0.84 V and a limiting current density of 5.7 mA/cm², which are well comparable with those of the best commercial Pt/C catalyst. This study takes advantage of block copolymer self‐assembly for the synthesis of 2D multifunctional mesoporous nanohybrids, and helps to understand the control of their structures and electrochemical performance.     

Binary Superlattices from {Mo132} Polyoxometalates and Maghemite Nanocrystals: Long‐Range Ordering and Fine‐Tuning of Dipole Interactions

In the present article, the successful coassembly of spherical 6.2 nm maghemite (γ‐Fe₂O₃) nanocrystals and giant polyoxometalates (POMs) such as 2.9 nm {Mo₁₃₂} is demonstrated. To do so, colloidal solutions of oleic acid‐capped γ‐Fe₂O₃ and long‐chain alkylammonium‐encapsulated {Mo₁₃₂} dispersed in chloroform are mixed together and supported self‐organized binary superlattices are obtained upon the solvent evaporation on immersed substrates. Both electronic microscopy and small angles X‐ray scattering data reveal an AB‐type structure and an enhanced structuration of the magnetic nanocrystals (MNCs) assembly with POMs in octahedral interstices. Therefore, {Mo₁₃₂} acts as an efficient binder constituent for improving the nanocrystals ordering in 3D films. Interestingly, in the case of didodecyldimethylammonium (C₁₂)‐encapsulated POMs, the long‐range ordered binary assemblies are obtained while preserving the nanocrystals magnetic properties due to weak POMs–MNCs interactions. On the other hand, POMs of larger effective diameter can be employed as spacer blocks for MNCs as shown by using {Mo₁₃₂} capped with dioctadecyldimethylammonium (C₁₈) displaying longer chains. In that case, it is shown that POMs can also be used for fine‐tuning the dipolar interactions in γ‐Fe₂O₃ nanocrystal assemblies.     

FeIII‐Doped Two‐Dimensional C3N4 Nanofusiform: A New O2‐Evolving and Mitochondria‐Targeting Photodynamic Agent for MRI and Enhanced Antitumor Therapy

Local hypoxia in tumors, as well as the short lifetime and limited action region of ¹O₂, are undesirable impediments for photodynamic therapy (PDT), leading to a greatly reduced effectiveness. To overcome these adversities, a mitochondria‐targeting, H₂O₂‐activatable, and O₂‐evolving PDT nanoplatform is developed based on Fe^III‐doped two‐dimensional C₃N₄ nanofusiform for highly selective and efficient cancer treatment. The ultrahigh surface area of 2D nanosheets enhances the photosensitizer (PS) loading capacity and the doping of Fe^III leads to peroxidase mimetics with excellent catalytic performance towards H₂O₂ in cancer cells to generate O₂. As such tumor hypoxia can be overcome and the PDT efficacy is improved, whilst at the same time endowing the PDT theranostic agent with an effective T ₁‐weighted in vivo magnetic resonance imaging (MRI) ability. Conjugation with a mitochondria‐targeting agent could further increase the sensitivity of cancer cells to ¹O₂ by enhanced mitochondria dysfunction. In vitro and in vivo anticancer studies demonstrate an outstanding therapeutic effectiveness of the developed PDT agent, leading to almost complete destruction of mouse cervical tumor. This development offers an attractive theranostic agent for in vivo MRI and synergistic photodynamic therapy toward clinical applications.     

Fluorescent Magnetic Fe3O4/Rare Earth Colloidal Nanoparticles for Dual‐Modality Imaging

Fluorescent magnetic colloidal nanoparticles (FMCNPs) are produced by a two‐step, seed emulsifier‐free emulsion polymerization in the presence of oleic acid and sodium undecylenate‐modified Fe₃O₄ nanoparticles (NPs). The Fe₃O₄/poly(St‐co‐GMA) nanoparticles are first synthesized as the seed and Eu(AA)₃Phen is copolymerized with the remaining St and GMA to form the fluorescent polymer shell in the second step. The uniform core–shell structured FMCNPs with a mean diameter of 120 nm exhibit superparamagnetism with saturation magnetization of 1.92 emu/g. Red luminescence from the FMCNPs is confirmed by the salient fluorescence emission peaks of europium ions at 594 and 619 nm as well as 2‐photon confocal scanning laser microscopy. The in vitro cytotoxicity test conducted using the MTT assay shows good cytocompatibility and the T₂ relaxivity of the FMCNPs is 353.86 mM^?1S^?1 suggesting its potential in magnetic resonance imaging (MRI). In vivo MRI studies based on a rat model show significantly enhanced T₂‐weighted images of the liver after administration and prussian blue staining of the liver tissue slice reveals accumulation of FMCNPs in the organ. The cytocompatibility, superparamagnetism, and excellent fluorescent properties of FMCNPs make them suitable for biological imaging probes in MRI and optical imaging.     

S‐Doped TiSe2 Nanoplates/Fe3O4 Nanoparticles Heterostructure

2D Sulfur‐doped TiSe₂/Fe₃O₄ (named as S‐TiSe₂/Fe₃O₄) heterostructures are synthesized successfully based on a facile oil phase process. The Fe₃O₄ nanoparticles, with an average size of 8 nm, grow uniformly on the surface of S‐doped TiSe₂ (named as S‐TiSe₂) nanoplates (300 nm in diameter and 15 nm in thickness). These heterostructures combine the advantages of both S‐TiSe₂ with good electrical conductivity and Fe₃O₄ with high theoretical Li storage capacity. As demonstrated potential applications for energy storage, the S‐TiSe₂/Fe₃O₄ heterostructures possess high reversible capacities (707.4 mAh g⁻¹ at 0.1 A g⁻¹ during the 100th cycle), excellent cycling stability (432.3 mAh g⁻¹ after 200 cycles at 5 A g⁻¹), and good rate capability (e.g., 301.7 mAh g⁻¹ at 20 A g⁻¹) in lithium‐ion batteries. As for sodium‐ion batteries, the S‐TiSe₂/Fe₃O₄ heterostructures also maintain reversible capacities of 402.3 mAh g⁻¹ at 0.1 A g⁻¹ after 100 cycles, and a high rate capacity of 203.3 mAh g⁻¹ at 4 A g⁻¹.     

Dipolar‐Distribution Cavity γ‐Fe2O3@C@α‐MnO2 Nanospindle with Broadened Microwave Absorption Bandwidth by Chemically Etching

Developing microwave absorption materials with ultrawide bandwidth and low density still remains a challenge, which restricts their actual application in electromagnetic signal anticontamination and defense stealth technology. Here a series of olive‐like γ‐Fe₂O₃@C core–shell spindles with different shell thickness and γ‐Fe₂O₃@C@α‐MnO₂ spindles with different volumes of dipolar‐distribution cavities were successfully prepared. Both series of absorbers exhibit excellent absorption properties. The γ‐Fe₂O₃@C@α‐MnO₂ spindle with controllable cavity volume exhibits an effective absorption (2O₃@C spindle reaches as high as ?45 dB because of the optimized electromagnetic impedance balance between polymer shell and γ‐Fe₂O₃ core. Intrinsic ferromagnetism of the anisotropy spindle is confirmed by electron holography. Strong coupling of magnetic flux stray lines between spindles is directly imaged. This unique morphology and facile etching technique might facilitate the study of core–shell type microwave absorbers.     

Multifunctional Yolk‐in‐Shell Nanoparticles for pH‐triggered Drug Release and Imaging

Multifunctional nanoparticles are synthesized for both pH‐triggered drug release and imaging with radioluminescence, upconversion luminescent, and magnetic resonance imaging (MRI). The particles have a yolk‐in‐shell morphology, with a radioluminescent core, an upconverting shell, and a hollow region between the core and shell for loading drugs. They are synthesized by controlled encapsulation of a radioluminescent nanophosphor yolk in a silica shell, partial etching of the yolk in acid, and encapsulation of the silica with an upconverting luminescent shell. Metroxantrone, a chemotherapy drug, was loaded into the hollow space between X‐ray phosphor yolk and up‐conversion phosphor shell through pores in the shell. To encapsulate the drug and control the release rate, the nanoparticles are coated with pH‐responsive biocompatible polyelectrolyte layers of charged hyaluronic acid sodium salt and chitosan. The nanophosphors display bright luminescence under X‐ray, blue light (480 nm), and near infrared light (980 nm). They also served as T₁ and T₂ MRI contrast agents with relaxivities of 3.5 mM^?1 s^?1 (r₁) and 64 mM^?1s^?1 (r₂). These multifunctional nanocapsules have applications in controlled drug delivery and multimodal imaging.     

Rational Design of Multifunctional Fe@γ‐Fe2O3@H‐TiO2 Nanocomposites with Enhanced Magnetic and Photoconversion Effects for Wide Applications: From Photocatalysis to Imaging‐Guided Photothermal Cancer Therapy

Titanium dioxide (TiO₂) has been widely investigated and used in many areas due to its high refractive index and ultraviolet light absorption, but the lack of absorption in the visible–near infrared (Vis–NIR) region limits its application. Herein, multifunctional Fe@γ‐Fe₂O₃@H‐TiO₂ nanocomposites (NCs) with multilayer‐structure are synthesized by one‐step hydrogen reduction, which show remarkably improved magnetic and photoconversion effects as a promising generalists for photocatalysis, bioimaging, and photothermal therapy (PTT). Hydrogenation is used to turn white TiO₂ in to hydrogenated TiO₂ (H‐TiO₂), thus improving the absorption in the Vis–NIR region. Based on the excellent solar‐driven photocatalytic activities of the H‐TiO₂ shell, the Fe@γ‐Fe₂O₃ magnetic core is introduced to make it convenient for separating and recovering the catalytic agents. More importantly, Fe@γ‐Fe₂O₃@H‐TiO₂ NCs show enhanced photothermal conversion efficiency due to more circuit loops for electron transitions between H‐TiO₂ and γ‐Fe₂O₃, and the electronic structures of Fe@γ‐Fe₂O₃@H‐TiO₂ NCs are calculated using the Vienna ab initio simulation package based on the density functional theory to account for the results. The reported core–shell NCs can serve as an NIR‐responsive photothermal agent for magnetic‐targeted photothermal therapy and as a multimodal imaging probe for cancer including infrared photothermal imaging, magnetic resonance imaging, and photoacoustic imaging.     

A General and Straightforward Route to Noble Metal‐Decorated Mesoporous Transition‐Metal Oxides with Enhanced Gas Sensing Performance

Controllable and efficient synthesis of noble metal/transition‐metal oxide (TMO) composites with tailored nanostructures and precise components is essential for their application. Herein, a general mercaptosilane‐assisted one‐pot coassembly approach is developed to synthesize ordered mesoporous TMOs with agglomerated‐free noble metal nanoparticles, including Au/WO₃, Au/TiO₂, Au/NbO_x, and Pt/WO₃. 3‐mercaptopropyl trimethoxysilane is applied as a bridge agent to cohydrolyze with metal oxide precursors by alkoxysilane moieties and interact with the noble metal source (e.g., HAuCl₄ and H₂PtCl₄) by mercapto (? SH) groups, resulting in coassembly with poly(ethylene oxide)‐b‐polystyrene. The noble metal decorated TMO materials exhibit highly ordered mesoporous structure, large pore size (≈14–20 nm), high specific surface area (61–138 m² g^?1), and highly dispersed noble metal (e.g., Au and Pt) nanoparticles. In the system of Au/WO₃, in situ generated SiO₂ incorporation not only enhances their thermal stability but also induces the formation of ε‐phase WO₃ promoting gas sensing performance. Owning to its specific compositions and structure, the gas sensor based on Au/WO₃ materials possess enhanced ethanol sensing performance with a good response (R_air/R_gas = 36–50 ppm of ethanol), high selectivity, and excellent low‐concentration detection capability (down to 50 ppb) at low working temperature (200 °C).     

Degradation‐Restructuring Induced Anisotropic Epitaxial Growth for Fabrication of Asymmetric Diblock and Triblock Mesoporous Nanocomposites

A novel degradation‐restructuring induced anisotropic epitaxial growth strategy is demonstrated for the synthesis of uniform 1D diblock and triblock silica mesoporous asymmetric nanorods with controllable rod length (50 nm to 2 µm) and very high surface area of 1200 m² g^?1. The asymmetric diblock mesoporous silica nanocomposites are composed of a 1D mesoporous organosilicate nanorod with highly ordered hexagonal mesostructure, and a closely connected dense SiO₂ nanosphere located only on one side of the nanorods. Furthermore, the triblock mesoporous silica nanocomposites constituted by a cubic mesostructured nanocube, a nanosphere with radial mesopores, and a hexagonal mesostructured nanorod can also be fabricated with the anisotropic growth of mesopores. Owing to the ultrahigh surface area, unique 1D mesochannels, and functionality asymmetry, the obtained match‐like asymmetric Au‐NR@SiO₂&EPMO (EPMO = ethane bridged periodic mesoporous organosilica) mesoporous nanorods can be used as an ideal nanocarrier for the near‐infrared photothermal triggered controllable releasing of drug molecules.     

Rattle‐Type Fe3O4@SiO2 Hollow Mesoporous Spheres as Carriers for Drug Delivery

Rattle‐type Fe₃O₄@SiO₂ hollow mesoporous spheres with different particle sizes, different mesoporous shell thicknesses, and different levels of Fe₃O₄ content are prepared by using carbon spheres as templates. The effects of particle size and concentration of Fe₃O₄@SiO₂ hollow mesoporous spheres on cell uptake and their in vitro cytotoxicity to HeLa cells are evaluated. The spheres exhibit relatively fast cell uptake. Concentrations of up to 150 µg mL^?1 show no cytotoxicity, whereas a concentration of 200 µg mL^?1 shows a small amount of cytotoxicity after 48 h of incubation. Doxorubicin hydrochloride (DOX), an anticancer drug, is loaded into the Fe₃O₄@SiO₂ hollow mesoporous spheres, and the DOX‐loaded spheres exhibit a somewhat higher cytotoxicity than free DOX. These results indicate the potential of Fe₃O₄@SiO₂ hollow mesoporous spheres for drug loading and delivery into cancer cells to induce cell death.