Hybrid “Golden Fleece”: Synthesis and Catalytic Performance of Uniform Carbon Nanofibers and Silica Nanotubes Embedded with a High Population of Noble‐Metal Nanoparticles

Carbon nanofibers produced by hydrothermal carbonization display remarkable reactivity and the capability for in situ loading with very fine noble‐metal nanoparticles of metals such as Pd, Pt, and Au. Large quantities of uniform carbon nanofibers embedded/confined with various kinds of noble‐metal nanoparticles can be easily prepared, resulting in the formation of the so‐called uniform and well‐defined “hybrid fleece” structures. In addition, a general method has been developed to synthesize uniform silica nanotubes embedded/confined with noble‐metal nanoparticles by using the “hybrid fleece” consisting of carbon nanofibers loaded with noble‐metal nanoparticles as a template. To the best of our knowledge, the filling of silica nanotubes with a dense population of noble‐metal nanoparticles has not been demonstrated so far. These hybrid carbon structures embedded with noble‐metal nanoparticles in a heterogeneous “fleece” geometry serve as excellent catalysts for a model reaction involving the conversion of CO to CO₂ at low temperatures.     

Incorporation of Functionalized Palladium Nanoparticles within Ultrathin Nafion Films: A Nanostructured Composite for Electrolytic and Redox‐Mediated Hydrogen Evolution

A novel ultrathin Nafion‐palladium nanocomposite film is developed by incorporating positively charged Pd nanoparticles, stabilized with dimethylaminopyridine (DMAP), into Nafion Langmuir‐Schaefer (LS) films. The films show considerable activity for the redox‐catalyzed hydrogen‐evolution reaction, the rate of which scales with film thickness. The Nafion film can be deposited on both insulating (glass) and electrode (indium‐tin oxide) surfaces. The quantity of Pd nanoparticles immobilized can be controlled simply via the thickness of the Nafion film. The morphology of the films are investigated using AFM, which allows the number density of nanoparticles to be estimated for the thinnest (10 layers; 18 nm) films. Incorporation of nanoparticles is also determined with cyclic voltammetry and UV‐visible spectroscopy. The former method allows estimation of the electrochemically active surface area of Pd wired to the underlying electrode. A novel scanning electrochemical microscopy (SECM) approach is used to investigate the kinetics of the hydrogen evolution reaction (HER) catalyzed by Pd nanoparticles within the Nafion film, which allows the intrinsic activity to be determined. Single nanoparticle reactivities are extracted and are comparable to the activity of native nanoparticles on glass and to bulk Pd. It is found that neither Nafion encapsulation nor DMAP functionalization impair the electrocatalytic activity of these nanoparticles towards the HER. Nafion encapsulation thus provides a framework for the formation of interfaces, whose activity scales with film thickness. The creation of 3D materials opens up the possibility of carrying out redox‐mediated hydrogen evolution using solution species as the electron donor.     

Synthesis of Metal Nanoparticles via Self‐Regulated Reduction by an Alcohol Surfactant

A new method for the synthesis of noble metal nanoparticles has been developed whereby an alcohol‐type surfactant, sodium alkyl sulfate (SC_nS), is used as the reductant, and there is no need for an external reducing agent. By changing the carbon chain length of the surfactant, the diameter of the nanoparticles could be controlled. The Pd nanoparticles/SDS (where SDS is sodium dodecyl sulfate) could be redispersed in both aqueous and non‐polar organic solvents, probably because 1‐dodecanol was released from SDS and then coadsorbed with SDS on the surface of the nanoparticles. Additionally, a highly ordered 3D “spheres–around–sphere” type nanostructure was found in the Pd nanoparticles/SC₁₀S system. This configuration involved the transformation of the liquid crystal phase of the micelle molecules from micellar to lamellar.     

“Ship‐in‐a‐Bottle” Growth of Noble Metal Nanostructures

Noble metal nanostructures are grown inside hollow mesoporous silica microspheres using “ship‐in‐a‐bottle” growth. Small Au seeds are first introduced into the interior of the hollow microspheres. Au nanorods with synthetically tunable longitudinal plasmon wavelengths and Au nanospheres are obtained through seed‐mediated growth within the microspheres. The encapsulated Au nanocrystals are further coated with Pd or Pt shells. The microsphere‐encapsulated bimetallic core/shell nanostructures can function as catalysts. They exhibit high catalytic performance and their stability is superior to that of the corresponding unencapsulated core/shell nanostructures in the catalytic oxidation of o‐phenylenediamine with hydrogen peroxide. Therefore, these hollow microsphere‐encapsulated metal nanostructures are promising as recoverable and efficient catalysts for various liquid‐phase catalytic reactions.     

Cover Picture: Synthesis of Gadolinium‐Labeled Shell‐Crosslinked Nanoparticles for Magnetic Resonance Imaging Applications (Adv. Funct. Mater. 8/2005)

Robust, amphiphilic core–shell nanoparticles that are selectively labeled with gadolinium in the hydrophilic and water‐swollen shell layer are depicted in the cover picture. These well‐defined nanostructured materials exhibit high relaxivity, a large loading capacity, and are based upon a biocompatible platform for ultimate function in magnetic resonance imaging (MRI) applications, as reported by Wooley and co‐workers on p. 1248. Shell‐crosslinked knedel‐like nanoparticles (SCKs; “knedel” is a Polish term for dumplings) were derivatized with gadolinium chelates and studied as robust magnetic‐resonance‐imaging‐active structures with hydrodynamic diameters of 40 ± 3 nm. SCKs possessing an amphiphilic core–shell morphology were produced from the aqueous assembly of diblock copolymers of poly‐(acrylic acid) (PAA) and poly(methyl acrylate) (PMA), PAA₅₂–b–PMA₁₂₈, and subsequent covalent crosslinking by amidation upon reaction with 2,2′‐(ethylenedioxy)bis(ethylamine) throughout the shell layer. The properties of these materials, including non‐toxicity towards mammalian cells, non‐immunogenicity within mice, and capability for polyvalent targeting, make them ideal candidates for utilization within biological systems. The synthesis of SCKs derivatized with Gd^III and designed for potential use as a unique nanometer‐scale contrast agent for MRI applications is described herein. Utilization of an amino‐functionalized diethylenetriaminepentaacetic acid–Gd analogue allowed for direct covalent conjugation throughout the hydrophilic shell layer of the SCKs and served to increase the rotational correlation lifetime of the Gd. In addition, the highly hydrated nature of the shell layer in which the Gd was located allowed for rapid water exchange; thus, the resulting material demonstrated large ionic relaxivities (39 s^–1 mM^–1) in an applied magnetic field of 0.47 T at 40 °C and, as a result of the large loading capacity of the material, also demonstrated high molecular relaxivities (20 000 s^–1 mM^–1).     

Synthesis of Gadolinium‐Labeled Shell‐Crosslinked Nanoparticles for Magnetic Resonance Imaging Applications

Shell‐crosslinked knedel‐like nanoparticles (SCKs; “knedel” is a Polish term for dumplings) were derivatized with gadolinium chelates and studied as robust magnetic‐resonance‐imaging‐active structures with hydrodynamic diameters of 40 ± 3 nm. SCKs possessing an amphiphilic core–shell morphology were produced from the aqueous assembly of diblock copolymers of poly‐(acrylic acid) (PAA) and poly(methyl acrylate) (PMA), PAA₅₂–b–PMA₁₂₈, and subsequent covalent crosslinking by amidation upon reaction with 2,2′‐(ethylenedioxy)bis(ethylamine) throughout the shell layer. The properties of these materials, including non‐toxicity towards mammalian cells, non‐immunogenicity within mice, and capability for polyvalent targeting, make them ideal candidates for utilization within biological systems. The synthesis of SCKs derivatized with Gd^III and designed for potential use as a unique nanometer‐scale contrast agent for MRI applications is described herein. Utilization of an amino‐functionalized diethylenetriaminepentaacetic acid–Gd analogue allowed for direct covalent conjugation throughout the hydrophilic shell layer of the SCKs and served to increase the rotational correlation lifetime of the Gd. In addition, the highly hydrated nature of the shell layer in which the Gd was located allowed for rapid water exchange; thus, the resulting material demonstrated large ionic relaxivities (39 s^–1 mM^–1) in an applied magnetic field of 0.47 T at 40 °C and, as a result of the large loading capacity of the material, also demonstrated high molecular relaxivities (20 000 s^–1 mM^–1).     

Enhanced Relaxometric Properties of MRI “Positive” Contrast Agents Confined in Three‐Dimensional Cubic Mesoporous Silica Nanoparticles

Mesoporous silica nanoparticles (MSNs) are of growing interest for the development of novel probes enabling efficient tracking of cells in vivo using magnetic resonance imaging (MRI). The incorporation of Gd³⁺ paramagnetic ions into highly porous MSNs is a powerful strategy to synthesize “positive” MRI contrast agents for more quantitative T₁‐weighted MR imaging. Within this context, different strategies have been reported to integrate Gd chelates to 2D pore network MSNs. As an alternative, we report on the modulation of the pore network topology through the preparation of a 3D pore network hybrid GdSi_xO_y MSN system. In this study, 2D GdSi_xO_y‐MSNs with similar porosity and particle size were also prepared and the relaxometric performances of both materials, directly compared. Both syntheses lead to water‐dispersible MSNs suspensions (particle size < 200 nm), which were stable for at least 48h. 3D GdSi_xO_y‐MSNs provided a significant increase in ¹H longitudinal relaxivity (18.5 s^?1mM^?1; 4.6 times higher than Gd‐DTPA) and low r₂/r₁ ratios (1.56) compatible with the requirements of “positive” contrast agents for MRI. These results demonstrate the superiority of a 3D pore network to host paramagnetic atoms for MRI signal enhancement using T₁‐weighted imaging. Such an approach minimizes the total amount of paramagnetic element per particle.     

PEGylated Polypyrrole Nanoparticles Conjugating Gadolinium Chelates for Dual‐Modal MRI/Photoacoustic Imaging Guided Photothermal Therapy of Cancer

Polypyrrole nanoparticles conjugating gadolinium chelates were successfully fabricated for dual‐modal magnetic resonance imaging (MRI) and photoacoustic imaging guided photothermal therapy of cancer, from a mixture of pyrrole and pyrrole‐1‐propanoic acid through a facile one‐step aqueous dispersion polymerization, followed by covalent attachment of gadolinium chelate, using polyethylene glycol as a linker. The obtained PEGylated poly­pyrrole nanoparticles conjugating gadolinium chelates (Gd‐PEG‐PPy NPs), sized around around 70 nm, exhibited a high T₁ relaxivity coefficient of 10.61 L mm ^?1 s^?1, more than twice as high as that of the relating free Gd³⁺ complex (4.2 L mm ^–1 s^?1). After 24 h intravenous injection of Gd‐PEG‐PPy NPs, the tumor sites exhibited obvious enhancement in both T₁‐weighted MRI intensity and photoacoustic signal compared with that before injection, indicating the efficient accumulation of Gd‐PEG‐PPy NPs due to the introduction of the PEG layer onto the particle surface. In addition, tumor growth could be effectively inhibited after treatment with Gd‐PEG‐PPy NPs in combination with near‐infrared laser irradiation. The passive targeting and high MRI/photo­acoustic contrast capability of Gd‐PEG‐PPy NPs are quite favorable for precise cancer diagnosing and locating the tumor site to guide the external laser irradiation for photothermal ablation of tumors without damaging the surrounding healthy tissues. Therefore, Gd‐PEG‐PPy NPs may assist in better monitoring the therapeutic process, and contribute to developing more effective “personalized medicine,” showing great potential for cancer diagnosis and therapy.     

Exceptional Oxygen Sensing Properties of New Blue Light‐Excitable Highly Luminescent Europium(III) and Gadolinium(III) Complexes

New europium(III) and gadolinium(III) complexes bearing 8‐hydroxyphenalenone antenna combine efficient absorption in the blue part of the spectrum and strong emission in polymers at room temperature. The Eu(III) complexes show characteristic red luminescence whereas the Gd(III) dyes are strongly phosphorescent. The luminescence quantum yields are about 20% for the Eu(III) complexes and 50% for the Gd(III) dyes. In contrast to most state‐of‐the‐art Eu(III) complexes the new dyes are quenched very efficiently by molecular oxygen. The luminescence decay times of the Gd(III) complexes exceed 1 ms which ensures exceptional sensitivity even in polymers of moderate oxygen permeability. These sensors are particularly suitable for trace oxygen sensing and may be good substitutes for Pd(II) porphyrins. The photophysical and sensing properties can be tuned by varying the nature of the fourth ligand. The narrow‐band emission of the Eu(III) allows efficient elimination of the background light and autofluorescence and is also very attractive for use e.g., in multi‐analyte sensors. The highly photostable indicators incorporated in nanoparticles are promising for imaging applications. Due to the straightforward preparation and low cost of starting materials the new dyes represent a promising alternative to the state‐of‐the‐art oxygen indicators particularly for such applications as, e.g., food packaging.     

A Micellar Route to Ordered Arrays of Magnetic Nanoparticles: From Size‐Selected Pure Cobalt Dots to Cobalt–Cobalt Oxide Core–Shell Systems

Starting with Co‐salt‐loaded inverse micelles, which form if the diblock copolymer polystyrene‐block‐poly(2‐vinylpyridine) is dissolved in a selective solvent like toluene and CoCl₂ is added to the solution, monomicellar arrays of such micelles exhibiting a significant hexagonal order can be prepared on top of various substrates with tailored intermicellar distances and structure heights. In order to remove the polymer matrix and to finally obtain arrays of pure Co nanoparticles, the micelles are first exposed to an oxygen plasma, followed by a treatment in a hydrogen plasma. Applying in‐situ X‐ray photoelectron spectroscopy, it is demonstrated that: 1) The oxygen plasma completely removes the polymer, though conserving the original order of the micellar array. Furthermore, the resulting nanoparticles are entirely oxidized with a chemical shift of the Co 2p_3/2 line pointing to the formation of Co₃O₄. 2) By the subsequent hydrogen plasma treatment the nanoparticles are fully reduced to metallic Co. 3) By exposing the pure Co nanoparticles for 100 s to various oxygen partial pressures pequation/tex2gif-inf-5.gif, a stepwise oxidation is observed with a still metallic Co core surrounded by an oxide shell. The data allow the extraction of the thickness of the oxide shell as a function of the total exposure to oxygen (pequation/tex2gif-inf-7.gif × time), thus giving the opportunity to control the ferromagnetic–antiferromagnetic composition of an exchange‐biased magnetic system.     

Preparation and Organization of Nanoscale Polyelectrolyte‐Coated Gold Nanoparticles

The layer‐by‐layer (LbL) desposition of oppositely charged polyelectrolytes from adsorption solutions of different ionic strength onto ～7 nm diameter carboxylic acid‐derivatized gold nanoparticles has been studied. The polyelectrolyte‐modified nanoparticles were characterized by UV‐vis spectrophotometry, microelectrophoresis, analytical ultracentrifugation, and transmission electron microscopy. UV‐vis data showed that the peak plasmon absorption wavelength of the gold nanoparticles red‐shifted after each adsorption step, and microelectrophoresis experiments revealed a reversal in the surface charge of the nanoparticles following deposition of each layer. These data are consistent with the formation of polyelectrolyte layers on the nanoparticles. Analytical ultracentrifugation showed an increase in mean nanoparticle diameter on adsorption of the polyelectrolytes, confirming the formation of gold‐core/polyelectrolyte‐shell nanoparticles. Transmission electron microscopy studies showed no signs of aggregation of the polyelectrolyte‐coated nanoparticles. The adsorption of the polyelectrolyte‐coated gold nanoparticles onto oppositely charged planar supports has also been examined. UV‐vis spectrophotometry and atomic force microscopy showed increased amounts of nanoparticles were adsorbed with increasing ionic strength of the nanoparticle dispersions. This allows control of the nanoparticle surface loading by varying the salt content in the nanoparticle dispersions used for adsorption. The LbL strategy used in this work is expected to be applicable to other nanoparticles (e.g., semiconductors, phosphors), thus providing a facile means for their controlled surface modification through polyelectrolyte nanolayering. Such nanoparticles are envisaged to have applications in the biomedical and bioanalytical fields, and to be useful building blocks for the creation of advanced nanoparticle‐based films.     

Targeted Tumor Hypoxia Dual‐Mode CT/MR Imaging and Enhanced Radiation Therapy Using Dendrimer‐Based Nanosensitizers

The efficacy of radiation therapy (RT) is often limited by the poor response of hypoxia inside most solid tumors. The development of a theranostic nanoplatform for precision‐imaging‐guided sensitized RT for tumor hypoxia is still challenging. Herein, the creation of hypoxia‐targeted dendrimer‐entrapped gold nanoparticles complexed with gadolinium(III) (Gd‐Au DENPs‐Nit) for dual‐mode CT/MR imaging and sensitized RT of hypoxic tumors is reported. In this work, generation 5 poly(amidoamine) dendrimers are partially conjugated with Gd(III) chelator, entrapped with Au nanoparticles, and conjugated with hypoxia‐targeting agent nitroimidazole via a polyethylene glycol linker, and ending with chelation of Gd(III) and conversion of their leftover amine termini to acetamides. The designed dendrimer‐based nanohybrids with 3.2 nm Au cores exhibit an excellent X‐ray attenuation effect, acceptable r₁ relaxivity (1.32 mM^?1 s^?1), and enhanced cellular uptake in hypoxic cancer cells, affording efficient dual‐mode CT/MR imaging of tumor hypoxia. Under X‐ray irradiation, the Gd‐Au DENPs‐Nit nanohybrids can produce reactive oxygen species, promote DNA damage, and prevent DNA repair, facilitating sensitized RT of hypoxic cancer cells in vitro and tumor hypoxia in vivo. The developed hypoxia‐targeted dendrimer‐based nanohybrids may be employed as both contrast agents and nanosensitizers for precision tumor hypoxia imaging and sensitized tumor RT.     

Programmable Arrays of “Micro‐Bubble” Constructs via Self‐Encapsulation

The fabrication of ordered arrays of self‐encapsulated “micro‐bubble” material constructs based on the capillary‐driven collapse of flexible silk fibroin sheets during propagation of the diffusion front of the encapsulated material is demonstrated. The individual micro‐bubbles of different shapes are composed of a sacrificial material encapsulated within the ultrathin silk coating, which covers and seals the inner material during dissolution of supporting layer. The array of microscopic rectangular multi‐layer silk sheets on supporting polymer layers can be selectively dissolved along the edges to initiate their self‐encapsulation. The resulting micro‐bubble morphology, shape, and arrangements can be readily pre‐programmed by controlling the geometry of the silk sheets, such as thickness, dimension, and aspect ratio. These micro‐bubble constructs can be utilized for encapsulation of various materials as well as nanoparticles in a single or multi compartmental manner. These biocompatible and biodegradable micro‐bubble constructs present a promising platform for one‐shot spatial and controllable loading and locking material arrays with addressable abilities.     

CdIn2S4 Nanotubes and “Marigold” Nanostructures: A Visible‐Light Photocatalyst

Nanostructured photocatalysts with high activity are sought for solar production of hydrogen. Spinel semiconductors with different nanostructures and morphologies have immense importance for photocatalytic and other potential applications. Here, a chemically stable cubic spinel nanostructured CdIn₂S₄ prepared by a facile hydrothermal method is reported as a visible‐light driven photocatalyst. A pretty, marigold‐like morphology is observed in aqueous‐mediated CdIn₂S₄, whereas nanotubes of good crystallinity, 25 nm in diameter, are obtained in methanol‐mediated CdIn₂S₄. The aqueous‐ and methanol‐mediated CdIn₂S₄ products show excellent photocatalytic activity compared to other organic mediated samples, and this is attributed to their high degree of crystallinity. The CdIn₂S₄ photocatalyst gives quantum yields of 16.8 % (marigold‐like morphology) and 17.1 % (nanotubes) at 500 nm, respectively, for the H₂ evolution reaction. The details of the characteristics of the photocatalyst, such as crystal and band structure, are reported. Considering the importance of hydrogen energy, CdIn₂S₄ will be an excellent candidate as a catalyst for “photohydrogen” production under visible light. Being a nanostructured chalcogenide semiconductor, CdIn₂S₄ will have other potential prospective applications, such as in solar cells, light‐emitting diodes, and optoelectronic devices.     

Synthesis of CeOx‐Decorated Pd/C Catalysts by Controlled Surface Reactions for Hydrogen Oxidation in Anion Exchange Membrane Fuel Cells

Due to the sluggish kinetics of the hydrogen oxidation reaction (HOR) in alkaline electrolytes, the development of more efficient HOR catalysts is essential for the next generation of anion‐exchange membrane fuel cells (AEMFCs). In this work, CeO_x is selectively deposited onto carbon‐supported Pd nanoparticles by controlled surface reactions, aiming to enhance the homogenous distribution of CeO_x and its preferential attachment to Pd nanoparticles, to achieve highly active CeO_x‐Pd/C catalysts. The catalysts are characterized by inductively coupled plasma–atomic emission spectroscopy, X‐ray diffraction, high‐resolution transmission electron microscopy, scanning transmission electron microscopy (STEM), electron energy loss spectroscopy, and X‐ray photoelectron spectroscopy to confirm the bulk composition, phases present, morphology, elemental mapping, local oxidation, and surface chemical states, respectively. The intimate contact between Pd and CeO_x is shown through high‐resolution STEM maps. The oxophilic nature of CeO_x and its effect on Pd are probed by CO stripping. The interfacial contact area between CeO_x and Pd nanoparticles is calculated for the first time and correlated to the electrochemical performance of the CeO_x‐Pd/C catalysts. Highest recorded HOR specific exchange current (51.5 mA mg^?1_Pd) and H₂–O₂ AEMFC performance (peak power density of 1,169 mW cm^?2 mg_Pd^?1) are obtained with a CeO_x‐Pd/C catalyst with Ce_0.38/Pd bulk atomic ratio.     

Unprecedented “All‐in‐One” Lanthanide‐Doped Mesoporous Silica Frameworks for Fluorescence/MR Imaging and Combination of NIR Light Triggered Chemo‐Photodynamic Therapy of Tumors

Designing a single multifunctional nanoparticle that can simultaneously impart both diagnostic and therapeutic functions is considered to be a long‐lasting hurdle for biomedical researchers. Conventionally, a multifunctional nanoparticle can be constructed by integrating organic dyes/magnetic nanoparticles to impart diagnostic functions and anticancer drugs/photosensitizers to achieve therapeutic outcomes. These multicomponents systems usually suffer from severe photobleaching problems and cannot be activated by near‐infrared (NIR) light. Here, it is demonstrated that all‐in‐one lanthanide‐doped mesoporous silica frameworks (EuGdOx@MSF) loaded with an anticancer drug, doxorubicin (DOX) can facilitate simultaneous bimodal magnetic resonance (MR) imaging with approximately twofold higher T₁‐MR contrast as compared to the commercial Gd(III)‐DTPA complex and fluorescence imaging with excellent photostability. Upon a very low dose (130 mW cm^?2) of NIR light (980 nm) irradiation, the EuGdOx@MSF not only can sensitize formation of singlet oxygen (¹O₂) by itself but also can phototrigger the release of the DOX payload effectively to exert combined chemo‐photodynamic therapeutic (PDT) effects and destroy solid tumors in mice completely. It is also discovered for the first time that the EuGdOx@MSF‐mediated PDT effect can suppress the level of the key drug resistant protein, i.e., p‐glycoprotein (p‐gp) and help alleviate the drug resistant problem commonly associated with many cancers.     

Formation Mechanism of Epitaxial Palladium–Platinum Core–Shell Nanocatalysts in a One‐Step Supercritical Synthesis

The scarcity of platinum group metals provides a strong incentive to optimize the catalytic activity and stability, e.g., through nanoalloys or core–shell nanoparticles. Here, time‐resolved X‐ray total scattering and transmission electron microscopy characterization are used to study the formation of palladium–platinum core–shell nanoparticles under solvothermal conditions. It is shown that Pd rapidly forms small (5–10 nm), disordered primary particles, which agglomerate and crystallize when reaching 20–25 nm. The primary Pd particles provide nucleation sites for Pt, and, with extended reaction time, the Pd cores become fully covered with Pt shells. The observed core–shell material is surprising when considering the Pt–Pd phase diagram and relative surface energies, but it can be rationalized through the kinetics of precursor conversion. To bridge the gap between scientific studies and industrial demand for large‐scale production, the synthesis process is successfully transferred to a continuous flow supercritical reactor providing a simple scalable and green process for production of bimetallic nanocatalysts.     

NIR‐Laser‐Controlled Hydrogen‐Releasing PdH Nanohydride for Synergistic Hydrogen‐Photothermal Antibacterial and Wound‐Healing Therapies

For decades, hydrogen (H₂) gas has been recognized as an excellent antioxidant molecule that holds promise in treating many diseases like Alzheimer's, stroke, cancer, and so on. For the first time, active hydrogen is demonstrated to be highly efficient in antibacterial, antibiofilm, and wound‐healing applications, in particular when used in combination with the photothermal effect. As a proof of concept, a biocompatible hydrogen‐releasing PdH nanohydride, displaying on‐demand controlled active hydrogen release property under near‐infrared laser irradiation, is fabricated by incorporating H₂ into Pd nanocubes. The obtained PdH nanohydride combines both merits of bioactive hydrogen and photothermal effect of Pd, exhibiting excellent in vitro and in vivo antibacterial activities due to its synergistic hydrogen‐photothermal therapeutic effect. Interestingly, combinational hydrogen‐photothermal treatment is also proved to be an excellent therapeutic methodology in healing rats' wound with serious bacterial infection. Moreover, an in‐depth antibacterial mechanism study reveals that two potential pathways are involved in the synergistic hydrogen‐photothermal antibacterial effect. One is to upregulate bacterial metabolism relevant genes like dmpI, narJ, and nark, which subsequently encode more expression of oxidative metabolic enzymes to generate substantial reactive oxygen species to induce DNA damage and another is to cause severe bacterial membrane damage to release intracellular compounds like DNA.     

Palladium Nanoparticles Supported on Magnetic Carbon‐Coated Cobalt Nanobeads: Highly Active and Recyclable Catalysts for Alkene Hydrogenation

Palladium nanoparticles are deposited on the surface of highly magnetic carbon‐coated cobalt nanoparticles. In contrast to the established synthesis of Pd nanoparticles via reduction of Pd(II) precursors, the microwave decomposition of a Pd(0) source leads to a more efficient Pd deposition, resulting in a material with considerably higher activity in the hydrogenation of alkenes. Systematic variation of the Pd loading on the carbon‐coated cobalt nanoparticle surface reveals a distinct trend to higher activities with decreased loading of Pd. The activity of the catalyst is further improved by the addition of 10 vol% Et₂O to iso‐propanol that is found to be the solvent of choice. With respect to activity (turnover frequencies up to 11 095 h^?1), handling, recyclability through magnetic decantation, and leaching of Pd (≤6 ppm/cycle), this novel magnetic hybrid material compares favorably to conventional Pd/C or Pd@CNT catalysts.     

Binary and Ternary Polymer‐Mediated “Bricks and Mortar” Self‐Assembly of Gold and Silica Nanoparticles

An amine‐functionalized polymer has been used to simultaneously assemble carboxylic acid functionalized gold and silica nanoparticles into extended aggregates. This three component assembly process is highly versatile, with aggregate morphology controlled through stoichiometry, and nanoparticle segregation within the aggregate regulated through order of component addition.