Cooperation between holey N-doped carbon and Ni nanoparticles as an efficient electrocatalyst for the hydrogen evolution reaction.

Exploring non-noble and high-performance metal catalysts to replace platinum-based catalysts for the hydrogen evolution reaction (HER) via electrochemical water splitting significantly alleviates environmental pollution and the energy crisis. However, the synthetic approaches of such electrocatalysts are generally complex and challenging for large-scale production. Herein, a facile and green solid-state synthesis of Ni nanoparticles decorated with N-doped porous carbon is presented. These materials are derived from chitosan as carbon, nitrogen sources, and nickel acetate as a nickel source with NaCl as a template. The synthesis procedure is simple to scale up without an organic solvent. Benefiting from its porous structure, splendid conductivity, and the synergistic effect of Ni nanoparticles and holey N-doped carbon, the as-prepared Ni@CN exhibits superior HER performance in 1 M KOH with a low potential of 121 mV at 10 mA cm-2. These findings indicate that the convenient and environmentally friendly synthesis approach provides a novel method for large-scale synthesis of HER electrocatalysts for industrial electrolytic water splitting applications.

Porous tremella-like NiMoP/CoP network electrodes as an efficient electrocatalyst.

The design of efficient, stable and cost-effective electrocatalysts for the hydrogen evolution reaction holds substantial significance in water electrolysis, but it remains challenging. Tremella-like nickel-molybdenum bimetal phosphide encapsulated cobalt phosphide (NiMoP/CoP) with hierarchical architectures has been effectively synthesized on nickel foam (NF) via a straightforward hydrothermal followed by low-temperature phosphating method. Based on the unique structural benefits, it significantly increases the number of redox active centers, enhances the electrical conductivity of materials, and diminishes the ion diffusion path lengths, thereby promoting efficient electrolyte penetration and reducing the inherent resistance. The as-obtained NiMoP/CoP/NF electrocatalyst exhibited remarkable catalytic activity with an ultralow overpotential of 38 mV (10 mA cm-2) and low Tafel slope of 83 mV dec-1. The straightforward synthesis process and exceptional electrocatalytic properties of NiMoP/CoP/NF demonstrate great potential for the HER to replace the precious metal catalyst.

One-pot self-assembled bimetallic sulfide particle cluster-supported three-dimensional graphene aerogel as an efficient electrocatalyst for the oxygen evolution reaction.

The preparation of an electrocatalyst for the oxygen evolution reaction (OER) with high catalytic activity, good long-term durability and rapid reaction kinetics through interface engineering is of great significance. Herein, we have developed a bimetallic sulfide particle cluster-supported three-dimensional graphene aerogel (FeNiS@GA), which serves as an efficient electrocatalyst for OER, by a one-step hydrothermal method. Profiting from the synergy of the FeNiS particle cluster with high capacitance and GA with its three-dimensional porous nanostructure, FeNiS@GA shows a high specific surface area, large pore volume, low contact resistance, and decreases the electron and ion transport routes. FeNiS@GA exhibits outstanding OER activity (when the current density is 50 mA cm-2, the overpotential is 341 mV), low Tafel slope (63.87 mV dec-1) and remarkable stability in alkaline solutions, outperforming FeNiS, NiS@GA, FeS@GA and RuO2. Due to its simple synthesis process and excellent electrocatalytic performance, FeNiS@GA shows great potential to replace noble metal-based catalysts in practical applications.

Polysulfide induced synthesis of a MoS2 self-supporting electrode with wide-layer-spacing for efficient electrocatalytic water splitting.

Efficient non-noble metal bifunctional electrocatalysts can increase the conversion rate of electric energy in the hydrogen evolution reaction (HER) and the oxygen evolution reaction (OER). Herein, a ball & sheet MoS2/Ni3S2 composite with wide-layer-spacing and high 1T-rich MoS2 is assembled on nickel foam (NF) via a two-step solvothermal method with polymeric sulfur (S-r-DIB) as the sulfur source. The obtained material serves as both the cathode and the anode toward overall water splitting in an alkaline electrolyte. The results proved that the interpenetration of MoS2/Ni3S2-p with a ball and sheet structure increased the material active surface area and exposed more catalytic active sites, which contributed to the penetration of solution and the transfer of charge/hydrion. Meanwhile, two different semiconductors of MoS2 and Ni3S2 along with the presence of ample active sulfur edge sites and few-layer, wide-layer-spacing structures of MoS2 lead to an outstanding electrocatalytic activity. In particular, the electrodes of MoS2/Ni3S2-p only need a battery voltage of 1.55 V at 10 mA cm-2. The bifunctional electrocatalyst MoS2/Ni3S2-p also shows excellent stability at large current densities during the electrochemical test.

Detailed formation process of Co@C catalysts and the influence of structural regulation on catalytic properties.

Co@C is a novel class of catalysts with many structural advantages, such as highly dispersed active species, developed pore structure, and special encapsulated structure. Although considerable progress has been made in the development of new Co@C materials, research on the formation mechanism of these materials is lacking. Herein, the overall microcosmic structure of the Co@C catalyst was investigated by systematic characterization. Subsequently, a pseudo in situ method was employed to explore the detailed structure of the Co@C catalyst pyrolyzed at different temperatures. The special carbon environment of materials is essential for synthesizing materials during pyrolysis at high temperatures. Co ions were reduced to Co0 by the surrounding carbon atoms at a high temperature. In return, the surrounding carbon atoms were catalyzed by Co0 particles to form carbon nanotubes. However, with the obstruction of amorphous carbon atoms that are not in contact with Co0, the paths through which the carbon nanotubes move forward formed the porous structure of the catalyst, as well as the graphitic encapsulated structure. Further, the effects of pretreatment conditions on the structure and properties of the Co@C catalyst were studied systematically.

Multifunctional theranostic agents based on prussian blue nanoparticles for tumor targeted and MRI-guided photodynamic/photothermal combined treatment.

The independence of photodynamic or photothermal modality create difficulties in the success of tumor therapy. In this current study, a multifunctional nanotheranostic agent of PDE-Ce6-HA was developed for tumor targeted and MRI-guided photodynamic/photothermal combined therapy (PDT/PTT). For this purpose, the near-infrared-absorbing nanoparticles of prussian blue were coated with polydopamine and successively conjugated with chlorin e6 (Ce6) for reactive oxygen species (ROS) generation. The resultant nanoparticles, denoted as PDE-Ce6, were then modified with hyaluronic acid (HA) through electrostatic interaction to yield the final therapeutic agent of PDE-Ce6-HA NPs. PDE-Ce6-HA NPs not only exhibited high colloid stability, good biocompatibility and suitable transverse relaxation rate (0.54 mM-1 s-1), but also high photothermal conversion efficiency (40.4%) and excellent ROS generation efficiency under NIR light irradiation. The confocal microscopy images demonstrated a selective uptake of PDE-Ce6-HA by CD44 overexpressed HeLa cells via HA-mediated endocytosis. Meanwhile, in vitro anti-cancer evaluation verified the significant photodynamic and photothermal combined effects of PDE-Ce6-HA on cancer cells. Moreover, PDE-Ce6-HA led to an increase of T1-MRI contrast in tumor site. Furthermore, in vivo anti-tumor evaluation proved that the PDE-Ce6-HA under both 808 and 670 nm laser showed significantly high tumor growth inhibition effects compared with individual PTT or PDT. Hence, PDE-Ce6-HA is applicable in tumor targeted and MRI-guided photodynamic/photothermal combined treatment.

Al18 F labeled sulfonamide-conjugated positron emission tomography tracer in vivo tumor-targeted imaging.

An ideal positron emission tomography (PET) tracer should be highly extractable by the tumor tissue or organ that contains low toxicity and can provide high-resolution images in vivo. In this work, the aim was to evaluate the application of Al18 F-labeled 1,4,7-triazacyclononane-1,4,7-triacetic acid containing sulfonamide group (18 F-Al-NOTA-SN) as a potential tumor-targeting signal-enhanced radioactive tracer in PET. SN as a tumor-targeting group was incorporated to NOTA to make a ligand. Subsequently, this ligand reacted with Na18 F and AlCl3 to produce a compound 18 F-Al-NOTA-SN. This compound was further characterized and its property in regard to cell cytotoxicity assay, microPET imaging, biodistribution, cell uptake assay, and tumor selectivity in vitro and in vivo, was also investigated. 18 F-Al-NOTA-SN possessed low cell cytotoxicity and uptake to COS-7 and 293T healthy cells and high cell cytotoxicity and uptake to MDA-MB-231, HepG2, and HeLa tumor cells in vitro. Moreover, 18 F-Al-NOTA-SN showed good tumor-targeting property and high PET signal enhancement of HeLa tumors, liver, and kidneys in mice, as well as the uptake ratios of tumor to blood and tumor to muscle, were 4.98 and 3.87, respectively. 18 F-Al-NOTA-SN can be accepted to be kidney and liver eliminated earlier and show a potential tumor-targeting signal-enhanced radioactive tracer in PET.

Efficient Uptake of 177 Lu-Porphyrin-PEG Nanocomplexes by Tumor Mitochondria for Multimodal-Imaging-Guided Combination Therapy.

The benefits to intracellular drug delivery from nanomedicine have been limited by biological barriers and to some extent by targeting capability. We investigated a size-controlled, dual tumor-mitochondria-targeted theranostic nanoplatform (Porphyrin-PEG Nanocomplexes, PPNs). The maximum tumor accumulation (15.6 %ID g-1 , 72 h p.i.) and ideal tumor-to-muscle ratio (16.6, 72 h p.i.) was achieved using an optimized PPN particle size of approximately 10 nm, as measured by using PET imaging tracing. The stable coordination of PPNs with 177 Lu enables the integration of fluorescence imaging (FL) and photodynamic therapy (PDT) with positron emission tomography (PET) imaging and internal radiotherapy (RT). Furthermore, the efficient tumor and mitochondrial uptake of 177 Lu-PPNs greatly enhanced the efficacies of RT and/or PDT. This work developed a facile approach for the fabrication of tumor-targeted multi-modal nanotheranostic agents, which enables precision and radionuclide-based combination tumor therapy.

Synergistic effect of LixSi/Li3N artificial interface and 3D framework for enabling Dendrite-free, long-life lithium metal anodes.

Lithium metal is highly favored as an ideal anode material in future high-capacity lithium batteries due to its appealing properties. Nevertheless, the implementation of lithium metal batteries (LMBs) is severely plagued by challenges such as instable solid electrolyte interface (SEI), uncontrolled growth of dendrite, and severe volume expansion. Herein, to address the aforementioned issues, an artificial SEI layer is fabricated, which is comprised of LixSi alloy and Li3N. The in-situ generated LixSi/Li3N interface is formed on the carbon fiber (denoted as CF/LixSi/Li3N) through a spontaneous reaction between molten Li and Si3N4. Density functional theory (DFT) calculations reveal that LixSi alloy has low ion diffusion energy barrier, which facilitates the low nucleation overpotential of Li+ and enables homogeneous lithium deposition. Li3N can further promote the rapid Li+ transport due to the excellent Li+ conductivity. In addition, the reserved 3D space effectively mitigates the volume change along cycling procedure. Owing to the synergistic effect of the LixSi/Li3N protective layer and the 3D structure, the composite anode shows higher cycling stability with a lifetime of more than 3000 cycles at 1 mA cm-2. Furthermore, matched with commercial LiFePO4 (LFP) and LiNi5Co2Mn3O2 (NCM523) cathodes, the full cells also exhibit impressive electrochemical properties. This work introduces an ingenious approach for constructing stable lithium metal anodes and effective lithium metal batteries.

Mechanical enhancement of nanofibrous scaffolds through polyelectrolyte complexation.

Optimization of mechanical properties is required in applications of tissue-engineered scaffolds. In this study, a polyelectrolyte complexation approach is proposed to improve the mechanical properties of the nanofibrous scaffolds. Through an electrospun chitosan/gelatin (CG) model system, it is demonstrated that the storage modulus of CG nanofiber-based complex membranes is over 10(3)-fold higher than that of neat chitosan or gelatin membranes. Further, an annealing process was found to promote the conjugation of the oppositely charged polymers and thus the tensile modulus of CG membranes is 1.9-fold elevated. When the molar ratio of aminoglucoside units in chitosan to carboxyl units in gelatin is 1:1, the complex nanofiber-based membranes (CG2) display the highest mechanical strength. In addition, the complex membranes reveal an excellent swelling capacity. By comparing the CG membranes electrospun with cast, it is deduced that the complexation is one of the main contributing factors to the improvement in mechanical properties. FTIR and DSC analyses confirm that more molecular interactions took place in the complexation. SEM observation clearly displays the electrospinnability of the complex. Therefore, polyelectrolyte complexation is an effective strategy for enhancing mechanical properties of nanofibrous scaffolds. These mechanically enhanced chitosan/gelatin nanofibrous membranes have wider applications than wound dressing.

Nanostructured polyvinylpyrrolidone-curcumin conjugates allowed for kidney-targeted treatment of cisplatin induced acute kidney injury.

Acute kidney injury (AKI) leads to unacceptably high mortality due to difficulties in timely intervention and less efficient renal delivery of therapeutic drugs. Here, a series of polyvinylpyrrolidone (PVP)-curcumin nanoparticles (PCurNP) are designed to meet the renal excretion threshold (∼45 kDa), presenting a controllable delivery nanosystem for kidney targeting. Renal accumulation of the relatively small nanoparticles, 89Zr-PCurNP M10 with the diameter between 5 and 8 nm, is found to be 1.7 times and 1.8 times higher than the accumulation of 89Zr-PCurNP M29 (20-50 nm) and M40 (20-50 nm) as revealed by PET imaging. Furthermore, serum creatinine analysis, kidney tissues histology, and tubular injury scores revealed that PCurNP M10 efficiently treated cisplatin-induced AKI. Herein, PCurNP offers a novel and simple strategy for precise PET image-guided drug delivery of renal protective materials.

Substrate-specific modifications on magnetic iron oxide nanoparticles as an artificial peroxidase for improving sensitivity in glucose detection.

Magnetic iron oxide nanoparticles (MION) were recently found to act as a peroxidase with intrinsic advantages over natural counterparts. Their limited affinity toward catalysis substrates, however, dramatically reduces their utility. In this paper, some effective groups were screened out and conjugated on MION as substrate-specific modifications for improving MION's affinity to substrates and hence utility. Nanoparticles of four different superficial structures were synthesized and characterized by TEM, size, zeta potential and SQUID, and assayed for peroxidase activity. Glucose detection was selected as an application model system to evaluate the bonus thereof. Catalysis was found to follow Michaelis-Menten kinetics. Sulfhydryl groups incorporated on MION (SH-MION) notably improve the affinity toward a substrate (hydrogen peroxide) and so do amino groups (NH2-MION) toward another substrate, proved by variation in the determined kinetic parameters. A synergistically positive effect was observed and an apparently elevated detection sensitivity and a significantly lowered detection limit of glucose were achieved when integrated with both sulfhydryl and amino groups (SH-NH2-MION). Our findings suggest that substrate-specific surface modifications are a straightforward and robust strategy to improve MION peroxidase-like activity. The high activity extends magnetic nanoparticles to wide applications other than glucose detection.

High topological tri-metal phosphide of CoP@FeNiP toward enhanced activities in oxygen evolution reaction.

The development of non-precious metal electrocatalysts with high activity, good durability and low cost to replace precious metal electrocatalysts is highly demanded for oxygen evolution reaction (OER). However, the higher overpotential, less catalytic sites and lower catalytic rate of precious metal electrocatalysts affect their practical application, which needs to be optimized from the aspects of structural design (e.g., specific morphology/particle size, geometric/electronic structures). In this study, we reported a high topological tri-metal phosphide of CoP@FeNiP derived from the composite structure of ZIF-67 twined on a FeNi-LDH shelled with ultrathin carbon networks (ZIF-67/FeNi-LDH) grown on a nickel foam. In the synthesis process of FeNi-LDH, the addition of polyvinylpyrrolidone (PVP) promoted the self-assembly of the topological structure of FeNi-LDH and further nucleation of the topological structure of the ZIF-67 precursor on FeNi-LDH. Besides, CoP@FeNiP inherits the topological structure of ZIF-67/FeNi-LDH. The obtained CoP@FeNiP/NF shows superior OER performance with a low overpotential of ∼283 mV at 100 mA cm-2, a low Tafel slope of ∼31.8 mV dec-1 and a conservation rate of catalytic activity of ∼98% after 110 h of continuous electrolysis at 10 mA cm-2. The remarkable activity of CoP@FeNiP/NF can be attributed to its unique structural features, such as the hierarchical morphology, large surface area, ultrathin carbon networks and the feature of phosphide, all of which simultaneously promote the OER process. The extraordinary catalytic activities and stability of CoP@FeNiP/NF are significant to meet the industrial requirements for bulk water electrocatalysis.

A new solvate of clonixin and a comparison of the two clonixin solvates.

A new solvate of clonixin (CLX), a dimethylacetamide (DMA) solvate, has been obtained by crystal growth in DMA. The new form was characterized by NMR, single-crystal X-ray diffraction, and PXRD. The crystal structure is stabilized by a strong hydrogen bond between the carboxylic acid OH of CLX and the DMA carbonyl, the strength of which is on par with those of the four solvent-free forms of CLX and the DMF solvate. These previously known forms are based on either the acid-acid homosynthon or the acid-pyridine heterosynthon, depending on the dihedral angle between the two aromatic rings of CLX, or the heterodimer between CLX and DMF. The new solvate loses DMA to convert into form I of CLX, as confirmed by differential scanning calorimetry (DSC) and powder X-ray diffraction (PXRD), similar to how the DMF solvate does. A comparison of the two solvates was carried out and theoretical studies were performed to shed light on the conformational difference between the two CLX molecules in the two solvates and the packing differences between them. The insight gained on this solvatomorphic system could aid the design of new solvates and cocrystals of CLX.

Concomitant induction to few-layer and 1T-rich two-dimensional MoS2 by rigid segment-containing polysulfide as a sulfur source and in situ intercalator.

Few-layer and 1T-rich MoS2 is synthesized by a one-step solvothermal process using a rigid segment-containing polysulfide as a concomitant sulfur source and in situ intercalator. The prepared MoS2 displays superior hydrogen evolution reaction activity, providing a facile and mild approach for the development of high performing MoS2 and other two-dimensional lamellar materials.

N-doped carbon-coated ultrasmall Nb2O5 nanocomposite with excellent long cyclability for sodium storage.

Niobium pentoxide (Nb2O5) has drawn significant interest as a promising anode for sodium ion batteries (SIBs) due to its large interplanar lattice spacing and relatively high diffusion efficiency. However, the intrinsic drawbacks of low electrical conductivity and substantial volume change greatly impede its practical applications in large-scale energy storage systems. In this work, ultrasmall Nb2O5 nanoparticles wrapped with nitrogen-doped carbon (denoted as Nb2O5@NC) were delicately synthesized via a facile sol-gel method and subsequent heat treatment. The unique structure of ultrasmall Nb2O5 nanoparticles in a carbonaceous matrix can not only effectively shorten the transmission distance for both ions/electrons but also relieve the strain and stress caused by volume variation during the sodiation/desodiation process. In addition, the synergistic effect of nitrogen doping and carbon coating can further improve the electronic conductivity and pseudocapacitive behavior of the active materials, thus promoting the rapid electrochemical reaction kinetics of the Nb2O5@NC composite. The obtained 600-Nb2O5@NC-2 anode exhibits superior rate capability and outstanding cycling stability, delivering a reversible capacity of 196 mA h g-1 at 1 A g-1 after 1000 cycles. Even at high current densities of 5 A g-1 and 10 A g-1, the long-life cycling tests show that the reversible capacities still remain at 128.4 mA h g-1 and 95.9 mA h g-1 after 3000 cycles, respectively, which is the best performance of Nb2O5-based anodes at high current densities so far. These results indicate that the feasible synthetic strategy of Nb2O5@NC is an effective approach to develop high-performance Nb2O5-based anodes for large-scale energy storage.

Superclear, Porous Cellulose Membranes with Chitosan-Coated Nanofibers for Visualized Cutaneous Wound Healing Dressing.

Easy and rapid continuous large-scale industrial production of transparent visualized cutaneous wound healing dressing from natural polymers is very worth studying in medical natural polymer materials and multifunction gauze dressing design fields. In this work, superclear, porous cellulose membranes (CMs) with chitosan-coated nanofibers were fabricated using a simple, one-step electrostatic spinning technology and evaluated as potential wound dressings. First, the pure CMs were dissolved by a simple physical method, and then, the membranes were regenerated in an acidic coagulation bath by the casting method. The chitosan solution was polarized into nanofibers and formed a continuous fiber mat on CMs because of the charge repulsion between molecules. The prepared chitosan-coated CMs (CM-CS) were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, differential scanning calorimetry, tensile tests, and so forth. The results indicated that CM-CS showed high wettability, hydrophilicity, and gas permeability, in addition to excellent light transmittance and mechanical compliance. Cell cytotoxicity and morphology assay and antibacterial activity against Escherichia coli and Staphylococcus aureus were also studied. They exhibited good biocompatibility and antibacterial activity of CM-CS. Moreover, evaluation of an in vivo wound healing model in mice revealed that CM-CS had a good effect in promoting wound healing. This work provided an easy and rapid continuous large-scale industrial design strategy for natural bioresource-based wound dressing materials, which could act as potential wound dressings for clinical use.

AgO-decorated multi-dimensional chrysanthemum-like NiCo2O4 mounted on nickel foam as a highly efficient and stable electrocatalyst for the oxygen evolution reaction.

AgO nanoparticles were successfully integrated into NiCo2O4 nanosheets for enhanced electrochemical catalysis ability and stability in the oxygen evolution reaction (OER). The chrysanthemum-like NiCo2O4/AgO composites mounted on nickel foam (NF) were synthesized by a hydrothermal-calcination method. AgO upgraded the ratio of Co3+/Co2+ and thus regulated the intrinsic activity of the species. The highly hierarchical structure of NiCo2O4/AgO composed of 0D AgO nanoparticles, 1D NiCo2O4 needles, 2D NiCo2O4 nanosheets, and 3D chrysanthemum-like bundles grown on NF bestowed the high surface area and mesoporous structure for the easy evolution of O2. The Ni atoms in NiCo2O4 originating in situ from NF in the process of AgO formation produced an integrated electrode of the active component of NiCo2O4 bound on NF with a superb highway for charge transfer. AgO significantly tuned the structure and physicochemical properties of NiCo2O4. As a result, NiCo2O4/AgO/NF exhibited excellent OER performance with an overpotential of 232 mV to obtain a current density of 10 mAcm-2 in an alkaline electrolyte, and the catalyst showed a small loss of the initial catalyst activity for 50 h and over 5000 cycles. This study provides a pathway for developing high-performance OER electrocatalysts.

Multifunctional theranostic nanosystems enabling photothermal-chemo combination therapy of triple-stimuli-responsive drug release with magnetic resonance imaging.

Theranostic nanosystems are emerging as a promising approach for controlled drug delivery, diagnosis and multimodal therapeutics. Herein, a multifunctional theranostic nanoplatform is reported for photothermal-chemo combination therapy functioned with magnetic and thermal imaging. Hyaluronic acid (HA) coated Fe3O4@polydopamine nanoparticles equipped with redox-sensitive disulfide linkers have been subsequently deposited with an anticancer drug, doxorubicin (DOX) (termed as FPCH-DOX NPs). These nanocomposites possess an average diameter of 120 nm, a saturation magnetization of 28.5 emu g-1, DOX loading capacity of 7.13% and a transverse relaxation rate of 171.76 mM-1 s-1. The drug release could be triggered by pH, glutathione (GSH) concentration and light irradiation. Prussian blue staining and confocal microscopy demonstrate that these nanoplatforms have improved biocompatibility and cellular uptake in CD44-positive HeLa cell lines rather than in CD44-negative NIH 3T3 normal cell lines. In vitro evaluations demonstrate that the combination therapy of FPCH-DOX NPs lowers the cell viability to 16.2%, less than that of individual chemotherapy (55.3%) or PTT (52.1%). In vivo MRI indicates that the tumor accumulation of FPCH-DOX NPs provides enhanced MRI contrast, and in vivo thermal imaging verified their localized photothermal conversion effect in tumor tissues. Importantly, FPCH-DOX NPs present remarkable anti-tumor efficacy by photothermal-chemo combination therapy. H&E and Ki67 staining tests show obvious necrosis and weak cell proliferation at the region of the tumor. Thus, FPCH-DOX NPs are promising multifunctional nanoplatforms for highly effective cancer theranostics.

Correction: Solution growth and thermal treatment of crystals lead to two new forms of 2-((2,6-dimethylphenyl)amino)benzoic acid.

[This corrects the article DOI: 10.1039/C7RA13353G.].