Dissolution Of Core Research Articles

FAP-activated liposomes achieved specific macropinocytosis uptake by pancreatic stellate cells for efficient desmoplasia reversal

The desmoplastic stroma in pancreatic ductal adenocarcinoma (PDAC) severely compromises drug delivery and efficacy. To disrupt stromal barriers, we constructed an all-trans retinoic acid (ATRA)-loaded liposome, FrLip@R, that contained calcium phosphate (CaP) cores and arginine 12-mer peptide (r12) ligands shielded by fibroblast activation protein (FAP)-detachable polyglutamate. Shielding r12 protected FrLip@R from nonspecific uptake, e.g., eluding the mononuclear phagocyte system (MPS) uptake for extended blood retention. Then, FrLip@R could be specifically activated by FAP overexpressed on activated pancreatic stellate cells (PSCs) to expose r12, thereby promoting its PSC uptake via an efficient macropinocytosis pathway. Accordingly, FrLip@R exhibited 2.42- and 2.85-fold higher internalization by in vivo PSCs than r12-modified and unmodified liposomes, respectively. In particular, the FrLip amount in the FAP+ PSCs was 54.46-fold higher than that in the other intratumoral cells. In addition, CaP core dissolution in acidic endosomes promoted ATRA release in the cytoplasm. Through efficient and specific ATRA delivery, FrLip@R induced PSC quiescence and disrupted stromal barriers, enhancing intratumoral drug delivery. Finally, in a murine pancreatic cancer model, FrLip@R combined with gemcitabine exerted antitumor efficacy superior to a 1.5-fold dose of gemcitabine while avoiding its severe side effects. Furthermore, FrLip@R modulation created a microenvironment adverse to tumor growth. Therefore, FrLip@R represents a potent and safe stromal barrier-disrupting agent that can amplify chemotherapeutic efficacy in desmoplastic PDAC.

Hollow Polyethyleneimine Nanoparticles with Drug Loaded DNA for Chemotherapeutic Applications.

The next generation of anticancer agents are emerging from rationally designed nanostructured materials. This work involved the synthesis and characterization of novel hollow DNA-conjugated gold nanoparticles (DNA-AuNPs) for controlled drug delivery. Polyethyleneimine (PEI) was bound to AuNPs, forming polymer-shell nanoparticles. Dissolution of the gold core via iodine formed hollow core polymeric nanoparticles (HCPNPs) and a high density (85 molecules/particle) of DNA intercalated with daunorubicin was conjugated. Particles were spherical with an average diameter of 105.7±17.3 nm and zeta potential of 20.4±3.54 mV. We hypothesize the DNA backbone electrostatically condensed to the primary amines on the surface of the particle toroidally, weaving itself within the polymer shell. During the DNA intercalation process, increasing the ionic concentration and decreasing the amine/phosphate ratio 10-fold increased drug intercalation 64 % and 61 %, respectively, allowing us to determine the optimal method of particle synthesis. As intercalation sites increased with increasing DNA strand length, drug loading increased. An average of 874±40.1 daunorubicin molecules were loaded per HCPNP. HCPNPs with drug intercalated DNA have strong potential to be clinically efficacious drug delivery vehicles due to the versatility of DNA and high drug loading capacities.

Paleoarchean sedimentation and Mesoarchean high-temperature metamorphism in northeastern Brazil: Tracing sources and depositional ages in polymetamorphic rocks

Supracrustal rocks offer a window into tectonic processes of the early Earth, since they are common in the Archean lithosphere. However, these rocks are usually affected by several episodes of metamorphism that can compromise their UPb systematics, leading to equivocal interpretations of depositional ages and sources. In northeast Brazil, supracrustal rocks are frequent within the Archean basement of the São José do Campestre Massif. These metapelitic migmatites show a high-temperature mineral assemblage, with garnet + sillimanite ± spinel and retrograde cordierite, with abundant anatectic melt migration at conditions of upper amphibolite to granulite facies. Zircon UPb dating coupled to trace elements analysis through LA-ICP-MS, as well as zircon internal zoning patterns suggest a maximum depositional age of 3305 ± 16 Ma followed by high-temperature metamorphism in the Mesoarchean, Paleoproterozoic and Neoproterozoic. Mesoarchean high temperature metamorphism occurred between 3084 ± 4 and 3006 ± 6 Ma and generated a wide range of textures that could be grouped in, at least, three stages of zircon growth. The first, during prograde heating, led to dissolution of detrital cores through the process of Ostwald Ripening and reprecipitation in oscillatory zoned rims. The second, probably at peak conditions, occurred above the stability of monazite, as evidenced by high Th/U ratios within zircon grains, rounded shape and sector-zoned cores. The third, during retrograde cooling, is mostly driven by garnet breakdown, and resulted in the crystallization of convoluted rims. Ti-in-zircon temperatures indicate minimum temperatures of 712 ± 21 °C for prograde/retrograde stages and 881 ± 50 °C for peak conditions. The Paleoarchean sedimentation and Mesoarchean metamorphism are coeval with similar events in Kaapvaal and Dharwar Cratons (South Africa and South India, respectively), but show no correlation to any Archean domains in South America to date. Solid-state recrystallization during the Paleoproterozoic (ca. 2.0 Ga) and the Neoproterozoic (ca. 0.6 Ga) correlates with orogenic events in both the Borborema Province and São Francisco Craton, suggesting a common evolution since the Rhyacian.

Rational design of Core-Shell heterostructured CoFe@NiFe Prussian blue analogues for efficient capacitive deionization

Rational design of stable and high-capacity faradaic electrode materials is crucial for enhancing the desalination performance of hybrid capacitive deionization (HCDI). In this work, to fully exploit the advantages of high-capacity CoFe Prussian blue analogs (PBA) and structurally stable NiFe PBA, a core–shell heterostructured CoFe@NiFe PBA is successfully synthesized by a two-step co-precipitation method. The construction of the core–shell heterostructure not only suppresses dissolution of the CoFe PBA core, but also facilitates fast charge transfer and efficient ion diffusion during Na+ ions insertion/extraction. With an optimal NiFe PBA shell thickness of 30 nm, the core–shell structured PBA electrode demonstrates outstanding cycling performance with a capacity retention of 72.6 % over 10,000 charge/discharge cycles. Moreover, when utilized as the cathode material in HCDI, the core–shell heterostructured PBA exhibits intriguing desalination performance, including a high desalination capacity of 49 mg g−1 and excellent desalination stability over 200 cycles (77.7 %). This paper presents a straightforward strategy for designing core–shell heterostructured PBA electrode, with the potential to advance the development of high-performance capacitive desalination.

Parametric Study of the Galvanic Reaction Parameters on the Synthesis of 1-Dimensional Cu-Ag Nanostructures

Recently, copper (Cu) and silver (Ag) nanowires have been widely employed as conductive fillers in flexible electronic devices due to their high aspect ratios leading to the formation of conductive networks in a polymeric substrate. This study combined Cu and Ag as a 1-dimensional nanostructures through galvanic replacement with a core-shell configuration. The effects of the galvanic replacement factors on the Cu-Ag core-shell nanostructures morphology was studied by varying the reaction time, temperature, and Ag concentration. SEM images show a more extensive Cu dealloying and Kirkendall voiding with longer reaction times, resulting in the Cu core dissolution. Homogenous nucleation of Ag occurs at higher reaction temperatures and Ag concentrations, producing separate Ag particles.

Synthesis of amine functionalized SiO2 microspheres loaded polymeric hydrogel and its application for simultaneous eviction of divalent metal ions (Pb2+, Cd2+, Cu2+ and Ni2+)

Recovery of divalent cationic elements from aquatic system is deliberated as reconciliation of rising industrial growth and access to quality drinking water. Herein we report tactically designed amino functionalized silica core-shell nanoparticle loaded polymeric hydrogel network as benchmark sorbent for divalent metal ions (Pb2+, Cd2+, Cu2+, Ni2+). The simple fabrication method for silica core-shell microspheres involves sol-gel synthesis of the polystyrene (PS) core, afterwards the formation of the silica shell by hydrolysis and condensation reaction, and finally the dissolution of the PS core. The surface of synthesized SiO2 microspheres was amine functionalized before being impregnated within a alginate matrix of polymer to generate amino functionalized SiO2 microsphere loaded polymeric hydrogel [NH2–SiO2MS-Ca-Alg] beads. Combining functionalized silica into polymeric hydrogel structure resulted extraordinary sorption capacities for divalent metal ions [191.4, 70.7, 64.9 and 35.8 mg g−1 respectively for Pb, Cd, Cu and Ni]. Density functional theory calculations were carried out to find out binding energies, preferred binding site of all four studied ions and structural changes due to their sorption. Structural evidence derived from experimental observations corroborate with the DFT analysis and speciation diagram of the divalent metal ion species. Plausible mechanistic pathway and differential uptake of four divalent metal ions were explained based on both experimental findings and theoretical studies. Developed NH2–SiO2 MS-Ca-Alg beads offered outstanding selectivity towards four divalent cations in a single prescription, excellent employability under ambient conditions without affecting essential water quality parameters which are significant breakthroughs for sustainable water remediation applications.

A novel method for improving interfacial joining strength of vacuum brazed TiAl/GH3536 thin-walled structure by Au coating

Lightweight components and materials based on the joining of dissimilar materials have attracted wide attention in aerospace field. To obtain the optimized micromorphology and interfacial microstructure of the brazed joints, a new method of Au layer deposition on TiAl base metal was proposed to assist the brazing of TiAl plate to GH3536 thin-walled structure. Significantly, the design of Au layer affected the brazing fillet, dissolution of GH3536 core and the evolution of interface, and then the maximum force under tensile loading of the hetero-thin-walled structure. The effect of Au layer thickness on the interfacial microstructure and mechanical properties was discussed in detail. Upon the deposition of an Au layer with a concentration of 0.2 wt% onto the TiAl plate, the load-bearing capacity of the brazed thin-walled structure was observed to undergo a significant enhancement. Specifically, the maximum force sustained under tensile loading was measured to be 391 N, thereby exhibiting a remarkable increase of 117 % relative to that of the Au-free system.

Fast and convenient delivery of fluidextracts liquorice through electrospun core-shell nanohybrids.

Introduction: As an interdisciplinary field, drug delivery relies on the developments of modern science and technology. Correspondingly, how to upgrade the traditional dosage forms for a more efficacious, safer, and convenient drug delivery poses a continuous challenge to researchers. Methods, results and discussion: In this study, a proof-of-concept demonstration was conducted to convert a popular traditional liquid dosage form (a commercial oral compound solution prepared from an intermediate licorice fluidextract) into a solid dosage form. The oral commercial solution was successfully encapsulated into the core-shell nanohybrids, and the ethanol in the oral solution was removed. The SEM and TEM evaluations showed that the prepared nanofibers had linear morphologies without any discerned spindles or beads and an obvious core-shell nanostructure. The FTIR and XRD results verified that the active ingredients in the commercial solution were compatible with the polymeric matrices and were presented in the core section in an amorphous state. Three different types of methods were developed, and the fast dissolution of the electrospun core-shell nanofibers was verified. Conclusion: Coaxial electrospinning can act as a nano pharmaceutical technique to upgrade the traditional oral solution into fast-dissolving solid drug delivery films to retain the advantages of the liquid dosage forms and the solid dosage forms.

In Situ Coatings of Polymeric Films with Core Polystyrene, Core-Shell Polystyrene/SiO2, and Hollow SiO2 Micro/Nanoparticles and Potential Applications.

In many industrial settings, films of polymers such as polypropylene (PP) and polyethylene terephthalate (PET) require surface treatment due to poor wettability and low surface energy. Here, a simple process is presented to prepare durable thin coatings composed of polystyrene (PS) core, PS/SiO2 core-shell, and hollow SiO2 micro/nanoparticles onto PP and PET films as a platform for various potential applications. Corona-treated films were coated with a monolayer of PS microparticles by in situ dispersion polymerization of styrene in ethanol/2-methoxy ethanol with polyvinylpyrrolidone as stabilizer. A similar process on untreated polymeric films did not yield a coating. PS/SiO2 core-shell coated microparticles were produced by in situ polymerization of Si(OEt)4 in ethanol/water onto a PS-coated film, creating a raspberry-like morphology with a hierarchical structure. Hollow porous SiO2-coated microparticles onto a PP/PET film were formed by in situ dissolution of the PS core of the coated PS/SiO2 particles with acetone. The coated films were characterized by E-SEM, FTIR/ATR, and AFM. These coatings may be used as a platform for various applications, e.g. magnetic coatings onto the core PS, superhydrophobic coatings onto the core-shell PS/SiO2, and solidification of oil liquids within the hollow porous SiO2 coating.

Investigating the role of dry compaction and layer-wise agglomeration to control the dissolution of granular urea fertilizer

Pore size distributions and degree of anisotropy (pore channel orientation) affect the mechanical properties, fragmentation, and dissolution kinetics of granular composites. Especially in porous solids such as granular urea fertilizers, uncontrolled dissolution leads to soil and water contamination from nutrient leaching. In this work, a dry compaction method and a bilayer granulation process were compared to investigate their ability to control the nutrient release from granular urea fertilizers. Urea and binary mixtures of urea and a xanthan and konjac gum binder were dry compacted. The compacts were then milled to specific particle sizes producing core granules. The core granules were drum granulated along with a known percent of fines and water to produce bilayer granules. The drum granulation parameters were optimized based on the granules' particle size distributions and color analysis. Dissolution and porosity distributions of core and bilayer granules were investigated and compared to market urea granules. Core granules with or without a binder compacted at 100 MPa had smaller pore size distributions compared with core granules compacted at 50 MPa, bilayer granules, and market urea granules. Core granules compacted at 100 MPa showed a significant decrease in the dissolution rate compared to less dense systems, such as core granules at 50 MPa, bilayer, and market urea granules. The addition of gums as binder caused an additional delay in the dissolution rate, indicating that formulation design is essential in controlling nutrient release. Less porous structures, i.e., higher compaction pressure to produce core granules, along with binder addition resulted in delayed dissolution rates due to binder migration and gelation at the solid-liquid interface. These results show that densification and formulation design can help control the release of urea from granular fertilizers with the potential of reducing leaching losses and pollution.

A model to predict drug release from a single-layer osmotic controlled-release tablet

A single-layer osmotic controlled-release tablet, also referred to as an extrudable core system (ECS) tablet, has been modelled to predict the drug release rate as function of various parameters related to the excipients and the active pharmaceutical ingredient, the geometry of the tablet and the coating thickness. The analysis leads to a better understanding of the drug release process resulting in a mathematical tool for design of new formulations. The model accounts for all the main events occurring during the drug release process from a tablet coated with a semi-permeable membrane, namely, the solvent influx driven by the difference in osmotic pressure across the coating, dispersion of core components (drug, polymer and osmogen), swelling of the tablet due to solvent accumulation, build-up of hydrostatic pressure inside the tablet, tensile stress acting on the coating, the extrusion of the dispersed core components and dissolution of drug particles outside the tablet in the bulk. We also derive the condition for successful entrainment of drug particles based on the viscosity of the hydrated phase and other parameters of the system. The model was validated by comparing the predictions with drug release data for two drugs of varying solubility. The agreement between the predicted release and the measurements confirmed the suitability of the model in describing the drug release process in the osmotic controlled-release tablet.

Construction of micelles and hollow spheres via the self-assembly behavior of poly(styrene-alt-pHPMI) copolymers with poly(4-vinylpyridine) derivatives mediated by hydrogen bonding interactions.

This study describes the preparation of hydrogen bonding connected micelles, consisting of a poly(styrene-alt-(para-hydroxyphenylmaleimide)) [poly(S-alt-pHPMI)] core and a poly(4-vinylpyridine) (P4VP) derivative shell in a selective solvent. The aim was to modify hydrogen bonding interaction sites at the core/shell interface by synthesizing P4VP derivatives in three different sequences, namely, P4VP homopolymers, PS-co-P4VP random copolymers, and block copolymers. TEM images showed the successful self-assembly of poly(S-alt-pHPMI)/PS-co-P4VP inter-polymer complexes into spherical structures. To dissolve the core structures, 1,4-dibromobutane was used as a cross-linking agent to tighten the PS-co-P4VP shell. The morphologies, particle sizes, hydrogen bonding, cross-linking reaction, and core dissolution were confirmed by TEM, DLS, FTIR, and AFM analyses. Poly(S-alt-pHPMI)/PS41-r-P4VP59 hydrogen bonding connected micelles, cross-linked micelles, and hollow spheres were larger and more irregular than poly(S-alt-pHPMI)/P4VP inter-polymer complexes due to the random copolymer architecture and the decrease in intermolecular hydrogen bonds. However, poly(S-alt-pHPMI)/PS68-b-P4VP32 resulted in rod- or worm-like structures after core dissolution.

Study of Cytotoxicity and Internalization of Redox-Responsive Iron Oxide Nanoparticles on PC-3 and 4T1 Cancer Cell Lines.

Redox-responsive and magnetic nanomaterials are widely used in tumor treatment separately, and while the application of their combined functionalities is perspective, exactly how such synergistic effects can be implemented is still unclear. This report investigates the internalization dynamics of magnetic redox-responsive nanoparticles (MNP-SS) and their cytotoxicity toward PC-3 and 4T1 cell lines. It is shown that MNP-SS synthesized by covalent grafting of polyethylene glycol (PEG) on the magnetic nanoparticle (MNP) surface via SS-bonds lose their colloidal stability and aggregate fully in a solution containing DTT, and partially in conditioned media, whereas the PEGylated MNP (MNP-PEG) without S-S linker control remains stable under the same conditions. Internalized MNP-SS lose the PEG shell more quickly, causing enhanced magnetic core dissolution and thus increased toxicity. This was confirmed by fluorescence microscopy using MNP-SS dual-labeled by Cy3 via labile disulfide, and Cy5 via a rigid linker. The dyes demonstrated a significant difference in fluorescence dynamics and intensity. Additionally, MNP-SS demonstrate quicker cellular uptake compared to MNP-PEG, as confirmed by TEM analysis. The combination of disulfide bonds, leading to faster dissolution of the iron oxide core, and the high-oxidative potential Fe3+ ions can synergically enhance oxidative stress in comparison with more stable coating without SS-bonds in the case of MNP-PEG. It decreases the cancer cell viability, especially for the 4T1, which is known for being sensitive to ferroptosis-triggering factors. In this work, we have shown the effect of redox-responsive grafting of the MNP surface as a key factor affecting MNP-internalization rate and dissolution with the release of iron ions inside cancer cells. This kind of synergistic effect is described for the first time and can be used not only in combination with drug delivery, but also in treatment of tumors responsive to ferroptosis.

PH-responsive drug release and antibacterial activity of chitosan-coated core/shell borate glass-hydroxyapatite microspheres

Multifunctional drug delivery system that can treat bone infection and concurrently accelerate bone tissue regeneration is highly desirable. In this study, we developed a pH-responsive local drug carrier in which a core/shell microsphere consisting of a borate glass core and a mesoporous hydroxyapatite HA shell (BG-HA) was coated with glutaraldehyde-crosslinked chitosan (CS). At neutral pH, a negligible concentration of vancomycin was released from the BG-HA@CS microspheres. However, in an acidic environment, the pores on the HA shell were uncapped due to the swelling of CS, thus accelerating the drug release. The advantage of the BG-HA@CS was evidenced by comparing with HA@CS that was prepared by fully converting borate glass followed by CS coating. The dissolution of the unconverted borate glass core upon immersing in PBS led to an increase in the local pH. This change of pH regulated the swelling/de-swelling behaviours of CS, thereby realizing more sustained drug release. Furthermore, it revealed that the vancomycin-loaded BG-HA@CS provided highly effective antibacterial activity against S. aureus and E. coli, while the vancomycin-loaded HA@CS did not show inhibitory effect on E. coli. The results indicated that the BG-HA@CS would be a promising multifunctional delivery system that can achieve self-regulated drug release, control the acidic environment of bone infection sites and promote bone tissue regeneration.

Incorporation of Functional Extraneous Cellulose in the Natural Fiber Welding Process

The efficient and non-derivatizing dissolution of natural biopolymers by ionic liquids (ILs) is poised to redefine the application of these ubiquitous and structurally robust materials on a grand industrial scale. In concert with this idea is Natural Fiber Welding (NFW), a technique which exploits the solvating properties of ionic liquids to partially dissociate the outer biopolymer layers in strands of fibrous thread, followed by solvent removal to collapse the structures in a reconfigured and entangled hydrogen bonding network. For cotton, this welding produces a layered motif of mesoporous cellulose atop a core of unmodified crystalline cellulose, creating a hierarchical structure which retains a semblance of the native biomaterial. Aggressive welding conditions increase the thickness and surface area of the mesoporous layer, though excessive welding leads to full dissolution of the crystalline core creating a tradeoff between an increase in surface area with loss of product integrity. In the present work, we seek to subvert aggressive welding conditions by supplementing dissolved cellulose as an additive in the welding solution. We will demonstrate how this extraneous cellulose can coat and weld to the underlying cotton substrate to increase the size of the amorphous shell around the crystalline core and, ultimately, bolster the mesoporous network and enhance the overall surface area. In addition, we will discuss how Raman-sensitive functionalization can be used to identify inclusion depth of the extraneous material and as a way to probe the potential for layer-by-layer deposition of functional cellulose during the NFW process.

Synergistic Hybrid Electrocatalysts of Platinum Alloy and Single-Atom Platinum for an Efficient and Durable Oxygen Reduction Reaction.

Pt single-atom materials possess an ideal atom economy but suffer from limited intrinsic activity and side reaction of producing H2O2 in catalyzing the oxygen reduction reaction (ORR); platinum alloys have higher intrinsic activity but weak stability. Here, we demonstrate that anchoring platinum alloys on single-atom Pt-decorated carbon (Pt-SAC) surmounts their inherent deficiencies, thereby enabling a complete four-electron ORR pathway catalysis with high efficiency and durability. Pt3Co@Pt-SAC demonstrates an exceptional mass and specific activities 1 order of magnitude higher than those of commercial Pt/C. They are durable throughout 50000 cycles, showing only a 10 mV decay in half-wave potential. An in situ Raman analysis and theoretical calculations reveal that Pt3Co core nanocrystals modulate electron structures of the adjacent Pt single atoms to facilitate the intermediate absorption for fast kinetics. The superior durability is attributed to the shielding effect of the Pt-SAC coating, which significantly mitigates the dissolution of Pt3Co cores. The hybridizing strategy might promote the development of highly active and durable ORR catalysts.

Improve crude oil recovery through geochemical methods – take the Longwangmiao formation in Moxi area of Sichuan Basin, China, as an example

During the study of Sinian-Cambrian system gas reservoirs in the middle paleo-uplift of Sichuan Basin, some wells of Longwangmiao formation in Moxi area had yellow fluorescent organic matter in thin sections under core-mirror was found. Based on the core observation and dissolution experiments, the characteristics of the biomarkers of saturated hydrocarbons under different conditions were determined by saturated hydrocarbon chromatography-mass spectrometry. The results show that the organic matter observed in the thin section under core-mirror is not the crude oil formed by multi-period accumulation, but polluted by oily substances in the drilling fluid during the drilling process. The presence of pollutants will affect the recovery of crude oil. Therefore, this study uses geochemical methods to identify the pollutants in the core and improve the recovery of crude oil.

Effect of Er, Cr:YSGG laser enamel etching with varying power output and irradiation time on the shear bond strength.

BACKGROUND:Laser etching addresses the disadvantages of conventional acid etching technique, such as enamel decalcification and formation of white spot lesions. The aim of the present study was to evaluate and compare the shear bond strength (SBS), adhesive remnant index (ARI), and the surface characteristics of the samples treated with conventional acid etching and Er, Cr: YSGG laser etching with variable output power and time durations.METHODOLOGY:The study sample included 78 extracted teeth divided into six groups of 13 teeth each, and 3 samples from each group were utilized for analyzing etch patterns, and the remaining 10 teeth from each group were used for evaluating the shear bond strength. In Group I phosphoric acid etching was done, whereas in Group II– VI Laser etching 1.5 W/10 s, 1.5 W/15 s, 3 W/5 s, 3 W/10 s, 3 W/15 s. Statistical analysis for shear bond strength testing was performed using one-way ANOVA followed by Post HOC tests.RESULTS:The mean shear bond strength of Group I was 7.16 Mpa and Group III of 5.43 Mpa. Group II, IV, V, and VI had mean shear bond strength of 4.93 Mpa, 3.88 Mpa, 4.05 Mpa, and 4.88 Mpa, respectively. The ARI scores Group I had a significant number of samples with scores 2 other groups showed increased Score 0. The etch pattern of groups I, II, III showed the combined dissolution of both prism cores, and peripheries were seen. In group IV, the etching pattern was irregular with the pitted type of surface. In groups V and VI, relatively flat and smooth enamel surface was seen.CONCLUSION:The bond strength attained by laser etching (1.5 W/10 s and 1.5 W/15 s) was comparable to that obtained by the acid etching technique.

Heterostructure of core–shell IrCo@IrCoO x as efficient and stable catalysts for oxygen evolution reaction

Although researches on non-noble metal electrocatalysts have been made some progress recently, their performance in proton exchange membrane water electrolyzer is still incomparable to that of noble-metal-based catalysts. Therefore, it is a more practical way to improve the utilization of precious metals in electrocatalysts for oxygen evolution reaction (OER) in the acidic medium. Herein, nanostructured IrCo@IrCoO x core–shell electrocatalysts composed of IrCo alloy core and IrCoO x shell were synthesized through a simple colloidally synthesis and calcination method. As expected, the hybrid IrCo-200 NPs with petal-like morphology show the best OER activities in acidic electrolytes. They deliver lower overpotential and better electrocatalytic kinetics than pristine IrCo alloy and commercial Ir/C, reaching a low overpotential (j = 10 mA cm−2) of 259 mV (versus RHE) and a Tafel slope of 59 mV dec−1. The IrCo-200 NPs displayed robust durability with life time of about 55 h in acidic solution under a large current density of 50 mA cm−2. The enhanced electrocatalytic activity may be associated with the unique metal/amorphous metal oxide core–shell heterostructure, allowing the improved charge transferability. Moreover, the *OH-rich amorphous shell functions as the active site for OER and prevents the further dissolution of the metallic core and thus ensures high stability.

MoO3-templated synthesis of TiO2@C-Ni microtubes for efficient catalysis and protein adsorption

The hybrid structure of metallic Ni nanoparticles (NPs)-decorated micro/nanotubes has the merits of both unique property of Ni NPs and tubular structure of micro/nanotubes, which is highly desired for many applications. In this study, Ni NPs decorated porous TiO2 microtubes with N-doped carbon layer from polydopamine (PDA) are directly synthesized by an extend stöber method, mussel chemistry and subsequent annealing treatment for the first time. In the synthetic process, a shell layer of nickel ion-embedded in polydopamine (PDA-Ni2+) was covered on the MoO3@TiO2 microcables by nickel ion mediated dopamine polymerization in ammonia solution, resulting in the formation of amorphous TiO2@PDA-Ni2+ microtubes. Notably, the coating of PDA-Ni2+ layer and the dissolution of the MoO3 cores were easily achieved within one-step reaction, greatly facilitating the synthetic progress. After being annealed in nitrogen atmosphere at different temperature, the TiO2@C-Ni microtubes with anatase, rutile phase of TiO2 can be obtained. Benefiting from the high coverage of Ni NPs, large specific surface area as well as one dimensional tubular structure, the as-prepared TiO2@C-Ni microtubes exhibited excellent performance on adsorption for histidine-rich proteins as well as the reduction of 4-nitrophenol. These results may pave a new avenue on constructing 1D TiO2-based microtubes for potential applications in energy storage, photocatalysis etc.