Electrochemical Synthesis of One-Dimensional Mesoporous Pt Nanorods Using the Assembly of Surfactant Micelles in Confined Space

Detection of rare CTCs by electrochemical biosensor built on quaternary PdPtCuRu nanospheres with mesoporous architectures

Circulating tumor cells (CTCs) are promising liquid biopsy biomarkers for early cancer detection and anti-cancer therapy evaluation. The ultra-low abundance of CTCs in blood samples requires highly sensitive and accurate detection ways. In this study, we propose the design of a dual-recognition electrochemical biosensor to improve both the specificity and signal response. PdPtCuRu mesoporous nanospheres (PdPtCuRu MNSs) with excellent three dimensions (3D) nanopore structures were synthesized by one-pot method and connected to mucin 1 (MUC1) aptamer to serve as signal amplification probe. Besides, superconductive carbon black, Ketjen Black (KB), and gold nanoparticles (AuNPs) modified organometallic frame (CeMOF-Au) were combined to work as signal transducer. The characteristic branching structure of KB provides abundant contact points to load CeMOF-Au to heighten the interface electron transfer rate. In addition, AuNPs were reduced on the surface of CeMOF, which could effectively bind the capture antibody and further enhance the conductivity. Under the optimized condition, the limit of detection (LOD) of the as-constructed biosensor was less than 10 cells mL^-1 for model A549 cells, and showed good specificity and accuracy in spiked serum samples. We envision the as-proposed electrochemical biosensor would alternate as a useful tool for the clinical detection of CTCs for cancer diagnosis.

One-pot synthesis of Au-based nanocrystals via a platinum group metal anion controlled growth strategy in citrate medium

Finding a facile manufacturing method of Au-based low PGM content nanocrystals by exploring the reaction process of a series of PGM anions with the in situ Au NW templates.

Electrodeposited Ni-Rich Ni-Pt Mesoporous Nanowires for Selective and Efficient Formic Acid-Assisted Hydrogenation of Levulinic Acid to γ-Valerolactone

In pursuit of friendlier conditions for the preparation of high-value biochemicals, we developed catalytic synthesis of γ-valerolactone by levulinic acid hydrogenation with formic acid as the hydrogen source. Both levulinic and formic acid are intermediate products in the biomass transformation processes. The objective of the work is twofold: the development of a novel approach for milder synthesis conditions to produce γ-valerolactone and the reduction of the economic cost of the catalyst. Ni-rich Ni-Pt mesoporous nanowires were synthesized in an aqueous medium using a combined hard-soft-template-assisted electrodeposition method, in which porous polycarbonate membranes controlled the shape and the Pluronic P-123 copolymer served as the porogen agent. The electrodeposition conditions selected favored nickel deposition and generated nanowires with nickel percentages above 75 atom %. The increase in deposition potential favored nickel deposition. However, it was detrimental for the porous diameter because the mesoporous structure is promoted by the presence of the platinum-rich micelles near the substrate, which is not favored at more negative potentials. The prepared catalysts promoted the complete transformation to γ-valerolactone in a yield of around 99% and proceeded with the absence of byproducts. The coupling temperature and reaction time were optimized considering the energy cost. The threshold operational temperature was established at 140 °C, at which, 120 min was sufficient for attaining the complete transformation. Working temperatures below 140 °C rendered the reaction completion difficult. The Ni₇₈Pt₂₂ nanowires exhibited excellent reusability, with minimal nickel leaching into the reaction mixture, whereas those with higher nickel contents showed corrosion.

Current Strategies for Noble Metal Nanoparticle Synthesis

Noble metals have played an integral part in human history for centuries; however, their integration with recent advances in nanotechnology and material sciences have provided new research opportunities in both academia and industry, which has resulted in a new array of advanced applications, including medical ones. Noble metal nanoparticles (NMNPs) have been of great importance in the field of biomedicine over the past few decades due to their importance in personalized healthcare and diagnostics. In particular, platinum, gold and silver nanoparticles have achieved the most dominant spot in the list, thanks to a very diverse range of industrial applications, including biomedical ones such as antimicrobial and antiviral agents, diagnostics, drug carriers and imaging probes. In particular, their superior resistance to extreme conditions of corrosion and oxidation is highly appreciated. Notably, in the past two decades there has been a tremendous advancement in the development of new strategies of more cost-effective and robust NMNP synthesis methods that provide materials with highly tunable physicochemical, optical and thermal properties, and biochemical functionalities. As a result, new advanced hybrid NMNPs with polymer, graphene, carbon nanotubes, quantum dots and core-shell systems have been developed with even more enhanced physicochemical characteristics that has led to exceptional diagnostic and therapeutic applications. In this review, we aim to summarize current advances in the synthesis of NMNPs (Au, Ag and Pt).

Review of the Mechanism of Nanocarriers and Technological Developments in the Field of Nanoparticles for Applications in Cancer Theragnostics

Cancer cannot be controlled by the usage of drugs alone, and thus, nanotechnology is an important technique that can provide the drug with an impetus to act more effectively. There is adequate availability of anticancer drugs that are classified as alkylating agents, hormones, or antimetabolites. Nanoparticle (NP) carriers increase the residence time of the drug, thereby enhancing the survival rate of the drug, which otherwise gets washed off owing to the small size of the drug particles by the excretory system. For example, for enhancing the circulation, a coating of nonfouling polymers like PEG and dextran is done. Famous drugs such as doxorubicin (DOX) are commonly encapsulated inside the nanocomposite. The various classes of nanoparticles are used to enhance drug delivery by aiding it to fight against the tumor. Targeted therapy aims to attack the cells with features common to the cancer cells while minimizing damage to the normal cell, and these therapies work in one in four ways. Some block the cancer cells from reproducing newer cells, others release toxic substances to kill the cancer cells, some stimulate the immune system to destroy the cancer cells, and some block the growth of more blood vessels around cancer cells, which starve the cells of the nutrients, which is needed for their growth. This review aims to testify the advancements nanotechnology has brought in cancer therapy, and its statements are supported with recent research findings and clinical trial results.

Uniformly dispersed platinum nanoparticles over nitrogen-doped reduced graphene oxide as an efficient electrocatalyst for the oxygen reduction reaction

Oxygen reduction reaction (ORR) with efficient activity and stability is significant for fuel cells. Herein, platinum (Pt) nanoparticles dispersed on nitrogen-doped reduced graphene oxide (N-rGO) were prepared by a hydrothermal and carbonized approach for the electrocatalysis of ORR. Polyvinylpyrrolidone plays a significant role in the reduction and dispersion of platinum particles (about 2 nm). The obtained Pt–N-rGO hybrids exhibited superior activity with an electron transfer number of ∼4.0, onset potential 0.90 eV of ORR, good stability and methanol tolerance in alkaline media. These results reveal the interactions between Pt–N-rGO and oxygen molecules, which may represent an oxygen modified growth in catalyst preparation. The excellent electrocatalysis may lead to the decreased consumption of expensive Pt and open up new opportunities for applications in lithium air batteries.

We developed a facile, yet general approach to prepare ultrafine Pt nanoparticles loaded on N-doped reduced graphene (Pt–N-rGO) composites, which showed excellent oxygen reduction reaction performance.

Recent advances in bioelectronics chemistry

Research in bioelectronics is highly interdisciplinary, with many new developments being based on techniques from across the physical and life sciences. Advances in our understanding of the fundamental chemistry underlying the materials used in bioelectronic applications have been a crucial component of many recent discoveries. In this review, we highlight ways in which a chemistry-oriented perspective may facilitate novel and deep insights into both the fundamental scientific understanding and the design of materials, which can in turn tune the functionality and biocompatibility of bioelectronic devices. We provide an in-depth examination of several developments in the field, organized by the chemical properties of the materials. We conclude by surveying how some of the latest major topics of chemical research may be further integrated with bioelectronics.

Mesoporous Nanoarchitectures for Electrochemical Energy Conversion and Storage

Mesoporous materials have attracted considerable attention because of their distinctive properties, including high surface areas, large pore sizes, tunable pore structures, controllable chemical compositions, and abundant forms of composite materials. During the last decade, there has been increasing research interest in constructing advanced mesoporous nanomaterials possessing short and open channels with efficient mass diffusion capability and rich accessible active sites for electrochemical energy conversion and storage. Here, the synthesis, structures, and energy-related applications of mesoporous nanomaterials are the main focus. After a brief summary of synthetic methods of mesoporous nanostructures, the delicate design and construction of mesoporous nanomaterials are described in detail through precise tailoring of the particle sizes, pore sizes, and nanostructures. Afterward, their applications as electrode materials for lithium-ion batteries, supercapacitors, water-splitting electrolyzers, and fuel cells are discussed. Finally, the possible development directions and challenges of mesoporous nanomaterials for electrochemical energy conversion and storage are proposed.

Polyelectrolyte-Induced Stereoassembly of Grain Boundary-Enriched Platinum Nanoworms on Ti3C2Tx MXene Nanosheets for Efficient Methanol Oxidation

Direct methanol fuel cells with high energy conversion efficiency and low hazard emissions have aroused great attention from both academic and industrial communities, but their large-scale commercial application has been blocked by high costs as well as short lifespan of the anode Pt catalysts. Here, we demonstrate a simple and scalable noncovalent strategy for the synthesis of quasi-one-dimensional (1D) Pt nanoworms grown on poly(diallyldimethyl-ammonium chloride) (PDDA)-functionalized Ti₃C₂T_x nanosheets as anode catalysts for methanol electrooxidation. Interestingly, the introduction of PDDA on Ti₃C₂T_x nanosheets can not only effectively adjust their surface charge property to strengthen the electrostatic interaction between metal and support but also induce the stereoassembly of worm-shaped Pt nanocrystals with abundant catalytically active grain boundaries, which enable the resulting hybrid to express high electrocatalytic activity, remarkable durability, and strong antipoisoning ability for methanol electrooxidation, which are better than those of the traditional Pt nanoparticle electrocatalysts loaded on carbon black, carbon nanotubes, reduced graphene oxide, and MXene matrixes. Theoretical simulations disclose that the more stable worm-shaped Pt configuration with an optimized electronic structure on the Ti₃C₂T_x surface possesses a weaker CO adsorption ability than that of the Pt nanoclusters, thereby providing a dramatically enhanced and sustainable electrocatalytic performance.

Use of silica-based homogeneously distributed gold nickel nanohybrid as a stable nanocatalyst for the hydrogen production from the dimethylamine borane

In this study, the effects of silica-based gold-nickel (AuNi@SiO2) nanohybrid to the production of hydrogen from dimethylamine borane (DMAB) were investigated. AuNi@SiO2 nanohybrid constructs were prepared as nanocatalysts for the dimethylamine borane dehydrogenation. The prepared nanohybrid structures were exhibited high catalytic activity and a stable form. The resulting nanohybrid, AuNi@SiO2 as a nanocatalyst, was tested in the hydrogen evolution from DMAB at room temperature. The synthesized nanohybrids were characterized using some analytical techniques. According to the results of the characterization, it was observed that the catalyst was in nanoscale and the gold-nickel alloys showed a homogenous distribution on the SiO2 surface. After characterization, the turn over frequency (TOF) of nanohybrid prepared for the production of hydrogen from dimethylamine was calculated (546.9 h-1). Also, the prepared nanohybrid can be used non-observed a significant decrease in activity even after the fifth use, in the same reaction. In addition, the activation energy (Ea) of the reaction of DMAB catalyzed AuNi@SiO2 nanohybrid was found to be 16.653 ± 1 kJmol-1 that facilitated the catalytic reaction. Furthermore, DFT-B3LYP calculations were used on the AuNi@SiO2 cluster to investigate catalyst activity. Computational results based on DFT obtained in the theoretical part of the study support the experimental data.

Cobalt-platinum nanomotors for local gas generation

Bimetallic Co-Pt nanorods exhibit an enhanced capacity for the production of gas from liquid-phase chemicals. Based on the systematic structural and magnetic characterization we discuss potential applications of these hybrid nanostructures for localized fuel generation in microdevices. Experimental proof of the feasibility for controlling the rate of catalytic reaction via external magnetic stimuli is shown. This unique functionality makes these hybrids promising candidates for optimizing the energy conversion rate in microfluidics fuel cells.

Self-assembly of block copolymers towards mesoporous materials for energy storage and conversion systems

This paper reviews the progress in the field of block copolymer-templated mesoporous materials, including synthetic methods, morphological and pore size control and their potential applications in energy storage and conversion devices.

Bimetallic platinum–rhodium nanocomposites for dimethylamine borane dehydrogenation: an experimental and density functional theory study

In this study, bimetallic platinum–rhodium nanocomposites supported on graphene oxide (PtRh@GO) were synthesized and used as a catalyst in the dimethylamine borane (DMAB) dehydrogenation.

Interface engineering of Ni5P2 nanoparticles and a mesoporous PtRu film heterostructure on Ni foam for enhanced hydrogen evolution

Engineering of multicomponent heterostructures can yield exceptional functionalities and enhance electrocatalytic activities by a synergistic effect. Herein, Ni₅P₂ nanoparticle-decorated mesoporous PtRu film on Ni foam (Ni₅P₂-mPtRu/NF) has been synthesized via a facile two-step strategy. Ni₅P₂-mPtRu/NF possesses a well-developed continuous mesoporous structure and strong electronic interaction between Ni₅P₂ and PtRu, exhibiting an enhanced electrocatalytic performance towards an alkaline hydrogen evolution reaction (HER). Ni₅P₂-mPtRu/NF achieves a current density of 10 mA cm^-2 at an overpotential of 28.8 mV and a low Tafel slope of 56.5 mV dec^-1, and has excellent durability. This work provides a promising pathway for developing self-supported mesoporous multicomponent heterostructures as efficient electrocatalysts for an alkaline HER.

Composites of Platinum-Iridium Alloy Nanoparticles and Graphene Oxide for the Dimethyl Amine Borane (DMAB) dehydrogenation at ambient conditions: An Experimental and Density Functional Theory Study

In this paper, we present the synthesis, characterization, catalytic and computational studies of Composites of Platinum-Iridium Alloy Nanoparticles and Graphene Oxide (PtIr@GO) for dimethylamine borane (DMAB) dehydrogenation. The prepared PtIr@GO nanocatalysts were synthesized using an ethanol super-hydride method, and the characterization procedures for PtIr@GO alloy nanoparticles were carried out by various advanced spectroscopic methods like X-ray Diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Transmission Electron Microscopy(TEM) and high-resolution transmission electron microscopy (HRTEM). Additionally, catalytic activity, reusability, substrate concentration, and catalyst concentration experiments were performed for DMAB dehydrogenation catalyzed by PtIr@GO alloy nanomaterials. According to the results obtained in this study, PtIr@GO NPs catalyst was found to be active and reusable for the DMAB even at ambient conditions. Besides, DFT-B3LYP calculations have been utilized on PtIr@GO cluster to reveal the prepared catalyst activity. The calculated findings based on DFT was found to be a good agreement with experimental results.

Selective Formation of Porous Pt Nanorods for Highly Electrochemically Efficient Neural Electrode Interfaces

The enhanced electrochemical activity of nanostructured materials is readily exploited in energy devices, but their utility in scalable and human-compatible implantable neural interfaces can significantly advance the performance of clinical and research electrodes. We utilize low-temperature selective dealloying to develop scalable and biocompatible one-dimensional platinum nanorod (PtNR) arrays that exhibit superb electrochemical properties at various length scales, stability, and biocompatibility for high performance neurotechnologies. PtNR arrays record brain activity with cellular resolution from the cortical surfaces in birds and nonhuman primates. Significantly, strong modulation of surface recorded single unit activity by auditory stimuli is demonstrated in European Starling birds as well as the modulation of local field potentials in the visual cortex by light stimuli in a nonhuman primate and responses to electrical stimulation in mice. PtNRs record behaviorally and physiologically relevant neuronal dynamics from the surface of the brain with high spatiotemporal resolution, which paves the way for less invasive brain-machine interfaces.

Highly monodispersed palladium-ruthenium alloy nanoparticles assembled on poly(N-vinyl-pyrrolidone) for dehydrocoupling of dimethylamine-borane: An experimental and density functional theory study

This study reports on one of the best heterogeneous catalysts for the dehydrogenation of dimethylamine-borane (DMAB). This new catalytic system consists of highly monodisperse Pd and Ru alloy nanoparticles supported by poly(N-vinyl-pyrrolidone) (PdRu@PVP). The prepared heterogeneous catalyst can be reproducibly formed using an ultrasonic reduction technique for DMAB dehydrogenation under mild conditions. For the characterization of PdRu@PVP nanomaterials, several spectroscopic and microscopic techniques were used. The prepared PdRu@PVP nanomaterials with an average particle size of 3.82 ± 1.10 nm provided an 808.03 h^-1 turnover frequency (TOF) in the dehydrogenation of DMAB and yielded 100% of the cyclic product (Me₂NBH₂)₂ under mild conditions. Furthermore, the activities of catalysts were investigated theoretically using DFT-B3LYP calculations. The theoretical results based on density functional theory were in favorable agreement with the experimental data.

Core-shell nanomaterials: Applications in energy storage and conversion

Materials with core-shell structures have attracted increasing attention in recent years due to their unique properties and wide applications in energy storage and conversion systems. Through reasonable adjustments of their shells and cores, various types of core-shell structured materials can be fabricated with favorable properties that play significant roles in energy storage and conversion processes. The core-shell material can provide an effective solution to the current energy crisis. Various synthetic strategies used to fabricate core-shell materials, including the atomic layer deposition, chemical vapor deposition and solvothermal method, are briefly mentioned here. A state-of-the -art review of their applications in energy storage and conversion is summarized. The involved energy storage includes supercapacitors, li-ions batteries and hydrogen storage, and the corresponding energy conversion technologies contain quantum dot solar cells, dye-sensitized solar cells, silicon/organic solar cells and fuel cells. In addition, the correlation between the core-shell structures and their performance in energy storage and conversion is introduced, and this finding can provide guidance in designing original core-shell structures with advanced properties.

Composites of Palladium-Nickel Alloy Nanoparticles and Graphene Oxide for the Knoevenagel Condensation of Aldehydes with Malononitrile

Herein, we have described uniformly dispersed palladium-nickel nanoparticles furnished on graphene oxide (GO-supported PdNi nanoparticles) as a powerful heterogeneous nanocatalyst for the promotion of Knoevenagel reaction between malononitrile and aromatic aldehydes under mild reaction conditions. The successful characterization of PdNi nanoparticles on the GO surface was shown by X-ray diffraction, X-ray photoelectron spectroscopy, high-resolution transmission electron microscopy (HR-TEM), and TEM. GO-supported PdNi nanoparticles, which are used as highly efficient, stable, and durable catalysts, were used for the first time for the Knoevenagel condensation reaction. The data obtained here showed that the GO-supported PdNi nanocatalyst had a unique catalytic activity and demonstrated that it could be reused five times without a significant decrease in the catalytic performance. The use of this nanocatalyst results in a very short reaction time under mild reaction conditions, high recyclability, excellent catalytic activity, and a straightforward work-up procedure for Knoevenagel condensation of malononitrile and aromatic aldehydes.

Trimetallic PtPdCo mesoporous nanopolyhedra with hollow cavities

The rational design of metallic mesoporous nanoarchitectures with hollow cavities offers an effective way to boost their performance in various catalytic fields. Herein, we report a facile two-step strategy for the fabrication of trimetallic PtPdCo mesoporous nanopolyhedra with hollow cavities (PtPdCo MHNPs), in which Pd@PtPdCo core-shell mesoporous nanopolyhedra (Pd@PtPdCo MNPs) are directly prepared by a simple chemical reduction reaction followed by etching of the Pd cores. The PtPdCo MHNPs show enhanced electrocatalytic activity and durability for the methanol oxidation reaction, enabled by their mesoporous and hollow nanoarchitectures coupled with trimetallic compositions.

A repertoire of biomedical applications of noble metal nanoparticles

The emerging properties of noble metal nanoparticles are attracting huge interest from the translational scientific community. In this feature article, we highlight recent advances in the adaptation of noble metal nanomaterials and their biomedical applications in therapeutics, diagnostics and sensing.

Citrate-Coated, Size-Tunable Octahedral Platinum Nanocrystals: A Novel Route for Advanced Electrocatalysts

The development of green and scalable syntheses for the preparation of size- and shape-controlled metal nanocrystals is of high interest in many areas, including catalysis, electrocatalysis, nanomedicine, and electronics. In this work, a new synthetic approach based on the synergistic action of physical parameters and reagents produces size-tunable octahedral Pt nanocrystals, without the use of catalyst-poisoning reagents and/or difficult-to-remove coatings. The synthesis requires sodium citrate, ascorbic acid, and fine control of the reduction rate in aqueous environment. Pt octahedral nanocrystals with particle size as low as 7 nm and highly developed {111} facets have been achieved, as demonstrated by transmission electron microscopy, X-ray diffraction, and electrochemical methods. The absence of sticky molecules together with the high quality of the surface makes these nanocrystals ideal candidates in electrocatalysis. Notably, 7 nm bismuth-decorated octahedral nanocrystals exhibit superior performance for the electrooxidation of formic acid in terms of both specific and mass activities.

Multimetallic Hollow Mesoporous Nanospheres with Synergistically Structural and Compositional Effects for Highly Efficient Ethanol Electrooxidation

Controlling the nanostructures and chemical compositions of the electrochemical nanocatalysts has been recognized as two prominent means to kinetically promote the electrocatalytic performance. Herein, we report a general "dual"-template synthesis methodology for the formation of multimetallic hollow mesoporous nanospheres (HMSs) with an adjustable interior hollow cavity and cylindrically opened mesoporous shell as a highly efficient electrocatalyst for ethanol oxidation reaction. Three-dimensional trimetallic PdAgCu HMSs were synthesized via in situ coreduction of Pd, Ag, and Cu precursors on "dual"-template structural directing surfactant of dioctadecyldimethylammonium chloride in optimal synthesis conditions. Due to synergistic advantages on hollow mesoporous nanostructures and multimetallic compositions, the resultant PdAgCu HMSs exhibited significantly enhanced electrocatalytic performance toward ethanol oxidation reaction with a mass activity of 5.13 A mg_Pd ^-1 at a scan rate of 50 mV s^-1 and operation stability (retained 1.09 A mg_pd ^-1 after the electrocatalysis). The "dual"-template route will open a new avenue to rationally design multimetallic HMSs with controlled functions for broad applications.

Micelle-Assisted Strategy for the Direct Synthesis of Large-Sized Mesoporous Platinum Catalysts by Vapor Infiltration of a Reducing Agent

Stable polymeric micelles have been demonstrated to serve as suitable templates for creating mesoporous metals. Herein, we report the utilization of a core-shell-corona type triblock copolymer of poly(styrene-b-2-vinylpyridine-b-ethylene oxide) and H₂PtCl₆·H₂O to synthesize large-sized mesoporous Pt particles. After formation of micelles with metal ions, the reduction process has been carried out by vapor infiltration of a reducing agent, 4-(Dimethylamino)benzaldehyde. Following the removal of the pore-directing agent under the optimized temperature, mesoporous Pt particles with an average pore size of 15 nm and surface area of 12.6 m²·g^-1 are achieved. More importantly, the resulting mesoporous Pt particles exhibit superior electrocatalytic activity compared to commercially available Pt black.

Photothermal exposure of polydopamine-coated branched Au-Ag nanoparticles induces cell cycle arrest, apoptosis, and autophagy in human bladder cancer cells

Purpose

Polydopamine-coated branched Au–Ag nanoparticles (Au–Ag@PDA NPs) exhibit good structural stability, biocompatibility, and photothermal performance, along with potential anticancer efficacy. Here, we investigated the cytotoxicity of Au–Ag@PDA NPs against human bladder cancer cells (T24 cells) in vitro and in vivo, as well as the underlying molecular mechanisms of photothermal therapy-induced T24 cell death.

Materials and methods

T24 cells were treated with different doses of Au–Ag@PDA NPs followed by 808 nm laser irradiation, and the effects on cell proliferation, cell cycle, apoptosis, and autophagy were analyzed. To confirm the mechanisms of inhibition, real-time PCR and Western blot analysis were used to evaluate markers of cell cycle, apoptosis, autophagy, and the AKT/ERK signaling pathway. Moreover, we evaluated the effects of the treatment on mitochondrial membrane potential and ROS generation to confirm the underlying mechanisms of inhibition. Finally, we tested the T24 tumor inhibitory effects of Au–Ag@PDA NPs plus laser irradiation in vivo using a xenograft mouse model.

Results

Au–Ag@PDA NPs, with appropriate laser irradiation, dramatically inhibited the proliferation of T24 cells, altered the cell cycle distribution by increasing the proportion of cells in the S phase, induced cell apoptosis by activating the mitochondria-mediated intrinsic pathway, and triggered a robust autophagy response in T24 cells. Moreover, Au–Ag@PDA NPs decreased the expression of phosphorylated AKT and ERK and promoted the production of ROS that function upstream of apoptosis and autophagy. In addition, Au–Ag@PDA NP-mediated photothermolysis also significantly suppressed tumor growth in vivo.

Conclusion

This preclinical study can provide a mechanistic basis for Au–Ag@PDA NP-mediated photothermal therapy toward promotion of this method in the clinical treatment of bladder cancer.

Microemulsion-Based One-Step Electrochemical Fabrication of Mesoporous Catalysts

Electrochemical technology has been proposed as an alternative or complementary method to classical inorganic synthesis for the fabrication of effective metallic solid catalysts. Microemulsion-based electrodeposition is a novel, fast, and one-step procedure to obtain mesoporous catalysts with extraordinarily effective areas, which can be used in heterogeneous catalysis for degradation of pollutants and clean energy production. The fabrication process involves conducting microemulsions containing ionic species (dissolved in aqueous solutions) as precursors of the metallic catalysts. The presence of nanometric droplets of organic or ionic-liquid components in the microemulsion defines the mesoporosity of the catalysts during a one-step electrodeposition process. This method also allows the fabrication of metal catalysts as supported mesoporous films or mesoporous nanowires with very high effective areas. Additionally, reactants have excellent accessibility to the overall surface of the catalysts. The different catalysts fabricated with the help of this technology have been tested for competitive degradation of organic pollutants and anodes' materials for fuel cell devices.

Engineering of Hollow PdPt Nanocrystals via Reduction Kinetic Control for Their Superior Electrocatalytic Performances

Synthesis of hollow metal nanocrystals (NCs) is greatly attractive for their high active surface areas, which gives rise to excellent catalytic activity. Taking PdPt alloy nanostructure as an example, we designed a synthetic tactic for the preparation of hollow metal nanostructures by delicate control over the difference in the reduction kinetic of metal precursors. At a high reduction rate difference, the Pd layer forms from H₂PdCl₄ and is subsequently etched, leading to the formation of a hollow space. A solid PdPt structure is achieved when the reduction rate of Pd and Pt precursor is comparable. Obviously, the hollow space and composition are tunable as well by adjusting the reduction rate difference. More importantly, the prepared hollow PdPt nanostructures exhibit a branched outer, porous wall, and rough hollow interior. The branched outer and rough hollow interior provide the higher density of unsaturated atoms, whereas the porous wall serves as channels connecting the inner, outer, and reactive agents. Moreover, the periodic self-consistent density function theory suggests that the d-band theory density of state of the PdPt nanoalloys is upshifted in comparison to the monometallic component, which will beneficial for improvement in their catalytic performances. Electrocatalytic tests reveal that the PdPt bimetallic NCs, especially for Pt₃₂Pd₆₈ nanostructures, show excellent catalytic activity and stability toward methanol oxidation reaction owing to their special structures as well as compositions.

Biosynthesis of Ag-Pd bimetallic alloy nanoparticles through hydrolysis of cellulose triggered by silver sulfate

We report a simple but efficient biological route based on the hydrolysis of cellulose to synthesize Ag-Pd alloy nanoparticles (NPs) under hydrothermal conditions. X-ray powder diffraction, ultraviolet-visible spectroscopy and scanning transmission electron microscopy-energy dispersive X-ray analyses were used to study and demonstrate the alloy nature. The microscopy results showed that well-defined Ag-Pd alloy NPs of about 59.7 nm in size can be biosynthesized at 200 °C for 10 h. Fourier transform infrared spectroscopy indicated that, triggered by silver sulfate, cellulose was hydrolyzed into saccharides or aldehydes, which served as both reductants and stabilizers, and accounted for the formation of the well-defined Ag-Pd NPs. Moreover, the as-synthesized Ag-Pd nanoalloy showed high activity in the catalytic reduction of 4-nitrophenol by NaBH4.

Electrochemical Deposition: An Advanced Approach for Templated Synthesis of Nanoporous Metal Architectures

Well-constructed porous materials take an essential role in a wide range of applications, including energy conversion and storage systems, electrocatalysis, photocatalysis, and sensing. Although the tailored design of various nanoarchitectures has made substantial progress, simpler preparation methods are compelled to meet large-scale production requirements. Recently, advanced electrochemical deposition techniques have had a significant impact in terms of precise control upon the nanoporous architecture (i.e., pore size, surface area, pore structure, etc.), enabling access to a wide range of compositions. In this Account, we showcase the uniqueness of electrochemical deposition techniques, detail their implementation toward the synthesis of novel nanoporous metals, and finally outline the future research directions. Nanoporous metallic structures are attractive in that they can provide high surface area and large pore volume, easing mass transport of reactants and providing high accessibility to catalytically active metal surface. The great merit of the electrochemical deposition approach does not only lie in its versatility, being applicable to a wide range of compositions, but also in the nanoscale precision it affords when it comes to crystal growth control, which cannot be easily achieved by other bottom-up or top-down approaches. In this Account, we describe the significant progress made in the field of nanoporous metal designed through electrochemical deposition approaches using hard templates (i.e., porous silica, 3D templates of polymer and silica colloids) and soft templates (i.e., lyotropic liquid crystals, polymeric micelles). In addition, we will point out how it accounts for precise control over the crystal growth and describe the unique physical and chemical properties emerging from these novel materials. Up to date, our group has reported the synthesis of several nanoporous metals and alloys (e.g., Cu, Ru, Rh, Pd, Pt, Au, and their corresponding alloys) under various conditions through electrochemical deposition, while investigating their various potential applications. The orientation of the channel structure, the composition, and the nanoporosity can be easily controlled by selecting the appropriate surfactants or block copolymers. The inherent properties of the final product, such as framework crystallinity, catalytic activity, and resistance to oxidation, are depending on both the composition and pore structure, which in turn require suitable electrochemical conditions. This Account is divided into three main sections: (i) a history of electrochemical deposition using hard and soft templates, (ii) a description of the important mechanisms involved in the preparation of nanoporous materials, and (iii) a conclusion and future perspectives. We believe that this Account will promote a deeper understanding of the synthesis of nanoporous metals using electrochemical deposition methods, thus enabling new pathways to control nanoporous architectures and optimize their performance toward promising applications such as catalysis, energy storage, sensors, and so forth.

Carbon nitride simultaneously boosted a PtRu electrocatalyst's stability and electrocatalytic activity toward concentrated methanol

Ruthenium dissolution is an inevitable issue for an anodic electrocatalyst in direct methanol fuel cells (DMFCs). Carbon nitride (C3N4) decoration derived from the carbonization of melamine simultaneously promoted a PtRu electrocatalyst's stability and electrocatalytic activity toward concentrated methanol ascribed to the additional active sites from C3N4.

Coercivity Modulation in Fe-Cu Pseudo-Ordered Porous Thin Films Controlled by an Applied Voltage: A Sustainable, Energy-Efficient Approach to Magnetoelectrically Driven Materials

Fe-Cu films with pseudo-ordered, hierarchical porosity are prepared by a simple, two-step procedure that combines colloidal templating (using sub-micrometer-sized polystyrene spheres) with electrodeposition. The porosity degree of these films, estimated by ellipsometry measurements, is as high as 65%. The resulting magnetic properties can be controlled at room temperature using an applied electric field generated through an electric double layer in an anhydrous electrolyte. This material shows a remarkable 25% voltage-driven coercivity reduction upon application of negative voltages, with excellent reversibility when a positive voltage is applied, and a short recovery time. The pronounced reduction of coercivity is mainly ascribed to electrostatic charge accumulation at the surface of the porous alloy, which occurs over a large fraction of the electrodeposited material due to its high surface-area-to-volume ratio. The emergence of a hierarchical porosity is found to be crucial because it promotes the infiltration of the electrolyte into the structure of the film. The observed effects make this material a promising candidate to boost energy efficiency in magnetoelectrically actuated devices.

Tri-metallic PtPdAu mesoporous nanoelectrocatalysts

The design of mesoporous materials with multi-metallic compositions is highly important for various electrocatalytic applications. In this paper, we demonstrate an efficient method to directly fabricate tri-metallic PtPdAu mesoporous nanoparticles (PtPdAu MNs) in a high yield, which is simply performed by heating treatment of the reaction mixture aqueous solution at 40 °C for 4 h. Profiting from its mesoporous structure and multi-metallic components, the as-prepared PtPdAu MNs exhibit enhanced electrocatalytic activities toward both methanol oxidation reaction and oxygen reduction reaction in comparison with bi-metallic PtPd MNs and commercial Pt/C catalyst.

Selective Etching Induced Synthesis of Hollow Rh Nanospheres Electrocatalyst for Alcohol Oxidation Reactions

The hollow noble metal nanostructures have attracted wide attention in catalysis/electrocatalysis. Here a two-step procedure for constructing hollow Rh nanospheres (Rh H-NSs) with clean surface is described. By selectively removing the surfactant and Au core of Au-core@Rh-shell nanostructures (Au@Rh NSs), the surface-cleaned Rh H-NSs are obtained, which contain abundant porous channels and large specific surface area. The as-prepared Rh H-NSs exhibit enhanced inherent activity for the methanol oxidation reaction (MOR) compared to state-of-the-art Pt nanoparticles in alkaline media. Further electrochemical experiments show that Rh H-NSs also have high activity for the electrooxidation of formaldehyde and formate (intermediate species in the course of the MOR) in alkaline media. Unfortunately, Rh H-NSs have low electrocatalytic activity for the ethanol and 1-propanol oxidation reactions in alkaline media. All electrochemical results indicate that the order of electrocatalytic activity of Rh H-NSs for alcohol oxidation reaction is methanol (C1 ) > ethanol (C2 ) > 1-propanol (C3 ). This work highlights the synthesis route of Rh hollow nanostructures, and indicates the promising application of Rh nanostructures in alkaline direct methanol fuel cells.