Nanoparticle Networks Research Articles

Hierarchical Metal-Organic Framework Films with Controllable Meso/Macroporosity.

The structuring of the metal‐organic framework material ZIF‐8 as films and membranes through the vapor‐phase conversion of ZnO fractal nanoparticle networks is reported. The extrinsic porosity of the resulting materials can be tuned from 4% to 66%, and the film thickness can be controlled from 80 nm to 0.23 mm, for areas >100 cm2. Freestanding and pure metal‐organic frameworks (MOF) membranes prepared this way are showcased as separators that minimize capacity fading in model Li‐S batteries.

Steady-state temperature distribution under near-field radiative heat transfer inside a linear chain of polaritonic nanoparticles

Thermal transport mediated by near-field interactions is superdiffusive in an ordered network of nanoparticles, such as linear chains. Based on such nanostructures, here we study a classical thermal-nonequilibrium problem, that is, the steady-state temperature distribution inside the chain of equally spaced polaritonic nanoparticles. The existence of the linear temperature profile and anomalous temperature variations in the inner region and near the boundary of a dense chain embedded in vacuum, respectively, is demonstrated by analyzing the effective radiative thermal conductivity within the system. Such temperature distributions are closely relevant to the strength of propagating surface modes sensitive to the chain density and dielectric material. We also demonstrate that, the presence of a homogeneous nonabsorbing background medium renders the steady-state temperature profile of the dense chain nonlinear, as well as enhancing drastically the long-distance heat exchange by two orders of magnitude relative to the vacuum case. This enhancement is a result of the high density of propagating waves in the medium, and is further confirmed by analyzing the energy density distribution over the chain. Furthermore, in a complex system consisting of many parallel chains, we show that, in steady state, temperatures of the thermal drive chain are allowed to tailor by its neighboring chains due to many-body interactions. This work opens ways to qualitatively assess and manipulate the stationary temperature field in advanced nanostructures, such as topological plasmonic chains and nanoparticle arrays.

Low thermal conductivity and enhanced Seebeck coefficient in Antimony and Selenium co-doped PbTe Nanopowders

We report a new method to synthesize Sb and Se co-doped PbTe nanopowders by a simple aqueous chemical method without the assistance of any surfactant or template. X-ray diffraction studies revealed that the prepared nanopowders are polycrystalline in nature and crystallize in the face-centered-cubic (fcc) PbTe structure. SEM and TEM studies reveal that Sb and Se co-doped PbTe nanopowders consist of an interconnected network of spherical nanoparticles with diameters around 12 nm. Seebeck coefficient of the undoped PbTe (436 µV/K at 301 K) and co-doped PbTe (627 µV/K at 301 K) is enhanced compared to that of the bulk PbTe (265 µV/K at 298 K) and the thermal conductivity is drastically decreased [undoped PbTe (0.265 W/m-K) and co-doped PbTe (0.525 W/m-K) at 378 K] compared with the value for the bulk PbTe (2.2 W/m-K at 300 K). The dimensionless figure of merit ZT attains its maximum value 0.055 at 378 K for undoped and 1.09 × 10−5 at 352 K for co-doped PbTe.

Guests mediated supramolecule-modified gold nanoparticles network for mimic enzyme application

Supramolecules mediated porous metal nanostructures are meaningful materials because of their specific properties and wide range of applications. Here, we describe a general and simple strategy for building Au networks based on the guest-induced 3D assembly of Au nanoparticle (AuNPs). Coming host-guest interaction resolved sulfonatocalix[4]arene (pSC 4 )-modified AuNP aggregate. The diverse guest molecules induced different porous network structures resulting in their different oxidize ability toward glucose. Among three different kinds of guest, hexamethylenediamine-pSC 4 -AuNPs have high sensitivity, wide linear range and good stability. By surface characterization and calculating the electrochemical properties of the AuNPs networks modified glassy carbon electrodes, the giving AuNPs network reveals good porosity, high surface areas and increased conductance and electron transfer for the electrocatalysis. The synthesized AuNPs nano-structures afford fast transport of glucose and ensure contact with a larger reaction surface due to high surface area. The fabricated sensor provides a platform for developing a more stable and efficient glucose sensor based on supramolecules mediated AuNPs networks.

Design of Highly Adhesive and Water-Resistant UV/Heat Dual-Curable Epoxy-Acrylate Composite for Narrow Bezel Display Based on Reactive Organic-Inorganic Hybrid Nanoparticles.

To attain the narrow bezel characteristic of information displays, functional sealing composite materials should possess high adhesion strength and water barrier performance due to their narrow line widths. In this study, highly adhesive UV/heat dual-curable epoxy–acrylate composites with outstanding water-resistant performance have been proposed using photoreactive organic–inorganic hybrid nanoparticles that can react with an acrylate resin, creating a crosslinked nanoparticle network within the sealing composite. The hybrid nanoparticles consisted of reactive methacrylate groups as a shell and an inorganic core of silica or aluminum oxide, and were facilely synthesized through sol–gel reaction and chemisorption process. The curing characteristics, adhesive strength, and moisture permeability of the proposed sealing composite have been compared to those of a conventional epoxy–acrylate composite containing inorganic silica particles. The composites including hybrid nanoparticles exhibited high UV and heat curing ratios owing to the numerous methacrylate groups on the nanoparticle surface and high compatibility with organic resins. Moreover, the proposed sealing composite showed high adhesion strength and extremely low water permeability due to the creation of densely photocrosslinked network with matrix resins. In addition, the sealing composite exhibited excellent narrow dispensing width as well as relatively low viscosity, suggesting the potential application in narrow bezel display.

Self‐Bondable and Stretchable Conductive Composite Fibers with Spatially Controlled Percolated Ag Nanoparticle Networks: Novel Integration Strategy for Wearable Electronics

AbstractAdvances in electronic textiles (E‐textiles) for next‐generation wearable electronics have originated from making a balance between electrical and mechanical properties of stretchy conductive fibers. Despite such progress, the trade‐off issue is still a challenge when individual fibers are woven and/or stretched undesirably. Time‐consuming fiber weaving has limited practical uses in scalable E‐textiles. Here, a facile method is presented to fabricate ultra‐stretchable Ag nanoparticles (AgNPs)/polyurethane (PU) hybrid conductive fibers by modulating solvent diffusion accompanied by in situ chemical reduction and adopting a tough self‐healing polymer (T‐SHP) as an encapsulation layer. First, the controlled diffusivity determines how formation of AgNPs is spatially distributed inside the fiber. Specifically, when a solvent with large molecular weight is used, the percolated AgNP networks exhibit the highest conductivity (30 485 S cm−1) even at 300% tensile strain and durable stretching cyclic performance without severe cracks by virtue of the efficient strain energy dissipation of T‐SHP encapsulation layers. The self‐bondable properties of T‐SHP encapsulated fibers enables self‐weavable interconnects. Using the new integration, mechanical and electrical durability of the self‐bonded fiber interconnects are demonstrated while stretching biaxially. Furthermore, the self‐bonding assembly is further visualized via fabrication of a complex structured E‐textile.

Ultrasensitive and Stretchable Conductive Fibers Using Percolated Pd Nanoparticle Networks for Multisensing Wearable Electronics: Crack-Based Strain and H2 Sensors.

The need for wearable electronic devices continues to grow, and the research is under way for stretchable fiber-type sensors that are sensitive to the surrounding atmosphere and will provide proficient measurement capabilities. Currently, one-dimensional fiber sensors have several limitations for their extensive use because of the complex structures of the sensing mechanisms. Thus, it is essential to miniaturize these materials with durability while integrating multiple sensing capabilities. Herein, we present an ultrasensitive and stretchable conductive fiber sensor using PdNP networks embedded in elastomeric polymers for crack-based strain and H2 sensing. The fiber multimodal sensors show a gauge factor of ∼2040 under 70% strain and reliable mechanical deformation tolerance (10,000 stretching cycles) in the strain-sensor mode. For H2 sensing, the fiber multimodal sensors exhibit a wide sensing range of high sensitivity: -0.43% response at 5 ppm (0.0005%) H2 gas and -27.3% response at 10% H2 gas. For the first time, we demonstrate highly stretchable H2 sensors that can detect H2 gas under 110% strain with mechanical durability. As demonstrated, their stable performance allows them to be used in wearable applications that integrate fiber multimodal sensors into industrial safety clothing along with a microinorganic light-emitting diode for visual indication, which exhibits proper activation upon H2 gas exposure.

Beta-Cyclodextrin-Assisted Synthesis of Silver Nanoparticle Network and Its Application in a Hydrogen Generation Reaction

The unsustainable nature of carbon-based fuels has prompted scientists and engineers to investigate alternative sources of energy. Silver nanoparticle networks (AgNPNs) were synthesized using beta-cyclodextrin for applications in hydrogen evolution reactions from sodium borohydride (NaBH4). The identities of the AgNPNs were confirmed using ultraviolet–visible spectroscopy, X-ray diffraction, and Transmission electron microscopy (TEM). The catalytic activity of the hydrogen evolution reactions was measured using a gravimetric water displacement system. The data collected show an increase in the efficiency of the hydrogen generation reaction with the addition of AgNPN. The silver nanoparticle network catalyst performed best at 22 °C with an increased concentration of NaBH4 producing hydrogen at a rate of 0.961 mL∙min−1∙mLcat−1. The activation energy was calculated to be 50.3 kJ/mol.

Synergistic Effect of Plasmonic Gold Nanoparticles Decorated Carbon Nanotubes in Quantum Dots/TiO2 for Optoelectronic Devices.

Here, a facile approach to enhance the performance of solar‐driven photoelectrochemical (PEC) water splitting is described by means of the synergistic effects of a hybrid network of plasmonic Au nanoparticles (NPs) decorated on multiwalled carbon nanotubes (CNTs). The device based on TiO2–Au:CNTs hybrid network sensitized with colloidal CdSe/(CdSexS1− x)5/(CdS)1 core/alloyed shell quantum dots (QDs) yields a saturated photocurrent density of 16.10 ± 0.10 mA cm−2 [at 1.0 V vs reversible hydrogen electrode (RHE)] under 1 sun illumination (AM 1.5G, 100 mW cm−2), which is ≈26% higher than the control device. The in‐depth mechanism behind this significant improvement is revealed through a combined experimental and theoretical analysis for QDs/TiO2–Au:CNTs hybrid network and demonstrates the multifaceted impact of plasmonic Au NPs and CNTs: i) hot‐electron injection from Au NPs into CNTs and TiO2; ii) near‐field enhancement of the QDs absorption and carrier generation/separation processes by the plasmonic Au NPs; iii) enhanced photoinjected electron transport due to the highly directional pathways offered by CNTs. These results provide fundamental insights on the properties of QDs/TiO2–Au:CNTs hybrid network, and highlights the possibility to improve the performance of other solar technologies.

Enhanced peroxydisulfate oxidation via Cu(III) species with a Cu-MOF-derived Cu nanoparticle and 3D graphene network

The contribution of Cu(III) produced during heterogeneous peroxydisulfate (PDS) activation to pollutant removal is largely unknown. Herein, a composite catalyst is prepared with Cu-based metal organic framework (Cu-MOF) derived Cu nanoparticles decorated in a three-dimensional reduced graphene oxide (3D RGO) network. The 3D RGO network overcomes the aggregation of nanosized zero-valent copper and reduces the copper consumption during the PDS activation reaction. The Cu/RGO catalyst exhibits high catalytic activity for 2,4-dichlorophenol (2,4-DCP) degradation in a wide pH range of 3–9, with a low Cu dosage that is only 0.075 times that of previous reports with zero-valent copper. Moreover, a high mineralization ratio (69.2 %) of 2,4-DCP is achieved within 30 min, and the Cu/RGO catalyst shows high reactivity toward aromatic compounds with hydroxyl and chlorinated groups. Unlike normal sulfate radical-based advanced oxidation, alcohols show negligible impacts on the reaction, suggesting that Cu(III), rather than SO4− and OH, dominates the degradation process. We believe that PDS activation by 3D Cu/RGO, with Cu(III) as the main active species, provides new insights in selective organic pollutant removal in wastewater treatment.

Characterization of a highly sensitive and selective hydrogen gas sensor employing Pt nanoparticle network catalysts based on different bifunctional ligands

A catalytic hydrogen gas sensor of superior sensitivity, selectivity, resolution and dynamic response was developed with catalysts composed of ligand-stabilized Pt nanoparticles. We have characterized different catalysts utilizing the bi-functional ligands trans-1,4-diaminocyclohexane (DACH), 1,5-diaminonaphthalene (DAN), 4,4´´-diamino-p-terphenyl (DATER), benzidine (BEN) and p-phenylene diamine (PDA) for hydrogen gas sensing. A comprehensive evaluation by comparison, with respect to both, structural aspects (TEM and SEM) and gas sensing performance of the 5 types of ligand-linked Pt nanoparticles and non-stabilized Pt nanoparticles was conducted to select the optimized catalysts. From this investigation, DATER-linked Pt nanoparticles appear immensely promising: the sensor is selective to hydrogen and shows extremely high sensitivity, around 400 mV/1% vol., but exhibits no crosssensitivity to methane and ethane. Likewise, sensors with DATER- and DAN-linked Pt nanoparticles can detect down to 0.001 % (10 ppm) alongside 650 ms average response time (t90).

Competitive impedimetric aptasensors for detection of small molecule pollutants by the signal amplification of self-assembled biotin-phenylalanine nanoparticle networks

Impedimetric aptasensors without signal amplification exhibit poor sensitivity for the detection of small molecule contaminants. In this work, biotinylated nanoparticles of biotin-FNPs were readily prepared by the self-assembly of biotin-phenylalanine (biotin-Phe) monomers. The biotin-FNPs were then used for the development of competitive impedimetric aptasensors by streptavidin–biotin (SA–biotin) coupling chemistry. Specifically, capture of biotinylated DNA (biotin-DNA) by the aptamer-modified electrode allowed for the in situ formation of SA–biotin-FNPs networks on the electrode surface, hampering the electron transfer by creating an insulating layer. The target–aptamer interaction prevented the capture of biotin-DNA, thus inhibiting the formation of SA–biotin-FNPs networks on the electrode surface and allowing for the electron transfer. To demonstrate the analytical performances of the strategy, aflatoxin B1 (AFB1) was determined as the model analyte. The aptasensor exhibited a linear range of 0.05–3 pg/mL. The detectable concentration is much lower than that achieved by other impedimetric aptasensors. The strategy may provide a general way for the design of biosensors to determine various small molecules by matching sequence-specific aptamers.

Cerebral Oximetry: Ultrastretchable Helical Conductive Fibers Using Percolated Ag Nanoparticle Networks Encapsulated by Elastic Polymers with High Durability in Omnidirectional Deformations for Wearable Electronics (Adv. Funct. Mater. 29/2020)

Cerebral Oximetry: Ultrastretchable Helical Conductive Fibers Using Percolated Ag Nanoparticle Networks Encapsulated by Elastic Polymers with High Durability in Omnidirectional Deformations for Wearable Electronics (Adv. Funct. Mater. 29/2020)

Two-dimensional Au & Ag hybrid plasmonic nanoparticle network: broadband nonlinear optical response and applications for pulsed laser generation

Abstract Localized surface plasmon resonance (LSPR) of metallic nanoparticles (NPs) can generate and enhance the nonlinear optical (NLO) response and has been widely used in biosensing, optical bistability, optical switch, and modulator, surface-enhanced spectroscopies, etc. Here, the two-dimensional (2D) Au & Ag hybrid plasmonic NP network (Au & Ag HPNN) were synthesized by assembling Au and Ag NPs in ethanol solvent and transferring onto a CaF2 substrate. The frequency-domain finite element method (FEM) simulations were performed to explore their LSPR properties, demonstrating the broadband optical responses throughout visible, near-infrared and mid-infrared regions. The ultrafast carrier relaxation times were determined to be 3.9, 5.6, and 8.6 ps, while the nonlinear absorption coefficients were −1.12 × 104, −1.71 × 104, and −2.54 × 104 cm/GW, respectively, for the three wavelengths matching the LSPRs peaks at 1.0, 2.0, and 3.0 μm bands. Furthermore, passively Q-switched (PQS) solid-state lasers operating at 1062.8, 1990.8, and 2947 nm were demonstrated with 2D Au & Ag HPNN based saturable absorbers. This work not only reveals desirable ultrafast broadband NLO responses of 2D HPNN, but also provides a platform for investigating their applications in nanophotonic devices.

Topochemical assembly of levodopa nanoparticles network as a high-performance biosensing platform coupling with π-π stacking and electrostatic repulsion interactions

Topochemical assembly carbon materials with unique structure rarely investigated and reported. Herein, we demonstrate the feasibility of using topochemical assembly levodopa nanoparticles with dendritic structure (LNDS) network as a new high-performance biosensing platform based on noncovalent functionalization of LNDS with a fluorescent oligonucleotide. The proposed platform is dependent on the competition of π-π stacking and electrostatic repulsion interactions between LNDS and fluorescent oligonucleotide. The obtained LNDS with 96.1% quenching efficiency is synthesized by using levodopa as the single precursor by natural oxidation or microwave irradiation. The constructed platform can be used for simple and efficient probing single-nucleotide polymorphisms (SNPs) and cDNA by fluorescence restoration with a highly sensitivity and selectivity, remarkably superior to those based on graphenes. Additionally, an aptasensor is further constructed for small molecule ATP detention in serum with a low detection limit of 4 μM. To the best of our knowledge, this is the first attempt to use LNDS to design a biosensing platform, and therefore opens possibilities for new types of nanoparticle-based molecule approaches, and sequencing technologies.

Voltammetric sensing of recombinant viral dengue virus 2 NS1 based on Au nanoparticle\u2013decorated multiwalled carbon nanotube composites

A homemade gold electrode is modified with a carbon nanotubes/gold nanoparticles nanocomposite to perform selective and sensitive electrochemical detection of dengue toxin. This nanostructured composite offers a large specific surface and a reactive interface allowing the immobilization of biological material. Dengue antibodies are immobilized on gold nanoparticles via covalent bonding for dengue toxin detection. The porous tridimensional network of carbon nanotubes and gold nanoparticles enhances the electrochemical signal and the overall performance of the sensor. After optimization, the system exhibits a high sensitivity of − 0.44 ± 0.01 μA per decade with wide linear range between 1 × 10−12 and 1 × 10−6 g/mL at a working potential of 0.22 V vs Ag/AgCl. The extremely low detection limit (3 × 10−13 g/mL) ranks this immunosensor as one of the most efficient reported in the literature for the detection of recombinant viral dengue virus 2 NS1. This biosensor also offers good selectivity, characterized by a low response to various non-specific targets and assays in human serum. The outstanding performances and the reproducibility of the system place the biosensor developed among the best candidates for future medical applications and for early diagnosis of dengue fever.Graphical abstract

Bioactive Glass Nanoparticles for Tissue Regeneration.

Sol–gel-derived bioactive glass nanoparticles have attracted special interest due to their potential as novel therapeutic and regenerative agents. Significant challenges are yet to be addressed. The fabrication of sol–gel-derived nanoparticles in binary and ternary systems with an actual composition that meets the nominal has to be achieved. This work addresses this challenge and delivers nanoparticles in a ternary system with tailored composition and particle size. It also studies how specific steps in the fabrication process can affect the incorporation of the metallic ions, nanoparticle size, and mesoporosity. Sol–gel-derived bioactive glass nanoparticles in the 62 SiO2–34.5 CaO–3.2 P2O5 (mol %) system have been fabricated and characterized for their structural, morphological, and elemental characteristics using Fourier transform infrared spectroscopy, X-ray diffraction analysis, scanning electron microscopy associated with elemental analysis, transmission electron microscopy, and solid-state nuclear magnetic resonance. The fabricated nanoparticles were additionally observed to form the apatite phase when immersed in simulated body fluid. This work highlights the effect of the different processing variables, such as the nature of the solvent, the order in which reagents are added, stirring time, and the concentrations in the catalytic solution on the controlled incorporation of specific ions (e.g., P and Ca) in the nanoparticle network and particle size.

Electroformed, Self‐Connected Tin Oxide Nanoparticle Networks for Electronic Reservoir Computing

AbstractInterconnected SnOx nanoparticle (NP) networks are electroformed within a semi‐insulating SnOx thin‐film and between lateral electrodes. During this top‐down process, Joule heating, disproportionation, and de‐wetting of the SnOx thin‐film precede the formation of the NP networks. The same lateral electrodes used for electroforming are used to probe the network and reveal its complex electrical characteristics. Higher‐order harmonic generation is observed and the internal short‐term memory effects of the NP networks enable temporal inputs to be mapped into reservoir states for subsequent linear readout without training. Reservoir computing functionality is demonstrated with no requirement for high‐vacuum or cryo‐cooled environments.

Modification-free amperometric biosensor for the detection of wild-type p53 protein based on the in situ formation of silver nanoparticle networks for signal amplification

Sensitive and accurate quantification of wild-type p53 protein is of great importance for biological research and clinical diagnosis. Herein, a modification-free amperometric biosensor was proposed for sensitive detection of wild-type p53 protein by the signal amplification of silver nanoparticles (AgNPs) networks formed in situ on electrode surface. Double-stranded DNA (dsDNA) probe containing two consensus sites was immobilized on gold electrode surface to capture wild-type p53 protein. The cysteine thiol and amine groups on the exterior of the protein allowed for the attachment of bare AgNPs through the AgS or AgN interactions. Meanwhile, benzene-1,4-dithiol (BDT) molecules in solution triggered the assembly of more AgNPs on electrode surface through the AgS interactions, thus leading to the in situ formation of AgNPs networks for signal amplification. The target at the concentration as low as 0.1 pM can be readily determined. This method was further applied to determine wild-type p53 protein in spiked human serum and cell lysates with satisfactory results. Moreover, the biosensor is regenerative and does not require the modification of AgNPs with recognition element for signal readout. The modification-free strategy can potentially be applied to develop novel biosensors for detection of other biological macromolecules.

Amplified electrochemical determination of UO22+ based on the cleavage of the DNAzyme and DNA-modified gold nanoparticle network structure.

A superior electrochemical biosensor was designed for the determination of UO22+ in aqueous solution by integration of DNAzyme and DNA-modified gold nanoparticle (DNA-AuNP) network structure. Key features of this method include UO22+ inducing the cleavage of the DNAzyme and signal amplification of DNA-AuNP network structure. In this electrochemical method, the DNA-AuNP network structure can be effectively modified on the surface of gold electrode and then employed as an ideal signal amplification unit to generate amplified electrochemical response by inserting a large amount of electrochemically active indicator methylene blue (MB). In the presenceof UO22+, the specific sites on DNA-AuNP network structure can be cleaved by UO22+, releasing the DNA-AuNP network structure with detectable reduction of electrochemical response intensity. The electrochemical response intensity isrelated to the concentration of UO22+. The logarithm of electrochemical response intensity and UO22+ concentration showed a wide linear range of 10~100pM, and the detection limit reached 8.1pM (S/N = 3). This method is successfully used for determination of UO22+ in water samples. Graphical abstract Fabricated DNAzyme network structure for enhanced electrical signal. Numerical experiments show that the current signal decreases as the concentration of UO22+ increases. It can be seen that the biosensors could be used to detect UO22+ in aqueous solution effectively.