Specific Nanostructures Research Articles

Vacancy-Activated Surface Reconstruction of Perovskite Nanofibers for Efficient Lattice Oxygen Evolution.

Inducing the surface reconstruction of perovskites to promote the oxygen evolution reaction (OER) has garnered increasing attention due to the enhanced catalytic activities caused by the self-reconstructed electroactive species. However, the high reconstruction potential, limited electrolyte penetration, and accessibility to the perovskite surface greatly hindered the formation of self-reconstructed electroactive species. Herein, trace Ce-doped La0.95Ce0.05Ni0.8Fe0.2O3-δ nanofibers (LCNF-NFs) were synthesized via electrospinning and postcalcination to boost surface reconstruction. The upshift of the O 2p band center induced by the rich oxygen vacancies lowered the reconstruction potential, and the specific one-dimensional nanostructure effectively enabled enhanced electrolyte accessibility and permeation to the LCNF-NFs. These collectively caused massive in situ generation of self-reconstructed electroactive Ni/FeO(OH) species on the surface. As a result, the surface-reconstructed LCNF-NFs exhibited accelerated lattice kinetics with a comparatively lower Tafel slope of 50.12 mV dec-1, together with an overpotential of only 342.3 mV to afford a current density of 10 mA cm-2 in 0.1 M KOH, which is superior to that of pristine LaNi0.8Fe0.2O3-δ nanoparticles (NPs) and the same stoichiometric La0.95Ce0.05Ni0.8Fe0.2O3-δ NPs, commercial IrO2, and most of the state-of-the-art OER electrocatalysts. This study provided deep insights into the surface reconstruction behaviors induced by oxygen defects and an intellectual approach for constructing electroactive species in situ on perovskites for various energy storage and conversion devices.

Self-assembled double-shelled hollow CeO2, carbon quantum dots and CdZnS heterostructured photocatalyst for enhanced photocatalytic hydrogen evolution

Aiming at the requirement of green energy, a Z-scheme photocatalyst for hydrogen production by water photolysis was proposed and determined. The photocatalyst is spherical and composed of three layers, namely double-shelled CeO2, carbon quantum dots (CQDs) and CdZnS. The synthesis strategy was mainly through layer-by-layer adsorption and reaction deposition. It is well known that morphology of nanosized materials strongly alter and influence their physical and chemical properties, thus we consider the structure of the photocatalyst as follows: the inner layer of the photocatalyst was double-shelled CeO2, outer layer was nanorod-like CdZnS, and in between CQDs as an electron mediator. Samples with various compositions were prepared, and after a series of structure characterization and performance test, the best photocatalytic activity of H2 evolution rate shows a value up to 89.1 mmol·g−1·h−1. It is concluded that the enhancement of hydrogen evolution performance can be explained as follows: First, CeO2 and CdZnS have both narrow band gap and special nanostructures, which broaden their light absorption spectra; Second, due to the CQDs at the heterojunction interface, the separation/transfer of photogenerated charge carriers is promoted and the lifetime of photocarriers is prolonged.

Titanium Dioxide Nanomaterials: Progress in Synthesis and Application in Drug Delivery.

Background: Recent developments in nanotechnology have provided efficient and promising methods for the treatment of diseases to achieve better therapeutic results and lower side effects. Titanium dioxide (TiO2) nanomaterials are emerging inorganic nanomaterials with excellent properties such as low toxicity and easy functionalization. TiO2 with special nanostructures can be used as delivery vehicles for drugs, genes and antigens for various therapeutic options. The exploration of TiO2-based drug delivery systems shows great promise for translating nanotechnology into clinical applications; Methods: Comprehensive data on titanium dioxide were collected from reputable online databases including PubMed, GreenMedical, Web of Science, Google Scholar, China National Knowledge Infrastructure Database, and National Intellectual Property Administration; Results: In this review, we discuss the synthesis pathways and functionalization strategies of TiO2. Recent advances of TiO2 as a drug delivery system, including sustained and controlled drug release delivery systems were introduced. Rigorous long-term systematic toxicity assessment is an extremely critical step in application to the clinic, and toxicity is still a problem that needs to be closely monitored; Conclusions: Despite the great progress made in TiO2-based smart systems, there is still a great potential for development. Future research may focus on developing dual-reaction delivery systems and single-reaction delivery systems like redox and enzyme reactions. Undertaking thorough in vivo investigations is necessary prior to initiating human clinical trials. The high versatility of these smart drug delivery systems will drive the development of novel nanomedicines for personalized treatment and diagnosis of many diseases with poor prognosis.

Thrombin and NIR dual-responsive system driven by heat-gas for thrombus targeted therapy

Drug thrombolysis is the main means of clinical treatment for thrombotic-related diseases. However, serious bleeding complications caused by low drug delivery efficiency and secondary vascular embolism usually lead to unsatisfactory therapeutic effects. Herein, we constructed a thrombin and near-infrared (NIR) dual-responsive drug-loaded intelligent system to solve the above problems. The CREKA-modified polydopamine (PDA) nanoparticles (NPs) were crosslinked by thrombin-responsive peptide (Pep), to obtain Pep-PPC nanocarriers with special mesoporous nanostructures. Subsequently, NO donor BNN6 and thrombolytic drug UK were loaded on the surface and into the mesoporous of Pep-PPC, to get the multifunctional Pep-NO@PPC/UK. In vitro and in vivo results proved that Pep-NO@PPC/UK could effectively recognize and aggregate at the thrombus site via CREKA-mediated active targeting. Then local abundant thrombin cleaved the nanoplatform to release UK. Meanwhile, PDA converted NIR light into heat and synchronously triggered NO release. This transformed the DDS into a “heat-gas” dual propulsion nanomotor in situ, driving deep penetration of UK in thrombus tissue. Under the combined action of UK and PTT, arterial thrombosis rapidly dissolved with relatively low bleeding risk. More importantly, NO generated in situ could prevent re-embolism of blood vessels at the thrombolytic site by inhibiting activated platelet aggregation, ultimately improving vascular reperfusion rate through a combination of attack and defense mode.

Ultrafast Quasi-Solid-State Microwave Construction of Spongy Cobalt-Molybdenum Phosphide for Hydrogen Production Over Wide pH Range.

The developed strategies for synthesizing metal phosphides are usually cumbersome and pollute the environment. In this work, an ultrafast (30s) quasi-solid-state microwave approach is developed to construct cobalt-molybdenum phosphide decorated with Ru (Ru/CoxP-MoP) featured porous morphology with interconnected channels. The specific nanostructure favors mass transport, such as electrolyte bubbles transfer and exposing rich active sites. Moreover, the coupling effects between metallic elements, especially the decorated Ru, also act as a pivotal role on enhancing the electrocatalytic performance. Benefiting from the effects of composition and specific nanostructure, the prepared Ru/CoxP-MoP exhibits efficient HER performance with a current density of 10mAcm-2 achieved in 1m KOH, 0.5mH2SO4, seawater containing 1mKOH and 1mPBS, with overpotentials of 52, 59, 55, 90mV, and coupling with good stability. This work opens a novel and fast avenue to design metal-phosphide-based nanomaterials in energy-conversion and storage fields.

Flower-like SnO2 nanorod aggregates modified with Co3O4 nanoparticles grown on reduced graphene oxide(rGO) sheets for xylene sensing

In this paper, the ternary composite of flower-like SnO2 nanorod aggregates modified with Co3O4 nanoparticles grown on rGO sheets were synthesized by a two-step process of water heating and water bath, and characterized by SEM, TEM, XRD, EDS, and XPS. The gas-sensitive performance test results revealed that the 15-rGO/SnO2/Co3O4 sensor exhibited a higher response value (I0/Ia=24.46) to 100 ppm xylene at the optimal working temperature of 175℃. In addition, the sensor could detect 10 ppb xylene, with a low detection limit. The gas-sensitive properties of 15-rGO/SnO2/Co3O4 were significantly improved due to the large specific surface area of rGO flakes and SnO2 slender nanorods, the catalytic action of p-type semiconductor Co3O4 and the existence of p-n-p double heterojunction. Due to the special nanostructure and synergistic effect of SnO2, rGO and Co3O4, the 15-rGO/SnO2/Co3O4 sensor enabled the efficient and selective detection of xylene.

Enhanced thermophysical and mechanical properties of gadolinium zirconate ceramics via non-stoichiometric design

Rare-earth zirconate ceramics are potential materials for thermal barrier coatings due to their low thermal conductivity and excellent structural stability. However, the low thermal expansion coefficient and fracture toughness limit their application and further improvements are needed. In this work, non-stoichiometric gadolinium zirconate ceramics with fluorite phase structure were successfully prepared using solid-state reaction method. HRTEM, iDPC-STEM, and in-situ XRD were employed to investigate nanostructure, lattice defects, and phase stability. The non-stoichiometric ratio introduces more defects and forms special nanostructures, enhancing the thermophysical properties of gadolinium zirconate ceramics. The non-stoichiometric gadolinium zirconate ceramics have lower phonon thermal conductivity with higher hardness and fracture toughness compared to stoichiometric ratio ceramics. In addition, the non-stoichiometric gadolinium zirconate ceramics exhibit excellent structural stability in a wide temperature range. These performances provide further applications for non-stoichiometric gadolinium zirconate ceramics as thermal barrier coatings.

Tailoring Defects in B, N-Codoped Carbon Nanowalls for Direct Electrochemical Oxidation of Glyphosate and its Metabolites.

Tailoring the defects in graphene and its related carbon allotropes has great potential to exploit their enhanced electrochemical properties for energy applications, environmental remediation, and sensing. Vertical graphene, also known as carbon nanowalls (CNWs), exhibits a large surface area, enhanced charge transfer capability, and high defect density, making it suitable for a wide range of emerging applications. However, precise control and tuning of the defect size, position, and density remain challenging; moreover, due to their characteristic labyrinthine morphology, conventional characterization techniques and widely accepted quality indicators fail or need to be reformulated. This study primarily focuses on examining the impact of boron heterodoping and argon plasma treatment on CNW structures, uncovering complex interplays between specific defect-induced three-dimensional nanostructures and electrochemical performance. Moreover, the study introduces the use of defect-rich CNWs as a label-free electrode for directly oxidizing glyphosate (GLY), a common herbicide, and its metabolites (sarcosine and aminomethylphosphonic acid) for the first time. Crucially, we discovered that the presence of specific boron bonds (BC and BN), coupled with the absence of Lewis-base functional groups such as pyridinic-N, is essential for the oxidation of these analytes. Notably, the D+D* second-order combinational Raman modes at ≈2570 cm-1 emerged as a reliable indicator of the analytes' affinity. Contrary to expectations, the electrochemically active surface area and the presence of oxygen-containing functional groups played a secondary role. Argon-plasma post-treatment was found to adversely affect both the morphology and surface chemistry of CNWs, leading to an increase in sp3-hybridized carbon, the introduction of oxygen, and alterations in the types of nitrogen functional groups. Simulations support that certain defects are functional for GLY rather than AMPA. Sarcosine oxidation is the least affected by defect type.

Pt single-atom electrocatalysts at Cu2O nanowires for boosting electrochemical sensing toward glucose

In electrochemical biosensors, rational design and synthesis of high-performance electrochemical glucose sensors based on emerging single-atom catalysts (SACs) are paramount. Herein, a facile approach is proposed for dispersing single-atom doping of cuprous oxide (Cu2O) nanowires with Pt on a copper foam substrate (Pt1/Cu2O@CF) via the electrochemical deposition process. The specific nanostructure of the single-atom catalyst has been elaborately revealed with the aid of atomic resolution scanning transmission electron microscopy (STEM) and X-ray absorption fine structure spectroscopy (XAS). The as-fabricated Pt1/Cu2O@CF biosensor with satisfactory scalability exhibits a low limit of detection (1 μM), ultrahigh sensitivity (31.55 mA mM−1 cm−2), excellent selectivity, and robust reliability toward glucose. The first principles simulations reveal that Pt SAC is beneficial to the adsorption of glucose on the surface and further facilitates the electron transfer for the deprotonation process, resulting in high glucose sensing performance. This work sheds light on the applications of SACs for designing ultrasensitive electrochemical biosensors.

N-Containing Porous Carbon-Based MnO Composites as Anode with High Capacity and Stability for Lithium-Ion Batteries.

MnO has attracted much attention as the anode for Li-ion batteries (LIBs) owing to its high specific capacity. However, the low conductivity limited its large application. An effective solution to solve this problem is carbon coating. Biomass carbon materials have aroused much interest for being low-cost and rich in functional groups and hetero atoms. This work designs porous N-containing MnO composites based on the chemical-activated tremella using a self-templated method. The tremella, after activation, could offer more active sites for carbon to coordinate with the Mn ions. And the as-prepared composites could also inherit the special porous nanostructures of the tremella, which is beneficial for Li+ transfer. Moreover, the pyrrolic/pyridinic N from the tremella can further improve the conductivity and the electrolyte wettability of the composites. Finally, the composites show a high reversible specific capacity of 1000 mAh g-1 with 98% capacity retention after 200 cycles at 100 mA g-1. They also displayed excellent long-cycle performance with 99% capacity retention (relative to the capacity second cycle) after long 1000 cycles under high current density, which is higher than in most reported transition metal oxide anodes. Above all, this study put forward an efficient and convenient strategy based on the low-cost biomass to construct N-containing porous composite anodes with a fast Li+ diffusion rate, high electronic conductivity, and outstanding structure stability.

Light management of solar cells by implementation of nano/microstructures

Research on the improvement of the photoelectric conversion efficiency of solar cells is always the focus. In this paper, an efficient anti-reflection micro/nanostructure is proposed to improve the conversion efficiency of the solar cell. Graded effective refractive index theory is used to achieve the anti-reflection effect while the simulation model is established by FDTD. A specific periodic nanostructure is obtained, which can achieve a good anti-reflection effect. According to the simulation model, the reflectivity of the solar cell is reduced by 0.85% and the transmittance is increased by 0.85% in the band range of 200 nm to 1000 nm. Specifically, high anti-reflection phenomena are obtained in the band range of ultraviolet and blue light, in which the reflectivity is reduced by 1.56% and the transmittance is increased by 1.55%. Based on the simulation results, the array nanostructure is produced by etching the self-assembled polystyrene (PS) microspheres. Finally, the required structure is formed on the silicon wafer by nanoimprinting and etching technology. The reflectivity of 2.8% is obtained on silicon, which can potentially increase the opto-electrical performance of the solar cell.

From Structure to Application: The Evolutionary Trajectory of Spherical Nucleic Acids.

Since the proposal of the concept of spherical nucleic acids (SNAs) in 1996, numerous studies have focused on this topic and have achieved great advances. As a new delivery system for nucleic acids, SNAs have advantages over conventional deoxyribonucleic acid (DNA) nanostructures, including independence from transfection reagents, tolerance to nucleases, and lower immune reactions. The flexible structure of SNAs proves that various inorganic or organic materials can be used as the core, and different types of nucleic acids can be conjugated to realize diverse functions and achieve surprising and exciting outcomes. The special DNA nanostructures have been employed for immunomodulation, gene regulation, drug delivery, biosensing, and bioimaging. Despite the lack of rational design strategies, potential cytotoxicity, and structural defects of this technology, various successful examples demonstrate the bright and convincing future of SNAs in fields such as new materials, clinical practice, and pharmacy.

PVA/PANI-DBSA Nanomesh Tactile Sensor for Force Feedback.

Touch serves as an important medium for human-environment interaction. The piezoresistive tactile sensor has attracted much attention due to its convenient technology, simple principle, and convenient signal acquisition and analysis. In this paper, conductive beads-on-string polyvinyl alcohol (PVA)/polyaniline doped with dodecyl benzene sulfonic acid (PANI-DBSA) nanofibers were fabricated via the electrospinning technique. Due to the special nanostructure of PVA-coated PANI-DBSA, the tactile sensor presented a wide measuring range of 12 Pa-121 kPa and appreciable sensitivity of 8.576 kPa-1 at 12 Pa~484 Pa. In addition, the response time and recovery time of the sensor were approximately 500 ms, demonstrating promising prospects in the field of tactile sensing for active upper limb prostheses.

The dual active sites reconstruction on gelatin in-situ derived 3D porous N-doped carbon for efficient and stable overall water splitting

The exploration of bifunctional electrocatalysts with high activity, stability, and economy is of great significance in promoting the development of water splitting. Herein, a dual active sites heterostructure NiCoS/NC was designed to be derived in situ on 3D N-doped porous carbon (NC) using gelatin as a nitrogen and carbon source. The characterization of experiments suggests that nanoflower-like Ni2CoS4 (abbreviated as NiCoS) was randomly distributed on the NC substrate, and the sheet-like NC formed a highly open porous network structure resembling a honeycomb, which provided more accessible active sites for electrolyte ions. In addition, the special nanostructures of the catalyst materials help to promote the surface reconstruction to the real active substance NiOOH/CoOOH, and the double active sites synergistically reduce the overpotential of OER and improve its kinetics. DFT (Density-functional theory) calculations reveal the electronic coupling of NiCoS/NC in atomic orbitals, modulation of electrons by the heterointerface and N-doping, and synergistic effect of dual active sites improving the inherent catalytic activity. The NiCoS/NC composite electrocatalyst exhibited a 177 mV small OER overpotential and a 132 mV small HER overpotential with Faraday efficiencies as high as 96 % and 98 % at 10 mA cm−2 current density. In the two-electrode system, it also requires only an ultra-low voltage of 1.52 V to achieve a 10 mA cm−2 current density, and it shows excellent long-term water splitting stability. This provides a new idea for the development of transition metal-based bifunctional electrocatalysts.

DNA Nanostructure-Templated Antibody Complexes Provide Insights into the Geometric Requirements of Human Complement Cascade Activation.

The classical complement pathway is activated by antigen-bound IgG antibodies. Monomeric IgG must oligomerize to activate complement via the hexameric C1q complex, and hexamerizing mutants of IgG appear as promising therapeutic candidates. However, structural data have shown that it is not necessary to bind all six C1q arms to initiate complement, revealing a symmetry mismatch between C1 and the hexameric IgG complex that has not been adequately explained. Here, we use DNA nanotechnology to produce specific nanostructures to template antigens and thereby spatially control IgG valency. These DNA-nanotemplated IgG complexes can activate complement on cell-mimetic lipid membranes, which enabled us to determine the effect of IgG valency on complement activation without the requirement to mutate antibodies. We investigated this using biophysical assays together with 3D cryo-electron tomography. Our data revealed the importance of interantigen distance on antibody-mediated complement activation, and that the cleavage of complement component C4 by the C1 complex is proportional to the number of ideally spaced antigens. Increased IgG valency also translated to better terminal pathway activation and membrane attack complex formation. Together, these data provide insights into how nanopatterning antigen-antibody complexes influence the activation of the C1 complex and suggest routes to modulate complement activation by antibody engineering. Furthermore, to our knowledge, this is the first time DNA nanotechnology has been used to study the activation of the complement system.

Weighted Mostar invariants of chemical compounds: An analysis of structural stability

The concept of the weighted Mostar invariant is a mathematical tool used in chemical graph theory to study the stability of chemical compounds. Several recent studies have explored the weighted Mostar invariant of various chemical structures, including hydrocarbons, alcohols, and other organic compounds. One of the key advantages of the weighted Mostar invariant is that it can be easily computed for large and complex chemical structures, making it a valuable tool for studying the stability of a wide range of chemical compounds. This notion has been utilized to build novel approaches for forecasting chemical compound stability, such as machine learning algorithms. The focus of the paper is to demonstrate the weighted Mostar indices of three specific nanostructures: silicon dioxide (SIO2, poly-methyl methacrylate network (PMMA(s)), and melem chains (MC(h)). The authors seek to provide the findings of their investigation of these nanostructures using the weighted Mostar invariant.

Hierarchical Cu3V2O8/Cu6Mo5O18/MXene nanostructures by ultrathin nanosheets for highly sensitive electrochemical detection of organophosphorus pesticides

Transition-metal oxides (TMOs) with hierarchical nanostructures derived from metal organic frameworks (MOFs) were widely applied in electrochemical investigation. In this paper, a rational synthesis strategy of TMOs with specific nanostructures and multiple components was reported. Three-dimensional (3D) CuMoV layered metal hydroxides (CuMoV LDHs) architecture was prepared by mild and facile wet-chemistry process to reshape Cu-MOF surface and realize the self-templated conversion. After thermal annealing, hierarchical CuMoV LDHs were transformed to polynary Cu3V2O8/Cu6Mo5O18 (CMVO) compounds. Based on the electrostatic attraction, CMVO/MXene (CMVON) compounds were assembled by combining the CMVO and few-layer Nb2CTx MXene (f-Nb2C) nanosheets and employed as modified materials on the electrode surface. Benefiting from the superior electronic conductivity, large surface area and shortened ion diffusion pathway, the CMVON hybrids demonstrated excellent electrochemical sensing properties. Upon optimum conditions, the constructed CMVON based AChE biosensor manifested markedly analytical performance with the low limit of detection (LOD) and wide linear ranges for parathion-methyl, malathion, and fenitrothion detection.

Advances in the application of logic gates in nanozymes.

Nanozymes are a class of nanomaterials with biocatalytic function and enzyme-like activity, whose advantages include high stability, low cost, and mass production. They can catalyze the substrates of natural enzymes based on specific nanostructures and serve as substitutes for natural enzymes. Their applied research involves a wide range of fields such as biomedicine, environmental governance, agriculture, and food. Molecular logic gates are a new cross-disciplinary discipline, which can simulate the function of silicon circuits on a molecular scale, perform single or multiple input logic operations, and generate logic outputs. A molecular logic gate is a binary operation that converts an input signal into an output signal according to the rules of Boolean logic, generating two signals, a high level, and a low level. The high and low levels represent the "true" and "false" values of the logic gates, and their outputs correspond to "l" and "0" of the molecular logic gates, respectively. The combination of nanozymes and logic gates is a novel and attractive research direction, and the cross-application of the two brings new opportunities and ideas for various fields, such as the construction of efficient biocomputers, intelligent drug delivery systems, and the precise diagnosis of diseases. This review describes the application of logic gates based on nanozymes, which is expected to provide a certain theoretical foundation for researchers' subsequent studies.

Suspended micro thermometer for anisotropic thermal transport measurements

The investigation of heat flow in nanostructures and low-dimensional system is still a challenging task, though it becomes more and more important for an effective thermal management of microdevices. In this work, we present the fabrication and characterization of a device designed to measure the in-plane thermal properties of nanomaterials in multiple directions. Additionally, the device allows to perform electrical and optical measurements simultaneously. This allows to spatially resolve eventual thermal property anisotropies and the correction of measurements by accounting for the contact resistances. The fabrication has no element that is related to the specific nanostructure to be investigated. The presented concept can be extended for other (quasi-) two dimensional systems and other nanostructures. Finally, we validated the accuracy of the device using a 250 nm thick silicon lamella, which serves as a reference system and offers the possibility to explore the impact of a dominant thermal contact resistance. We have used Raman thermometry to calculate the effective lattice temperature of the lamella as a function of the applied temperature on the membranes. We extracted an average interfacial thermal conductance of 2.4±0.8×104WK−1m−2.

Carbon-Based Nanostructures as Emerging Materials for Gene Delivery Applications.

Gene therapeutics are promising for treating diseases at the genetic level, with some already validated for clinical use. Recently, nanostructures have emerged for the targeted delivery of genetic material. Nanomaterials, exhibiting advantageous properties such as a high surface-to-volume ratio, biocompatibility, facile functionalization, substantial loading capacity, and tunable physicochemical characteristics, are recognized as non-viral vectors in gene therapy applications. Despite progress, current non-viral vectors exhibit notably low gene delivery efficiency. Progress in nanotechnology is essential to overcome extracellular and intracellular barriers in gene delivery. Specific nanostructures such as carbon nanotubes (CNTs), carbon quantum dots (CQDs), nanodiamonds (NDs), and similar carbon-based structures can accommodate diverse genetic materials such as plasmid DNA (pDNA), messenger RNA (mRNA), small interference RNA (siRNA), micro RNA (miRNA), and antisense oligonucleotides (AONs). To address challenges such as high toxicity and low transfection efficiency, advancements in the features of carbon-based nanostructures (CBNs) are imperative. This overview delves into three types of CBNs employed as vectors in drug/gene delivery systems, encompassing their synthesis methods, properties, and biomedical applications. Ultimately, we present insights into the opportunities and challenges within the captivating realm of gene delivery using CBNs.