Cerium Vanadate Nanorod Arrays from Ionic Chelator-Mediated Self-Assembly

Novel Dumbbell-like CeVO4 Carrier-Based Immunochromatographic Assay for Highly Sensitive T-2 Toxin Detection in Food Samples

Improving the sensitivity of immunochromatographic assays (ICAs) lies in the signal strength and probe activity of the labeled tracers, and the color properties and structure of the labeled tracers are key factors affecting the biological activity. In this study, cerium vanadate (CeVO4) of different sizes and shapes (230, 1058, and 710 nm) was synthesized to investigate its impact on the performance of ICA for T-2 detection. The prepared CeVO4 possessed outstanding stability, a large specific surface area, superior biocompatibility, and high compatibility with T-2 mAb (affinity constant was 3.14 × 108 M-1). As labeling probes for competitive ICA, the results showed that 1058 nm of CeVO4 as labels exhibited the best detection performance, with a limit of detection (LOD) of 0.079 ng/mL, which was substantially 19-fold less than the average of gold nanoparticle ICA. Additionally, CeVO4-ICA was effectively used to detect T-2 toxin, and the recovery rate for spiking corn and oatmeal samples was determined to be 81.27-115.44% (relative standard deviation <9.16%). The above information demonstrates the efficiency and applicability of CeVO4-ICA as a technique for quick and thorough identification of T-2 toxin residues in food.

A Redox Modulatory SOD Mimetic Nanozyme Prevents the Formation of Cytotoxic Peroxynitrite and Improves Nitric Oxide Bioavailability in Human Endothelial Cells

The endothelium-derived signalling molecule nitric oxide (NO) in addition to controlling multifarious servo-regulatory functions, suppresses key processes in vascular lesion formation and prevents atherogenesis and other vascular abnormalities. The conversion of NO into cytotoxic and powerful oxidant peroxynitrite (ONOO- ) in a superoxide (O2 .- )-rich environment has emerged as a major reason for reduced NO levels in vascular walls, leading to endothelial dysfunction and cardiovascular complications. So, designing superoxide dismutase (SOD) mimetics that can selectively catalyze the dismutation of O2 .- in the presence of NO, considering their rapid reaction is challenging and is of therapeutic relevance. Herein, the authors report that SOD mimetic cerium vanadate (CeVO4 ) nanozymes effectively regulate the bioavailability of both NO and O2 .- , the two vital constitutive molecules of vascular endothelium, even in the absence of cellular SOD enzyme. The nanozymes optimally modulate the O2 .- level in endothelial cells under oxidative stress conditions and improve endogenously generated NO levels by preventing the formation of ONOO- . Furthermore, nanoparticles exhibit size- and morphology-dependent uptake into the cells and internalize via the clathrin-mediated endocytosis pathway. Intravenous administration of CeVO4 nanoparticles in mice caused no definite organ toxicity and unaltered haematological and biochemical parameters, indicating their biosafety and potential use in biological applications.

A Cerium Vanadate Nanozyme with Specific Superoxide Dismutase Activity Regulates Mitochondrial Function and ATP Synthesis in Neuronal Cells

Nanoparticles that functionally mimic the activity of metal-containing enzymes (metallo-nanozymes) are of therapeutic importance for treating various diseases. However, it is still not clear whether such nanozymes can completely substitute the function of natural enzymes in living cells. In this work, we show for the first time that a cerium vanadate (CeVO₄ ) nanozyme can substitute the function of superoxide dismutase 1 and 2 (SOD1 and SOD2) in the neuronal cells even when the natural enzyme is down-regulated by specific gene silencing. The nanozyme prevents the mitochondrial damage in SOD1- and SOD2-depleted cells by regulating the superoxide levels and restores the physiological levels of the anti-apoptotic Bcl-2 family proteins. Furthermore, the nanozyme effectively prevents the mitochondrial depolarization, leading to a significant improvement in the cellular levels of ATP under oxidative stress.

The role of oxygen adsorption and gas sensing mechanism for cerium vanadate (CeVO4) nanorods

Square-section CeVO₄ nanorods with highly active and exposed (010) facets have been shown to be highly promising as an acetone gas sensor.

Synthesis of EDTA-assisted CeVO4 nanorods as robust peroxidase mimics towards colorimetric detection of H2O2

CeVO₄ nanorods were developed as novel, simple and highly sensitive biomimetic catalysts and used for colorimetric detection of H₂O₂.

Enhancing oxygen reduction reaction durability via coating graphene layers on iron-nitrogen supported carbon nanotubes

Fe-N-CNT@GN catalyst was designed through coating several graphene layers derived from the disodium edentate to enhance ORR durability.

Large-scale growth of hierarchical transition-metal vanadate nanosheets on metal meshes as monolith catalysts for De-NO(x) reaction

A facile method is developed for the large-scale growth of hierarchical transition-metal (Cu, Fe, and Ni) vanadate nanosheets on corresponding metal mesh as supports. The hierarchical transition-metal vanadate nanosheets were in situ grown on the metal meshes through an orientational etching process and simultaneous nucleation and growth process. Interestingly, the morphologies of the vanadate nanosheets are governed by the balance between dissolution rate and nucleation rate. Thus, the sizes and the thicknesses of the nanosheets could be facilely controlled by the reaction duration, the acidity of the solution and the concentration of vanadate precursor. Furthermore, the hierarchical transition-metal vanadate nanosheets supported on metal meshes are used as monolith catalysts for the selective catalytic reduction (SCR) of NO with NH3. The iron mesh based monolith catalyst shows excellent de-NOx performance with high efficiency and stability in the presence of SO2 and H2O, which provide a promising monolith de-NOx catalyst for stationary source at medium temperatures.

Controlling directed self-assembly of gold nanorods in patterned PS-b-PMMA thin films

We present a facile strategy for the directed self-assembly of gold nanorods (AuNRs) in patterned block copolymer (BCP) thin films. Parallel arrangement of AuNRs relative to the geometric confinement generated by selective removal of one block domain was achieved. Deposition of AuNRs with aspect ratios from 3.3 to 5.8 was accomplished and the alignment of the NRs within the channels was controlled primarily by capillary forces and the channel geometry. Ordered AuNR assembly in the BCP pattern can be achieved at high surface coverages, >30%, though the surface coverage depends on the aspect ratio of the NRs. Larger NRs align in the channels more readily, but pack at slightly lower densities.

Mesoporous ZnS-NiS Nanocomposites for Nonenzymatic Electrochemical Glucose Sensors

Mesoporous ZnS-NiS composites are prepared via ion- exchange reactions using ZnS as the precursor. The prepared mesoporous ZnS-NiS composite materials have large surface areas (137.9 m(2) g(-1)) compared with the ZnS precursor. More importantly, the application of these mesoporous ZnS-NiS composites as nonenzymatic glucose sensors was successfully explored. Electrochemical sensors based on mesoporous ZnS-NiS composites exhibit a high selectivity and a low detection limit (0.125 μm) toward the oxidation of glucose, which can mainly be attributed to the morphological characteristics of the mesoporous structure with high specific surface area and a rational composition of the two constituents. In addition, the mesoporous ZnS-NiS composites coated on the surface of electrodes can be used to modify the mass transport regime, and this alteration can, in favorable circumstances, facilitate the amperometric discrimination between species. These results suggest that such mesoporous ZnS-NiS composites are promising materials for nonenzymatic glucose sensors.

Bottom-up assembly of hydrophobic nanocrystals and graphene nanosheets into mesoporous nanocomposites

A general strategy for constructing graphene-based nanocomposites is achieved by emulsion-based bottom-up self-assembly of hydrophobic nanocrystals (NCs) to positively charged colloidal spheres, followed by the electrostatic assembly of NC colloidal spheres with negatively charged graphene oxide in an acidulous aqueous solution. With a simple heat treatment, 3D mesoporous NC spheres/graphene composites are obtained. TiO2/graphene composites typically exhibit a better rate capability and cycle performance than do the corresponding isolated TiO2 spheres.

Probing structural variation and multifunctionality in niobium doped bismuth vanadate materials

Multifunctional materials in BiV_1−xNb_xO₄ solid solutions display high NIR reflecting brilliant yellow hues with notable MB dye degradation under sunlight.

Facile synthesis of cerium oxide nanostructures for rechargeable lithium battery electrode materials

A facile method is developed to synthesize cerium oxides with plate and brick morphologies by the thermal decomposition of nanostructured oxalate precursors.

End-to-end alignment of nanorods in thin films

A simple approach to obtain end-to-end assemblies of nanorods over macroscopic distances in thin films is described. Nanorods with aspect ratio of 8-12 can be aligned parallel to the surface in an end-to-end fashion by imposing geometric confinement via block copolymer-based supramolecular assemblies. Successful control over the orientation and location of nanorods requires a balance of particle-particle interactions and entropy associated with geometric confinement from the supramolecular framework, as well as consideration of the kinetics of assembly.

3D quantitative analysis of platinum nanocrystal superlattices by electron tomography

The work reported herein focuses on the 3D relative arrangement of individual platinum nanocrystals with a size of about 5 nm, and on the structure of the superlattices, they spontaneously form. Electron tomography was systematically used in this study because it allows obtaining quantitative 3D information in real space. Performing tomography in the bright-field TEM mode allowed investigating the short and long-range orderings of the nanoparticles packed as self-organized supercrystals. Systematic fcc pilings were observed with a mean lattice parameter measured to be 19.5 nm, the nature of the arrangement being controlled by the truncated octahedral morphology of platinum nanocrystals and the associated steric effects. A numerical 3D quantitative analysis of the ordering characteristics of the superlattice with a nanometer resolution has been performed that, for the first time, showed a direct correlation between single entities' characteristics and their ordering in periodic arrays. It has been shown that the lattice parameter is different in two orthogonal directions of the fcc structure, which indicates the presence of a slightly compressed superlattice. Inside the superstructure, vacancies and axial defects were observed that would blur the occurrence of potential collective effects from the supercrystals.

Direct nanorod assembly using block copolymer-based supramolecules

Developing routes to control the organization of one-dimensional nanomaterials, such as nanorods, with high precision is critical to generate functional materials since the collective properties depend on their spatial arrangements, interparticle ordering, and macroscopic alignment. We have systematically investigated the coassemblies of nanorods and block copolymer (BCP)-based supramolecules and showed that the energetic contributions from nanorod ligand-polymer interactions, polymer chain deformation, and rod-rod interactions are comparable and can be tailored to disperse nanorods with control over inter-rod ordering and the alignment of nanorods within BCP microdomains. By varying the supramolecular morphology and chemical nature of the nanorods, two highly sought-after morphologies, that is, nanoscopic networks of nanorods and nanorod arrays parallel to cylindrical BCP microdomains can be obtained. The supramolecular approach can be applied to achieve morphological control in nanorod-containing nanocomposites toward fabrication of optical and electronic nanodevices.

Self-assembly of gold nanorods into symmetric superlattices directed by OH-terminated hexa(ethylene glycol) alkanethiol

The self-assembly of anisotropic gold nanorods (GNRs) into ordered phases remains a challenge. Herein, we demonstrated the fabrication of symmetric circular- or semicircular-like self-assembled superlattices composed of multilayers of standing GNRs by fine-tuning the repulsive interactions among GNRs. The repulsive force is tailored from electrostatic interaction to steric force by replacing the surface coating of cetyltrimethylammonium bromide (CTAB) (ζ potential of 20-50 mV) with an OH-terminated hexa(ethylene glycol) alkanethiol (here termed as EG(6)OH, ζ potential of -10 mV). The assembly mechanism is discussed via theoretical analyses of the major interactions, and an effective balance between the repulsive steric and attractive depletion interactions is the main driving force for the self-assembly. The real-time observations of solution assembly (UV-vis-NIR absorption spectroscopy) supports the mechanism that we suggested. The superlattices obtained here not only enrich the categories of the self-assembled structures but more importantly deepen the insight of the self-assembly process and pave the way for various potential applications.