Oxide Hybrid Nanoparticles Research Articles

Synergistic tribological performance of a water based lubricant using graphene oxide and alumina hybrid nanoparticles as additives

Abstract Graphene oxide (GO) and alumina (Al2O3) nanoparticles were added in deionized water in order to synthesise a dimensionally integrated nanolubricant. Tribological tests were performed using an alloy/stainless steel contact pair. A 0.12 wt% 1:1 GO-Al2O3 lubricant produced 64% and 47% reductions in the COF as well as 63% and 60% improvements in the Ra compared with 0.06 wt% Al2O3 and 0.06 wt% GO solutions. Analysis of the worn surface indicated that a thin film consisting of a layer of GO and a tribo-layer of Al2O3 was formed during testing. The GO layer prevented the direct contact of surface asperities, leading to a low resistance to sliding, whilst the Al2O3 tribo-layer acted as a load bearer to strengthen the GO layer.

Synthesis of Polyvinylcarbazole/Reduced Graphite Oxide‐ZnO Nanocomposites

In this work, the efficiency of in situ polymerization for the production of polyvinylcarbazole nanocomposites with reduced graphite oxide‐zinc oxide hybrid nanoparticles is evaluated. The ZnO nanoparticles are previously synthesized by the sol‐gel method. The cationic polymerization of polyvinylcarbazole is successfully performed in the presence of the nanoparticles using boron trifluoride as initiator and dichloromethane as solvent at 0 °C. The incorporation of the nanoparticles into the polymer can be observed by X‐ray diffraction (XRD) analysis, where the characteristic peaks of the structures are observed. In addition, the XRD indicates a hexagonal wurtzite structure of the ZnO nanoparticles. Polymerization shows a yield of almost 100%, with a short reaction time and total conversion of the monomer to high molar mass polyvinylcarbazole, having very high stability to thermal degradation.

Composition-Based Separation of Pt–Fe3O4 Hybrid Nanoparticles by Thermal Field-Flow Fractionation

Colloidal hybrid nanoparticles integrate two or more material domains into a single construct to achieve multifunctionality and synergistic properties. The synthesis of these complex multicomponent hybrid nanoparticles often yields size and composition distributions that subsequently impact observed properties and complicate structure–function studies. Analyses of nanoparticle systems such as these that contain multiple simultaneously occurring distributions are highly challenging. In this work, we introduce thermal field-flow fractionation (ThFFF) as an analytical method to separate and characterize iron oxide (Fe3O4), platinum (Pt), and multicomponent platinum–iron oxide (Pt–Fe3O4) hybrid nanoparticles by composition. The transport of matter by a temperature gradient or thermal diffusion is exploited in the ThFFF separation and characterization of inorganic nanoparticles. Thermal diffusion coefficient (DT) values are determined from measured ThFFF retention times and translational diffusion coefficients...

Enhancing the Mechanical and Electrical Properties of Poly(Vinyl Chloride)-Based Conductive Nanocomposites by Zinc Oxide Nanorods

A simple approach to decorate multi-walled carbon nanotube (MWCNT)–reduced graphene oxide (RGO) hybrid nanoparticles with zinc oxide (ZnO) nanorods is developed to improve the electrical and mechanical properties of poly(vinyl chloride) (PVC)/MWCNT–RGO composites. The ZnO nanorods act as “joint” in three-dimensional (3D) MWCNT–RGO networks and the hybrid particles strongly interact with PVC chains via p-π stacking, hydrogen bonds, and electrostatic interactions, which we confirmed by scanning electron microscopy (SEM) and Raman analysis. By introducing the ZnO nanorods, the RGO–ZnO–MWCNT hybrid particles increased 160% in capacitance compared with MWCNT–RGO hybrids. Moreover, the addition of RGO–ZnO–MWCNT to PVC resulted in the mechanical properties of PVC being enhanced by 30.8% for tensile strength and 60.9% for Young’s modulus at the loadings of 2.0 weight percent (wt.%) and 1.0 wt.%, respectively. Meanwhile, the electrical conductivity of PVC increased by 11 orders of magnitude, from 1 × 10−15 S/m to 1 × 10−4 S/m for MWCNT–ZnO–RGO loading at 5.0 wt.%.

Phyto-mediated synthesized multifunctional Zn/CuO NPs hybrid nanoparticles for enhanced activity for kidney cancer therapy: A complete physical and biological analysis

Cancer in human society is one of the most problematic health issue responsible for outnumbered deaths worldwide. The consumption of developed NPs in cancer diagnosis is a rapidly emerging field of bio-medical nanotechnology. Recent years, greener synthesized metal oxide hybrid nanoparticles have attracted great attention in cytotoxicity to different cancer therapy. Herein, we report that Duchesnea indica plant mediated green synthesis plant extract mediated Zn doped CuO (Zn/CuO) nanoparticles (NPs) prepared by hydrothermal method and these physico-chemical properties were characterized by XRD, UV-DRS, FTIR, and SEM with EDAX analytical techniques. The XRD pattern findings indicated that the crystal structure of the base CuO matrix are not distorted by the substitution of Cu2+ (0.73 Å) ions by Zn2+ (0.65 Å) ions. The average crystallite size of undoped and Zn/CuO NPs samples are found to be in between the range of 23 to 36 nm. And we can see that the Zn/CuO NPs are large aggregates, containing small particles with sizes of 100–300 nm with spherical shaped morphology by SEM and TEM microscopic images. The normal cell viability and cancer cell inhibition results on A-498 cancer cells and also normal human epithelial cells exhibited that no significant changes in the cell viability with normal kidney epithelial cells and doped NPs given excellent cell inhibition treated on A-498 kidney tumor cells.

Colorimetric hydrogen gas sensor based on PdO/metal oxides hybrid nanoparticles

We have synthesized new colorimetric hydrogen-sensing materials, PdO/metal oxide hybrid nanoparticles, in which palladium oxide was loaded upon surface of substrate materials via an acid-base reaction between a H2PdCl4 solution and substrate materials, ZnO, MgO, TiO2, and SiO2 respectively at 25 °C. The colorimetric hydrogen gas sensing properties of all the samples, PdO/ZnO, PdO/MgO, PdO/TiO2 and PdO/SiO2, were characterized and compared in order to investigate how hydrogen gas sensitivity would be affected by surface property of substrate materials. It was confirmed that the amount of the loaded PdO, which was thought to be closely related with the colorimetric hydrogen sensitivity, was quite different according to the substrate materials and was increased with increasing of the basicity of substrate materials (ZnO > MgO > TiO2 > SiO2). Consequently, among the PdO/metal oxide hybrid nanoparticles, the largest amount of PdO was observed to be loaded on ZnO substrate nanoparticles due to its highest basicity. The best colorimetric hydrogen gas sensing properties (color difference, ΔE = 71.57) was observed in PdO/ZnO hybrid nanoparticles, showing the most prominent color change from brown to black, when the sample was exposed to hydrogen gas of 4 vol% balanced with nitrogen for 2 min.

Tannin-mediated assembly of gold–titanium oxide hybrid nanoparticles for plasmonic photochemical applications

Plasmonic nanostructures have received increasing attention for photochemical applications due to high light absorptivity, tunability, sensitivity, and robustness. However, the short lifetime of hot electrons limits their efficient extraction, requiring the well-defined assembly of neighboring functional materials (e.g., electron filters and catalysts) along with the plasmonic nanostructures. Here we report the polyphenol-mediated assembly of gold nanoparticles (AuNPs) and titanium dioxide nanoparticles (TiO2 NPs) into colloidal plasmonic heterostructures. Tannic acid (TA) is deposited on the surface of TiO2 NPs through metal-ligand coordination, where TA serves as a reducing agent to synthesize AuNPs on the surface of TiO2 NPs. The generation and injection of hot carriers from the plasmonic heterostructures exhibit faster electron transfer kinetics under visible light illumination as determined using ferricyanide as a redox agent. Subsequent surface coatings of TiO2 NPs with phosphate-functionalized polyethylene glycol is shown as an effective means of selective surface passivation to suppress the charge transfer in the semiconductor/electrolyte interface. We expect that the interface control of plasmonic heterostructures for functional assembly and passivation can be utilized for their photochemical applications through integration with catalytic and sensing components.

Colloidal zinc oxide-copper(I) oxide nanocatalysts for selective aqueous photocatalytic carbon dioxide conversion into methane

Developing catalytic systems with high efficiency and selectivity is a fundamental issue for photochemical carbon dioxide conversion. In particular, rigorous control of the structure and morphology of photocatalysts is decisive for catalytic performance. Here, we report the synthesis of zinc oxide-copper(I) oxide hybrid nanoparticles as colloidal forms bearing copper(I) oxide nanocubes bound to zinc oxide spherical cores. The zinc oxide-copper(I) oxide nanoparticles behave as photocatalysts for the direct conversion of carbon dioxide to methane in an aqueous medium, under ambient pressure and temperature. The catalysts produce methane with an activity of 1080 μmol gcat−1 h−1, a quantum yield of 1.5% and a selectivity for methane of >99%. The catalytic ability of the zinc oxide-copper(I) oxide hybrid catalyst is attributed to excellent band alignment of the zinc-oxide and copper(I) oxide domains, few surface defects which reduce defect-induced charge recombination and enhance electron transfer to the reagents, and a high-surface area colloidal morphology.

Fabrication of Crumpled Ball-Like Nickel Doped Palladium-Iron Oxide Hybrid Nanoparticles with Controlled Morphology as Effective Catalyst for Suzuki–Miyaura Coupling Reaction

We report a facile synthetic strategy for nickel-doped palladium-iron oxide hybrid nanoparticles with controllable morphology. In this synthetic method, the morphology of the nanoparticles was regulated by the amount of triphenylphosphine used. When 1 mmol of triphenylphosphine was used as a capping agent, the main morphology of the nanoparticles was crumpled balls composed of nanosheets with an average particle size of 215 nm. The nanoparticles showed higher catalytic activity in the Suzuki–Miyaura coupling reaction than did other nanoparticles at equal amounts of Pd. This strategy allowed the reduction of the Pd loading in hybrid nanoparticles while still providing the performance level required for the reaction.

Synergistic effect of Chitosan-Zinc Oxide Hybrid Nanoparticles on antibiofouling and water disinfection of mixed matrix polyethersulfone nanocomposite membranes

Antifouling polyethersulfone (PES) membranes for water disinfection were fabricated by incorporating varying concentrations of carbohydrate polymer chitosan and Zinc oxide hybrid nanoparticles (CS-ZnO HNPS). The CS-ZnO HNPS were prepared using chemical precipitation method and were characterized using SEM, XRD and FTIR. The membranes were then fabricated by incorporating nanoparticles of CS-ZnO HNPS with three different concentrations of 5%, 10% and 15% w/w in the casting solution of PES through phase inversion method. The influence of nano-sized CS-ZnO HNPS on the properties of PES was characterized to study morphology, contact angle, water retention, surface roughness and permeability flux. The membranes with the maximum concentrations of 15% HNPS resulted in larger mean pore sizes and lowest contact angle value as compare to the pristine PES membrane. The prepared membranes exhibited significant water permeability, hydrophilicity and prevention against microbial fouling. The prepared membranes were observed to have significant antibacterial as well as antifungal properties due to the synergistic effect of chitosan and ZnO against both bacteria of the type of S. Aureus, B. Cereus, E. coli, and fungi such as S. typhi, A. fumigatus and F. solani.

Synthesis of graphene-transition metal oxide hybrid nanoparticles and their application in various fields.

Single layer graphite, known as graphene, is an important material because of its unique two-dimensional structure, high conductivity, excellent electron mobility and high surface area. To explore the more prospective properties of graphene, graphene hybrids have been synthesised, where graphene has been integrated with other important nanoparticles (NPs). These graphene–NP hybrid structures are particularly interesting because after hybridisation they not only display the individual properties of graphene and the NPs, but also they exhibit further synergistic properties. Reduced graphene oxide (rGO), a graphene-like material, can be easily prepared by reduction of graphene oxide (GO) and therefore offers the possibility to fabricate a large variety of graphene–transition metal oxide (TMO) NP hybrids. These hybrid materials are promising alternatives to reduce the drawbacks of using only TMO NPs in various applications, such as anode materials in lithium ion batteries (LIBs), sensors, photocatalysts, removal of organic pollutants, etc. Recent studies have shown that a single graphene sheet (GS) has extraordinary electronic transport properties. One possible route to connecting those properties for application in electronics would be to prepare graphene-wrapped TMO NPs. In this critical review, we discuss the development of graphene–TMO hybrids with the detailed account of their synthesis. In addition, attention is given to the wide range of applications. This review covers the details of graphene–TMO hybrid materials and ends with a summary where an outlook on future perspectives to improve the properties of the hybrid materials in view of applications are outlined.

Construction of N-halamine labeled silica/zinc oxide hybrid nanoparticles for enhancing antibacterial ability of Ti implants

The traditional antibiotic treatment for bacterial infections often induces antibiotic resistance in bacteria. In this work, we developed hybrid nanoparticles (NPs) with a self-antibacterial ability on Ti implants using monodispersed polystyrene-acrylic acid (PSA) nanoparticles as colloidal templates followed by the electrostatic adsorption of zinc oxide (ZnO) and the subsequent deposition of silica (SiO2) membrane on the outside. These synthesized PSA-ZnO-SiO2 NPs were pretreated by 5,5-dimethylhydantoin (DMH) before chlorination in a diluted NaClO solution. These nanoparticles (PSA-ZnO-SiO2-DMH) were subsequently labeled by N-halamines and then immobilized on the surface of titanium plates through hydrogen bonding. Field emission scanning electron microscopy (FE-SEM) and X-ray photoelectron spectroscopy (XPS) were utilized to characterize the modified surface. Antibacterial tests disclosed that the PSA-ZnO-SiO2-DMH-Cl NPs modified surface exhibited excellent antibacterial activity against both Pseudomonas aeruginosa (P.au), Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). In vitro cell culture results revealed that PSA-ZnO-SiO2-DMH-Cl had no obvious cytotoxicity for an MC3T3-E1 preosteoblast. This novel surface system provides a promising self-antibacterial bioplatform for metallic implants without using antibiotics.

Cytotoxic and Apoptotic Effects of Three Types of Silver-Iron Oxide Binary Hybrid Nanoparticles.

Multifunctional nanostructures have received great deal of attention in biomedical area due to their capabilities in the development of new therapeutic and diagnostic agents. Silver and iron oxide nanoparticles, owing to their specific characteristics, are considered to develop bifunctional hybrid nanoparticles for magnetic delivery of silver nanoparticles as cytotoxic agent toward cancer cells. This study was designed to explore the in-vitro cytotoxic and apoptotic activities of three different silver-iron oxide binary hybrid nanoparticles on human liver hepatocellular carcinoma cell line. Three different silver-iron oxide binary hybrid nanoparticles were synthesized and characterized through the designed procedures. Apoptosis induction was investigated through flow cytometry and the influence on bax gene expression level was analyzed using quantitative real time polymerase chain reaction. All the three types of silver-iron oxide hybrid nanoparticles (possessing different characteristics) exhibited cytotoxic and apoptotic effects. Furthermore, the up regulation of bax gene expression suggested the involvement of the intrinsic pathway of apoptosis. Some of the transcription regulators which could interact with bax gene promoter were analyzed and found out to be mostly contributed in the stress responses. Among the test nanoparticles, the strongest cytotoxic and apoptotic effect was induced by the binary hybrid nanoparticle which was synthesized with glucose as reducing agent; suggesting that the biological activity was affected by different characteristics of the designed nanoparticles. Combined properties of silver and magnetic nanoparticles in the binary hybrid nanoparticles, provide a great potential to be exploited in the cancer therapy, where the combination of cytotoxicity and magnetic targeting is desired.

Hydrothermal Synthesis of CuWO<sub>4</sub>-Reduced Graphene Oxide Hybrids and Supercapacitor Application

This study reports a facile hydrothermal synthesis of Copper tungsten oxide (CuWO4) and CuWO4-reduced graphene oxide hybrid nanoparticles and its application as an electrode for supercapacitor application. The morphology and composition has been characterized using X-Ray Diffraction (XRD), Field Emission Scanning Electron Microscopy (FESEM) and EDAX. The supercapacitive behavior has been studied from cyclic voltammetry and galvanostatic charge-discharge tests. The CuWO4-reduced graphene oxide hybrid nanoparticles show highest specific capacitance of 35.71 F/g at a current density of 0.25 A/g with excellent cycling stability.

Novel method for preparation of the hybrid metal (I)-metal (II) oxide nanoparticles

Metal-based core–shell nanoparticles (NPs) as a research topic has attracted attention owing to their unique catalytic, biomedical, magnetic and electric properties compared to their bulk counter parts. Surface functionalisation of free-standing metal NPs by coupling with another metal oxide provides means to prepare a hybrid nanomaterial with target properties. A novel bottom-up strategy has been developed to synthesise metal (I)–metal (II) oxide hybrid NPs, which involves electrochemical formation of metal (I) nanoparticles spatially stabilised by organic shell molecules and coupling with a metal (II) oxide formed via oxide-precursor reduction by organic shell. This paper describes application of a novel strategy to synthesise Ag–MnO2 nanocomposites with improved catalytic properties. Kinetic study indicates relatively fast three-step reduction of a permanganate ion (MnO2 precursor) by an oleic acid (shell material) catalysed by a silver core. Surface analytical (SEM, TEM and EDX), spectroscopic (UV–VIS, FT-IR and XRD) and thermal stability (TGA and DTA) studies of Ag–MnO2 nanocomposites reveal strong chemical bonding of the components in a bi-composite. The catalytic properties of supported Ag–MnO2 nanocomposites were tested for oxidation of carbon monoxide. The improvement of a CO conversion rate compared to a single AgNP nanocatalyst was demonstrated.

Interfacial strain and defects in asymmetric Fe–Mn oxide hybrid nanoparticles

Asymmetric Fe-Mn oxide hybrid nanoparticles have been obtained by a seed-mediated thermal decomposition-based synthesis route. The use of benzyl ether as the solvent was found to promote the orientational growth of Mn1-xO onto the iron oxide nanocube seeds yielding mainly dimers and trimers whereas 1-octadecene yields large nanoparticles. HRTEM imaging and HAADF-STEM tomography performed on dimers show that the growth of Mn1-xO occurs preferentially along the edges of iron oxide nanocubes where both oxides share a common crystallographic orientation. Fourier filtering and geometric phase analysis of dimers reveal a lattice mismatch of 5% and a large interfacial strain together with a significant concentration of defects. The saturation magnetization is lower and the coercivity is higher for the Fe-Mn oxide hybrid nanoparticles compared to the iron oxide nanocube seeds.

In Vitro and In Vivo Tumor Targeted Photothermal Cancer Therapy Using Functionalized Graphene Nanoparticles.

Despite the tremendous progress that photothermal therapy (PTT) has recently achieved, it still has a long way to go to gain the effective targeted photothermal ablation of tumor cells. Driven by this need, we describe a new class of targeted photothermal therapeutic agents for cancer cells with pH responsive bioimaging using near-infrared dye (NIR) IR825, conjugated poly(ethylene glycol)-g-poly(dimethylaminoethyl methacrylate) (PEG-g-PDMA, PgP), and hyaluronic acid (HA) anchored reduced graphene oxide (rGO) hybrid nanoparticles. The obtained rGO nanoparticles (PgP/HA-rGO) showed pH-dependent fluorescence emission and excellent near-infrared (NIR) irradiation of cancer cells targeted in vitro to provide cytotoxicity. Using intravenously administered PTT agents, the time-dependent in vivo tumor target accumulation was exactly defined, presenting eminent photothermal conversion at 4 and 8 h post-injection, which was demonstrated from the ex vivo biodistribution of tumors. These tumor environment responsive hybrid nanoparticles generated photothermal heat, which caused dominant suppression of tumor growth. The histopathological studies obtained by H&E staining demonstrated complete healing from malignant tumor. In an area of limited successes in cancer therapy, our translation will pave the road to design stimulus environment responsive targeted PTT agents for the safe eradication of devastating cancer.

Microbial glucose biosensors based on glassy carbon paste electrodes modified with Gluconobacter Oxydans and graphene oxide or graphene-platinum hybrid nanoparticles

We have performed a study on the performance of two microbial glucose sensors based on immobilized Gluconobacter oxydans (G. oxydans). The first one was prepared by modifying a glassy carbon paste electrode (GCPE) containing the microbial cells with graphene oxide (GO), the other one by modifying it with graphene-platinum hybrid nanoparticles (graphene-Pt NPs). The electrode was characterized by following the voltammetric signals of the oxidation of hexacyanoferrate(II) to hexacyanoferrate(III) via the oxidative enzymes contained in G. oxydans which convert glucose to gluconic acid. Optimizations were conducted with a conventional GCPE containing G. oxydans. After material optimization, the biosensors were applied to the determination of glucose. The linear and analytical ranges for GO based biosensor range from 1 to 75 μM (linear) and 1 to 100 μM (analytical), respectively, with a limit of detection (LOD) of (3 s/m) 1.06 μM (at an S/m of 3). On the other hand, the graphene-Pt hybrid nanoparticle based biosensor showed two linear ranges (from 0.3 to 1 µM and from 1 to 10 μM), a full analytical range from 1 to 50 μM, and an LOD of 0.015 μM. The graphene-Pt hybrid NP based sensors performs better and was applied to the determination of glucose in synthetically prepared plasma samples where it gave recoveries as 101.8 and 104.37 % for two different concentrations. Selectivity studies concerning fructose, galactose, L-ascorbic acid and dopamine were also conducted.

Increasing the Collision Rate of Particle Impact Electroanalysis with Magnetically Guided Pt-Decorated Iron Oxide Nanoparticles.

An integrated microfluidic/magnetophoretic methodology was developed for improving signal response time and detection limits for the chronoamperometric observation of discrete nanoparticle/electrode interactions by electrocatalytic amplification. The strategy relied on Pt-decorated iron oxide nanoparticles which exhibit both superparamagnetism and electrocatalytic activity for the oxidation of hydrazine. A wet chemical synthetic approach succeeded in the controlled growth of Pt on the surface of FeO/Fe3O4 core/shell nanocubes, resulting in highly uniform Pt-decorated iron oxide hybrid nanoparticles with good dispersibility in water. The unique mechanism of hybrid nanoparticle formation was investigated by electron microscopy and spectroscopic analysis of isolated nanoparticle intermediates and final products. Discrete hybrid nanoparticle collision events were detected in the presence of hydrazine, an electrochemical indicator probe, using a gold microband electrode integrated into a microfluidic channel. In contrast with related systems, the experimental nanoparticle/electrode collision rate correlates more closely with simple theoretical approximations, primarily due to the accuracy of the nanoparticle tracking analysis method used to quantify nanoparticle concentrations and diffusion coefficients. Further modification of the microfluidic device was made by applying a tightly focused magnetic field to the detection volume to attract the magnetic nanoprobes to the microband working electrode, thereby resulting in a 6-fold increase to the relative frequency of chronoamperometric signals corresponding to discrete nanoparticle impact events.

Preparation of SiO2–GO hybrid nanoparticles and the thermal properties of methylphenylsilicone resins/SiO2–GO nanocomposites

Silica–graphene oxide (SiO2–GO) hybrid nanoparticles have been prepared by the hydrolysis of tetraethoxysilane (TEOS) in the presence of GO sheets. The results indicated that silica nanoparticles were densely and uniformly grafted onto the GO surface by covalent linkage. The thermal stability of SiO2–GO has been improved greatly according to thermogravimetric analysis (TGA). Methylphenylsilicone resins (MPSR) with various proportions of SiO2–GO were synthesized by solution blending method. The incorporation of SiO2–GO was beneficial to improve the thermal stability and oxidation resistance of composites. The 5% weight loss temperature of the composites at 1wt% SiO2–GO loading was detected 34.8°C higher than that of pure MPSR. And the Tg of composites was increased by 10.4°C. Additionally, the short-term and long-term stability of composites were improved greatly by adding SiO2–GO. These enhancements can be attributed to better dispersion of SiO2–GO in MPSR and improved interfacial adhesion between MPSR and SiO2–GO.