Nanoparticle Nanohybrids Research Articles

Hybrid polymer dot-magnetic nanoparticle based immunoassay for dual-mode multiplexed detection of two mycotoxins.

We designed polymer dot-magnetic nanoparticle nanohybrids for signal enhancement in a test strip platform. Besides, the multicolor emissions of the Pdots embed multiplexing ability for this test strip. Two mycotoxins, aflatoxin B1 and zearalenone, were tested with the determined limits of detection of 2.15 ng mL-1 and 4.87 ng mL-1, respectively.

Dynamics of Polymer Chains in Poly(ethylene oxide)/Silica Nanocomposites via a Combined Computational and Experimental Approach.

The dynamics of polymer chains in poly(ethylene oxide)/silica (PEO/SiO2) nanoparticle nanohybrids have been investigated via a combined computational and experimental approach involving atomistic molecular dynamics simulations and dielectric relaxation spectroscopy (DRS) measurements. The complementarity of the approaches allows us to study systems with different polymer molecular weights, nanoparticle radii, and compositions across a broad range of temperatures. We study the effects of spatial confinement, which is induced by the nanoparticles, and chain adsorption on the polymer's structure and dynamics. The investigation of the static properties of the nanocomposites via detailed atomistic simulations revealed a heterogeneous polymer density layer at the vicinity of the PEO/SiO2 interface that exhibited an intense maximum close to the inorganic surface, whereas the bulk density was reached for distances ∼1-1.2 nm away from the nanoparticle. For small volume fractions of nanoparticles, the polymer dynamics, probed by the atomistic simulations of low-molecular-weight chains at high temperatures, are consistent with the presence of a thin adsorbed layer that exhibits slow dynamics, with the dynamics far away from the nanoparticle being similar to those in the bulk. However, for high volume fractions of nanoparticles (strong confinement), the dynamics of all polymer chains were predicted slower than that in the bulk. On the other hand, similar dynamics were found experimentally for both the local β-process and the segmental dynamics for high-molecular-weight systems measured at temperatures below the melting temperature of the polymer, which were probed by DRS. These differences can be attributed to various parameters, including systems of different molecular weights and nanoparticle states of dispersion, the different temperature range studied by the different methods, the potential presence of a reduced-mobility PEO/SiO2 interfacial layer that does not contribute to the dielectric spectrum, and the presence of amorphous-crystalline interfaces in the experimental samples that may lead to a different dynamical behaviors of the PEO chains.

Dual-mode immunoassay for diethylstilbestrol based on peroxidase activity and photothermal effect of black phosphorus-gold nanoparticle nanohybrids

Nanozyme-mediated 3,3′,5,5′-tetramethylbenzidine (TMB) - H2O2 systems have spawned the establishment of multiple colorimetric sensing platforms that are effective but sometimes subject to low sensitivity. Taking temperature as the output signal, photothermal effects lead to new strategies for sensitive detection. In this paper, a colorimetric and photothermal dual-mode immunoassay for diethylstilbestrol (DES) was constructed. It is based on the oxidation reaction of TMB catalyzed by black phosphorus-gold nanoparticle (BP/Au) nanohybrids, and the kinetics as well as catalytic mechanism of the nanohybrids were investigated in detail for the first time. Herein, the nanohybrids playcatalytic and photothermal dual roles. Moreover, the one-electron oxidation product of TMB (oxidized TMB) not only acts as chromogenic agent but also an excellent NIR laser-driven photothermal agent. The temperature (ΔT/°C) was gauged by a portable digital thermometer. Through an indirect competition strategy, a simple, sensitive, and economic immunosensor was proposed. Higher DES content in the sample correlated with less BP/Au nanohybrids conjugated to the surface of ELISA microplate, a weaker color change, and a lower temperature variation when exposed to laser irradiation. This method was applied for DES determination in real samples with gratifying recovery rates, showing great promise in food safety inspection applications.

Silver-Graphene Oxide Nanohybrids for Highly Sensitive, Stable SERS Platforms.

Graphene oxide–silver nanoparticle nanohybrids were synthesized by simple reduction of the silver nitrate and graphene oxide (GO) mixture in water using the mild reducing agent ascorbic acid. The concentration of ascorbic acid was varied to verify the possible influence of the GO surface composition on the efficiency of the hybrid material as substrates for surface enhanced Raman spectroscopy (SERS). Furthermore, the composites were conditioned in ammonia solution or in potassium hydroxide diluted solution. For comparison, the graphene oxide–silver nanoparticle composite has been synthesized using the ammonia-treated GO. All materials were characterized using spectroscopic and microscopic methods including UV–Vis, infrared, and Raman spectroscopy and scanning electron microscopy. The SERS efficiency of the nanohybrids was tested using 4-aminothiophenol (PATP). The optimal synthesis conditions were found. Ammonia and potassium peroxide drop-casted on the composite changed the SERS properties. The sample treated with KOH showed the best SERS enhancement. The variation of the SERS enhancement was correlated with the shape of the UV–Vis characteristics and the surface structure of the composites.

Multi-walled carbon nanotubes and chromium ferrites nanoparticles nanohybrids as anode materials for lithium-ion batteries

Two-step synthesis route was opted for the preparation of multi-walled carbon nanotubes (MWCNTs) and chromium ferrites (CrFe2O4) nanoparticles nanohybrids. In the first step, CrFe2O4 nanoparticles were prepared through co-precipitation route, while in second step an ultra-sonication assisted route was chosen for dispersion of these nanoparticles on the surface of MWCNTs. A polar solvent toluene was used for the dispersion of these nanoparticles and MWCNTs to obtain the final product (MWCNTs)x/CrFe2O4; x = 0–20 wt% nanohybrids. X-rays diffraction (XRD) confirmed the corresponding crystal structures of MWCNTs and (MWCNTs)x/CrFe2O4 nanohybrids. It was evident from scanning electron microscopy (SEM) that CrFe2O4 nanoparticles were evenly distributed on the surface of MWCNTs. The morphology of (MWCNTs)x/CrFe2O4 nanohybrids confined the pulverization of active material that ensured electron-ion transport efficiency during lithiation and de-lithiation. Consequently, these nanohybrids exhibited prime cyclic performance at different values of current densities. These (MWCNTs)x/CrFe2O4 nanohybrids revealed better Li+ storage properties with high Coulombic efficiency ‘Ce’, better cyclic stability, improved reversible specific discharge capacity after 100 cycles and enhanced rate capability. Thus, current study offered a low-cost and facile synthesis route to prepare these nanohybrids as anode materials for lithium-ion batteries.

Symmetric Supercapacitors with layer-by-layer Molybdenum disulfide - reduced graphene oxide structures and poly(3,4-ethylenedioxythiophene) nanoparticles nanohybrid electrode

Fabrication of electrode material with stable cycling performances, enhanced surface area, improved electrode/ electrolyte interactions and interfaces is expected in order to reach supercapacitor goal and worth exploring for ternary nanocomposites of PEDOT nanoparticles (PEDOTNP) with 2D-2D MoS2-rGO heterostructures. Herein, layer-by-layer structures of MoS2-rGO have been prepared availing the opposite surface charges of GO nanosheets and MoS2 nanosheets (self-assembly method) followed by reduction, confirmation of which have been understood from the co-existence of MoS2 layers and rGO layers at hetero-interfaces from HR-TEM analysis. Ternary MoS2-rGO/ PEDOTNP based nanocomposites were fabricated by in-situ reduction of GO in presence of pre-synthesized PEDOTNP. Mesoporous and hydrophilic ternary MoS2-rGO/PEDOTNP/NF electrode exhibits specific capacitance of 1143.7 F g−1 at 1-fold of current density and retains 73.3% (840 F g−1) of capacitance at 9-fold of current density with 97.7% of cycle life after repeated 3000 GCD cycles. MoS2-rGO/PEDOTNP // MoS2-rGO/PEDOTNP symmetric supercapacitor (SSC) delivers specific capacitance of 289.25 F g−1 at 1-fold of current density, 49% of rate capability at 20-fold of current density, and excellent cycling stability of 93.17% after 10,000 GCD cycles at 20-fold of current density. Moreover, MoS2-rGO/PEDOTNP // MoS2-rGO/PEDOTNP SSC exhibits specific energy of 33.56 W h kg−1 at specific power of 450.03 W kg−1 based on the total mass at 1-fold of current density.

Graphene Oxide-Silver Nanoparticle Nanohybrids: Synthesis, Characterization, and Antimicrobial Properties.

Drug resistance of pathogenic microorganisms has become a global public health problem, which has prompted the development of new materials with antimicrobial properties. In this context, antimicrobial nanohybrids are an alternative due to their synergistic properties. In this study, we used an environmentally friendly one-step approach to synthesize graphene oxide (GO) decorated with silver nanoparticles (GO–AgNPs). By this process, spherical AgNPs of average size less than 4 nm homogeneously distributed on the surface of the partially reduced GO can be generated in the absence of any stabilizing agent, only with ascorbic acid (L-AA) as a reducing agent and AgNO3 as a metal precursor. The size of the AgNPs can be controlled by the AgNO3 concentration and temperature. Smaller AgNPs are obtained at lower concentrations of the silver precursor and lower temperatures. The antimicrobial properties of nanohybrids against Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa, Gram-positive Staphylococcus aureus, and the yeast Candida albicans were found to be concentration- and time-dependent. C. albicans and S. aureus showed the highest susceptibility to GO–AgNPs. These nanohybrids can be used as nanofillers in polymer nanocomposites to develop materials with antimicrobial activity for applications in different areas, and another potential application could be cancer therapeutic agents.

Electrochemically Reduced Graphene Oxide – Noble Metal Nanoparticles Nanohybrids for Sensitive Enzyme-Free Detection of Hydrogen Peroxide

Electrochemically reduced graphene oxide (ERGO) is a versatile material for the electrode modification, which enables modification of the physicochemical properties of the surface by the reduction and reoxidation of oxygen groups. The oxygen functional groups and structural defects of ERGO deposited on a layer of metal nanoparticles facilitate the electron transport and enhance the electrocatalytic properties of the nanoparticles. ERGO layers show moderate-intrinsic electrocatalytic properties towards the electrochemical reduction of hydrogen peroxide. In this contribution, we present studies of ERGO layers on the top of the nanoparticle layer composed of gold nanoparticles stabilized with silicotungstate ligands (Au/SiW12), silver nanoparticles stabilized with silicotungstate ligands (Ag/SiW12), and silver nanoparticles stabilized with phosphomolybdate ions (Ag/PMo12). The nanoparticles are prepared by the reduction of the chloroauric acid or silver nitrate by the partially reduced forms of H4SiW12O40 or H3PMo12O40 acid. The films of nanoparticles are conditioned by the repetitive potential cycling at pH = 6 before the deposition of the graphene oxide (GO) layer. The GO layer is reduced by scanning the potential between − 0.4 and − 1.2 V vs. SCE. Combination of ERGO with Au/SiW12 or Ag/SiW12 nanoparticles results in synergistic enhancement of amperometric responses to hydrogen peroxide. The electrocatalytic current values observed for the NPs-ERGO layers are higher than the sum of the current for the pure NPs layers and the ERGO layer deposited on a glassy carbon electrode. The Ag/PMo12 nanoparticles show poor electrocatalytic currents due to possible formation of aggregate structures. Infrared and Raman spectroscopies are applied to investigate the electrocatalytic layers.

Synergistically enhanced oxygen reduction electrocatalysis by atomically dispersed and nanoscaled Co species in three-dimensional mesoporous Co, N-codoped carbon nanosheets network

Metal-nitrogen-codoped carbon (M-N-C) nanostructures are promising electrocatalysts for oxygen reduction reaction (ORR). Despite the great progress that has been achieved, synthesizing three-dimensional porous nanoarchitectures derived from Co-N-C nanosheets or related nanohybrids with high content (> 5 wt%) of exposed single-atom sites remains a challenge. Herein, novel three-dimensional mesoporous Co-N-C nanosheets network enwrapping small amount of Co nanoparticles nanohybrids are fabricated by molten-salt template-assisted pyrolysis of Co-folic acid precursors and chemical etching. In the obtained nanohybrids, the content of single-atom-like Co (SA-Co%) is 7.4 wt% < SA-Co%<19.4 wt%. Due to the unique mesoporous nanosheets network structure and efficient synergy of atomic and nanoscaled Co species, such nanohybrids manifest enhanced ORR activity with a half-wave potential of 0.85 V, outperforming pure Co-N-C, Pt/C and most of other reported catalysts. Moreover, their stability exceeds that of Pt/C. This work will lead to the optimization of M-N-C nanostructures and accelerate their applications in fuel cells.

Achieving Highly Electrocatalytic Performance by Constructing Holey Reduced Graphene Oxide Hollow Nanospheres Sandwiched by Interior and Exterior Platinum Nanoparticles

Two-dimensional (2D) graphene nanosheets are considered as an attractive support to load metal nanoparticles for applications in fuel cells due to their extraordinary physicochemical properties arising from the 2D nanostructure. However, fabricating graphene/metal nanoparticle nanohybrids with superior electrochemical performance remains a great challenge to date. In this work, we, for the first time, demonstrate a novel and ingenious approach to fabricate holey reduced graphene oxide hollow nanospheres sandwiched by interior and exterior Pt nanoparticles (denoted as Pt@holey r-GO@Pt hollow nanospheres), using uniform SiO2 nanospheres as the templates. The Pt@holey r-GO@Pt hollow nanospheres represent a new type of metal/graphene heteroarchitecture due to their rich porosity, abundant active sites, facilitated reaction kinetics, and outstanding structural stability. Thanks to these distinguished merits, the as-prepared Pt@holey r-GO@Pt hollow nanospheres exhibit greatly enhanced electrocatalytic performan...

Simple and efficient polyoxomolybdate-mediated synthesis of novel graphene and metal nanohybrids for versatile applications

The application of nanohybrids based on polyoxomolybdates, reduced graphene oxide (rGO) and/or metal nanoparticles (NPs) high-performance electrode materials in electrocatalysis and energy storage devices is promising but still limited due to the complexity and the cost of the synthesis. Here we introduce a simple polyoxomolybdate, [MoV4O8(OH)2(H2O)2(C4O4)2]2− (MoS), as reducing and stabilizing agent for the facile and one-pot syntheses of large quantity of highly stable MoS/rGO and MoS/Au NPs nanohybrids in aqueous solution without any catalyst or toxic co-solvent. They were characterized by various physical techniques and electrochemistry which confirm strong interaction between MoS and rGO sheets. We also used DFT calculations to investigate the affinity between MoS or its neutral form with graphene. The adsorption energy for the most stable configuration is −1.97 eV, indicating a strong adsorption process of MoS, which can also be confirmed by the distance (3.04 Å) and the charge transfer (0.86 e) between MoS and graphene. These observations are also consistent with the electrochemical results which underscore the excellent redox properties and high stability of MoS/rGO. Importantly, the MoS/rGO nanohybrids are excellent noble metal-free electrocatalysts for hydrogen peroxide reduction with high sensitivity, large detection range and low detection limit. Finally, the preliminary tests reveal that the electrode materials based on MoS/rGO and a low-cost carbon cloth (CC) composite MoS/rGO/CC may have a potential for an application in energy storage as performant and flexible supercapacitor, showing specific capacitance as high as 870 F g−1 at 10 mV s−1 and excellent stability after 5000 cycles.

Nitrogen doped graphene anchored cobalt oxides efficiently bi-functionally catalyze both oxygen reduction reaction and oxygen revolution reaction

A series of efficient bifunctional electrocatalyst composed of nitrogen-doped graphene-cobalt oxide nanoparticles nano-hybrids (Co-N/G) are fabricated by one-pot hydrothermal synthesis, which involves in-situ growth of cobalt oxides nanocrystals and nitrogen doping into graphene. 2, 4, 6-Triaminopyrimidine used as nitrogen precursor could anchor cobalt oxides nanoparticles on graphene oxide as active centers for oxygen electrode reactions. The TEM, Raman, XRD and XPS confirm the germination of nitrogen doped graphene and nano-sized cobalt oxides. The optimized Co-N/G catalyst consists of the highest contents of pyridinic nitrogen and CoO, which efficiently catalyze both ORR and OER. The strong coupling between cobalt oxides and N-graphene endows Co-N/G 600 with a low reversible overvoltage of 0.96 V between ORR and OER in alkaline medium, which is superior to novel catalysts such as Pt/C (1.24 V), IrO2 (1.43 V) and RuO2 (1.35 V), rendering it bi-catalyst efficient and economical for reversible oxygen electrode reactions.

A novel nonenzymatic hydrogen peroxide sensor based on the synthesized mesoporous carbon and silver nanoparticles nanohybrid

Here, we report the synthesis and characterization of a novel nanohybrid composed of mesoporous carbon and silver nanoparticles (MC/AgNPs) to use in amperometric sensing of hydrogen peroxide (H2O2). In this process, the MC was synthesized by using the mesoporous silica as a template and glucose as a carbon source. The AgNPs were produced by in situ chemical reduction of silver nitrate through glucose as a reducing and stabilizing agent in the presence of MC to give the desired MC/AgNPs nanohybrid. It was investigated by field emission scanning electron microscopy, transmission electron microscopy, X-ray diffraction, and electrochemical measurements. The obtained nanohybrid was used to modify a glassy carbon electrode and to fabricate an amperometric sensor for H2O2 determination at a working potential of −200mV vs. silver/silver chloride electrode in aqueous 0.1M phosphate buffer solution (pH 7.0). The resulted sensor can detect H2O2 in the concentration range of 0.1–41μM with a detection of limit 50nM at a signal-to-noise ratio of 3.

Non-enzymatic Hydrogen Peroxide Sensors Based on Multi-wall Carbon Nanotube/Pt Nanoparticle Nanohybrids.

A novel strategy to fabricate a hydrogen peroxide (H2O2) sensor was developed by using platinum (Pt) electrodes modified with multi-wall carbon nanotube-platinum nanoparticle nanohybrids (MWCNTs/Pt nanohybrids). The process to synthesize MWCNTs/Pt nanohybrids was simple and effective. Pt nanoparticles (Pt NPs) were generated in situ in a potassium chloroplatinate aqueous solution in the presence of multi-wall carbon nanotubes (MWCNTs), and readily attached to the MWCNTs convex surfaces without any additional reducing reagents or irradiation treatment. The MWCNT/Pt nanohybrids were characterized by transmission electron microscope (TEM), and the redox properties of MWCNTs/Pt nanohybrids-modified Pt electrode were studied by electrochemical measurements. The MWCNTs/Pt-modified electrodes exhibited a favorable catalytic ability in the reduction of H2O2. The modified electrodes can be used to detect H2O2 in the range of 0.01–2 mM with a lower detection limit of 0.3 μM at a signal-to-noise ratio of 3. The sensitivity of the electrode to H2O2 was calculated to be 205.80 μA mM−1 cm−2 at working potential of 0 mV. In addition, the electrodes exhibited an excellent reusability and long-term stability as well as negligible interference from ascorbic acid, uric acid, and acetaminophen.

Preparation of graphene oxide–silver nanoparticle nanohybrids with highly antibacterial capability

A simple method based on electrostatic interactions was utilized to assemble silver nanoparticles (AgNPs) to graphene oxide (GO) sheets. This method allows conjugation of AgNPs with desired morphologies (densities, sizes and shapes) onto GO. In this process, poly(diallyldimethylammonium chloride) (PDDA) was introduced as an adhesive agent. The as-prepared graphene oxide-AgNPs composites (GO-AgNPs) have enhanced colloid stability and photo-stability than that of AgNPs. After conjugating to GO sheets, the antibacterial activities of AgNPs against Gram negative (G-) bacterial strain (Escherichia coli, E. coli) and Gram positive (G+) bacterial strain (Bacillus subtilis, B. subtilis) have been improved significantly. The antibacterial activity of GO-AgNPs is dependent on the size of AgNPs, i.e. the small AgNPs modified GO sheets show more effective antibacterial capability than that of large AgNPs modified GO sheets. Compared with AgNPs, the enhanced antibacterial activity of GO-AgNPs might not only be due to high stability of AgNPs anchored on GO sheets, but also the positive charged surface of hybrids which increases the electrostatic interaction of bacterial cell membrane with nanohybrids.

Preparation and application of thionin-bridged graphene-gold nanoparticle nanohybrids.

A universal approach for controllable assembly of gold nanoparticles (AuNPs) on chemically reduced graphene oxide (rGO) is presented. AuNPs were conjugated to thionin (TH)-modified rGO through formation of amide bonds. TH has been used as a bridge to link the AuNPs with rGO in this work. The as-prepared AuNP-TH-rGO nanohybrids were characterized by means of transmission electron microscopy (TEM), ultraviolet-visible-near infrared spectroscopy (UV-vis-NIR), X-ray photoelectron spectroscopy (XPS), Fourier Transform infrared (FTIR) and Raman measurements. The experimental results indicate that the particle size and distribution density of AuNPs on the graphene sheets can be well controlled by adjusting the original size and concentration of AuNPs in the reaction mixture. The AuNPs on the surface of graphene were stable under harsh treatment (e.g., acid, alkaline or ultrasonic treatment). Ligand exchange experimental results show that the AuNP-TH-rGO can be easily further functionalized by sulfhydryl-containing ligands. Compared to poly-l-lysine (PLL) coated rGO, PLL coated AuNP-TH-rGO shows higher NIR absorbance and more effective photothermal efficiency.

Glycolic acid-g-chitosan–Pt–Fe3O4 nanoparticles nanohybrid scaffold for tissue engineering and drug delivery

This work presents the potential use of novel nanohybrid based on chitosan-g-glycolic acid and Pt–Fe3O4 composite nanoparticles in drug delivery and tissue engineering applications. The Pt–Fe3O4 hybrid nanoparticles are prepared by thermal decomposition of H2PtCl6·6H2O at high temperature. The prepared nanoparticles were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS) and physical property measurement system (PPMS). Next step of this paper reveals the potential use of novel hybrids of chitosan-g-glycolic acid and Pt–Fe3O4 hybrid nanoparticles in controlled drug delivery applications. The drug loaded nanohybrid scaffold is prepared by freeze drying of grafted polymer solution. Drug loading and grafting of chitosan was characterized by Fourier transform infrared spectroscopy (FTIR). The cell proliferation also shows that the prepared nanohybrids are biocompatible. The nanohybrid was found to be stable regardless of pH of the medium. Therefore, Pt–Fe3O4 hybrid nanoparticles are viable additive for sustained drug delivery and it could be applied in the field of biomedical.

A novel nonenzymatic hydrogen peroxide sensor based on multi-wall carbon nanotube/silver nanoparticle nanohybrids modified gold electrode

A novel strategy to fabricate hydrogen peroxide (H 2O 2) sensor was developed based on multi-wall carbon nanotube/silver nanoparticle nanohybrids (MWCNT/Ag nanohybrids) modified gold electrode. The process to synthesize MWCNT/Ag nanohybrids was facile and efficient. In the presence of carboxyl groups functionalized multi-wall carbon nanotubes (MWCNTs), silver nanoparticles (Ag NPs) were in situ generated from AgNO 3 aqueous solution and readily attached to the MWCNTs convex surfaces at room temperature, without any additional reducing reagent or irradiation treatment. The formation of MWCNT/Ag nanohybrids product was observed by transmission electron microscope (TEM), and the electrochemical properties of MWCNT/Ag nanohybrids modified gold electrode were characterized by electrochemical measurements. The results showed that this sensor had a favorable catalytic ability for the reduction of H 2O 2. The resulted sensor could detect H 2O 2 in a linear range of 0.05–17 mM with a detection limit of 5 × 10 −7 M at a signal-to-noise ratio of 3. The sensitivity was calculated as 1.42 μA/mM at a potential of −0.2 V. Additionally, it exhibited good reproducibility, long-term stability and negligible interference of ascorbic acid (AA), uric acid (UA), and acetaminophen (AP).