Hybrid nanomaterials

In the frame of a project aimed at developing a new type of optical solar reflectors we present the scientific and technological issues addressed during irradiations of nano-hybrid polyimide films deposited on quartz by using 20 keV electron beam from a modified use of Scanning Electron Microscope and with ultraviolet (UV) dose equal to 300 space-equivalent Sun hours.

The aim of this publication is to present a general strategy to engineer more efficient photoluminescent dendritic molecules based on polyhedral oligomeric silsesquioxane (POSS) cores. A series of chromophores were grafted
on POSS cores to form dendritic molecules for which steric hindrance was used as a trigger to tune their photophysical properties. For fluorescence in the blue/near-UV spectral ranges, 4-vinylbiphenyl molecules were chosen as model chromophores to present a general approach based on stable chemistry and bulky groups grafted to the chromophores to enhance photoluminescence efficiency of the dendritic molecules.
Photoluminescence quantum yields as well as steady-state and time-resolved solution spectroscopy along with molecular dynamics investigation and electronic structure calculations on a family of new materials are reported. We highlight an apparent contrast between free chromophore and dendritic molecules photophysical properties and show that chromophores’ engineering and confinement around an inorganic core allows the design of more efficient photoluminescent dendritic molecules relevant to sensors and hybrid light-emitting diodes.

Innumerable studies are conducted on nanofluids containing single type nanoparticles and attributes of such colloidal mixture have been well elucidated and prospected. Furtherance in nano-composites has entitled production of hybrid nanomaterials (nanoparticles) and remarkable researchers are exploring hybrid nanofluid characteristics. The cardinal objective of this study is to provide a comprehensive review on thermal conductivity of hybrid nanofluids by overviewing experimental, numerical and ANN (artificial neural networking) studies. Assorted factors that affect thermal conductivity such as nanoparticle type, concentration of nanoparticles, types of base fluid, size of nanoparticle, temperature, addition of surfactant, pH variation and sonication time are analyzed in present paper. Additionally, synthesis of hybrid nano-composites, preparation of hybrid nanofluids, approaches for stability measurement and enhancement, methods of thermal conductivity measurement and reasons for thermal conductivity enhancement are discussed. Miscellaneous empirical correlations developed by researchers for thermal conductivity prediction of hybrid nanofluids are also compiled and presented. Results suggest that enhancing temperature and concentration increases thermal conductivity and proper selection of hybrid nanoparticles plays a prime role in attaining stability of hybrid nanofluids.

Hybrid nanoliquid as an expansion of nanoliquid is acquired by scattering combination of nano-powder or numerous distinct nanomaterials in the regular liquid. Hybrid nanofluids are impeding fluids which furnish better performance of heat transport and thermo-physical properties than convectional heat transport fluids (ethylene glycol, water and oil) and nanofluids with single material. At this juncture, a sort of hybrid nanofluid comprising nano-size materials through an ethylene glycol as a regular liquid is modeled to expand the magnetic impact on the mixed convection flow through a shrinking/stretched wedge. The impacts of Joule heating and viscous dissipation are also revealed. The PDEs which governed the flow problem with heat transport are changed into a dimensionless ODEs system through a similarity technique. Then these equations are numerically exercised by utilizing bvp4c solver. The impact of emerging constraints on the flow field with heat transport is discussed with the aid of plots. Also, the stability analysis is implemented to classify which result is physically reliable and stable.

In this paper, ZnO/Ag core-shell hybrid nanocomposites have been prepared by a very simple chemical methodology. ZnO nanorods were employed as core material for Ag seeds, and subsequent nucleation and growth of Ag nanoparticle by a cationic surfactant cetyltrimethylammonium bromide (CTAB) formed the ZnO NRs/Ag core-shell nanocomposites. In addition, their morphology, microstructure and optical properties have been characterized by X-ray diffraction, Raman Spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, UV-Vis absorption and photoluminescence spectroscopy. It was found that face-center-cubic Ag nanoparticles with an average diameter of 20 nm were coated onto the surface of hexagonal phase ZnO nanorods with a minimum of 0.09 mmol concentration of CTAB. The excitonic absorption band and surface plasmon absorption band of the ZnO NRs/Ag nanocomposites revealed red-shifts relative to pure ZnO nanorods and metallic Ag nanoparticles. The coating of Ag nanoparticles onto the ZnO nanorods show red-shift in the near band edge (NBE) luminescence spectra and a reasonable detraction in the deep level emission (DLE) spectra compared with the pure ZnO nanorods. These interpretations demonstrated the strong interfacial interaction between Ag nanoparticles and ZnO nanorods. Furthermore, the annealing of ZnO NRs/Ag nanocomposite at 200°C was done and improvement occurs in the crystallinity and binding strength of Ag nanoparticles.

Iron oxide-graphene oxide (Fe 3 O 4-GO) hybrid nanoparticle-nanoplates was synthesized in multistep process for achieving higher performance and synergetic effect of magnetic properties of the Fe 3 O 4 nanoparticles and conductive properties of GO nanoplates. Then, novel multifunctional Fe 3 O 4-GO/PVDF nanocomposite fiber mats were prepared using solution mixing and electrospinning methods. The effect of the Fe 3 O 4-GO contents on the morphological, piezoelectric and electromagnetic microwaves absorption properties of the PVDF nanocomposite fiber mats was investigated. The morphology of the nanofibers was investigated by scanning electron microscope (SEM). Transformation of α to β crystals in fiber nanocomposites was studied using Fourier transform infrared (FTIR) spectroscopy and X-ray diffraction techniques (XRD). The thermal behavior of Fe 3 O 4-GO/PVDF nanofi-bers were studied by differential scanning calorimetry (DSC) technique. Also, to verify the piezoelectric properties of the Fe 3 O 4-GO/PVDF nanofibers, a piezoelectric properties oscilloscope sensor was used. Microwave absorption performance of the synthesized nanofibers was investigated in the X-band and ku-band. Results demonstrate that the Fe 3 O 4-GO hybrid nanoparticles had a great influence on the α to β phase transformation of the PVDF crystals, piezoelectric response and microwave absorption properties in fiber mats of the PVDF hybrid nanocomposites.

Antimicrobial materials with immobilized/entrapped silver nanoparticles (AgNPs) are of considerable interest. There is significant debate on the mode of bactericidal action of AgNPs, and both contact killing and/or ion mediated killing have been proposed. In this study, AgNPs were immobilized on an amine-functionalized silica surface and their bactericidal activity was studied concurrently with the silver release profile over time. This was compared with similar studies performed using colloidal AgNPs and AgCl surfaces that released Ag ions. We conclude that contact killing is the predominant bactericidal mechanism and surface immobilized nanoparticles show greater efficacy than colloidal AgNPs, as well as a higher concentration of silver ions in solution. In addition, the AgNP immobilized substrate was used multiple times with good efficacy, indicating this immobilization protocol is effective for retaining AgNPs while maintaining their disinfection potential. The antibacterial surface was found to be extremely stable in aqueous medium and no significant leaching ($1.15% of total silver deposited) of the AgNPs was observed. Thus, immobilization of AgNPs on a surface may promote reuse, reduce environmental risks associated with leaching of AgNPs and enhance cost effectiveness. † Electronic supplementary information (ESI) available: Photographic image of silanization chamber; FEG-TEM image to show particle distribution of as-synthesized silver nanoparticles; photographic image of pristine amino-silanized glass and AgNPs immobilized glass; batch reactor fabrication for disinfection and silver release studies; surface coverage of silver nanoparticle immobilized glass substrate; and EDX analysis of the treated bacterial (E. coli) cells. See

We investigated the vapour sensing properties of different graphene-gold hybrid nanostructures. We observed the shifts in the optical spectra near the local surface plasmon resonance of the gold nanoparticles by changing the concentration and nature of the analytes (ethanol, 2-propanol, and toluene). The smaller, dome-like gold nanoparticles proved to be more sensitive to these vapours compared to slightly larger, flat nanoparticles. We investigated how the optical response of the gold nanoparticles can be tuned with a corrugated graphene overlayer. We showed that the presence of graphene increased the sensitivity to ethanol and 2-propanol, while it decreased it towards toluene exposure (at concentrations higher than 30%). The slope changes observed on the optical response curves were discussed in the framework of capillary condensation. These results can have potential impact on the development of new sensors based on graphene-gold hybrids.

We examine a variant of so-called carbon nanotube peapods by packing C 60 molecules inside the open edge ducts of collapsed carbon nanotubes. C 60 insertion is accomplished through a facile single-step solution-based process. Theoretical modeling is used to evaluate favorable low-energy structural configurations. Overfilling of the collapsed tubes allows infiltration of C 60 over the full crosssection of the tubes and consequent partial or complete reinflation, yielding few-wall, large diameter cylindrical nanotubes packed with crystalline C 60 solid cores.

Hybrids of semiconductor nanomaterials often demonstrate properties that are superior to those of their components. In this study, we prepared hybrid nanomaterials of TiO 2 and ZnO, which are among the most actively studied semiconductors, by means of millisecond-pulsed laser and analyzed how their morphology, particle size, and surface composition depend on preparation conditions. A series of nanomaterials were obtained via sequentially ablating Zn and Ti metal plates (in different sequences) in water, while laser pulses of lower (2.0 J/pulse) and higher (5.0 J/pulse) energy were applied. The properties of laser-produced hybrid TiO 2-ZnO nanomaterials were shown to be governed by experimental conditions such as laser pulse width, pulse peak power, and reaction media (either pure water or colloid with nanoparticles). The morphology revealed nanospheres of TiO 2 that decorate nanorods of ZnO or flower-like aggregates of zinc oxide. Intriguingly, after extended ablation time, titania was found to be self-doped with Ti 3+ and Ti 2+ ions, and the contribution of lower oxidation states of titanium could be controlled by the applied laser pulse energy. The physicochemical characteristics of hybrid nanomaterials were compared with pure ZnO and TiO 2 prepared under the same laser conditions.

In this investigation, a smart nanocarrier-loaded docetaxel, a microtubules disrupting agent and vorinostat, a histone deacetylase inhibitor was developed to achieve a synergistic anticancer effect. Dual drug-loaded lipid polymer hybrid nanoparticles were prepared, with easy fabrication and favorable properties including small size, narrow distribution and a high loading efficacy. The in vitro drug release conducted in phosphate-buffered saline, pH 7.4 and acetate-buffered saline, pH 5.5 media demonstrated the sustained, pH-dependent release profile. The nanoparticles were effectively taken up by cells, which ensured greater suppression of cell growth. The co-delivery of both drugs exhibited a synergistic effect on the induction of cancer cell apoptosis, resulting in greater inhibition of SCC-7, MCF-7, and MDA-MB-231 cancer cells by the drug-loaded carrier. These promising results may lead to clinical applications with enhanced docetaxel activity.

Recently, hybrid nanoparticles (NPs) consisting of various
materials and systems have been investigated to enhance delivery and efficacy of DNA and RNA [1]. Among them, lipid–polymer hybrid nanoparticles (LPHNPs) comprising a polymer core and lipid/lipid PEG shell are one of the versatile carriers due to their complementary
characteristics of both polymeric nanoparticles and liposomes
[2]. In this study, we fabricated protamine incorporated cationic
DOTAP lipid layered PLGA hybrid nanoparticles (LPHNPs) as a gene
delivery system by convenient double emulsion solvent evaporation
method and examined the effect of lipid concentration on the
properties of LPHNPs (i.e. size). DLS results confirmed relatively
monodisperse LPHNPs with a Z-average size of 153 nm and low
polydispersity (PDI-0.07) and TEM result confirmed the structure of
a hydrophobic PLGA core and cationic lipid shell (Fig. 1). The zeta
potential shifted from a negative value (−24 mV) to a positive value
(+60) with the incorporation of cationic lipid on the surface of
PLGA, which was probably induced by the hydrophobic interaction
between lipids and PLGA. We also found that the size and surface
charge of LPHNPs increased with the increase of cationic lipid
concentration indicating easy modulation of the surface properties of
LPHNPs. Long term stability of those complexes was also observed. Additionally, transfection and viability of HEK 293 cells treated with LPHNPs/DNA complexes with different concentrations were evaluated by flow cytometry. In all concentrations, LPHNPs/DNA complexes exhibited strong transfection efficiency while maintaining high cell viability, suggesting LPHNPs as an excellent and versatile gene delivery system.

We report a general and simple approach to take control of the color of light-emitting two-luminophore hybrid nanowires (NWs). Our strategy is based on the spatial control at the nanoscale (coaxial geometry) and the spectral selection of the two kinds of luminophores in order to restrict complex charge and energy transfers. Thus, it is possible to control the color of the photoluminescence (PL) as an interpolation of the CIE (Commission Internationale de l'Eclairage) coordinates of each luminophore. For this purpose, we selected a green-emitting semiconducting polymer and a red-emitting hexanuclear metal cluster compound, (n-Bu4N)2Mo6Br8F6, dispersed in a poly(methyl-methacrylate) (PMMA) matrix. The great potential and the versatility of this strategy have been demonstrated for two configurations. First, a yellow PL with a continuous change along the nanowire has been evidenced when the proportion of the PPV shell versus the nanocomposite core, that is, the green/red volumic ratio, progressively shifts from 1:2 to 1:5. Second, an extremely abrupt change in the PL color with red-green-yellow segments has been achieved. A simple model corroborates the effectiveness of this strategy. PL excitation and time-resolved experiments also confirm that no significant charge and energy transfers are involved. The two-luminophore hybrid nanowires may find widespread nanophotonic applications in multicolor emitting sources, lasers and chemical and biological sensors.

In this study, in order to enhance acoustic properties of polyurethane (PU) foams multi‐walled carbon nanotubes (MWCNT) and/or silica nanoparticles were added to polyol‐isocyanate composition up to 2 wt%, and acoustic properties of polyurethane foam samples with small amount of carbon nanotubes and silica nanoparticles (spherical and/or amorphous types) were determined in the frequency range from 50 Hz up to 6400 Hz. Acoustic properties, especially absorption coefficient of the produced samples were measured for all the prepared samples and results were investigated to come up with the best polyurethane samples that can be applied for sound absorption application at the desired frequency range. It was found that double combination of carbon nanotubes and silica nanoparticles, especially 0.7 wt% carbon nanotubes and 0.2 wt% spherical silica nanoparticle added polyurethane composition has better sound absorption ratio overall all frequencies levels compared to the other samples. Thus, it is possible to obtain polyurethane nanocomposite with a higher amount of carbon nanotube by weight at the same time enhancing sound absorption properties. Moreover, there is a synergic effect between carbon nanotubes and silica nanoparticles when mixed and added into polyurethane matrix at predetermined levels to get enhanced acoustic response with a higher level of carbon nanotube in polyurethane foam.

Antimicrobial materials with immobilized/entrapped silver nanoparticles (AgNPs) are of considerable interest. There is significant debate on the mode of bactericidal action of AgNPs, and both contact killing and/or ion mediated killing have been proposed. In this study, AgNPs were immobilized on an amine-functionalized silica surface and their bactericidal activity was studied concurrently with the silver release profile over time. This was compared with similar studies performed using colloidal AgNPs and AgCl surfaces that released Ag ions. We conclude that contact killing is the predominant bactericidal mechanism and surface immobilized nanoparticles show greater efficacy than colloidal AgNPs, as well as a higher concentration of silver ions in solution. In addition, the AgNP immobilized substrate was used multiple times with good efficacy, indicating this immobilization protocol is effective for retaining AgNPs while maintaining their disinfection potential. The antibacterial surface was found to be extremely stable in aqueous medium and no significant leaching ($1.15% of total silver deposited) of the AgNPs was observed. Thus, immobilization of AgNPs on a surface may promote reuse, reduce environmental risks associated with leaching of AgNPs and enhance cost effectiveness. † Electronic supplementary information (ESI) available: Photographic image of silanization chamber; FEG-TEM image to show particle distribution of as-synthesized silver nanoparticles; photographic image of pristine amino-silanized glass and AgNPs immobilized glass; batch reactor fabrication for disinfection and silver release studies; surface coverage of silver nanoparticle immobilized glass substrate; and EDX analysis of the treated bacterial (E. coli) cells. See

The aim of this publication is to present a general strategy to engineer more efficient photoluminescent dendritic molecules based on polyhedral oligomeric silsesquioxane (POSS) cores. A series of chromophores were grafted on POSS cores to form dendritic molecules for which steric hindrance was used as a trigger to tune their photophysical properties. For fluorescence in the blue/near-UV spectral ranges, 4-vinylbiphenyl molecules were chosen as model chromophores to present a general approach based on stable chemistry and bulky groups grafted to the chromophores to enhance photoluminescence efficiency of the dendritic molecules. Photoluminescence quantum yields as well as steady-state and time-resolved solution spectroscopy along with molecular dynamics investigation and electronic structure calculations on a family of new materials are reported. We highlight an apparent contrast between free chromophore and dendritic molecules photophysical properties and show that chromophores' engineering and confinement around an inorganic core allows the design of more efficient photoluminescent dendritic molecules relevant to sensors and hybrid light-emitting diodes.