Incorporation Of Gold Nanoparticles Research Articles

Polyaniline–Graphene–Gold Nanocomposite for Visible Light Active Photo Catalysis and Enhanced Thermal Electrical Stability

Polyaniline/graphene composite has been recognized as an excellent material for various photocatalytic, electrical and electronic applications. We have incorporated gold nanoparticles into polyaniline/graphene in order to enhance its visible light photocatalytic activity, electrical conductivity and thermal electrical stability at room temperature. Gold nanoparticles are known to absorb visible light efficiently. Graphene has been used as a conductive binding material for polyaniline and gold nanoparticle. A simple facile in situ oxidative chemical polymerization technique has been used to produce composite material. Additionally, structural and optical properties have also been investigated. TEM images clearly revealed that graphene and gold nanoparticles were well dispersed within the PANI matrix for better translation of its properties. Synthesized polyaniline/graphene/gold composite materials showed excellent visible light photocatalytic activity, enhanced electrical conductivity, and thermal electrical stability.

Adsorption of catechol onto PEDOT films doped with gold nanoparticles: Electrochemical and spectroscopic studies

In this work, the electrochemical processes at the electrode/electrolyte interface of PEDOT:PSS modified electrodes were studied. A detailed investigation using Electrochemical Impedance Spectroscopy (EIS) was done to determine the adsorption and electrochemical effects caused by the interaction of catechol at the conductive substrate. Different parameters such as double-layer capacitance, charge transfer resistance and intercalation charge distribution were analyzed in the presence of different amounts of catechol in the electrolyte. It was found a direct response of the charge transfer resistance (Rct) with catechol concentration, in the same way, the electrocatalytical response of the reversible redox reaction of catechol was observed. The investigation of the incorporation of gold nanoparticles (AuNPs) onto the PEDOT:PSS substrates showed an intrinsic increment in the conductivity, favoring the interaction between catechol and PEDOT, presenting an interesting tool for the construction of impedimetric sensors. The modified electrodes were further characterized by Scanning Electron Microscopy and Raman Spectroscopy.

Nuclear Uptake of Gold Nanoparticles Deduced Using Dual‐Angle X‐Ray Fluorescence Mapping

AbstractStudies into the cell nucleus' incorporation of gold nanoparticles (AuNPs) are often limited by ambiguities arising from conventional imaging techniques. Indeed, it is suggested that to date there is no unambiguous imaging evidence for such uptake in whole cells, particularly at the single nanoparticle level. This shortcoming in understanding exists despite the nucleus being the most important subcellular compartment in eukaryotes and gold being the most commonly used metal nanoparticle in medical applications. Here, dual‐angle X‐ray flouresence is used to show individually resolved nanoparticles within the cell nucleus, finding them to be well separated and 79% of the intranuclear population to be monodispersed. These findings have important implications for nanomedicine, illustrated here through a specific exemplar of the predicted enhancement of radiation effects arising from the observed AuNPs, finding intranuclear dose enhancements spanning nearly five orders of magnitude.

Gold nanoparticles decorated rGO-ZnCo2O4 nanocomposite: A promising positive electrode for high performance hybrid supercapacitors

Herein, we have engineered gold nanoparticles decorated reduced graphene oxide-ZnCo2O4 hybrid material by a hydrothermal process. With exercising benefit of a synergistic influence of reduced graphene oxide and gold nanoparticles, the nanohybrid ensures that internal microstructure is altered from ZnCo2O4 microflower to Au@rGO-ZnCo2O4 cauliflower. The prepared Au@rGO-ZnCo2O4 cauliflower electrode shows a high specific capacity of 288.5 mAh g−1 at 2 mV s−1 scan rate. The more detailed electrochemical interpretation is carried out to understand the charge storage abilities of the electrodes occurred from the capacitive- and diffusion-controlled kinetics processes. These excellent electrochemical performances can be assigned to the incorporation of gold nanoparticles and reduced graphene oxide nanosheets that alleviate electrons exchange and transmit through electrochemical active sites, which create an electronic and structural heterogeneity of the electro-active material. Further, Au@rGO-ZnCo2O4//AC hybrid solid-state supercapacitor cell is designed with polymeric gel electrolyte that delivered a good power density of 2121 W kg−1 at an energy density of 31 Wh kg−1 with excellent capacitance retention over 5000 cycles highlights convenience of the utility of mixing high capacity with high electronic transport. The experimental results reveal that the noble metal nanoparticles incorporated hybrid nanostructures are promising electrode materials for energy storage applications.

Tuning the Microenvironment of Gold Nanoparticles Encapsulated within MIL-101(Cr) for the Selective Oxidation of Alcohols with O2 : Influence of the Amino Terephthalate Linker.

This manuscript reports a comparative study of the catalytic performance of gold nanoparticles (NPs) encapsulated within MIL-101(Cr) with or without amino groups in the terephthalate linker. The purpose is to show how the amino groups can influence the microenvironment and catalytic stability of incorporated gold nanoparticles. The first influence of the presence of this substituent is the smaller particle size of Au NPs hosted in MIL-101(Cr)-NH2 (2.45±0.19 nm) compared with the parent MIL-101(Cr)-H (3.02±0.39 nm). Both materials are highly active to promote the aerobic alcohol oxidation and exhibit a wide substrate scope. Although both catalysts can achieve turnover numbers as high as 106 for the solvent-free aerobic oxidation of benzyl alcohol, Au@MIL-101(Cr)-NH2 exhibits higher turnover frequency values (12 000 h-1 ) than Au@MIL-101(Cr)-H (6800 h-1 ). Au@MIL-101(Cr)-NH2 also exhibits higher catalytic stability, being recyclable for 20 times with coincident temporal conversion profiles, in comparison with some decay observed in the parent Au@MIL-101(Cr)-H. Characterization by transmission electron microscopy of the 20-times used samples shows a very minor particle size increase in the case of Au@MIL-101(Cr)-NH2 (2.97±0.27 nm) in comparison with the Au@MIL-101(Cr)-H analog (5.32±0.72 nm). The data presented show the potential of better control of the microenvironment to improve the performance of encapsulated Au nanoparticles.

Control of Silver Coating on Raman Label Incorporated Gold Nanoparticles Assembled Silica Nanoparticles.

Signal reproducibility in surface-enhanced Raman scattering (SERS) remains a challenge, limiting the scope of the quantitative applications of SERS. This drawback in quantitative SERS sensing can be overcome by incorporating internal standard chemicals between the core and shell structures of metal nanoparticles (NPs). Herein, we prepared a SERS-active core Raman labeling compound (RLC) shell material, based on Au–Ag NPs and assembled silica NPs (SiO2@Au@RLC@Ag NPs). Three types of RLCs were used as candidates for internal standards, including 4-mercaptobenzoic acid (4-MBA), 4-aminothiophenol (4-ATP) and 4-methylbenzenethiol (4-MBT), and their effects on the deposition of a silver shell were investigated. The formation of the Ag shell was strongly dependent on the concentration of the silver ion. The negative charge of SiO2@Au@RLCs facilitated the formation of an Ag shell. In various pH solutions, the size of the Ag NPs was larger at a low pH and smaller at a higher pH, due to a decrease in the reduction rate. The results provide a deeper understanding of features in silver deposition, to guide further research and development of a strong and reliable SERS probe based on SiO2@Au@RLC@Ag NPs.

Success and failure in the incorporation of gold nanoparticles inside ferri/ferrocyanide thermogalvanic cells

Thermogalvanic systems represent a means to convert a temperature gradient into electricity, using only redox chemistry. However, the kinetics of electron transfer and physical mass transport of the redox couples are known limitations. In this study we present self-contained gelled thermogalvanic cells (or thermocells) containing the ferricyanide/ferrocyanide redox couple, which additionally have gold nanoparticles either immobilised at the gel/electrode interface, or distributed throughout the entire gel. Both methods of introducing the gold nanoparticles result in an apparent electrocatalytic improvement, as demonstrated by significant decreases in the electron transfer resistance. However, when used as thermogalvanic cells, only minor improvements were observed in power generation, and relatively rapid dissolution of the gold nanoparticles was observed, to yield passivating gold analogues of Prussian blue. Therefore successful preparation and short-term improvements have been demonstrated, but are offset by long-term stability issues. The relatively surprising instability of the generally inert gold nanoparticles in the presence of ferricyanide/ferrocyanide, particularly under thermogalvanic conditions, is of particular note.

Enhancement of energy storage density in antiferroelectric PbZrO3 films via the incorporation of gold nanoparticles

AbstractIn this work, antiferroelectric Au–PbZrO3 (Au–PZO) nanocomposite thin films were prepared by chemical solution deposition (CSD), and the effects of Au concentration on the antiferroelectric properties and the recoverable energy density were investigated. The results showed that the optimal Au concentration in the Au–PZO nanocomposite thin films was about 1 mol% for structural and electric properties. In the Au–PZO nanocomposite thin films with 1 mol% Au, Au nanoparticles (NPs) were distributed uniformly in the perovskite PZO matrix. Moreover, the recoverable energy density was 10.8 J/cm3 at 600 kV/cm, which is 42% higher than that of the pure PZO films. The results demonstrate that adding an appropriate amount of noble metal NPs in antiferroelectric thin films is an effective method to improve the energy storage properties.

Enhancement of power conversion efficiency of bulk heterojunction polymer solar cells using core/shell, Au/graphene plasmonic nanostructure

Abstract We demonstrate power conversion efficiency improvement in polymer solar cells (PSCs) through incorporating gold nanoparticles with graphene shell (Au NPs@Gr), positioned between hole transport and active layers. Au NPs@Gr improves roughness and can penetrate to active layer, enhance optical absorption and induce more balanced charge transfer. Band gap of the donor was analyzed by Tauc's formula which showed band gap decline in Au@Gr-based solar cells (1.89 eV). Life time, recombination rate and bulk resistance were analyzed by impedance spectroscopy. Graphene shell over Au NPs incorporates in charge transport and the life time of the charges improved 80% when charge recombination resistance increased from 2.08 to 2.37 KΩ. Solar cell photovoltaic parameters also showed higher short circuit current (42%) and higher power conversion efficiency (100%) in comparison to reference. Results indicated that Au NPs@Gr structure can be considered as an effective material for high performance PSCs and future high-tech applications.

Q-switched Ytterbium doped fibre laser using gold nanoparticles saturable absorber fabricated by electron beam deposition

A stable Q-switched Ytterbium doped fibre laser (YDFL) is demonstrated based on ring cavity by incorporating gold nanoparticles (AuNPs) based saturable absorber (SA). The SA is fabricated by depositing AuNPs onto polyvinyl alcohol thin-film surface using electron beam deposition technique. The proposed laser generates Q-switching pulses train as the pump power is increased beyond 61.1 mW. The laser operates at 1063.5 nm with the maximum repetition rate of 61.88 kHz and the thinnest pulse width of 4.23 μs are recorded at the 87.3 mW pump power. The output power increases linearly up to 3.14 mW, while the pulse energy varies from 10.55 nJ to 50.74 nJ as a pump power increased. Meanwhile, the maximum peak power of 12 mW is obtained at the pump power of 87.3 mW.

A calcium alginate sponge with embedded gold nanoparticles as a flexible SERS substrate for direct analysis of pollutant dyes.

A surface-enhanced Raman scattering (SERS) substrate with good flexibility and high water absorbing capacity is reported. It consists of a calcium alginate sponge incorporating gold nanoparticles. These are in close contactwith thesponge without the need for amino or sulfhydryl modification. The substrate is capable of detecting the dyes crystal violet (CV) and malachite green (MG) in water directly and rapidly by immersing it into the liquid sample. Preconcentration and separation are not required. The dyes absorbed on the sponge can be detected without drying and thus the whole analytical process can be completed within 3min. The results show that the lowest detectable concentrations are 0.1 and 0.25μg⋅L-1 for CV and MG, respectively. This is lower than the minimum required performance limits set by the European Commission and the US EPA. Moreover, MG and CV can be simultaneously detected in liquid samples due to their different SERS bands (at 1216 and 1534cm-1, respectively). It should be noted that the molecular structures of MG and CV are very similar. Therefore, the method has a large potential for determination of several analytes simultaneously even in complex sample metrics. Graphical abstract Schematic presentation of the fabrication ofa sodium alginate sponge loaded with gold nanoparticles. Gold nanoparticles together with gel-like alginate were freeze-dried to form the sponge. The sponge was cross-linked by CaCl2 solution and then it was freeze-dried again.

Incorporation of gold nanoparticles into the bilayer of polydiacetylene unilamellar vesicles

Gold nanoparticles made with three different alkanethiol surface passivating agents were loaded into the hydrophobic bilayers of polydiacetylene liposomes. The physical and optical properties of the vesicles were compared to each other and a nanoparticle-free control. Small gold nanoparticles were utilized to minimize the plasmon absorption and thereby minimize the effects of energy transfer processes on the optical behavior of the polydiacetylene moiety. The size and structure of the liposomes were examined with dynamic light scattering and electron microscopy, while the stability of the bilayer was investigated through differential scanning calorimetry. Optical spectroscopy was used to monitor the photopolymerization of the vesicles as well as the stress-induced polydiacetylene blue to red transition. Specifically, changes to the absorption frequency, fluorescence frequency, and the fluorescence intensity were monitored. This system can serve as a model system for the optimization of liposomes containing nanoparticles with specialized optical, magnetic, or chemical functionality.

A novel label free electrochemiluminescent aptasensor for the detection of lysozyme

In this paper we describe a novel ultrasensitive electrochemiluminescent (ECL) aptasensor based on the quenching effect of aptamer and lysozyme incubation on co-reactant ECL mechanism of nitrogen-doped graphene quantum dots and persulfate. Incorporation of gold nanoparticles let to enhancement of electron transfer process of co-reactant mechanism species. The electrochemical behavior of each step modification of aptasensor was investigated using electrochemical impedance spectroscopy and verified by ECL responses. The aptasensor showed high stability, sensitivity, reliable reproducibility, wide linear range (10 fM to 10 nM) with a low detection limit of 0.8 fM (at an S/N ratio of 3, n = 10) can be successively applied to the human serum samples analysis. Recoveries ranged between 91 and 104% (with RSDs of <3.1%).

Tailoring the properties of zinc oxide films by incorporating gold nanoparticles using RF magnetron sputtering

Nanoscale noble metal-incorporated ZnO nanostructures can have potential applications in developing chemical and biological sensors, optical filters, ultrafast switching devices, etc. The structural, morphological and optical properties of the as-deposited pure and Au-incorporated RF-sputtered ZnO films were investigated. XRD analysis suggests that the presence of Au nanoparticles strongly promotes the growth of well-crystalline grains of ZnO along $$\left\langle {00{\text{1}}} \right\rangle$$ direction. Surface morphology examined using AFM and FESEM micrographs and compositional analysis using EDX spectra reveal that Au acts as a nucleating center for the growth of high-crystalline grains, leading to the formation of specific structures. The observed reduction in transmittance with Au incorporation concentration can be attributed to LSPR of gold nanoparticles, scattering, increased surface roughness and increased thicknesses of the films. Systematic increase in the intensity of the plasmonic peak along with a shift in its position towards longer wavelength region is observed with increase in Au incorporation concentration. The PL spectra of the films show a NBE emission due to excitonic transition in ZnO and blue emission originating from deep-level defects in ZnO. The influence of Au nanoparticles on the crystallization of ZnO grains, evolution of surface morphology of ZnO nanostructured films and modification in the UV emission efficiency of ZnO films due to SPR of Au nanoparticles are studied in detail.

The development of nanofiber tubes based on nanocomposites of polyvinylpyrrolidone incorporated gold nanoparticles as scaffolds for neuroscience application in axons

In this report, nanofiber-based tubes as scaffolds for potential neuroscience application in the axon were fabricated by polyvinylpyrrolidone incorporated with gold nanoparticles (PVP/Au) in five d...

Behavior of hybrid thermosensitive nanosystem dextran-graft-PNIPAM/gold nanoparticles: characterization within LCTS

Thermally responsive polymers based on poly (N-isopropylacrylamide) (PNIPAM) with lower critical solution temperature (LCST) in the region of physiological temperatures become a subject of a study as promising material for biomedical application. In the present work, the star-like dextran-graft-PNIPAM with incorporated gold nanoparticles (AuNPs) in water suspension were studied by quasi-elastic light scattering (QELS), transmission electron microscopy (TEM), and spectroscopic methods in the temperature range around LCST. The analysis of QELS results revealed the individual polymer macromolecules with incorporated inside AuNPs and their aggregates, which demonstrate the LCST near 34 °C with the collapse of individual macromolecules and polymer aggregates too. The absorption spectroscopy measurements showed that the polymer structure is reversible at LCST and heating of polymer/AuNP nanosystems from room temperatures to LCTS does not accompany with a release of AuNPs from the polymer matrix. Raman spectra of nanohybrids were measured below and above LCTS and analyzed in details by employing DFT calculations. Two intense bands in the region 50–300-cm−1 region were observed for the first time. They were assigned to the stretching vibrations of Au-Au and Au-O (NIPAM) bonds. The presented work shows that the synthesized polymer with AuNPs has high stability going through LCST encouraging their use as a perspective system for drug delivery strategy.

Effect of localized surface plasmon resonance from incorporated gold nanoparticles in PEDOT:PSS hole transport layer for hybrid solar cell applications

We report optical and structural properties of poly (3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) incorporated gold nanoparticles capped by citrates (Au-citrates) as hole transport layer for hybrid organic-inorganic solar cell applications. PEDOT:PSS and Au-citrates both are water solution and the mixed are done in 2.378 wt%, 2.978 wt% and 3.144 wt% of Au-citrates. Plasmonic peak in the wavelength area of ∼525 nm for Au-citrates is found quite stable after addition of iso-propanol for wettability purpose. In our result, enhanced absorbance spectra of PEDOT:PSS incorporated Au-citrates indicates the effect of localized surface plasmon resonance from Au-citrates and it is estimated to enhance performance of hybrid solar cell efficiency. Optical properties of the thin films in hybrid solar cell device are done in the structure of ITO/ZnO/P3HT:PCBM(active layer)/(PEDOT:PSS:Au-citrates). The complete layer structure shows the enhancement of optical property in all UV-vis region in comparison to that structure without Au-citrates.

Controlled gene and drug release from a liposomal delivery platform triggered by X-ray radiation

Liposomes have been well established as an effective drug delivery system, due to simplicity of their preparation and unique characteristics. However conventional liposomes are unsuitable for the on-demand content release, which limits their therapeutic utility. Here we report X-ray-triggerable liposomes incorporating gold nanoparticles and photosensitizer verteporfin. The 6 MeV X-ray radiation induces verteporfin to produce singlet oxygen, which destabilises the liposomal membrane and causes the release of cargos from the liposomal cavity. This triggering strategy is demonstrated by the efficiency of gene silencing in vitro and increased effectiveness of chemotherapy in vivo. Our work indicates the feasibility of a combinatorial treatment and possible synergistic effects in the course of standard radiotherapy combined with chemotherapy delivered via X-ray-triggered liposomes. Importantly, our X-ray-mediated liposome release strategy offers prospects for deep tissue photodynamic therapy, by removing its depth limitation.

TiO2 nanofiber photoelectrochemical cells loaded with sub-12 nm AuNPs: Size dependent performance evaluation

Incorporation of gold nanoparticles (AuNPs) into titanium dioxide (TiO2) photoelectrodes has been used traditionally to increase the performance of photoelectrochemical cells (PECs) through their tailored optical properties. In contrast to larger AuNPs, previous studies have suggested that smaller AuNPs are the most catalytic or effective at increasing the photovoltaic (PV) performance of TiO2 photoelectrodes based on PECs. Despite this, AuNPs are often only compared between sizes of 12–300 nm in diameter due to the most common synthesis, the Turkevich method, being best controlled in this region. However, the optimum radius for citrate-capped AuNPs sized between 5 and 12 nm, and their influence on the PV performances has not yet been investigated. In addition to using AuNPs in the photoelectrodes, replacing traditional TiO2 NPs with one-dimensional nanofibers (NFs) is a promising strategy to enhance the PV efficiency of the PECs due their capability to provide a direct pathway for charge transport. Herein, we exploit the advantages of two different nanostructured materials, TiO2 NFs and sub-12 nm AuNPs (5, 8, 10, and 12 nm), and fabricate composite based photoelectrodes to conduct a size dependent performance evaluation. The PECs assembled with 8 nm AuNPs showed ∼20% improvement in the average power conversion efficiency compared to the control PECs without AuNPs. The highest performing PEC achieved a power conversion efficiency of 8%, which to the best of our knowledge, is among the highest reported for scattering layers based on pure anatase TiO2 NFs. On the basis of our comprehensive investigations, we attribute this enhanced device performance using 8 nm AuNPs in the TiO2 NF photoelectrodes to the improved spectral absorption, decreased series resistance, and an increase in electron transport and injection rate leading to an increase in current density and fill factor.

Determining the Radiation Enhancement Effects of Gold Nanoparticles in Cells in a Combined Treatment with Cisplatin and Radiation at Therapeutic Megavoltage Energies.

Combined use of chemotherapy and radiation therapy is commonly used in cancer treatment, but the toxic effects on normal tissue are a major limitation. This study assesses the potential to improve radiation therapy when combining gold nanoparticle (GNP) mediated radiation sensitization with chemoradiation compared to chemoradiation alone. Incorporation of GNPs with 2 Gy, 6 MV (megavoltage) radiation resulted in a 19 ± 6% decrease in survival of MDA-MB-231 cells. Monte-Carlo simulations were performed to assess dosimetric differences in the presence of GNPs in radiation. The results show that physics dosimetry represents a small fraction of the observed effect. The survival fraction of the cells exposed to GNPs, cisplatin, and radiation was 0.16 ± 0.007, while cells treated with cisplatin and radiation only was 0.23 ± 0.011. The presence of GNPs resulted in a 30 ± 6% decrease in the survival, having an additive effect. The concentration of the GNPs and free drug used for this study was 0.3 and 435 nM, respectively. These concentrations are relatively lower and achievable in an in vivo setting. Hence, the results of our study would accelerate the incorporation of GNP-mediated chemoradiation into current cancer therapeutic protocols in the near future.