Combination Of Gold Nanoparticles Research Articles

Combination of gold nanoparticles with low-LET irradiation: an approach to enhance DNA DSB induction in HT29 colorectal cancer stem-like cells.

High-linear energy transfer (high LET) irradiation has significant cytotoxic effects on different cancerous stem-like cells (CSLCs) such as colorectal CSLCs. A review of the literature has indicated that the presence of gold nanoparticles (GNPs) enables low-LET irradiation to produce highly non-homogeneous dose distributions like high-LET irradiation. The purpose of this study was to evaluate the radioresponsiveness of HT29 colorectal CSLCs under low-LET irradiation (X-ray) and in the presence of GNPs. Radioresponsiveness was evaluated using the ϒ-H2AX foci formation assay, the clonogenic assay, the cell cycle progression assay and analyses of radiobiological parameters. In the presence of GNPs, the survival fraction of HT29 CSLCs was significantly reduced and caused significant changes in the radiobiological parameters after irradiation. In addition, ϒ-H2AX assay showed that in the presence of GNPs, the persistent DNA double-strand breaks were significantly increased in irradiated HT29 CSLCs. The relative biological effectiveness value of GNPs with X-rays was about 1.6 for HT-29 CSLCs at the 10% of cell survival fraction (D10 level) when compared to X-rays alone. Therefore, the combination of GNPs with X-ray irradiation has the potential to kill HT29 CSLCs greater than the X-ray alone, and may be considered as an alternative for high-LET irradiation.

Voltammetric determination of aluminium(III) at tannic acid capped-gold nanoparticle modified electrodes

The contamination of drinking water and food products by aluminium represents a serious health issue, as it is associated with chronic neurodegenerative diseases. Herein we report an analytical electrochemical method for the determination of aluminium(III) at glassy carbon electrodes, modified with commercially available tannic acid-capped gold nanoparticles. The combination of gold nanoparticles and tannic acid as capping/chelating agent results in an accurate and sensitive detection of aluminium(III) in aqueous solutions by square wave voltammetry (SWV). Employing the presented methodology, clear measurable signals are seen even at the low limit of 10.0 pM, markedly and usefully lower than the permissible level of 7.4 μM for drinking water as defined by the WHO and which compares favourably with alternative detection methods.

Recent Progress of Synthesis and Application in Au@MOFs Hybrid Materials

The combination of gold nanoparticles and metal–organic frameworks is one of the new directions of current research. It has applications in many aspects, especially as a catalyst for a variety of reactions. Therefore, this paper describes recent progress of synthesis and application in Au@MOFs hybrid materials.

Lipid Nanodisc-Templated Self-Assembly of Gold Nanoparticles into Strings and Rings.

Gold nanoparticles (AuNPs) exhibit strong fluorescent and electromagnetic properties, which can be enhanced upon clustering and used in therapeutic, imaging, and sensing applications. A combination of gold nanoparticles with lipid nanodiscs can be attractive for AuNP self-assembly and useful in biomedical applications. Using molecular dynamics simulations we show that lipid nanodiscs can serve as templates for AuNP clustering into rings and string-like structures. We demonstrate that equilibrium encapsulation of 1 nm hydrophobically modified AuNPs into lipid nanodiscs composed of a mixture of dipalmitoylphosphatidylcholine (DPPC) and dihexanoylphosphatidylcholine (DHPC) lipids occurs at the rim and results in formation of a ring of gold. The interior of the nanodisc is inaccessible to AuNPs due to the DPPC liquid crystalline order. With temperature increase the lipid order diminishes, initiating the nanodisc transformation into a vesicle, upon which encapsulated AuNPs cluster into a close-packed string or nanoring, thereby stalling the vesiculation process at a "round vase" or cup-like stage depending on the AuNP concentration. In contrast, encapsulation of AuNPs by an equilibrium lipid vesicle results in its deformation with randomly clustered AuNPs, in agreement with experimental observations. We characterize the AuNP cluster size and surface-to-surface pair distribution, both of which impact the AuNP luminescent properties. We investigate the effect of alkane tether length on the nanodisc stability and AuNP clustering inside the nanodiscs and vesicles. Our results show that lipid nanodiscs can enhance gold cluster formation, which can be further exploited in imaging applications.

Electrochemical Determination of the p53 Tumor Suppressor Gene Using a Gold Nanoparticle-Graphene Nanocomposite Modified Glassy Carbon Electrode

ABSTRACTA novel sensitive and simple electrochemical DNA sensor is reported for the determination of p53 tumor suppressor gene. A gold nanoparticle/graphene nanocomposite-modified glassy carbon electrode was prepared and methylene blue was used as the hybridization redox indicator. Scanning electron microscopic and electrochemical characterization demonstrated that the gold nanoparticles and graphene were present on the electrode. The resulting sensor provided suitable electrochemical response to the p53 tumor suppressor gene with a linear dynamic range from 0.1 to 1000 nM. The limit of detection was 0.012 nM. The sensor was able to differentiate a complete complementary DNA sequence, single-base mismatched DNA sequence, and a three-base mismatched DNA sequence. The precision of the device was satisfactory, with a relative standard deviation of 4.1% for 11 measurements. The combination of gold nanoparticles and a graphene nanocomposite provided enhanced capabilities for the determination of DNA for clinical applications.

Cellulose-gold nanoparticle hybrid materials.

Cellulose and gold nanoparticles have exciting characteristics and new combinations of both materials may lead to promising functional nanocomposites with unique properties. We have reviewed current research on cellulose-gold nanoparticle composite materials, and we present an overview of the preparation methods of cellulose-gold composite materials and discuss their applications. We start with the nanocomposite fabrication methods, covering in situ gold reduction, blending, and dip-coating methods to prepare gold-cellulose nanocomposite hybrids. We then move on to a discussion of the ensuing properties where the combination of gold nanoparticles with cellulose results in functional materials with specific catalytic, antimicrobial, sensing, antioxidant and Surface Enhanced Raman Scattering (SERS) performance. Studies have also been carried out on orientationally ordered composite materials and on the chiral nematic phase behaviour of these nanocomposites. To exert even more control over the structure formation and the resultant properties of these functional materials, fundamental studies on the physico-chemical interactions of cellulose and gold are necessary to understand better the driving forces and limitations towards structuring of gold-cellulose hybrid materials.

Gold promoted Cu/ZnO/Al2O3 catalysts prepared from hydrotalcite precursors: Advanced materials for the WGS reaction

Outstanding catalysts for the water was shift reaction are reported in this work. The combination of gold nanoparticles with Cu/ZnO/Al2O3 prepared from hydrotalcite-like precursors leads to very promising systems for pure hydrogen production. Full CO conversion is reached at temperatures as low as 180°C. The key point seems to be the cooperation of Au and Cu and the optimal metal-oxide contact derived from the synthesis method. The high activity of gold for low temperature CO oxidation and the suitability of copper for the WGS results in a perfect synergy. Moreover the materials developed in this work present good stability and tolerance towards start/stop cycles an indispensable requisite for a realistic application in an integrated hydrogen fuel processor.

Adsorbent Assisted in Situ Electrocatalysis: An Ultra-Sensitive Detection of As(III) in Water at Fe3O4 Nanosphere Densely Decorated with Au Nanoparticles.

Most gold nanoparticle-based electrodes have been utilized for the analysis of highly toxic As(III), while nano-Fe3O4 materials are currently attracting considerable interest as an adsorbent for the removal of As(III). However, the combination of gold nanoparticles with Fe3O4 nanoadsorbents for stripping voltammetry is, to the best of our knowledge, unexplored. Here, a sensing interface for ultrasensitive detection of As(III) is designed and constructed by abundantly dispersing Au nanoparticles (Au NPs) on the surface of the Fe3O4 nanosphere. The Au@Fe3O4 nanospheres are covered by the room temperature ionic liquid (RTIL) and then modified on the screen-printed carbon electrode (SPCE). By combining the excellent catalytic properties of the Au nanoparticles (∼3-9 nm in diameter) with the good adsorption capacity of Fe3O4 nanospheres toward As(III), as well as the good conductivity of RTIL, the Au@Fe3O4-RTIL shows excellent performance in the detection of arsenic under nearly neutral conditions without modifying the morphology of the sensing interface. Through optimization of the experimental conditions, an ultrahigh sensitivity of 458.66 μA ppb(-1) cm(-2) from 0.1 to 1 ppb with a detection limit (3σ method) of 0.0022 ppb was obtained. The reproducibility and reliability of the Au@Fe3O4-RTIL sensing interface was also evaluated with good results. Finally, we used this platform to analyze real samples.

Endothelial-like nitric oxide synthase immunolocalization by using gold nanoparticles and dyes.

Immunofluorescence is a biological technique that allows displaying the localization of the target molecule through a fluorescent microscope. We used a combination of gold nanoparticles and the fluorescein isothiocianate, FITC, as optical contrast agents for laser scanning confocal microscopy imaging to localize the endothelial-like nitric oxide synthase in skeletal muscle cells in a three-dimensional tissue phantom at the depth of 4µm. The FITC detected fluorescence intensity from gold-nanoparticles-labelled cells was brighter than the emission intensity from unlabelled cells.

A proposed mechanism of the influence of gold nanoparticles on DNA hybridization.

A combination of gold nanoparticles (AuNPs) and nucleic acids has been used in biosensing applications. However, there is a poor fundamental understanding of how gold nanoparticle surfaces influence the DNA hybridization process. Here, we measured the rate constants of the hybridization and dehybridization of DNA on gold nanoparticle surfaces to enable the determination of activation parameters using transition state theory. We show that the target bases need to be detached from the gold nanoparticle surfaces before zipping. This causes a shift of the rate-limiting step of hybridization to the mismatch-sensitive zipping step. Furthermore, our results propose that the binding of gold nanoparticles to the single-stranded DNA segments (commonly known as bubbles) in the duplex DNA stabilizes the bubbles and accelerates the dehybridization process. We employ the proposed mechanism of DNA hybridization/dehybridization to explain the ability of 5 nm diameter gold nanoparticles to help discriminate between single base-pair mismatched DNA molecules when performed in a NanoBioArray chip. The mechanistic insight into the DNA-gold nanoparticle hybridization/dehybridization process should lead to the development of new biosensors.

Unraveling the synergy between gold nanoparticles and chromium-hydrotalcites in aerobic oxidation of alcohols

The combination of gold nanoparticles (AuNPs) with chromium-substituted hydrotalcite (Cr-HT) supports makes very efficient heterogeneous catalysts (Au/Cr-HT) for aerobic alcohol oxidation under soluble-base-free conditions. The Au-support synergy increases with increasing Cr content of the support and decreasing AuNP size. In situ UV-Raman, X-ray absorption and photoelectron spectroscopic studies firmly establish that the strong Au–Cr synergy is related to a Cr3+↔Cr6+ redox cycle at the Au/Cr-HT interface, where O2 activation takes place accompanied by electron transfer from Cr-HT to Au. The interfacial Cr6+ species can be reduced by surface Au–H hydride and negative-charged Au species to close the catalytic cycle. A study of kinetic isotope effect indicates that alcohol O–H cleavage is facilitated by the presence of Cr, making α-C–H bond cleavage step more rate-controlling. Accordingly, a dual synergistic effect of Au/Cr-HT catalysts on the activation of O2 and alcohol reactants is proposed.

Nanoparticle-Related Heat Transfer Phenomenon and Its Application in Biomedical Fields

Recent years have seen intensive interest in the synthesis and application of nanomaterials in different fields extending from energy to biomedicine sectors. Many biomedical applications involve delivering biomodified nanoparticles to malignant cells and rapidly heating nanoparticles with an external source such as laser, ultrasound, or an electromagnetic wave to produce a therapeutic thermal effect or to release drugs. The interaction of nanoparticles with the external source and the subsequent heating effect are fundamental for the successful deployment of these novel techniques. This study reviews nanoparticle-related heat transfer phenomenon and its medical applications. Some initial theoretical and experimental studies are conducted to reveal the potentials of this exciting field. The combination of gold nanoparticles with ultrasound irradiation or electromagnetic waves in the radiofrequency spectrum has been shown to be a promising strategy for future medical applications. Further understanding of the heating of nanoparticles in situ and thermal response at the nanoscale, which is essential for successful medical applications, call for a cross-disciplinary collaboration among engineers, scientists, and clinicians.

Improving Colorimetric Assays through Protein Enzyme-Assisted Gold Nanoparticle Amplification

The discovery of the DNA-mediated assembly of gold nanoparticles was a great moment in the history of science; this understanding and chemical control enabled the rational design of functional nanomaterials as novel probes in biodetection. In contrast with conventional probes such as organic dyes, gold nanoparticles exhibit high photostability and unique size-dependent optical properties. Because of their high extinction coefficients and strong distance dependent optical properties, these nanoparticles have emerged over the past decade as a promising platform for rapid, highly sensitive colorimetric assays that allow for the visual detection of low concentrations of metal ions, small molecules, and biomacromolecules. These discoveries have deepened our knowledge of biological phenomena and facilitated the development of many new diagnostic and therapeutic tools. Despite these many advances and continued research efforts, current nanoparticle-based colorimetric detection systems still suffer from several drawbacks, such as limited sensitivity and selectivity. This Account describes the recent development of colorimetric assays based on protein enzyme-assisted gold nanoparticle amplification. The benefits of such detection systems include significantly improved detection sensitivity and selectivity. First, we discuss the general design of enzyme-modified nanoparticle systems in colorimetric assays. We show that a quantitative understanding of the unique properties of different enzymes is paramount for effective biological assays. We then examine the assays for nucleic acid detection based on different types of enzymes, including endonucleases, ligases, and polymerases. For each of these assays, we identify the underlying principles that contribute to the enhanced detection capability of nanoparticle systems and illustrate them with selected examples. Furthermore, we demonstrate that the combination of gold nanoparticles and specific enzymes can probe enzyme dynamics and function with high specificity, offering substantial advantages in both sensitivity and specificity over conventional detection methods. The screening of nuclease, methyltransferase, protease, and kinase activities can be colorimetrically performed in a straightforward manner. Finally, we discuss examples of colorimetric assays for metal ions and small molecules that constitute important advances toward visual monitoring of enzyme catalytic functions and gene expression. Although these enzyme-assisted assay methods hold great promise for myriad applications in biomedicine and bioimaging, the application of the described techniques in vivo faces formidable challenges. In addition, researchers do not fully understand the interactions of gold nanoparticles with enzyme molecules. This understanding will require the development of new techniques to probe enzyme substrate dynamics at the particle interface with higher spatial resolution and chemical specificity.

Simultaneous determination of ascorbic acid, dopamine, uric acid and tryptophan on gold nanoparticles/overoxidized-polyimidazole composite modified glassy carbon electrode

A novel electrode was developed through electrodepositing gold nanoparticles (GNPs) on overoxidized-polyimidazole (PImox) film modified glassy carbon electrode (GCE). The combination of GNPs and the PImox film endowed the GNPs/PImox/GCE with good biological compatibility, high selectivity and sensitivity and excellent electrochemical catalytic activities towards ascorbic acid (AA), dopamine (DA), uric acid (UA) and tryptophan (Trp). In the fourfold co-existence system, the peak separations between AA–DA, DA–UA and UA–Trp were large up to 186, 165 and 285mV, respectively. The calibration curves for AA, DA and UA were obtained in the range of 210.0–1010.0μM, 5.0–268.0μM and 6.0–486.0μM with detection limits (S/N=3) of 2.0μM, 0.08μM and 0.5μM, respectively. Two linear calibrations for Trp were obtained over ranges of 3.0–34.0μM and 84.0–464.0μM with detection limit (S/N=3) of 0.7μM. In addition, the modified electrode was applied to detect AA, DA, UA and Trp in samples using standard addition method with satisfactory results.

Unique catalysis of gold nanoparticles in the chemoselective hydrogenolysis with H2: cooperative effect between small gold nanoparticles and a basic support

Gold nanoparticles on hydrotalcite act as a heterogeneous catalyst for the chemoselective hydrogenolysis of various allylic carbonates to the corresponding terminal alkenes using H(2) as a clean reductant. The combination of gold nanoparticles and basic supports elicited significantly unique and selective catalysis in the hydrogenolysis.

A Radio-Frequency Coupling Network for Heating of Citrate-Coated Gold Nanoparticles for Cancer Therapy: Design and Analysis

Gold nanoparticles (GNPs) are nontoxic, can be functionalized with ligands, and preferentially accumulate in tumors. We have developed a 13.56-MHz RF-electromagnetic field (RF-EM) delivery system capable of generating high E-field strengths required for noninvasive, noncontact heating of GNPs. The bulk heating and specific heating rates were measured as a function of NP size and concentration. It was found that heating is both size and concentration dependent, with 5 nm particles producing a 50.6 ± 0.2 °C temperature rise in 30 s for 25 μg/mL gold (125 W input). The specific heating rate was also size and concentration dependent, with 5 nm particles producing a specific heating rate of 356 ± 78 kW/g gold at 16 μg/mL (125 W input). Furthermore, we demonstrate that cancer cells incubated with GNPs are killed when exposed to 13.56 MHz RF-EM fields. Compared to cells that were not incubated with GNPs, three out of four RF-treated groups showed a significant enhancement of cell death with GNPs (p<0.05). GNP-enhanced cell killing appears to require temperatures above 50 °C for the experimental parameters used in this study. Transmission electron micrographs show extensive vacuolization with the combination of GNPs and RF treatment.

Glucose biosensor based on nanohybrid material of gold nanoparticles and glucose oxidase on a bioplatform

A simple and relatively cheap glucose biosensor based on a combination of gold nanoparticles (Au NPs) and glucose oxidase (GO(x) ) immobilized on a bioplatform eggshell membrane was established. Scanning electron microscopy showed successful immobilization of Au NPs/GO(x) on the eggshell membrane. The effects of pH, phosphate buffer concentration, and temperature on the glucose biosensor were studied in detail. The biosensor shows a linear response at a glucose concentration range of 5-525 μM. The detection limit of the biosensor is 2.5 μM (S/N = 3). The biosensor exhibits good repeatability with RSD = 3.6% (n = 6), good operational stability with over 300 measurements and long-term storage stability with a shelf life of at least 6 months. The response time is less than 60 s. The glucose level in commercial food samples has been successfully determined. The proposed work shows potential to develop cost-effective biosensors for biotechnological, biomedical and industrial use.

Fabrication of color changeable polystyrene spheres decorated by gold nanoparticles andtheir label-free biosensing

A novel and simple method for gold nanoshell synthesis with controllable core and shellsizes is reported here. A new ‘tree-shape’ surfactant bis(amidoethyl-carbamoylethyl)octadecylamine (C18N3) was synthesized and used as the glue for the fast combination ofgold nanoparticles and the subsequent gold shell outside. The functionalized polystyrene(PS) cores were covered by a surfactant (PS@C18N3) bilayer. The presence of thesurfactant double layer played the role of ‘glue’ in this method, so that upon controlling theamount of surfactant, it was possible to achieve: the manipulation of gold seed density onthe PS@C18N3 spheres, the preparation of PS@Au hybrid structures, and a red-shift in theextinction absorption from 520 to 750 nm. Besides, the as-prepared PS@Au compositessupported on a glass substrate exhibited excellent effectiveness in the molecular recognitionof human-immunoglobulin G (h-IgG) and goat anti-human-immunoglobulin G (goatanti-h-IgG), showing a rapid response within 20 min with a low detection limit of10 ng ml−1. This demonstrates that PS@Au prepared and assembled using our method is potentiallyuseful as a nanosensor platform for immunoassay.

Highly Sensitive Gold Nanoparticle-Based Colorimetric Sensing of Mercury(II) through Simple Ligand Exchange Reaction in Aqueous Media

A strategy for the rational design of a novel colorimetric sensor based on dithioerythritol-modified gold nanoparticles for the selective recognition of Hg2+ in aqueous media is presented. This approach relies on the combination of gold nanoparticles with Hg2+ through sulfur-Hg2+-sulfur interaction. The gold nanoparticles showed high selectivity toward Hg2+ with binding-induced red shift in the absorption spectra, with no response to major interfering cations such as Pb2+, Cd2+, and Cu2+ in the presence of ethylenediamine tetraacetic acid. The system responds to Hg2+ with a detection limit of 100 nM and might open a new avenue for the development of Hg2+ sensing probes.

Sensitive label-free electrochemical immunoassay by electrocatalytic amplification

A label-free electrochemical immunosensor for the detection of protein analytes without redox-active centers is for the first time developed based on the combination of gold nanoparticles and the mediated charge transport through the multilayer films that is related to an electrocatalytic process. Given the low detection limit, high sensitivity and selectivity, the success achieved here seems plausibly to serve as a significant step toward the development of versatile label-free immunoassay.