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PubMed1983

Second course gold therapy in the treatment of rheumatoid arthritis.

Twenty-three rheumatoid arthritis patients who had previously received gold therapy were selected for second course gold. Eleven patients had developed complete remission during the first course of gold therapy. Four of these had a complete response to second course gold. Of the 10 nonresponders and 2 partial responders to first course gold, none responded to second course gold. We conclude that individuals in whom first course gold is unsuccessful respond poorly to repeated gold treatments. In addition, only 36% of the patients who initially had a complete response sustained complete remission with second course gold.

Adult↗

PubMed1980

X-ray microanalysis of colloidal-gold-labelled lysosomes in rat liver sinusoidal cells after incubation for acid phosphatase activity.

The lysosomal apparatus of the Kupffer and endothelial cells of the sinusoidal lining of the rat liver was found to take up colloidal-gold particles with a mean diameter of 5 nm, prepared according to a modified method. After incubation of the glutaraldehyde-perfusion-fixed tissue in a lead-containing medium for the demonstration of acid phosphatase activity, a reaction product was observed in the gold-loaded lysosomes. By X-ray microanalysis of such lysosomes, the presence of osmium, gold and lead was detected qualitatively in the unstained sections from the tissue, which after the incubation had been post-fixed with an OsO4-solution to which K4Fe(CN)6 had been added to enhance the contrast. The quantitative computer-assisted processing of the X-ray microanalytical data from such lysosomes enabled to determine the gold-to-lead ratio and the individual gold and lead peak intensities derived from both the M chi and L chi values in the spectra. On the basis of these results and those obtained similarly in control lysosomes containing either only gold or only lead phosphate precipitate, it was found that only the L chi values were reliable, whereas the M chi values from the same lysosomal spectra were unrealistic, due to deconvolution problems in the computer programs applied. Based upon the L chi values it was found that among the population of lysosomes in single Kupffer cells, studied after a 60-min interval between the injection of the gold colloid and fixation, three types of lysosomal contents could be quantitated by X-ray microanalysis, viz. one type with only gold, one with only lead, one with gold and lead, in various ratios. This quantitative approach might make it possible to detect variations in lysosomal composition associated with ageing.

Acid Phosphatase↗

PubMed1985

Effects of coordinated gold compounds on in vitro and in situ DNA replication.

Auranofin, a coordinated gold compound, inhibits in vitro DNA synthesis and displays in vivo antitumor activity. To understand the mechanisms of inhibition of DNA replication, we have examined the effects of auranofin and other gold complexes on the activities of purified cellular and herpesvirus-induced DNA polymerases, and on in situ DNA replication in permeabilized S phase KB cells. Evaluation of the data suggests the following conclusions. (1) The gold compounds varied in their abilities to inhibit DNA polymerase activities. DNA polymerase alpha was more sensitive to inhibition by gold compounds than DNA polymerase beta; (2) Inhibition of purified DNA polymerases by gold (I) compounds was noncompetitive with both DNA template and triphosphate substrates. Inhibition by SKF 101675, a gold (III) complex was competitive with DNA. (3) None of the gold compounds tested preferentially inhibited herpesvirus-induced DNA polymerases. (4) The gold complexes that inhibited in vitro DNA replication also inhibited in situ DNA synthesis. However, the potency and order of potency of the compounds varied between the in vitro and in situ systems. (5) Auranofin and other gold compounds inhibited the clonogenic capacity of KB cells in a concentration-dependent manner. The IC50 values measured in the clonogenic assay were significantly lower than those obtained from the in vitro and in situ DNA replication assays.

Anti-Inflammatory Agents↗

PubMed1983

Colloidal gold, a useful marker for antigen localization on follicular dendritic cells.

Bovine serum albumin (BSA) bound to colloid gold particles (BSA-gold; 20 nm diameter) and injected into preimmunized mice was found at ultrastructural level in different locations of the lymph nodes. It was detected particularly in the secondary lysosomes of macrophages and between the cytoplasmic processes of the follicular dendritic cells. Between these processes the gold particles were isolated or grouped in clusters; they were in close contact with cell membranes or embedded in dense material. Colloidal gold injected alone was not retained on these cells. The presence of anti-BSA antibodies in the serum was necessary for trapping of BSA-gold particles on follicular dendritic cells. Injections of BSA alone after BSA-gold had been administered to preimmunized mice eliminated most of the BSA-gold from the dendritic processes. BSA-gold is thus trapped in the form of immune complexes which behave characteristically. BSA-gold is thus a suitable marker for antigen localization. Being small and electron dense it permits more precise location than radioactive markers.

Animals↗

PubMed1994

Comparative effects of chelating agents on distribution, excretion, and renal toxicity of gold sodium thiomalate in rats.

The effects of various chelating agents, such as (2S)-1-(3-mercaptopropionyl)-L-proline (captopril), N-(2-mercaptopropionyl)-glycine (tiopronin), L-cysteine (L-Cys), D-cysteine (D-Cys), N-acetyl-L-cysteine (L-NAC), N-benzyl-D-glucamine dithiocarbamate (BGD), and ethylenediaminetetraacetate (EDTA), on the distribution, excretion, and renal toxicity of gold sodium thiomalate (AuTM) in rats were investigated. Rats were intraperitoneally injected with the chelating agents (1.2 mmol/kg each) immediately after intravenous injection of AuTM (0.026 mmol/kg). Treatment with captopril or tiopronin significantly prevented increases in the urinary excretion of protein, aspartate aminotransferase (AST), and glucose and the blood urea nitrogen (BUN) level after AuTM injection. L-NAC and D-Cys significantly prevented increases in the urinary excretion of protein, AST, and glucose after AuTM injection, but did not reduce to control levels. Treatment with BGD, EDTA, or L-Cys did not prevent AuTM-induced increases in the urinary excretion of protein, AST, and glucose and BUN level. Tiopronin significantly increased the urinary excretion of gold. Captopril slightly promoted both the urinary and fecal excretion of gold, resulting in the significant increase in the total excretion of the metal. Tiopronin and captopril significantly decreased the gold concentration in the kidney and liver. L-Cys, D-Cys, L-NAC, BGD, and EDTA had no significant effect on the excretion or distribution of gold at 7 days after AuTM injection. These results indicate that tiopronin and captopril can ameliorate the renal toxicity induced by AuTM. In addition, the comparative effects of 2,3-dimercaptopropane sulfonate (DMPS), N-(2-mercapto-2-methylpropanoyl)-L-cysteine (bucillamine), captopril, and tiopronin at various dose levels (1.2, 0.4 or 0.2 mmol/kg) on the distribution and renal toxicity of gold were studied. DMPS was effective in removing gold from the kidney and in protecting against the renal toxicity after AuTM injection at the even lower dose level (0.2 mmol/kg). Bucillamine and tiopronin protected against the renal toxicity of gold at dose levels of 0.4 and 1.2 mmol/kg and captopril ameliorated the gold toxicity only at higher dose level (1.2 mmol/kg).

Animals↗

PubMed2006

Loading of gold nanoparticles inside the DPPC bilayers of liposome and their effects on membrane fluidities.

Gold nanoparticles were loaded in the bilayer of dipalmitoylphosphatidylcholine (DPPC) liposomes, named as gold-loaded liposomes. Above the gel to liquid-crystalline phase transition temperature, membrane fluidities of DPPC liposomes were changed by loading the gold nanoparticles. Compared with liposomes without loading the gold nanoparticles, gold-loaded liposomes showed the lower fluorescence anisotropy values. That is, the membrane fluidities of DPPC bilayer were increased by loading the gold nanoparticles. The membrane fluidities were increased as the amount of gold nanoparticles increased. The existence of gold nanoparticles in the DPPC bilayer was observed by transmission electron microscopy. Through the energy dispersive X-ray spectrometer, the particles in DPPC bilayer were confirmed to be gold nanoparticles.

1,2-Dipalmitoylphosphatidylcholine↗

PubMed2006

Cellular pharmacological properties of gold(III) porphyrin 1a, a potential anticancer drug lead.

The development of gold(III) complexes as potential anticancer drugs with higher cytotoxicity and fewer side effects than existing metal anticancer drugs has been actively pursued in recent years. In this study, we explored the cellular pharmacological properties of gold(III) porphyrin 1a, an anticancer drug lead we previously described. The cytotoxicity study of gold(III) porphyrin 1a by naphthol blue black (NBB) staining assay demonstrated that the higher cytotoxicity of gold(III) porphyrin 1a was not related to its photosensitizing activity. Serum dependent test revealed that serum proteins exhibited lesser effects on the activity of gold(III) porphyrin 1a. In addition, in vivo and in vitro binding assays showed that gold(III) porphyrin 1a acted on DNA noncovalently, which was differently from cisplatin. Flow cytometric study indicated that gold(III) porphyrin 1a inhibited cell growth partly through abrogating cell cycle at G(0)-G(1), and induced apoptosis in SUNE1 cells. The enhanced expression of p53, a cell cycle-controlling and apoptosis-related protein, further demonstrated that the cell cycle arrest and apoptosis induced by gold porphyrin 1a were p53 dependent. Our results highlighted the potential of gold(III) porphyrin 1a as an anticancer drug.

Animals↗

PubMed2004

An electrochemical quartz crystal microbalance study of the etching of gold surfaces in the presence of tetramethylthiourea.

The oxidation of tetramethylthiourea (TMTU) at gold electrodes in acetonitrile, leading to dissolution of the electrode, has been studied by electrochemical methods and by an electrochemical quartz crystal microbalance (EQCM). TMTU in acetonitrile readily adsorbs at gold electrodes and an estimated coverage of 5.5 x 10(-10) mol cm(-2) (30 A2 per molecule) was measured electrochemically. Nevertheless, the oxidation of TMTU in solution is a diffusion-controlled process and is strongly influenced by the electrode material, as observed by comparison of gold electrodes with glassy carbon and platinum working electrodes. In the absence of TMTU, EQCM cyclic voltammetry experiments showed dissolution of gold through a 1e- oxidation process at potentials more positive than 1.20 V vs saturated calomel electrode (SCE). Potential step and cyclic voltammetry EQCM experiments performed using gold surfaces in the presence of TMTU revealed TMTU-assisted etching of gold at potentials as low as 0.35 V vs SCE. In the potential region from 0.35 to 1.20 V the current response of TMTU oxidation mimics the response expected for a redox-active species in solution, including the presence of a mass-transfer-limited region, which supports the conclusion that the etching process in this potential region is initiated by the oxidation of TMTU at the gold surface. The current efficiency of the TMTU-assisted etching was found to vary between 12 electrons per gold atom dissolved (e/Au) (E = 0.50 V vs SCE) and 2 e/Au (0.90 V < E < 1.20 V). At potentials <0.90 V the dominant electrochemical process is the formation of TMTU+, whereas at higher potentials the etching of the gold surface by formation of a Au(I)-TMTU+ species becomes equally important. At potentials above 1.20 V the etching is no longer dependent on the diffusion of TMTU and the e/Au value approaches 1.

Acetonitriles↗

PubMed2004

Facile synthesis of chlorophyll analog possessing a disulfide bond and formation of self-assembled monolayer on gold surface.

A chlorophyll analog forming self-assembled monolayers (SAMs) on a gold surface was synthesized for the first time. 13(2)-(Demethoxycarbonyl)pheophorbide-a, which was converted from naturally occurring chlorophyll-a, was condensed with 2-hydroxyethyl disulfide to give a chlorin dyad linked by a disulfide bond. The chlorin analog was spontaneously immobilized on a gold substrate by soaking in an acetone solution of the dyad for 24 h. The resulting gold plate exhibited a visible absorption spectrum with about 420- and 675-nm maxima as the Soret and Qy peaks, respectively, indicating that chlorin pi-conjugates were modified on the gold substrate through Au-S bonding. Both visible absorption and fluorescence emission bands of the chlorin chromophores on the gold substrate were red-shifted compared with those of the synthesized chlorin dyad in a homogeneous acetone solution. The measured absorbance at the Soret maximum suggests that the chlorin chromophores on the gold plate were densely packed on a gold surface to form a SAM. Cathodic photocurrents were generated from SAMs of the chlorins on a gold substrate with irradiation of visible-lights above 400 nm. Photoinduced electron transfer from chlorins on the gold substrate to oxygen molecules in an electrolyte solution were attributed to the cathodic photocurrent generation.

Chlorophyll↗

PubMed2001

Vacuum metal deposition: developing latent fingerprints on polyethylene substrates after the deposition of excess gold.

A previously identified difficulty with the development of latent fingerprints on low-density polyethylene (LDPE) by vacuum metal deposition (VMD) is that excess gold deposition prevents effective zinc deposition and so inhibits latent print development [1]. The investigation of a means to correct for excess gold deposition was the basis for this study. Exposure to zinc and the readmission of air into the vacuum chamber followed by VMD development results in the deactivation of the initial gold clusters due to the formation of zinc oxide and the adsorption of air and water molecules. As a result, the majority of the gold deposited during the second treatment creates new gold clusters rather than adding to the gold clusters previously formed. After excess gold deposition on LDPE, the deposition of 1.5 times the optimum gold amount will result in good-quality normal development. The results also indicate that, on all surfaces, at least twice the initial gold count should be used for re-treatment when further development is required after air has been readmitted to the chamber.

Dermatoglyphics↗

PubMed2006

Gold-coated magnetic particles for solid-phase immunoassays: enhancing immobilized antibody binding efficiency and analytical performance.

The preparation and characterization of gold-coated magnetic particles are described for use as more efficient solid-phase materials in immunoassay development. A thin gold coating on commercial tosylated magnetic polystyrene particles (4.5 microm) is achieved via an electroless plating method involving initial reaction of the particles with Sn(II), followed by redox deposition of Ag0, that serves as a catalytic site for the subsequent reduction of Na3Au(SO3)2 in the presence of formaldehyde to yield the adhered gold layer. Scanning electron microscopy, energy-dispersive X-ray analysis, and X-ray photoelectron spectroscopy indicate the presence of the desired Au0 outer layer. To characterize the improved yield of antibody binding sites on such gold-coated phases, the modified particles are reacted with the free thiols of Fab' fragments of an anti-alkaline phosphatase (ALP) antibody to orient all the antigenic binding sites in a favorable direction. After equilibration with ALP, the amount of ALP bound to the surface of such particles is nearly 2.5-fold greater than on non-gold-coated particles possessing the same amount of immobilized anti-ALP Fab', but oriented randomly on the surface. The new gold-coated magnetic particles are further used as a solid phase for developing a sandwich-type enzyme immunoassay to detect C-reactive protein (CRP) using horseradish peroxidase as the enzyme label. The gold-coated magnetic particles with anti-CRP monoclonal Fab' reagents provide assays with enhanced assay slope (1.8-fold), lower nonspecific adsorption, and a detection limit improvement of nearly 10-fold (0.14 vs 1.9 ng/mL) compared to the same Fab' anti-CRP immobilized on the initial tosylated polystyrene magnetic particles. The improved assay performance is attributed to the more favorable binding orientation of the self-assembled monolayer of Fab' fragments on the gold-coated particles compared to the random orientation on the non-gold-coated surfaces.

Alkaline Phosphatase↗

PubMedDate not supplied

Synthesis of chitosan-stabilized gold nanoparticles in the absence/presence of tripolyphosphate.

Gold nanoparticles were prepared by reducing gold salt with a polysaccharide, chitosan, in the absence/presence of tripolyphosphate (TPP). Here, chitosan acted as a reducing/stabilizing agent. The obtained gold nanoparticles were characterized with UV--vis spectroscopy and transmission electron microscopy. The results indicated that the shape and size distribution of gold nanoparticles changed with the molecular weight and concentration of chitosan. More interestingly, the gelation of chitosan upon contacting with polyanion (TPP) can also affect the shape and size distribution of gold nanoparticles. By adding TPP to chitosan solution before the reduction of gold salt, gold nanoparticles have a bimodal size distribution, and at the same time, polygonal gold particles were obtained in addition to spherical gold nanoparticles.

Biocompatible Materials↗

PubMed2005

Electrochemical synthesis of gold nanocrystals and their 1D and 2D organization.

Size-controlled gold nanocrystals were conveniently synthesized through direct electroreduction of bulk AuCl(4)(-) ions in the presence of poly(N-vinylpyrrolidone) (PVP). PVP greatly enhanced the gold particle formation process and also significantly retarded the gold electrodeposition process, allowing the electrochemical synthesis of gold nanocrystals to be carried out in the form of simple electroreduction. This novel electrochemical method may be extended to synthesis of other noble metal nanoparticles with controllable size on a large scale. The PVPK90-protected gold nanocrystals spontaneously self-assembled into nearly ordered 2D close-packed arrays and interesting 1D nanostructures. The aggregation of unstable PVPK17-protected gold nanocrystals resulted in the formation of ultrathin single-crystalline films. PVP plays multifunctional roles in controlling the size and shape of gold nanocrystals and in inducing individual gold nanocrystals to construct 1D nanostructures. The nanoparticle self-assembling technique based on PVP offers a simple, but effective, path to organize individual gold nanoparticles into various 1D and 2D nanostructured materials.

Crystallization↗

PubMed2005

Complexes of DNA bases and Watson-Crick base pairs with small neutral gold clusters.

The nature of the DNA-gold interaction determines and differentiates the affinity of the nucleobases (adenine, thymine, guanine, and cytosine) to gold. Our preliminary computational study [Kryachko, E. S.; Remacle, F. Nano Lett. 2005, 5, 735] demonstrates that two major bonding factors govern this interaction: the anchoring, either of the Au-N or Au-O type, and the nonconventional N-H...Au hydrogen bonding. In this paper, we offer insight into the nature of nucleobase-gold interactions and provide a detailed characterization of their different facets, i.e., geometrical, energetic, and spectroscopic aspects; the gold cluster size and gold coordination effects; proton affinity; and deprotonation energy. We then investigate how the Watson-Crick DNA pairing patterns are modulated by the nucleobase-gold interaction. We do so in terms of the proton affinities and deprotonation energies of those proton acceptors and proton donors which are involved in the interbase hydrogen bondings. A variety of properties of the most stable Watson-Crick [A x T]-Au3 and [G x C]-Au3 hybridized complexes are described and compared with the isolated Watson-Crick A x T and G x C ones. It is shown that enlarging the gold cluster size to Au6 results in a rather short gold-gold bond in the Watson-Crick interbase region of the [G x C]-Au6 complex that bridges the G x C pair and thus leads to a significant strengthening of G x C pairing.

Base Pairing↗

PubMed2006

Calculated absorption and scattering properties of gold nanoparticles of different size, shape, and composition: applications in biological imaging and biomedicine.

The selection of nanoparticles for achieving efficient contrast for biological and cell imaging applications, as well as for photothermal therapeutic applications, is based on the optical properties of the nanoparticles. We use Mie theory and discrete dipole approximation method to calculate absorption and scattering efficiencies and optical resonance wavelengths for three commonly used classes of nanoparticles: gold nanospheres, silica-gold nanoshells, and gold nanorods. The calculated spectra clearly reflect the well-known dependence of nanoparticle optical properties viz. the resonance wavelength, the extinction cross-section, and the ratio of scattering to absorption, on the nanoparticle dimensions. A systematic quantitative study of the various trends is presented. By increasing the size of gold nanospheres from 20 to 80 nm, the magnitude of extinction as well as the relative contribution of scattering to the extinction rapidly increases. Gold nanospheres in the size range commonly employed ( approximately 40 nm) show an absorption cross-section 5 orders higher than conventional absorbing dyes, while the magnitude of light scattering by 80-nm gold nanospheres is 5 orders higher than the light emission from strongly fluorescing dyes. The variation in the plasmon wavelength maximum of nanospheres, i.e., from approximately 520 to 550 nm, is however too limited to be useful for in vivo applications. Gold nanoshells are found to have optical cross-sections comparable to and even higher than the nanospheres. Additionally, their optical resonances lie favorably in the near-infrared region. The resonance wavelength can be rapidly increased by either increasing the total nanoshell size or increasing the ratio of the core-to-shell radius. The total extinction of nanoshells shows a linear dependence on their total size, however, it is independent of the core/shell radius ratio. The relative scattering contribution to the extinction can be rapidly increased by increasing the nanoshell size or decreasing the ratio of the core/shell radius. Gold nanorods show optical cross-sections comparable to nanospheres and nanoshells, however, at much smaller effective size. Their optical resonance can be linearly tuned across the near-infrared region by changing either the effective size or the aspect ratio of the nanorods. The total extinction as well as the relative scattering contribution increases rapidly with the effective size, however, they are independent of the aspect ratio. To compare the effectiveness of nanoparticles of different sizes for real biomedical applications, size-normalized optical cross-sections or per micron coefficients are calculated. Gold nanorods show per micron absorption and scattering coefficients that are an order of magnitude higher than those for nanoshells and nanospheres. While nanorods with a higher aspect ratio along with a smaller effective radius are the best photoabsorbing nanoparticles, the highest scattering contrast for imaging applications is obtained from nanorods of high aspect ratio with a larger effective radius.

Absorption↗

PubMed2005

Carboranethiol-modified gold surfaces. A study and comparison of modified cluster and flat surfaces.

Four different carboranethiol derivatives were used to modify the surfaces of gold nanoparticles and flat gold films. The novel materials engendered from these modifications are extraordinarily stable species with surfaces that support self-assembled monolayers of 1-(HS)-1,2-C2B10H11, 1,2-(HS)2-1,2-C2B10H10, 1,12-(HS)2-1,12-C2B10H10, and 9,12-(HS)2-1,2-C2B10H10, respectively. Surprisingly, characterization of these materials revealed that a number of molecules of the carboranethiol derivatives are incorporated inside the nanoparticles. This structural feature was studied using a number of techniques, including X-ray photoelectron spectroscopy (XPS), UV-vis, and IR spectroscopies. Thermal desorption experiments show that carborane molecules detach and leave the nanoparticle surface mostly as 1,2-C2B10H10 isotopic clusters, leaving sulfur atoms bound to the gold surface. The surfaces of both the gold nanoparticles and the flat gold films are densely packed with carboranethiolate units. One carborane cluster molecule occupies an area of six to seven surface gold atoms of the nanoparticle and eight surface gold atoms of the flat film. XPS data showed that molecules of 1,12-(HS)2-1,12-C2B10H10 bind to the flat gold surface with only half of the thiol groups due to the steric demands of the icosahedral carborane skeleton. Electrochemical measurements indicate complete coverage of the modified gold surfaces with the carboranethiol molecules.

Boron Compounds↗

PubMed1999

Interaction of Saccharomyces cerevisiae with gold: toxicity and accumulation.

This paper examines the effects of ionic gold on Saccharomyces cerevisiae, as determined by long-term (growth in gold-containing media) and short-term interactions (H+ efflux activity). An increasing gold concentration inhibited growth and at < 0.2 mM Au, growth was not observed. Transmission electron microscopy revealed no differences in ultrastructure but fine electron dense particles were observed in unstained preparations from gold-containing medium. After glucose addition (to 10 mM) to starved suspensions of S. cerevisiae, glucose-dependent reduction of external pH occurred as the cells extruded protons. In the presence of increasing gold concentrations, the lag time before proton extrusion did not change but the rate and duration decreased significantly with a marked influence on proton efflux rate being observed at < or = 10 microM. Extension of preincubation time of yeast cells in gold-containing medium resulted in a decreasing proton efflux rate and colloidal phase formation in the cell suspensions, the time between gold addition and the beginning of colloidal phase formation depending on the gold concentration used. Both Ca and Mg enhanced the inhibitory effect of gold on the yeast cells with Ca showing a stronger inhibitory effect than Mg.

Biological Transport↗

PubMed1998

Recovery of gold from thiourea solutions using microorganisms.

The recovery of gold from gold-thiourea solutions using various types of waste biomass was investigated. All organisms tested, namely, Saccharomyces cerevisiae, Spirulina platensis and Streptomyces erythraeus removed gold rapidly from gold-thiourea solutions. The process of gold accumulation was pH-dependent for Saccharomyces ceresvisiae and Streptomyces erythraeus and independent of pH in the case of Spirulina platensis. Of all strains of microorganisms examined, Spirulina platensis had the highest affinity and capacity for gold even at low pH values. Thus, all three microorganisms tested for their ability to recover gold from gold-thiourea solutions can therefore be used in biotechnological applications, especially Spirulina platensis which has the highest binding capacity for gold at low pH values.

Bacterial Proteins↗