Hepatic metabolism of colloidal gold-low-density lipoprotein complexes in the rat: evidence for bulk excretion of lysosomal contents into bile

Rats were treated with 17 alpha-ethinyl estradiol to induce high levels of low-density lipoprotein receptors in hepatocytes. When these rats were given intravenous injections of low-density lipoprotein-colloidal gold complexes, most of the gold (labeled with 195Au) appeared to be taken up by Kupffer cells, as were complexes of colloidal gold with albumin or polyvinylpyrrolidone. However, when these rats were also administered gadolinium chloride, which blocks Kupffer cell activity, most of the low-density lipoprotein-gold (but not gold complexed with albumin or polyvinylpyrrolidone) was taken up into hepatocytes by receptor-mediated endocytosis and concentrated in peribiliary lysosomes, as determined by electron microscopy. Colloidal gold taken up as a complex with low-density lipoprotein was excreted into the feces via the common bile duct at a maximal rate of about 5% daily, 4 to 12 days after injection. Thereafter, the rate of gold excretion fell off until reaching a plateau after 3 weeks. At this late time, most of the colloidal gold was shown by electron microscopy to be in Kupffer cells, whereas earlier (6 days after injection) it was contained mainly in older hepatocytic lysosomes, identified by lipofuscin granules. It is concluded that, in rats, hepatocytic lysosomes empty most of their contents into bile every week or two, apparently by exocytosis.     

Human insulin-specific immunoglobulin G antibody and hypoglycemic attacks after the injection of gold thioglucose.

A 56-year-old woman with granulomas of gold thioglucose in her hips exhibited recurrent bouts of hypoglycemic attacks. The first attack occurred 2 years after the last injection of gold thioglucose, when large amounts of extractable insulin and human insulin-specific antibody were noted in her serum. Histological examination of the resected granulomas showed marked infiltration of lymphocytes, plasma cells, and macrophages containing yellowish-brown granules, which proved to be gold by electron microscopy using X-ray microanalysis. After resection of the granuloma, however, the frequency of the hypoglycemic attacks decreased remarkably as well as the levels of both extractable insulin and human insulin-specific antibody.     

Colloidal gold uptake as a marker for monocyte differentiation and maturation in normal and leukemic cells.

The uptake of colloidal gold particles by human monocytes was studied by electron microscopy, with special emphasis on changes in this uptake during the differentiation and maturation of these cells. The way in which leukemic cells of childhood acute non-lymphocytic leukemia (ANLL) can function in this gold uptake was also examined. In monocytes, microendocytosis was temperature-dependent; colloidal gold uptake increased as temperatures rose from 4 degrees C to 37 degrees C. It appeared that gold particles first adhered to the cell surface membrane, were then incorporated into the cytoplasmic vesicles, and then were transported into the granules. Original HL-60 cells and retinoic acid (RA)-treated HL-60 cells, which were differentiating and maturing along the granulocyte lineage, did not ingest colloidal gold particles, but 1,25(OH)2D3-treated HL-60 cells showed colloidal gold uptake during their differentiation and maturation along the monocyte lineage: 68.6% of the cells contained gold particles. Gold uptake was demonstrated in 27.3% of original U937 cells; the percentage increased to 70.3% when they were induced to mature by RA. In 15 specimens of childhood ANLL, none of the M1, M2 or M3 cells showed colloidal gold uptake, whereas 76-97% of M4 and M5 cells showed this uptake. These findings indicate that colloidal gold uptake is a marker of monocyte differentiation and maturation and can provide additional information for ANLL cytology.     

Entomopathogenic fungus generated Nanoparticles for enhancement of efficacy in Culex quinquefasciatus and Anopheles stephensi

ObjectiveTo evaluate to efficacy of silver and gold generated larvicide with the help of entomopathogenic fungus Chrysosporium tropicum against the Culex quinquefasciatus and Anopheles stephensi larvae.MethodsThe silver and gold nanoparticles were quantified and observed by the Micro-scan reader and X-ray diffraction technique. The micrographs of silver and gold nanoparticles were obtained by the Transmission electron microscope and Scanning electron microscope. The larvicidal efficacy was then performed at six different log concentrations by the probit analysis.ResultsThe characterization study confirmed the spherical shaped and sized (20–50 and 2–15 nm) of silver and gold nanoparticles. The all larval stages of Cx. quinquefasciatus were found more susceptible to the synthesized silver nanoparticles. Whereas, the larvae of An. stephensi were found more susceptible to larvicide synthesized with gold nanoparticles.ConclusionsThe results suggested that the silver and gold nanoparticles generated by the entomopathogenic fungus C. tropicum is an environmentally safer and greener approach for mosquito control and new possibility in vector control strategy.     

Bio-Synthesis of Aspergillus terreus Mediated Gold Nanoparticle: Antimicrobial,Antioxidant, Antifungal and In Vitro Cytotoxicity Studies

Gold nanoparticles (GNP) were bio-fabricated utilizing the methanolic extract of the endophytic isolate Aspergillus terreus. The biosynthesised gold nanoparticles (GNP023) were characterised using UV-visible spectroscopy (UV-Vis); transmission electron microscopy (TEM), Fourier-transform nfrared spectroscopy (FTIR) and X-ray diffraction (XRD) studies. The bio-fabricated GNP023 displayed a sharp SPR peak at 536 nm, were spherically shaped, and had an average size between 10–16 nm. The EDX profile confirmed the presence of gold (Au), and XRD analysis confirmed the crystalline nature of GNP023. The antimicrobial activity of GNP023 was investigated against several food-borne and phytopathogens, using in vitro antibacterial and antifungal assays. The maximum zone of inhibition was observed for S. aureus and V. cholera at 400 μg /mL, whereas inhibition in radial mycelial growth was observed against Fusarium oxysporum and Rhizoctonia solani at 52.5% and 65.46%, respectively, when challenged with GNP023 (200 μg/mL). Moreover, the gold nanoparticles displayed significant antioxidant activity against the ABTS radical, with an IC₅₀ of 38.61 µg/mL, and were non-toxic when tested against human kidney embryonic 293 (HEK293) cells. Thus, the current work supports the application of myco-synthesised gold nanoparticles as a versatile antimicrobial candidate against food-borne pathogens.     

Variation in physical and biological properties of solid gold sodium thiomalate on dissolution: an electron microscopic and energy dispersive spectroscopic study

The dissolution of solid gold sodium thiomalate (GSTM) in water results in loss of yellow color. We studied the initial reaction on dissolution. It was associated with the disappearance of 2 absorption peaks on ultraviolet spectrum, one a well defined peak at 335 nm and the other a shoulder at 370 nm. This solution caused platelet aggregation and on transmission electron microscopy, dense gold containing particles measuring 125 nm are seen. Within 10 min of onset of dissolution, no gold containing particulate matter was detectable on electron microscopy. By 20 min, fibrillar particles measuring 40-150 nm appear. These resembled in general morphology and element composition the particles seen within aurosomes in platelets treated with Myochrysine (GSTM) and in synovium and other tissues by other workers. Our data elaborate on previous physical and chemical studies and correlate with morphological variations of gold containing particles at different phases. These variations in GSTM may be due to polymer size and/or structural change within the polymer. The biochemical significance of our data should provide better understanding of the biological effects of these gold thiol compounds in vivo.     

Concentration of SARS-CoV-2-Infected Cell Culture Supernatants for Detection of Virus-like Particles by Scanning Electron Microscopy

There is currently a need for new rapid viral diagnostic electron microscopy methods. Although the gold standard remains the transmission electron microscopy (TEM) negative staining method for electron microscopic examination of samples containing a virus, difficulties can arise when the virus particle content of the sample that has to be examined is poor. Such samples include supernatants of virus-infected cells that can be difficult to examine, as sometimes only a few virus particles are released in the culture medium upon infection. In addition to TEM, scanning electron microscopy (SEM) can also be used for visualizing virus particles. One advantage of SEM over TEM is its ability to rapidly screen several large specimens, such as microscopy slides. In this study, we investigated this possibility and tested different coating molecules as well as the effect of centrifugation for analyzing SARS-CoV-2-virus-infected cell culture supernatants deposited on microscopy glass slides by SEM. We found that centrifugation of 25XConcanavalinA-coated microscopy glass slides in shell vials provided an improved method for concentrating SARS-CoV-2-virus-infected cell supernatants for virus-like particle detection by SEM.     

Gold colitis induced by auranofin treatment of rheumatoid arthritis: case report and review of the literature.

A case of ulcerative colitis occurred during treatment of rheumatoid arthritis with the new oral gold preparation auranofin after a cumulative dose of 2160 mg. A barium enema showed loss of mucosal pattern and a rectal biopsy disclosed deep erosions, mucosal inflammation, and crypt abscesses. Precipitates of gold were seen in the periglandular stroma. On electron microscopy the gold deposits seemed to be identical to granules described in gold nephropathy. As the extrapolated serum gold level was within the normal range at the onset of the complication, the morphological findings suggested a local toxicity of the drug. The patient recovered within 14 days of withdrawal of auranofin and the start of therapy with sulphasalazine and steroids. A review of the published work shows that the previously reported mortality in gold colitis of 40% has decreased in recent years. The causes of this decrease may be both the earlier diagnosis of gold colitis and the improved intensive care of its severe complications.     

pH-controlled delivery of luminescent europium coated nanoparticles into platelets

Water soluble, luminescent gold nanoparticles are delivered into human platelets via a rapid, pH-controlled mechanism using a pH low insertion peptide, pHLIP. The approach introduces cocoating of gold nanoparticles with a europium luminescent complex, EuL and the pHLIP peptide to give pHLIP•EuL•Au. The 13-nm diameter gold nanoparticles act as a scaffold for the attachment of both the luminescent probe and the peptide to target delivery. Their size allows delivery of approximately 640 lanthanide probes per nanoparticle to be internalized in human platelets, which are not susceptible to transfection or microinjection. The internalization of pHLIP•EuL•Au in platelets, which takes just minutes, was studied with a variety of imaging modalities including luminescence, confocal reflection, and transmission electron microscopy. The results show that pHLIP•EuL•Au only enters the platelets in low pH conditions, pH 6.5, mediated by the pHLIP translocation across the membrane, and not at pH 7.4. Luminescence microscopy images of the treated platelets show clearly the red luminescence signal from the europium probe and confocal reflection microscopy confirms the presence of the gold particles. Furthermore, transmission electron microscopy gives a detailed insight of the internalization and spatial localization of the gold nanoparticles in the platelets. Thus, we demonstrate the potential of the design to translocate multimodal nanoparticle probes into cells in a pH dependent manner.     

Gold pneumonitis. A case report with electronmicroscopy and electron probe analysis

A case of classical RA developed severe interstitial pulmonary disease and respiratory failure while on chrysotherapy. A high concentration of gold was found in lung tissue. Electron microscopic and electron probe examinations confirmed the presence of gold in the interstitial and intra-alveolar macrophages. The clinical course and possible pathogenic mechanism were discussed.     

Immunogold labelling of human von Willebrand factor adsorbed to collagen

von Willebrand factor (vWF) mediates adhesion of platelets to the exposed subendothelium at sites of vascular injury. This function is expressed through binding of vWF to both collagen and receptors on the platelet membrane. We have developed a new method using immunogold staining and electron microscopy, permitting visualization of human vWF adsorbed to collagen fibrils. The electron micrographs revealed strings of gold beads reflecting the polymeric structure of vWF. Our data showed dramatic differences in the binding of vWF to collagens of different sources: high binding density was observed using a collagen preparation isolated from aortic tissue whereas colloidal gold was virtually absent from tendon collagen. Using the immunogold labelling method we demonstrated that high shear rate enhanced vWF binding to aortic collagen.     

Influence of different stent materials on endothelialization in vitro

The objective of our study was to investigate the influence of different stent materials on endothelialization in vitro. Using the non-destructive Alamar Blue assay and scanning electron microscopy, we compared long-term growth and morphology of vascular cells on disks of three prospective stent materials, i.e., 316 L stainless steel, 18 K, and 24 K gold. Our results demonstrate superior human EC proliferative capacity on gold surfaces compared to that on 316 L stainless steel. Thus, both the hyperplasia and thrombotic complications which often follow stenting might be minimized by employing gold stents, which have a greater capacity than steel in supporting a functional neo-endothelium.     

Laser Superficial Fusion of Gold Nanoparticles with PEEK Polymer for Cardiovascular Application

This paper analyses the possibility of obtaining surface-infused nano gold particles with the polyether ether ketone (PEEK) using picosecond laser treatment. To fuse particles into polymer, the raw surface of PEEK was sputtered with 99.99% Au and micromachined by an A-355 laser device for gold particle size reduction. Biomimetic pattern and parameters optimization were key properties of the design for biomedical application. The structures were investigated by employing surface topography in the presence of micron and sub-micron features. The energy of the laser beam stating the presence of polymer bond thermalisation with remelting due to high temperature was also taken into the account. The process was suited to avoid intensive surface modification that could compromise the mechanical properties of fragile cardiovascular devices. The initial material analysis was conducted by power–depth dependence using confocal microscopy. The evaluation of gold particle size reduction was performed with scanning electron microscopy (SEM), secondary electron (SE) and quadrant backscatter electron detector (QBSD) and energy dispersive spectroscopy (EDS) analysis. The visibility of the constituted coating was checked by a commercial grade X-ray that is commonly used in hospitals. Attempts to reduce deposited gold coating to the size of Au nanoparticles (Au NPs) and to fuse them into the groove using a laser beam have been successfully completed. The relationship between the laser power and the characteristics of the particles remaining in the laser irradiation area has been established. A significant increase in quantity was achieved using laser power with a minimum power of 15 mW. The obtained results allowed for the continuation of the pilot study for augmented research and material properties analysis.     

Gold Nanostructures for Surface-Enhanced Raman Spectroscopy,Prepared by Electrodeposition in Porous Silicon

Electrodeposition of gold into porous silicon was investigated. In the present study, porous silicon with ~100 nm in pore diameter, so-called medium-sized pores, was used as template electrode for gold electrodeposition. The growth behavior of gold deposits was studied by scanning electron microscope observation of the gold deposited porous silicon. Gold nanorod arrays with different rod lengths were prepared, and their surface-enhanced Raman scattering properties were investigated. We found that the absorption peak due to the surface plasmon resonance can be tuned by changing the length of the nanorods. The optimum length of the gold nanorods was ~600 nm for surface-enhanced Raman spectroscopy using a He–Ne laser. The reason why the optimum length of the gold nanorods was 600 nm was discussed by considering the relationship between the absorption peak of surface plasmon resonance and the wavelength of the incident laser for Raman scattering.     

Scanning immunoelectron microscopy of hairy cell leukemia

Scanning electron microscopy has shown a typical cell surface morphology in hairy cell leukemia. Scanning immunoelectron microscope techniques, utilizing monoclonal antibodies and colloidal gold particles, have recently become available. Eight patients with hairy cell leukemia have been studied with a panel of monoclonal antibodies of which B1, BA1, OKM1, anti-TAC and LeuM5 were shown to be suitable for scanning immunoelectron microscopy and reactive with hairy cells. The combination of typical cell surface features with reactivity for the B1 and LeuM5 monoclonal antibodies permits accurate diagnosis of hairy cell leukemia, particularly when low percentages of hairy cells are present as in hypocellular or in interferon-treated patients.     

An approach to long-range electron transfer mechanisms in metalloproteins: In situ scanning tunneling microscopy with submolecular resolution

In situ scanning tunneling microscopy (STM) of redox molecules, in aqueous solution, shows interesting analogies and differences compared with interfacial electrochemical electron transfer (ET) and ET in homogeneous solution. This is because the redox level represents a deep indentation in the tunnel barrier, with possible temporary electronic population. Particular perspectives are that both the bias voltage and the overvoltage relative to a reference electrode can be controlled, reflected in spectroscopic features when the potential variation brings the redox level to cross the Fermi levels of the substrate and tip. The blue copper protein azurin adsorbs on gold(111) via a surface disulfide group. Well resolved in situ STM images show arrays of molecules on the triangular gold(111) terraces. This points to the feasibility of in situ STM of redox metalloproteins directly in their natural aqueous medium. Each structure also shows a central brighter contrast in the constant current mode, indicative of 2- to 4-fold current enhancement compared with the peripheral parts. This supports the notion of tunneling via the redox level of the copper atom and of in situ STM as a new approach to long-range electron tunneling in metalloproteins.     

Gold-induced changes in the morphology and functional capabilities of human monocytes

The capacity of gold compounds to induce morphologic changes and alterations in the functional activity of human mononuclear phagocytes (MΦ) in vitro was examined. Human peripheral blood mononuclear cells were incubated with gold sodium thiomalate (25 μg/ml) for 96 hours. As a result, MΦ developed electron dense precipitates within phagolysosomes, as well as marked dilatation of these organelles. Gold incubation also altered a number of MΦ functions. While viability and adherence were unaffected, the capacity to spread on surfaces was diminished. Pinocytosis of soluble proteins and phagocytosis of opsonized sheep erythrocytes were impaired, but Fc mediated particle binding was not. These data indicate that gold can alter certain functional activities of MΦ and support the idea that the major action of gold in rheumatoid arthritis results from its capacity to alter MΦ function.     

Gold-induced changes in the morphology and functional capabilities of human monocytes.

The capacity of gold compounds to induce morphologic changes and alterations in the functional activity of human mononuclear phagocytes (M phi) in vitro was examined. Human peripheral blood mononuclear cells were incubated with gold sodium thiomalate (25 microgram/ml) for 96 hours. As a result, M phi developed electron dense precipitates within phagolysosomes, as well as marked dilatation of these organelles. Gold incubation also altered a number of M phi functions. While viability and adherence were unaffected, the capacity to spread on surfaces was diminished. Pinocytosis of soluble proteins and phagocytosis of opsonized sheep erythrocytes were impaired, but Fc mediated particle binding was not. These data indicate that gold can alter certain functional activities of M phi and support the idea that the major action of gold in rheumatoid arthritis results from its capacity to alter M phi function.     

Reducing Efficiency of Fucoxanthin in Diatom Mediated Biofabrication of Gold Nanoparticles

In the present investigation, fucoxanthin—one of the major pigments in diatoms—has been extracted from Nanofrustulum shiloi SZCZM1342, and its reducing efficiency in the biogenesis of gold nanoparticles (GNPs) was checked. Fucoxanthin extracted from golden-brown cells of N. shiloi was compared to the healthy, growing biomass of N. shiloi and standard fucoxanthin after separate exposure to 25 mg L⁻¹ aqueous hydrogen tetrachloroaurate solutions at room temperature. Isolated and standard fucoxanthin were found to be able to reduce gold ions within 12 h whereas, the whole biomass turned pink in color after 72 h of reaction. The synthesized particles were characterized by UV-vis spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). UV–vis spectroscopy of purple-colored suspensions showed the absorption band at approximately 520–545 nm, indicating a strong positive signal for GNP synthesis. The SEM study revealed the deposition of GNPs on siliceous frustules of metal-treated diatom cells. The TEM analysis confirmed the GNPs synthesized by whole biomass are triangular, spherical and hexagonal in nature, whereas the particles produced by extracted and standard fucoxanthin are all spherical in nature. This study demonstrates the involvement of fucoxanthin in the reduction of gold ions and subsequent production of gold nanospheres.     

Comparison of gold levels and distribution in guinea pig serum

Serum levels after oral administration of 30 mg/kg of sodium aurothiomalate (Myocrisin), triethylphosphine gold chloride, or triphenylphosphine gold chloride to guinea pigs indicated that all were orally absorbed. However, the serum gold level of triethylphosphine gold chloride was three to four times that of Myocrisin or triphenylphosphine gold chloride and was comparable with the serum level produced when the same dose of Myocrisin was injected intramuscularly. A comparative time-course study between intramuscular administration of Myocrisin and oral administration of triethylphosphine gold chloride indicated that during the first 24 hours after intramuscular injection of Myocrisin, a large fraction of the gold was not protein-bound, whereas all detectable gold in serum after oral administration of triethylphosphine gold chloride was protein-bound. Gold levels in the separated protein fractions indicate that the γ-globulin level after oral administration of triethylphosphine gold chloride is approximately three times higher after 24 hours than with intramuscular Myocrisin.