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PubMed2004

Molecular weight evaluation of poly(dimethylsiloxane) on solid surfaces using silver deposition/TOF-SIMS.

Molecular ions include information about end groups, functional groups and molecular weight. A method for the direct detection of these in the high mass range (m/z > 1000) from poly(dimethylsiloxane) (PDMS) on a solid surface was investigated. It was found that a TOF-SIMS analysis of silver-deposited surfaces (silver deposition/TOF-SIMS) is useful for this purpose. Using the silver-deposition/TOF-SIMS method, silver-cationized quasi-molecular ions were clearly detected from PDMS on solid surfaces, and their structure and molecular weight were evaluated. In addition, their images were observed without the interference of deposited silver. By applying to the analysis of paint defects etc., it was confirmed that this technique is useful to analyze actual industrial materials. Silver-cationized ions were detected not only from PDMS, but also from other organic materials, such as lubricant additives and oils on solid surfaces. Therefore, the silver deposition/TOF-SIMS method was proved to be useful for the analysis of ultrathin substances on solid surfaces.

Journal Article↗
PubMed1999

Molecular basis for resistance to silver cations in Salmonella.

Here we report the genetic and proposed molecular basis for silver resistance in pathogenic microorganisms. The silver resistance determinant from a hospital burn ward Salmonella plasmid contains nine open reading frames, arranged in three measured and divergently transcribed RNAs. The resistance determinant encodes a periplasmic silver-specific binding protein (SilE) plus apparently two parallel efflux pumps: one, a P-type ATPase (SilP); the other, a membrane potential-dependent three-polypeptide cation/proton antiporter (SilCBA). The sil determinant is governed by a two-component membrane sensor and transcriptional responder comprising silS and silR, which are co-transcribed. The availability of the sil silver-resistance determinant will be the basis for mechanistic molecular and biochemical studies as well as molecular epidemiology of silver resistance in clinical settings in which silver is used as a biocide.

ATP Binding Cassette Transporter, Subfamily B↗
PubMed1986

Stabilization of silver chromate Golgi impregnation in rat central nervous system neurons using photographic developers. I. Light microscopy.

Deterioration of Golgi impregnation begins immediately after impregnated tissue blocks are sectioned with the Vibratome. The first signs of deterioration are fading of delicate impregnated processes, the disruption and fragmentation of dendrites, and, eventually, fading of entire neurons. These changes can be prevented by stabilization, i.e., by converting the water soluble silver chromate Golgi precipitate into metallic silver or by replacing the silver with some other dense, insoluble material. A technique is described using photographic developers to treat Vibratome sections containing Golgi-rapid or Golgi-Kopsch impregnated CNS neurons. In this way part of the silver chromate Golgi precipitate is reduced to metallic silver, and the remaining silver chromate is then removed with sodium thiosulfate. Of the various developers tested, Kodalith and Elon-ascorbic acid gave the best results, with excellent stabilization of the most delicate structures, such as the stalks of dendritic spines and finely woven axonal plexuses. Treatment with other developers (HC-110, Neutol, D-19, D-76, D-163, Kodak Universal, Rodinal, Atomal, Diafine, Eukobrom, Microdol-X) resulted in stabilization ranging from good to poor. Good stabilization of Golgi impregnation could also be achieved by first exposing the sections to sodium bromide (bromide substitution) followed by treatment with D-19, Kodalith, Elon-ascorbic acid or HC-110. After stabilization, the sections can be counterstained with aqueous cresyl violet or with alcoholic thionin without degradation of the stabilized Golgi image. The counterstain permits exact determination of the position of impregnated neurons in cortical layers or subcortical nuclei.

Animals↗
PubMed2004

[Comparison of several silver staining methods for DNA polyacrylamide gel electrophoresis].

OBJECTIVE: To compare 4 silver staining methods for DNA detection in polyacrylamide gel electrophoresis. METHODS: After the electrophoresis was completed, the gels were stained separately by four different methods, namely using ammonia-silver-citric acid, low-concentration silver nitrate, 0.1% and 0.2% silver nitrate. RESULTS: DNA was detected only by staining with 0.1% and 0.2% silver nitrate. CONCLUSION: 0.2% silver nitrate used along with sodium hydroxide shows the highest sensitivity in DNA detection, while its use with sodium carbonate produces the best quality of the image.

DNA↗
PubMed2004

[The study of adsorption of L-aspartic acid on silver sol by surface-enhanced Raman scattering].

The adsorption state and the characteristics of L-aspartic acid adsorbed on silver sol were studied by the Surface-Enhanced Raman Scattering (SERS) method. Strong Raman signals were detected in the experiments. The results suggested that L-aspartic acid adsorbed on the silver surfaces through carboxyl and nitrogen atoms since the signals were mainly due to the carboxyl and the nitrogen of the molecule of L-aspartic acid. The adsorption of carboxyl on the silver surfaces is chemical adsorption, which is based on the mechanism of charge-transfer, while the adsorption of nitrogen on the silver surfaces is physical type, which is due to the electromagnetic mechanism. The intensity of surface-enhanced Raman scattering of L-aspartic acid adsorbed on silver surface was also analyzed, and it was found that the intensity of surface-enhance Raman scattering will change with different concentrations of L-aspartic acid adsorbed on the silver surfaces. The intensity will reach the top value when the concentration of L-aspartic acid was 10(-3) mol x L(-1). When the concentration of L-aspartic acid decreased to 10(-4) mol x L(-1), the intensity of surface-enhanced Raman scattering became a little weaker than that with 10(-3) mol x L(-1). With further decrease in the concentration of L-aspartic acid, the intensity of surface-enhanced Raman scattering also decreased gradually. When the concentration of L-aspartic acid decreased to 10(-6) mol x L(-1), the intensity of surface-enhanced Raman scattering was very low. The above study will be helpful to the further study of peptide and other complex biological systems.

Adsorption↗
PubMed2006

[Effect of silver nanoparticle dressing on second degree burn wound].

OBJECTIVE: To explore the influence of silver nanoparticle dressing on prevention of infection and healing of the second degree burn wound. METHODS: One hundred and ninety-one burn patients with second degree including superficial and deep burn wound were randomly divided into three groups. Group A including 65 cases was treated by silver nanoparticle dressing on wounds, and group B (63 cases) and group C (63 cases) were treated by 1% silver sulfadiazine cream and vaseline gauze on their wounds, respectively. Dressing was changed daily, and wound swab bacterial cultures were performed before and after dressing change, and also wound healing times were recorded in each patient. RESULTS: Group A and B were similar in their bacterium colonizations on wound after treatment with the silver nanoparticle dressing and 1% silver sulfadiazine cream, and they had a similar effect on reducing bacterium colonization on wound after treatment, while in vaseline gauze group bacterium colonization on wound increased after treatment. In group A the wound healing time of superficial second degree was significantly shorter than those in group B and group C (P < 0.01). In deep second degree wounds the healing time in group A was much shorter than that in group C (P < 0.01), but had no significant difference when compared with group B (P > 0.05). CONCLUSION: Silver nanoparticle dressing can be used on second degree burn wound and can decrease the risk of wound infection and accelerate wound healing.

Adult↗
PubMed1990

Corneal silver deposits following Crede's prophylaxis an examination with electron dispersive x-ray analysis (EDX-analysis) and scanning electron microscope (SEM).

In a case of silver nitrate injury after Credé's prophylaxis, the cornea of a newborn presented yellow-brown, lime-like plaques on the nasal part of the right eye. A paracentral ulcerating stromal opacification undermined these appositions, when the patient was admitted to the eye-clinic at Aachen. In the material obtained by a lamellar keratectomy scanning electron microscopical examination was able to prove the existence of granules, previously described in light-microscopy. These granules measured 100 to 300 nm in diameter. An earlier chemical analysis of necrotic material showed no silver specific reaction. By means of EDX-analysis these granules could be identified as silver-containing. Injuries by silver nitrate solutions used for Credé's prophylaxis are seldom but still reported. The mechanism of injury in this case of a child, born by sectio remains unknown. Neither the use of an unusual silver nitrate solution, that was taken from a disposable ampoule (Mova-Nitrat R) was reported, nor any corneal injury during sectio mentioned. Nevertheless the method of EDX-analysis and SEM proved the diagnosis of corneal silver deposits, so that the origin of the granullar opacification of the cornea could be determined.

Cornea↗
PubMed1999

Silver cationization of thia fatty acids and esters in laser desorption/ionization time-of-flight mass spectrometry.

A laser desorption/ionization (LDI) time-of-flight mass spectrometric (TOF-MS) technique was used for the molecular mass analysis of thia fatty acids and esters, samples without appreciable light absorption at the laser wavelength. After a sample overlayer is deposited by solvent evaporation on a thin silver film substrate, it is subjected to 355 or 532 nm Nd : YAG laser irradiation. Photoablation of the Ag film substrate occurs with sufficient laser fluence, producing silver cluster cations, which can react with the desorbed thia fatty acid or ester molecules in the gas phase. Silver cation attachment of thia fatty esters may produce a silver-cationized analyte and fragments of structural diagnostic value, whereas thia fatty acids would not. With oxygen(s) present on the sulfur in sulfoxy fatty acids and esters, a silver-cationized analyte and additional fragments are produced. Formation of these fragments is consistent with charge-remote mechanisms through simple cleavage and rearrangement pathways. The structural reactivity of these compounds with ablated silver cations is hence comprehensively analyzed.

Esters↗
PubMed1999

Characterization and inhibitory effect of antibacterial dental resin composites incorporating silver-supported materials.

Resin composites with antibacterial activity may be useful for preventing the secondary caries frequently seen around restorations. The purposes of this study were to investigate antibacterial light-activated dental resin composites incorporating each of two silver-supported antibacterial materials and evaluate their long-lasting inhibitory effect against Streptococcus mutans. Two types of silver-supported antibacterial materials, Novaron (N) and Amenitop (AM) were used. These antibacterial materials were incorporated into TEGDMA-UDMA-based light-activated resin composites, and the antibacterial activities and mechanical properties of these composites, and also the release of silver ions, were examined. Two silver-supported antibacterial materials inhibited the growth of the major oral pathogen S. mutans. The minimum inhibitory concentration in suspensions of N and AM against S. mutans was 40 microg/mL and 30 microg/mL, respectively. Composites incorporating 5 wt % (N-5) or more of Novaron and 7 wt % (AM-7) or more of Amenitop inhibited the growth of S. mutans after immersion in water for 6 months. There was no or extremely little release of silver ions from the N-5 and AM-7 composites after 1 day or after 6 months of immersion in water. No significant difference in either compressive or flexural strength was observed between the control and the N-5 composites after 1 day or after 6 months of storage in water. However, for the AM-5 composite, there was a significant difference in both strength parameters between the two immersion periods. These results indicate that a light-activated dental resin composite incorporating silver-supported antibacterial material such as Novaron may be useful clinically because of its long-lasting inhibitory effect against S. mutans and its favorable mechanical properties.

Anti-Bacterial Agents↗
PubMed2000

Striated muscle microvascular response to silver implants: A comparative in vivo study with titanium and stainless steel.

Local microvascular perfusion is the primary line of defense of tissue against microorganisms and plays a considerable role in reparative processes. The impairment of the microcirculation by a biomaterial may therefore have profound consequences. Silver is known to have excellent antimicrobial activity and, although regional and systemic toxic effects have been described, silver is regularly discussed as an implant material in bone surgery. Because little is known about the influence of silver implants on the adjacent host tissue microvasculature, we studied in vivo nutritive perfusion and leukocytic response, and compared these results with those of the conventionally used materials titanium and stainless steel. Using the hamster dorsal skinfold chamber preparation and intravital microscopy, the implantation of a commercially pure silver sample led to a distinct and persistent activation of leukocytes combined with a marked disruption of the microvascular endothelial integrity, massive leukocyte extravasation, and considerable venular dilation. Whereas animals with stainless-steel implants showed a moderate increase in these parameters with a tendency to recuperate, titanium implants caused only a transient increase of leukocyte-endothelial cell interaction within the first 120 min and no significant change in macromolecular leakage, leukocyte extravasation and venular diameter. After 3 days, five of six preparations with silver samples showed severe inflammation and massive edema. Thus, the use of silver as an implant material should be critically judged despite its bactericidal properties. The implant material titanium seems to be well tolerated by the local vascular system and currently represents the golden standard.

Animals↗
PubMed2000

A modified silver staining protocol for visualization of proteins compatible with matrix-assisted laser desorption/ionization and electrospray ionization-mass spectrometry.

The growing availability of genomic sequence information, together with improvements in analytical methodology, have enabled high throughput, high sensitivity protein identification. Silver staining remains the most sensitive method for visualization of proteins separated by two-dimensional gel electrophoresis (2-D PAGE). Several silver staining protocols have been developed which offer improved compatibility with subsequent mass spectrometric analysis. We describe a modified silver staining method that is available as a commercial kit (Silver Stain PlusOne; Amersham Pharmacia Biotech, Amersham, UK). The 2-D patterns abtained with this modified protocol are comparable to those from other silver staining methods. Omitting the sensitizing reagent allows higher loading without saturation, which facilitates protein identification and quantitation. We show that tryptic digests of proteins visualized by the modified stain afford excellent mass spectra by both matrix-assisted laser desorption/ionization and tandem electrospray ionization. We conclude that the modified silver staining protocol is highly compatible with subsequent mass spectrometric analysis.

Animals↗
PubMed2003

Effects of metallic silver island films on resonance energy transfer between N,N'-(dipropyl)-tetramethyl- indocarbocyanine (Cy3)- and N,N'-(dipropyl)-tetramethyl- indodicarbocyanine (Cy5)-labeled DNA.

Resonance energy transfer (RET) is typically limited to distances below 60 A, which can be too short for some biomedical assays. We examined a new method for increasing the RET distances by placing donor- and acceptor-labeled DNA oligomers between two slides coated with metallic silver particles. A N,N'-(dipropyl)-tetramethylindocarbocyanine donor and a N,N'-(dipropyl)-tetramethylindodicarbocyanine acceptor were covalently bound to opposite 5' ends of complementary 23 base pair DNA oligomers. The transfer efficiency was 25% in the absence of silver particles or if only one slide was silvered, and it increased to an average value near 64% between two silvered slides. The average value of the Forster distance increased from 58 to 77 A. The energy transfer data were analyzed with a model assuming two populations of donor-acceptor pairs: unaffected and affected by silver island films. In an affected fraction of about 28%, the apparent energy transfer efficiency is near 87% and the Forster distance increases to 119 A. These results suggest the use of metallic silver particles to increase the distances over which RET occurs in biomedical and biotechnology assays.

Carbocyanines↗
PubMedDate not supplied

Consecutive silver staining and autoradiography of 35S and 32P-labeled cellular proteins: application for the analysis of signal transducing pathways.

The methodology for the simultaneous analysis of protein synthesis concomitant with protein phosphorylation/dephosphorylation is described. The technique consists of metabolic labeling of rat liver epithelial (RLE) cells with [32P]orthophosphate and [35S]methionine, performing two-dimensional polyacrylamide gel electrophoresis (2-D PAGE) of the mixed samples, followed by silver staining and subsequent autoradiography of the dried silver stained 2-D PAGE electrophoretograms using two films placed back-to-back. The first film, which is positioned in direct contact with the dried silver-stained gel, visualized both exposure to 35S and 32P while the second film recorded exposure to only 32P due to the differential energy levels of the two isotopes. The juxta-positioning of the silver-stained images with the two autoradiographic film images permits the unambiguous mapping of the phosphorylated polypeptides back to their corresponding silver-stained and methionine-labeled counterparts. This strategy provides quantitative information utilizing both silver staining (measure of constitutive levels of protein expression) and metabolic labeling to measure rates of protein synthesis and/or degradation and phosphorylation and/or dephosphorylation using [35S]methionine and [32P]orthophosphate, respectively. We have utilized this methodology for the in vitro analysis of transforming growth factor type beta 1 (TGF-beta 1)-mediated signal transduction in RLE cells and have identified three nuclear polypeptides, 1 (pI 4.95/M(r) 97 kDa), 2 (5.00/85 kDa) and 3 (4.90/84 kDa) whose phosphorylation status is rapidly and transiently modulated by TGF-beta 1. The methodology described should have wide applications in studies where it is desirous to measure protein synthesis and/or degradation concomitant with signal transduction pathways involving protein phosphorylation.

Animals↗
PubMedDate not supplied

Bacterial inhibition by electrical activation of percutaneous silver implants.

Percutaneous silver wire implants were looped through the dorsal skin of rats and inoculated with Staphylococcus aureus to test the effect on bacteria in the tract. The silver was activated with four brief daily applications of anodic microcurrent. Contralateral 316L stainless steel implants, identically inoculated, served as controls. Cultures from the silver tracts showed a marked reduction or elimination of bacteria, which persisted for the 3-week study period. In tracts with colonization established for 1 week, subsequent electrical activation of the silver also suppressed the bacteria. Inflammatory reactions at 3 weeks were mild at both the silver and stainless implants and no giant cells or toxicity were seen. This suggests that electrically activated silver may be useful in preventing or treating infection at percutaneous devices.

Administration, Topical↗
PubMed2005

Corrosion resistance of titanium-silver alloys in an artificial saliva containing fluoride ions.

Dental gels and rinses for caries prophylactic contain fluoride at concentrations ranging from 0.1 to 1%. In addition, many types of fluoride-releasing materials have been used in dental applications. The purpose of the study was to investigate the addition effect of fluoride into artificial saliva on the corrosion resistance of pure titanium and titanium-silver alloys. Titanium and titanium-silver alloys were arc melted, homogenized at 950 degrees C for 72 h, hot rolled, and solution heat treated and quenched. In order to investigate the effect of the fluoride ions on the corrosion resistance, potentiodynamic polarization testing, potentiostatic testing, and open-circuit potential measurements were performed in plain artificial saliva and 0.1 and 1% NaF-added artificial saliva. The passive current densities of titanium and titanium-silver alloys increased with increasing fluoride-ion concentration. Ti2.0Ag and Ti3.0Ag exhibited a low current density relatively and showed a stable behavior compared to titanium. The open-circuit potential of titanium decreased and current density at 250 mV (SCE) potentiostatic testing reacted sensitively with increasing fluoride concentration. On the other hand, the open-circuit potential of titanium-silver alloys with a high silver content (3.0-4.0 at %) reacted less sensitively to the fluoride-ion concentration. Among titanium-silver alloys, Ti3.0Ag alloy had a higher resistance against the attack of fluoride ions and showed a more stable open-circuit potential and current density than titanium in the fluoride-containing solution. It is concluded that they are electrochemically stable and maintained good corrosion resistance in fluoride-containing artificial saliva.

Biocompatible Materials↗
PubMed1993

Kinetic silver staining and quantification of proteins adsorbed to microtiter plates.

A silver stain was used to detect and quantitate proteins adsorbed to microtiter plate wells. The kinetics of the development of the silver stain were analyzed with an automated microtiter plate reader. The lag time for stain development was found to be a consistent indicator of the amount of protein adsorbed to a microtiter plate well. Protein which was not preadsorbed to the microtiter plate was not effectively stained by silver. Complete adsorption of protein applied to the microtiter plate was possible by drying small amounts of protein in very dilute buffers. Variations in sensitivity for different proteins were less than 30% for the panel of proteins examined. Determinations from kinetic silver staining agreed with those from copper staining for bovine albumin adsorbed to microtiter plates. The precision of kinetic silver staining assay was optimal in the range of 40 to 200 ng per microtiter plate well. In this range, the standard deviations averaged less than 5%. Even smaller amounts of protein can be detected and interpolated down to approximately 10 ng per well. The kinetic silver staining method can be used on standard microtiter plate readers without special filters and is readily adaptable to automated systems.

Adsorption↗
PubMed1995

Genetic susceptibility to silver-induced anti-fibrillarin autoantibodies in mice.

Similar to mercuric chloride, silver nitrate has recently been shown to induce IgG autoantibodies targeting the nucleolar 34-kDa protein fibrillarin i SJL (H-2s) mice. In the present study we show that the autoimmunogenic effect of silver is dependent on intact T-cell function since SJL/N mice homozygous for the nude mutation (athymic), in contrast to the functionally T-cell-intact SJL/N-nu/+ littermates, did not develop anti-nucleolar/anti-fibrillarin autoantibodies (ANoA/AFA). The genetic susceptibility for silver-induced AFA was localized to the H-2A locus using congenic and intra-H-2-recombinant strains. However, background (non-H-2) genetic factors substantially influenced both the response rate and the titer of ANoA/AFA attained. Strains bearing H-2As on the SJL and A backgrounds (SJL, A.SW, A.TH) showed 100% response rate and high ANoA titers (3750 +/- 246, mean reciprocal titer +/- SEM), whereas H-2As mice on the B10 background (B10.S) showed 60% response rate and significantly lower ANoA titers (1170 +/- 305) in the responding mice. Expression of H-2E [B10.S(9R) mice] further reduced the response rate (22%) and the ANoA titer (640 +/- 0). A suppressive effect on the B10 background has previously been observed in mercury treatment, but the effect was stronger in silver-treated mice. Two major differences were noted between silver- and mercury-induced murine autoimmunity. First, silver-treated mice did not show elevated titers of other autoantibody specificities, specifically not of antichromatin and anti-histone antibodies, which develop in mercury-treated SJL mice.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1984

Cytochemistry of the chromatin replication band in hypotrichous ciliated protozoa staining with silver and thiol-specific coumarin maleimide.

A modification of the silver-staining techniques for nucleolar organizing regions (NORs) was used to stain selectively the macronuclear replication bands (RBs) and nucleoli in hypotrichous ciliated protozoa (Euplotes, Stylonychia, and Oxytricha). Silver staining of both types of structures was trypsin-sensitive and DNase I-insensitive, suggesting the involvement of proteins. Silver-staining proteins in the RB were differentially extracted with acid, without any decrease in nucleolar staining. Triton-acid-urea gel electrophoresis of an acid extract of Euplotes macronuclei revealed enhanced silver reaction with a single protein upon selective silver staining. An abundance of thiol groups was also demonstrated in the RBs and nucleoli by the fluorochrome 3-(4-maleimidylphenyl)-7-diethylamino-4-methyl coumarin (coumarin maleimide). Histochemical studies, including blocking thiols with N-ethyl maleimide (NEM), indicated that thiols were not necessary for silver staining, and that proteins in the RBs and nucleoli reacting with coumarin maleimide were not acid extractable.

Animals↗