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PubMed2005

Scanning tunneling microscopy, Fourier transform infrared spectroscopy, and electrochemical characterization of 2-naphthalenethiol self-assembled monolayers on the Au surface: a study of bridge-mediated electron transfer in Ru(NH3)6(2+)/Ru(NH3)6(3+) redox reactions.

We have studied the structure, adsorption kinetics, and barrier properties of self-assembled monolayers of 2-naphthalenethiol on Au using electrochemical techniques, grazing-angle Fourier transform infrared (FTIR) spectroscopy, and scanning tunneling microscopy (STM). The results of cyclic voltammetric and impedance measurements using redox probes show that 2-naphthalenethiol on Au forms a stable and reproducible, but moderately blocking, monolayer. Annealing of the self-assembled monolayer (SAM)-modified surface at 72 +/- 2 degrees C remarkably improves the blocking property of the monolayer of 2-naphthalenethiol on Au. From the study of kinetics of SAM formation, we find that the self-assembly follows Langmuir adsorption isotherm. Our STM and FTIR results show that the molecules are adsorbed with the naphthalene ring tilted from the surface normal by forming a square root 3 x 3 R30 degrees overlayer structure. From our studies, we conclude that the electron-transfer reaction of ferro/ferricyanide in the freshly formed monolayer occurs predominantly through the pinholes and defects present in the monolayer. However, in the case of thermally annealed specimen, although the ferro/ferricyanide reaction is almost completely blocked, the electron-transfer reaction of hexaammineruthenium(III) chloride is not significantly inhibited. It is proposed that the electron-transfer reaction in the case of the ruthenium redox couple takes place by a tunneling mechanism through the high-electron-density aromatic naphthalene ring acting as a bridge between the monolayer-modified electrode and the ruthenium complex.

Journal Article↗
PubMed1999

The effect of autoclave resterilisation on polyester vascular grafts.

OBJECTIVES: polyester grafts are expensive, single-use items. Some manufacturers of uncoated, woven grafts include instructions for autoclave resterilisation to be performed at the surgeon's own request. Others warn against such manipulation. Theoretically, the glass transition point of polyester at 70-80 degrees C and the possible acceleration of hydrolysis suggest that autoclave resterilisation at 135 degrees C might be a problem. MATERIALS AND METHODS: a DeBakey Soft Woven Dacron Vascular Prosthesis (Bard) and a Woven Double Velour Dacron Graft (Meadox) were autoclave-resterilised 0 to 20 times, having been weighed before and after sterilisation. Tactile testing was performed. Mechanical properties were examined by probe puncture and single-filament testing, the surface was examined by scanning electron microscopy and the degree of hydrolysis by infra-red spectroscopy. RESULTS: tactile testing revealed a change of feeling with increasing cycles of resterilisation. Investigation of weight, textile strength, single-filament strength, electron microscopy of the surface and infra-red spectroscopy showed no change of the material. CONCLUSIONS: changes felt are presumably a surface phenomenon, not measurably affecting strength or chemistry of material after autoclave resterilisation. We therefore feel that it is safe to use once-autoclave-resterilised surplus uncoated polyester grafts, provided that sterility is guaranteed.

Blood Vessel Prosthesis↗
PubMed2006

Defective one- or two-electron reduction of the anticancer anthracycline epirubicin in human heart. Relative importance of vesicular sequestration and impaired efficiency of electron addition.

One-electron quinone reduction and two-electron carbonyl reduction convert the anticancer anthracycline doxorubicin to reactive oxygen species (ROS) or a secondary alcohol metabolite that contributes to inducing a severe form of cardiotoxicity. The closely related analogue epirubicin induces less cardiotoxicity, but the determinants of its different behavior have not been elucidated. We developed a translational model of the human heart and characterized whether epirubicin exhibited a defective conversion to ROS and secondary alcohol metabolites. Small myocardial samples from cardiac surgery patients were reconstituted in plasma that contained clinically relevant concentrations of doxorubicin or epirubicin. In this model only doxorubicin formed ROS, as detected by fluorescent probes or aconitase inactivation. Experiments with cell-free systems and confocal laser scanning microscopy studies of H9c2 cardiomyocytes suggested that epirubicin could not form ROS because of its protonation-dependent sequestration in cytoplasmic acidic organelles and the consequent limited localization to mitochondrial one-electron quinone reductases. Accordingly, blocking the protonation-sequestration mechanism with the vacuolar H+-ATPase inhibitor bafilomycin A1 relocalized epirubicin to mitochondria and increased its conversion to ROS in human myocardial samples. Epirubicin also formed approximately 60% less alcohol metabolites than doxorubicin, but this was caused primarily by its higher Km and lower Vmax values for two-electron carbonyl reduction by aldo/keto-reductases of human cardiac cytosol. Thus, vesicular sequestration and impaired efficiency of electron addition have separate roles in determining a defective bioactivation of epirubicin to ROS or secondary alcohol metabolites in the human heart. These results uncover the molecular determinants of the reduced cardiotoxicity of epirubicin and serve mechanism-based guidelines to improving antitumor therapies.

Aconitate Hydratase↗
PubMed2000

Neochlamydia hartmannellae gen. nov., sp. nov. (Parachlamydiaceae), an endoparasite of the amoeba Hartmannella vermiformis.

Free-living amoebae are increasingly being recognized to serve as vehicles of dispersal for various bacterial human pathogens and as hosts for a variety of obligate bacterial endocytobionts. Several Chlamydia-like Acanthamoeba endocytobionts constituting the recently proposed family Parachlamydiaceae are of special interest as potential human pathogens. In this study coccoid bacterial endocytobionts of a Hartmannella vermiformis isolate were analysed. Infection of H. vermiformis with these bacteria resulted in prevention of cyst formation and subsequent host-cell lysis. Transfection experiments demonstrated that the parasites were not capable of propagating within other closely related free-living amoebae but were able to infect the distantly related species Dictyostelium discoideum. Electron microscopy of the parasites revealed typical morphological characteristics of the Chlamydiales, including the existence of a Chlamydia-like life-cycle, but indicated that these endocytobionts, in contrast to Chlamydia species, do not reside within a vacuole. Comparative 16S rRNA sequence analysis showed that the endocytobiont of H. vermiformis, classified as Neochlamydia hartmannellae gen. nov., sp. nov., is affiliated to the family Parachlamydiaceae. Confocal laser scanning microscopy in combination with fluorescence in situ hybridization using rRNA-targeted oligonucleotide probes confirmed the intracellular localization of the parasites and demonstrated the absence of other bacterial species within the Hartmannella host. These findings extend our knowledge of the phylogenetic diversity of the Parachlamydiaceae and demonstrate for the first time that these endocytobionts can naturally develop within amoebae of the genus Hartmannella.

Animals↗
PubMed1995

Localization of major allergens in the dust mite Lepidoglyphus destructor with confocal laser scanning microscopy.

The dust mite Lepidoglyphus destructor is the dominating source of allergens giving rise to asthma and rhinitis among farmers. In a previous study of the localization of allergens in L. destructor we demonstrated that the 39 kDa allergen is associated with digestion. Here we describe the localization of the principal 15 kDa allergen and the high molecular weight allergen complex (79 and 93 kDa) in L. destructor with confocal laser scanning microscopy (CLSM). Cryostat-cut sections of mite bodies and faecal pellets were probed with mouse monoclonal antibodies (MoAbs) raised against the allergens. The 15 kDa allergen disclosed labelling of the mite body and most of the faecal pellets but left the exoskeleton unlabelled. The binding was widespread, and most intense in the mouth region. However, some staining was also observed around the gastrointestinal tract. In contrast, the 79 and 93 kDa allergen complex stained the exoskeleton and the front part of the mite. Interestingly, we detected no labelling of the faecal pellets with the MoAb against the 79/93 kDa allergen. The study indicates that the 15 kDa allergen is associated with the digestive tract whereas the function of the 79 and 93 kDa allergen complex remains to be elucidated.

Allergens↗
PubMed1993

Contractile properties of skinned muscle fibres from young and adult normal and dystrophic (mdx) mice.

1. Single muscle fibres were enzymatically isolated from the soleus and extensor digitorum longus (EDL) muscles of genetically dystrophic mdx and normal (C57BL/10) mice aged 3-6 or 17-23 weeks. 2. Fibres of both muscles were chemically skinned with the non-ionic detergent Triton X-100 (2% v/v). Ca(2+)- and Sr(2+)-activated contractile responses were recorded and comparisons were made between several contractile parameters of various fibre types of normal and dystrophic mice of similar age. 3. There were no significant differences in the following contractile parameters of skinned fibres of normal and mdx mice of the same age: sensitivity to activating Ca2+ (pCa50) or Sr2+ (pSr50) and differential sensitivity to the activating ions (pCa50-pSr50). However the maximum isometric tension (Po) and the frequency of myofibrillar force oscillations in EDL fast-twitch fibres of young mdx mice were significantly lower than those of soleus fast-twitch fibres of the same animals, or fast-twitch fibres (EDL or soleus) of normal mice. 4. Age-related differences were apparent in some contractile parameters of both normal and mdx mice. In particular the steepness of force-pCa and force-pSr curves increased with age in normal mice, yet decreased with age in fibres of mdx mice. 5. A fluorescent probe, ethidium bromide, which interchelates with DNA, was used with laser-scanning confocal microscopy to determine the distribution of myonuclei in fibres. Fibres isolated from either muscle type of normal animals displayed a characteristic peripheral spiral of myonuclei. Fibres from muscles of mdx mice displayed three major patterns of nuclear distribution; the normal peripheral spiral, long central strands of nuclei, and a mixture of these two patterns. 6. The contractile characteristics of mdx fibres were not markedly influenced by the nuclear distribution pattern in that there were no discernible differences in the major contractile parameters (the Hill coefficients nCa and nSr, which are associated with the steepness of the Ca2+ and Sr2+ activation curves, pCa50, pSr50, pCa50-pSr50) of skinned fibres possessing peripheral or central nuclei. However, except for nSr, these values were all lower in individual fibres which displayed similar proportions of central and peripheral nuclei. The presence of mixed nucleation and absence of fibres with embryonic contractile characteristics in mdx mice suggest that the dystrophin-negative fibres can repair locally occurring muscle damage.

Aging↗
PubMed2004

"Candidatus hepatoplasma crinochetorum," a new, stalk-forming lineage of Mollicutes colonizing the midgut glands of a terrestrial isopod.

Uncultivated bacteria that densely colonize the midgut glands (hepatopancreas) of the terrestrial isopod Porcellio scaber (Crustacea: Isopoda) were identified by cloning and sequencing of their 16S rRNA genes. Phylogenetic analysis revealed that these symbionts represent a novel lineage of the Mollicutes and are only distantly related (<82% sequence identity) to members of the Mycoplasmatales and Entomoplasmatales. Fluorescence in situ hybridization with a specific oligonucleotide probe confirmed that the amplified 16S rRNA gene sequences indeed originated from a homogeneous population of symbionts intimately associated with the epithelial surface of the hepatopancreas. The same probe also detected morphotypically identical symbionts in other crinochete isopods. Scanning and transmission electron microscopy revealed uniform spherical bacterial cells without a cell wall, sometimes interacting with the microvilli of the brush border by means of stalk-like cytoplasmic appendages, which also appeared to be involved in cell division through budding. Based on the isolated phylogenetic position and unique cytological properties, the provisional name "Candidatus Hepatoplasma crinochetorum" is proposed for this new taxon of Mollicutes colonizing the hepatopancreas of P. scaber.

Animals↗
PubMed2004

Isolation, characterization, and in situ detection of a novel chemolithoautotrophic sulfur-oxidizing bacterium in wastewater biofilms growing under microaerophilic conditions.

We successfully isolated a novel aerobic chemolithotrophic sulfur-oxidizing bacterium, designated strain SO07, from wastewater biofilms growing under microaerophilic conditions. For isolation, the use of elemental sulfur (S(0)), which is the most abundant sulfur pool in the wastewater biofilms, as the electron donor was an effective measure to establish an enrichment culture of strain SO07 and further isolation. 16S rRNA gene sequence analysis revealed that newly isolated strain SO07 was affiliated with members of the genus Halothiobacillus, but it was only distantly related to previously isolated species (89% identity). Strain SO07 oxidized elemental sulfur, thiosulfate, and sulfide to sulfate under oxic conditions. Strain SO07 could not grow on nitrate. Organic carbons, including acetate, propionate, and formate, could not serve as carbon and energy sources. Unlike other aerobic sulfur-oxidizing bacteria, this bacterium was sensitive to NaCl; growth in medium containing more than 150 mM was negligible. In situ hybridization combined with confocal laser scanning microscopy revealed that a number of rod-shaped cells hybridized with a probe specific for strain SO07 were mainly present in the oxic biofilm strata (ca. 0 to 100 micro m) and that they often coexisted with sulfate-reducing bacteria in this zone. These results demonstrated that strain SO07 was one of the important sulfur-oxidizing populations involved in the sulfur cycle occurring in the wastewater biofilm and was primarily responsible for the oxidation of H(2)S and S(0) to SO(4)(2-) under oxic conditions.

Biofilms↗
PubMed1992

Intracellular Ca2+ dynamics in response to Ca2+ influx and Ca2+ release in autonomic neurones.

Spatial and temporal changes in the intracellular free Ca2+ concentration in response to Ca2+ influx at the cell membrane and to Ca2+ release from intracellular organelles were studied by recording fluorescence of Ca(2+)-sensitive probes, fura 2 or indo 1, with conventional epifluorescence or confocal laser-scanning microscopy combined with recordings of Ca(2+)-dependent membrane responses in bullfrog sympathetic ganglion cells. It was found that an increase in the intracellular Ca2+ induced by (an) action potential(s) in freshly ganglion cells bathed in Ringer's solution was solely a result of Ca2+ influx, while a rise in the intracellular Ca2+ by Ca2+ current in voltage-clamped cultured neurones was caused by not only Ca2+ influx but also Ca2+ release. This Ca2+ release was suggested to occur by a voltage-dependent (and graded) mode of activation of a Ca(2+)-induced Ca2+ release mechanism, explaining the lack of Ca2+ release by action potentials (because of their short-lasting depolarization) in freshly isolated neurons. In both cases, there was an inward spread of an increase in intracellular Ca2+. On the other hand, all or nothing activation of Ca(2+)-induced Ca2+ release occurred in the presence of caffeine, leading to the oscillation of Ca2+ in the cells. Characteristics of this mode of Ca2+ release and unique properties of drugs to block Ca2+ release were described. Finally, the physiological significance of different types of Ca2+ release was discussed.

Animals↗
PubMedDate not supplied

The relationship between [Ca2+]i and cell death using an in vivo model: a study using the ced-1 mutant strain of C. elegans.

The ced-1 mutant of the free-living nematode, Caenorhabitis elegans, was used to study cell injury and cell death in relation to changes in intracellular ionized calcium ([Ca2+]i). This animal, which is being genetically characterized, may prove to be extremely useful for certain toxicologic studies because of its small size, optical transparency, rapid generation time, and the morphologic and genetic data currently available. During the development of this animal, 131 of 1,090 ultimate somatic cells undergo programmed cell death. Using mutagenesis techniques, several genes responsible for this death have been identified. In this study, we have taken advantage of the ced-1 mutant in which dead cells accumulate, as they cannot be phagocytized and removed. Although changes in [Ca2+]i have been studied in relation to cell injury and cell death, observations have been essentially restricted to in vitro monolayer cultures because of the methodology involved. To study the relationship between changes in [Ca2+]i and injury in vivo, we selected this animal model for further study and report here the morphological changes following the effects of ionomycin treatment in relation to increases of [Ca2+]i and cell death as measured using the fluorescent probes Fluo-3/AM and propidium iodide, respectively. The technique of confocal laser scanning microscopy is ideally adapted to such measurements in these living animals, and the results can be readily correlated with those made with Nomarski differential interference contrast microscopy as well as with transmission electron microscopy. The results support previous in vitro observations and show that early increases of [Ca2+]i accompany early reactions to injury. Furthermore, the results also show that changes in this small invertebrate metazoan parallel those seen in mammalian systems, including human. Thus, the current study indicates that ced-1 C. elegans can potentially serve as an in vivo model not only for evaluating the possible temporal relationship of [Ca2+]i elevation with cell death but also for evaluating the [Ca2+]i elevation observed in relation to other phenomena and in evaluating toxic agents.

Animals↗
PubMed1999

Sperm viability in ram semen diluted and stored in three different extenders.

Semen was collected with an artificial vagina from 4 one-year-old rams, in order to study the changes in sperm motility and membrane integrity of spermatozoa split-diluted and stored at 5 degrees C during 7 days in sodium citrate, Tris, and milk-based extenders, respectively. Sperm motility was assessed subjectively and sperm membrane integrity was determined using the fluorescent probes Calcein-AM and Ethidium homodimer. Representative samples were studied using scanning electron microscopy (SEM). The average incidence of sperm motility decreased over time in all the extenders (p < 0.001). The incidence of spermatozoa showing progressive motility and intact plasma membrane was significantly higher in semen diluted with sodium citrate than in the other 2 extenders following 4 days of dilution until the end of the study. Evaluation with SEM confirmed the findings obtained with the supra vital fluorescent dyes. The results of the present study indicated that there were no differences between sodium citrate-, Tris- or milk-based extenders when ovine liquid semen was stored at 5 degrees C during a short period (2 days). However, when semen was stored for longer time, spermatozoa in the sodium citrate-based extender sustained its viability better.

Animals↗
PubMed1998

[Monitoring calcium in outer hair cells with confocal microscopy and fluorescence ratios of fluo-3 and fura-red].

Calcium distribution and mobilization during mechanical stimulation in outer hair cells of the guinea pig were monitored using laser scanning confocal microscopy and co-loaded fluo-3 and fura-red fluorescent probes. Spatial calcium gradients were revealed among various subcellular areas. The ratios of the fluorescence intensity of fluo-3 and fura-red were 1.71 +/- 0.85, 1.61 +/- 0.75, 1.47 +/- 0.65 and 1.39 +/- 0.66 for the cytoplasm, the cytoplasmic membrane, the cuticular plate and the nucleus respectively, indicating that free calcium ion concentrations are the highest in the cytoplasm and the lowest in the nucleus. While the calcium concentration remained relatively constant under resting conditions, it increased during mechanical stimulation. The results show that confocal ratio imaging of fluo-3 and fura-red enables us to determine more accurately the subcellular calcium distribution and that the calcium ions make a contribution to the mechanic-electrical transduction in hair cells.

Aniline Compounds↗
PubMed2000

[Mechanisms of opioid receptor-induced elevation in intracellular calcium by confocal laser scanning microscopy].

OBJECTIVE: To determine the acute and chronic effects of opioid receptor agonists on the intracellular free calcium concentration ([Ca2+]i) in NG-LNCXiNOS cells, stably expressing iNOS gene, and regulation of G-protein on opioid-induced response in [Ca2+]i. METHODS: A single cell [Ca2+]i is measured by confocal laser scanning microscopy using Ca(2+)-sensitive dye Fluo-3 as an new calcium fluorescent probe. RESULTS: DPDPE(D-Pen2, D-Pen5-enkephalin), a delta-opioid receptor agonist, and morphine acutely induced the increase in [Ca2+]i of NG-LNCXiNOS cells. The elevation in [Ca2+]i by DPDPE could be abolished with naloxone. Pretreatment of the cells with pertussis toxin (PTX) at 100 ng/ml for 24 hours almost completely blocked morphine-evoked response. In contrast to acute effect of opioid agonists on [Ca2+]i, the cells exposed to 1 mumol/L DPDPE or 10 mumol/L morphine for 48 hours also appeared to raise [Ca2+]i. However, the elevation in [Ca2+]i was not greater than that caused by acute effect of DPDPE or morphine. After cell "withdrawal" was precipitated by the addition of 10 mumol/L naloxone, the increase in [Ca2+]i could further be intensified. CONCLUSIONS: The opioid agonist-induced increase in [Ca2+]i is mediated by opioid receptor and regulated though PTX-sensitive G-protein. The attenuation of this response in chronically treated cells with opioid agonist is associated with receptor desensitization.

Calcium↗
PubMed1990

Scanning electron microscopic studies and x-ray microanalysis of hyaline bodies in odontogenic cysts.

70 odontogenic cysts with hyaline bodies (HB) were examined by light and scanning electron microscopy. The scanning electron microscopic studies were performed on dried tissue material, which had been previously examined by light microscopy and energy dispersive x-ray analysis of the histologic sections. The form and basic structure of both the early forms of HB as well as the HB Type I and II could be identified more closely. The early forms, the outer component of the HB Type II and the inner and outer component of the HB Type I consisted of a fine-grained substance, which presumably goes through varying "partial homogenization", thus giving the HB an increased firmness and elasticity. The HB are a product of the epithelium of odontogenic cysts and have direct contact to the outer layer of the adjacent cyst epithelium via its intercellular bridges.

Calcium↗
PubMed1995

Effects of fluoride on the calcium phosphate precipitation method for dentinal tubule occlusion.

Use of the calcium phosphate precipitation (CPP) method makes possible the occlusion of dentinal tubules to approximately 10 to 15 microns from the dentinal surface, and thus shows good potential for the treatment of dentin hypersensitivity. The precipitate formed in the dentinal tubules by the CPP method is, however, not apatite [HAP; Ca10(PO4)6(OH)2], a component of tooth and bone, but dicalcium phosphate dihydrate (DCPD; CaHPO4.2H2O). Since fluoride enhances the conversion of DCPD to HAP, we evaluated the effects of fluoride on the texture of the precipitate formed by the CPP method and on its capacity to occlude dentinal tubules in this in vitro study. CPP solution (1.0 mol/L CaHPO4.2H2O dissolved in 2.0 mol/L H3PO4) was applied to a dentin disk and was subsequently neutralized with a post-treatment solution (1 mol/L NaOH, from 0 to 0.1 mol/L NaF). Scanning electron microscopy revealed that the precipitate occluded dentinal tubules to a depth of approximately 10 to 15 microns from the dentinal surface, regardless of the NaF concentration (from 0 to 0.1 mol/L) in the post-treatment solution. Also, dentin permeability was reduced to 15% by the CPP treatment regardless of the NaF concentration. The Ca/P molar ratio of the precipitate, measured by x-ray micro-analysis, was higher (1.25 +/- 0.04) in the presence of NaF than in its absence (1.03 +/- 0.01). For further identification of the precipitate formed in the dentinal tubules, the same procedure was used in glass tubes (diameter, 1 mm), so that a larger amount of precipitate would be obtained.(ABSTRACT TRUNCATED AT 250 WORDS)

Calcium Phosphates↗
PubMed1993

Gold in the dermis following chrysotherapy: histopathology and microanalysis.

Paraffin-embedded sections of skin from patients with rheumatoid arthritis treated with gold who had developed skin rashes were examined by light microscopy and scanning electronmicroscopy with microanalysis. Sparse, small, brown or black granules in plump, often elongated cells in the dermis were shown to contain gold by energy dispersive X-ray microanalysis. These cells expressed some macrophage markers. The amount of gold present showed some correlation with the total gold dose. Gold was not confined to lesional skin. In one case where uninvolved skin was examined, more gold was found there than in lesional skin.

Aged↗
PubMed1997

Long-term in vivo alterations of polyester vascular grafts in humans.

OBJECTIVES: To examine the influence of in vivo hydrolysis on the physical properties of polyester grafts and their correlation to the period of implantation in the human body. MATERIALS AND METHODS: Sixty-five explanted vascular grafts were obtained after 0-23 years of implantation due to suture aneurysms (18), occlusion (12), graft infection (12), failure of graft material (7) and post-mortem (16). The surface was examined by scanning electron microscopy, the molecular integrity by infra-red spectroscopy and physical strength by probe puncture. RESULTS: Scission of macromolecular chains and loss of strength were shown. It was demonstrated that hydrolytic degradation of polyester takes place with increasing time of implantation in humans. Analysis by linear regression showed that polyester grafts lose 31.4% of their bursting strength in 10 years and 100% in 25-39 years after implantation. CONCLUSIONS: Regular follow-ups of patients with aged vascular grafts and the precise documentation of implanted materials are necessary to estimate graft degradation.

Blood Vessel Prosthesis↗
PubMed1994

Electrochemical and XPS studies of titanium for biomaterial applications with respect to the effect of hydrogen peroxide.

Electrochemical measurements, x-ray photoelectron spectroscopy, and scanning tunneling microscopy have been used to study the effect of hydrogen peroxide on the passivity of titanium in a phosphate-buffered saline (PBS) solution. The results indicate that the passive film formed in the PBS solution--with and without addition of H2O2--may be described with a two-layer structure model. The inner layer has a structure close to TiO2 whereas the outer layer consists of hydroxylated compounds. The introduction of H2O2 in the PBS solution broadens the hydroxylate-rich region, probably due to the formation of a Ti(IV)-H2O2 complex. Furthermore, the presence of H2O2 results in enhanced dissolution of titanium and a rougher surface on a microscopic scale. Finally, a dark pigmentation (blue color) is observed when titanium has been exposed--for several weeks--to PBS with additions of H2O2.

Color↗