Overview of metalomics research and its application prospect in mineral Chinese medicine research / 中国中药杂志

Metallomics is a frontier interdisciplinary subject at its vigorous development stage. Its goal is to systematically study the content, distribution, chemical species, structural characteristics and functions of metal elements in biological system. It is also a comprehensive discipline to study the existing state and function of free or complex metal elements in life. Metallomics is an ideal tool to study the biological behavior of inorganic elements, which can be used to solve many problems in the research of mineral Chinese medicine(MCM). It provides a strong theoretical basis and technical support for the research of MCM. Its theory and methods provide re-ference and enlightenment for the in-depth study of MCM, and also provide new ideas and open up new ways for the research of MCM. The application of metallomics theory and methods in the research of MCM is of great significance to reveal the material basis and mec-hanism of MCM, promote the process of basic research on MCM, fully exploit and utilize medicinal mineral resources and carry forward the traditional MCM treasure in China. In this paper, we introduced the concept, academic development, research content and research methods of metallomics, and discussed the application prospects of metallomics in the analysis of inorganic element composition characteristics and quality control, material basis and mechanism of MCM, so as to provide reference for further researches on MCM.

Effects of metal ions and small molecules on reduction of Cr (VI) resistant strain M52 / 吉林大学学报(医学版)

Objective: To investigate the growth of Sporosarcina saromensis M52 obtained from the sediment samples in Xiamen, to locate the Cr (VI) reduetase, and to study the effects of metal ions and small molecules on the reducing ability of Cr (VI) resisistant strain M52. Methods: The seed solution of M52 strain was inoculated into the LB medium containing different concentrations (0-600 mg · L-1) of Cr (VI). After cultivating for 0-48 h, the absorbance (A) value of M52 strain liquid at 600 nm was measured by UV spectrophotometry. The growth of M52 strain in LB medium containing 0, 50, 100, 200, 400, and 600 mg · L: Cr (VI) was observed. The intracellular and extracellular active substances obtained by centrifugation of M52 bacteria solution before and after sonication and the M52 in control group were cultured at 37°C and pH 7.5, respectively. Using diphenylcarbazide spectrophotometry, the concentrations of Cr (VI) in the solution at 0, 12, 24, and 48 h were measured, and the reduction rates of Cr (VI) in intracellular and extracellular active substances at each time point were calculated. 0. 2 mmol · L-1Mn21, Fe2 and Cu2, 1 mmol · L-1SDS and 1% Triton X-100, Tween 80 were added to the LB medium as treatment groups, and the untreated LB liquid medium was used as control group. The seed solution was inoculated in treatment groups and control group at 4% concentration. The reduction rates of Cr (VI) by M52 at 0, 6, 12, 24, 36, and 48 h were calculated. The changes of the reduction rates of Cr (VI) by M52 in metal ion and small molecule treatment groups were investigated. Results: When the concentration of Cr (VI) was lower than 100 mg · L-1, the growth of strain was promoted with the increase of concentration; when the concentration of Cr (VI) was higher than 100 mg · L-1, the growth of the strain was inhibited with the increase of concentration; when the concentration of Cr (VI) was higher than 600 mg · L-1, the M52 strain hardly grew. Compared with control group, the reduction rates of Cr (VI) by M52 occurred both inside and outside the cells were increased (P Fe21; the reduction rate was reduced in the presence of Mn21 (P Triton X-100 > Tween 80. Conclusion: Low concentration of Cr (VI) can promote the growth of the M52 strain, and high concentration of Cr (VI) can inhibit the growth of the strain. The reduction of Cr (VI) by M52 mainly occurs in the cells. Cu2 and Fe2 can promote the reduction of Cr (VI) by M52. Tween 80, Triton X-100, and SDS can inhibit the reduction of Cr (VI) by M52.

Research progresses on the role of metal ions in the pathogenesis of Parkinson's disease / 中华神经科杂志

In the patients of Parkinson's disease,dopaminergic neurons' degeneration is the main pathological change.In the central nervous system,biometal ions' imbalance and heavy metals' accumulation are often connected with the oxidative stress,decreased enzyme activities,increased protein aggregations and so on.They lead to cascade reactions,resulting in dopaminergic neurons' degeneration and death.In this paper,the research progresses on the main ions' roles in the pathogenesis of Parkinson's disease are reviewed,in order to further understand the pathogenic mechanism of Parkinson's disease.

Concentrations of SO42-,NO3-,Cl- and NH4+ in atmospheric PM2.5 in Zhoushan / 预防医学

Objective@#To understand the concentrations and source of SO42-,NO3-,Cl- and NH4+ in atmospheric PM2.5 in Zhoushan,and to provide reference for controlling PM2.5 and formulating effective environmental protection measures.@*Methods@#Monitoring sites in new districts of Zhoushan were set up to continuously collect PM2.5 from 10th to 16th of each month and under the hazy weather during 2015-2016（AQI > 200）. The mass concentration of PM2.5 was measured by weighing method,and the concentrations of SO42-,NO3-,Cl- and NH4+ in PM2.5 components was detected by ion chromatography. @*Results@#The average daily concentration of PM2.5 in Zhoushan from 2015 to 2016 was（40.91±27.39）μg/m3. The concentration of the four water-soluble non-metal ions in PM2.5 components was 3.56-103.03 μg/m3,with an average of（23.06±20.00）μg/m3,accounting for about 56.64% of PM2.5 contents. The average monthly concentration of SO42- was the highest[（10.35±6.48）μg/m3],while the average monthly concentration of Cl- was the lowest [（0.49±0.73）μg/m3]. The concentration of the four ions was the highest in winter[（37.56±27.74）μg/m3]and the lowest in summer[（12.32±5.88）μg/m3]. The differences between different seasons was statistically significant（P<0.05）. The highest concentration of NO3- occurred in winter,which was（14.48±13.28）μg/m3. The concentration ratio of NO3- to SO42- ranged from 0 to 2.58,with an average of 0.55. There were 28 days（14.74%）with the ratio greater than one,22 days of which was in winter.@*Conclusion@#The concentration of SO42- was the highest and Cl- was the lowest in atmospheric PM2.5 in Zhoushan. The highest concentration of the four ions occurred in winter. The concentration of NO3- in winter was higher than that of SO42-,suggesting that motor vehicle exhaust might be the main source of PM2.5 in winter.

Progress on Detection of Metals Ions by Functional Nucleic Acids Biosensor / 分析化学

Functional nucleic acids are natural or artificialnucleic acid sequences with specific functions and special structures. Special metal ions are essential trace elements for human health, but excessive metal ions will be harmful to human health. The functional nucleic acids are widely used in the detection of metal ions because of their advantages such as easy modification, low price, high stability and strong specificity. This review describes the function of functional nucleic acid and metal ions, mainly including cutting type, link type, metal ion-mediated base pairing, click chemical type, conformation change type, and other types. Then, biosensor of functional nucleic acid combined with different signal output is introduced. Finally, the research significance and problems of functional nucleic acid in metal ion detection are discussed, and the future development direction and application prospect of functional nucleic acid biosensor are prospected.

Determination of Trace ZnⅡ, CdⅡ and PbⅡ Metal Ions Using In-situ Bismuth-modified Boron Doped Diamond Electrode / 分析化学

Bismuth modified boron doped diamond (BDD) film electrode was employed for simultaneous determination of trace ZnⅡ,CdⅡand PbⅡby anodic stripping voltammetry.BiⅢwas simultaneously in-situ deposited on bismuth modified boron doped diamond electrode with ZnⅡ,CdⅡ and PbⅡ by pre-concentration.In the presence of BiⅢ,the sensitivity for determination of ZnⅡ,CdⅡ and PbⅡ was remarkably enhanced.Influence factors such as bismuth concentration,boron doped concentrations of BDD electrode,pH,preconcentration potential were investigated and optimized.Under the optimal conditions,the stripping peak currents increased linearly with the increasing concentration of ZnⅡ,CdⅡ and PbⅡ in the range of 10-300 μg/L.The limit of detection was 0.56 μg/L for ZnⅡ,0.32 μg/L for CdⅡand 0.75 μg/L for PbⅡ (S/N=3),respectively.The interference experiments showed that common ions had little influence on the determination except CuⅡ.In addition,the developed electrode displayed a good repeatability.The method was successfully applied to determination of ZnⅡ,CdⅡ and PbⅡ in real water samples with the standard addition recoveries of 92.0%-114.0%.

Effect of Hydrostatic Pressure on the Fluorescence of Tryptophan in the Presence of Metal Ions Running title: Effect of pressure on the tryptophan

ABSTRACT The effect of pressure on the fluorescence of tryptophan in the presence of metal ions was studied by fluorescence spectrometry. It was found that at 60 MPa, the fluorescence intensity of M/Trp mixtures (M represented metal ions) increased compared to that at atmosphere pressure. The relative fluorescence efficiency of M/Trp mixtures increased with pressure. When the M/Trp ratio was above 10:1, the relative fluorescence efficiency in decreasing order was Cu2+/Trp mixtures, Ni2+/Trp mixtures and Mg2+ (K+)/Trp mixtures. When the ratio was below 10:1, the decreasing order was Cu2+/Trp mixtures and Ni2+ (Mg2+, K+)/Trp mixtures. The relative fluorescence efficiency increased with the concentration of Cu2+ and Ni2+. The variation was relate to the quenching of tryptophan fluorescence in the presence of metal ions. A red shift was also observed, but the red shift was independent of metal ions.

Detection of toxic substances in microbial fuel cells / 生物工程学报

Microbial fuel cells (MFCs) is a highly promising bioelectrochemical technology and uses microorganisms as catalyst to convert chemical energy directly to electrical energy. Microorganisms in the anodic chamber of MFC oxidize the substrate and generate electrons. The electrons are absorbed by the anode and transported through an external circuit to the cathode for corresponding reduction. The flow of electrons is measured as current. This current is a linear measure of the activity of microorganisms. If a toxic event occurs, microbial activity will change, most likely decrease. Hence, fewer electrons are transported and current decreases as well. In this way, a microbial fuel cell-based biosensor provides a direct measure to detect toxicity for samples. This paper introduces the detection of antibiotics, heavy metals, organic pollutants and acid in MFCs. The existing problems and future application of MFCs are also analyzed.

Effect of some phytoconstituents on Fe2+/ascorbate induced lipid peroxidation.

Transition metals like iron and copper, present inside the body system play a key role in the production of reactive oxygen radicals. These free radicals, causative agents of lipid peroxidation, not only damage proteins and DNA but also gradually changes the cellular membrane structure and ultimately leads to the loss of function and integrity. Uncontrolled lipid peroxidation results in various age related diseases, malignancy, infective diseases and injuries. Antioxidants and other phytochemical constituents present in the various plants are known to protect cells from such reactive oxygen species (ROS)-mediated damages. Here, we evaluated the effect of certain phytoconstituents present in the well-known medicinal plants on ROS scavenging using rat liver homogenate. The basal lipid peroxidation was found to be 0.1625±0.0095 ngMDA/min/mg protein, which got induced to 0.7938±0.0478 ngMDA/min/mg protein in the presence of Fe2+/ascorbate system. In this context, acteoside, berberine, catechin, 3´5-dihydroxyflavone7-o-ß-D-galacturonide-4-o-ß-D-glucopyranoside (a flavonoid glycoside from cumin), silibin and tetrahydrocurcumin decreased both basal and Fe2+/ascorbate induced lipid peroxidation as determined by thiobarbituric acid reaction. On the other hand, agnuside, andrographolide, picroside-I, negunoside, oleanolic acid, and glycerrihizin, showed enhancement in both basal and induced lipid peroxidation. Phytoconstituents which have decreased both basal and Fe2+/ascorbate induced lipid peroxidation may act as defensive against the deadly effects of ROS, causative agents of lipid peroxidation and other diseases either alone or in combination with diet/nutritional supplements.

Optimization of Endoglucanase Production from a Novel Bacterial Isolate, Arthrobacter sp. HPG166 and Characterization of Its Properties

ABSTRACTIn this study, a potential novel cellulolytic bacteriumArthrobacter sp. HPG166 was isolated from the hindgut of root-feeding larvaeHolotrichia parallela. Optimization of fermentation factors for endoglucanase production byArthrobacter sp. HPG166 was carried out via response surface methodology. Sodium carboxymethylcellulose 1.19% (w/v) and beef extract 0.35% (w/v) were the ideal combination of carbon and nitrogen sources for enzyme production; the optimum temperature and pH for cellulase production were 34°C and pH 8.0 respectively. Under the optimized fermentation conditions, the maximum endoglucanase activity of 1.411 U mL-1 was obtained. The crude endoglucanase was thermotolerant as it retained 50.31% of its activity after incubation at 70°C for an hour. Metal profile of the enzyme indicated that Mg2+ and Na+ were strong stimulators while Mn2+ and Co+ drastically inhibited its activity. Due to its particular characteristics, this enzyme could have potential for industrial applications.

Cloning, expression and characterization of the endoglucanase gene from Bacillus subtilis UMC7 isolated from the gut of the indigenous termite Macrotermes malaccensis in Escherichia coli

Background Bacillus subtilis UMC7 isolated from the gut of termite Macrotermes malaccensis has the ability to secrete a significant amount of extracellular endoglucanase, with an enzyme activity of 0.12 ± 0.01 μmol/min/mL. However, for economically viable industrial applications, the enzyme needs to be expressed in a heterologous host to overcome the low enzyme production from the wild-type strain. Results The endoglucanase gene from B. subtilis UMC7 was successfully cloned and expressed. A higher enzyme activity was observed in the intracellular fraction of the recombinant clone (0.51 ± 0.02 μmol/min/mL) compared with the cell-bound fraction (0.37 ± 0.02 μmol/min/mL) and the extracellular fraction (0.33 ± 0.01 μmol/min/mL). The recombinant endoglucanase was approximately 56 kDa, with optimal enzyme activity at 60°C and pH 6.0. The activity of the enzyme was enhanced by the addition of Ca2 +. However, the enzyme was inhibited by other metal ions in the following order: Fe3 + > Ni2 + > Cu2 + > Mn2 + = Zn2 + > Mg2 + > Cd2 + > Cr2 +. The enzyme was able to hydrolyze both low- and high-viscosity carboxymethyl-cellulose (CMC), avicel, cotton linter, filter paper and avicel but not starch, xylan, chitin, pectin and p-nitrophenyl α-d-glucopyranoside. Conclusions The recombinant endoglucanase showed a threefold increase in extracellular enzyme activity compared with the wild-type strain. This result revealed the potential of endoglucanase expression in E. coli, which can be induced for the overexpression of the enzyme. The enzyme has a broad range of activity with high specificity toward cellulose.

Development of Android Platform Based Portable Trace Heavy Metal Ions Detector / 分析化学

Based on the Android platform, a portable electrochemical analyzer was designed for the detection of heavy metal ions. Its output voltage range was ±3 V with accuracy of 0. 1% and resolution of <1 mV. The current acquisition range was±10 mA with accuracy of 0. 1% and the minimum resolution of 10 pA. With the human-computer interaction advantage of Android smart devices, professional and fast detection mode which could meet the needs of professional and ordinary users respectively were developed to simplify the complex process of electrochemical detection and analysis. Some common heavy metal ions including copper, cadmium, lead and mercury were detected with this detector. The results of linearity, repeatability and accuracy were satisfactory.

TiO2-coated Hollow Fiber Micro-Extraction Combined with Electrothermal Vaporization-Inductively Coupled Plasma Mass Spectrometry for Trace Elements Analysis in Environmental Water Samples / 分析化学

TiO2 coated hollow fiber ( HF) was prepared by sol-gel method and characterized by X-ray powder diffraction and scanning electron microscope. The adsorption performances of the self-prepared TiO2 coated HF for interest metal ions were explored. The sample solution was extracted for 30 min at pH 8. 0 under stirring at speed of 700 r/min, then desorpted with 100μL of 1 mol/L HNO3 . On the basis of this, a method combining TiO2 coated HF micro-solid phase extraction with electrothermal vaporization-inductively coupled plasma mass spectrometry ( ICP-MS ) was developed for the determination of trace metal ions in environmental water samples. Under the optimized conditions, the limits of detection obtained by the proposed method were 0. 039, 0 . 021 , 0 . 009 and 0 . 018 ng/mL for CrⅢ, CuⅡ, CdⅡ and PbⅡ with enrichment factors of 12 . 5 , 11 . 7 , 10. 3 and 18. 6, respectively. The preparation reproducibility of self-prepared TiO2 coated HF ranged from 4. 5% to 6. 8% (n=9) in one batch, and from 7. 7% to 9. 6% (n=7) in batch-to-batch. The developed method has been validated by analyzing a certified reference material ( GSBZ50009-88 200925 ) and also applied to the analysis of CrⅢ, CuⅡ, CdⅡ and PbⅡ in East Lake water and snow water successfully. Meanwhile, TiO2 coated HF stir bar was prepared for a comparison and it was demonstrated that TiO2 coated HF displayed higher extraction efficiency and adsorption capacity for target ions.

HIF-1alpha Upregulation due to Depletion of the Free Ubiquitin Pool

Hypoxia-inducible factor 1alpha (HIF-1alpha), which transactivates a variety of hypoxia-induced genes, is rapidly degraded under nomoxia through the hydroxylation-ubiquitination-proteasome pathway. In this study, we addressed how HIF-1alpha is stabilized by proteasome inhibitors. The ubiquitin pool was rapidly reduced after proteasome inhibition, followed by the accumulation of non-ubiquitinated HIF-1alpha. The poly-ubiquitination of HIF-1alpha was resumed by restoration of free ubiquitin, which suggests that the HIF-1alpha stabilization under proteasome inhibition is attributed to depletion of the free ubiquitin pool. Ni2+ and Zn2+ also stabilized HIF-1alpha with depletion of the free ubiquitin pool and these effects of metal ions were attenuated by restoration of free ubiquitin. Ni2+ and Zn2+ may disturb the recycling of free ubiquitin, as MG132 does. Based on these results, the state of the ubiquitin pool seems to be another critical factor determining the cellular level of HIF-1alpha.

Enzymatic Activity of Lactobacillus Grown in a Sweet Potato Base Medium.

Aim: To study the impact of sweet potatoes on α-glucosidase, β-glucosidase, acid phosphatase, and phytase activity of Lactobacillus. Study Design: Enzymatic activity of seven strains of Lactobacillus grown in a sweet potato medium (SPM) was determined and compared to the standard lactobacilli MRS. Strains having the highest enzymatic activity were further enhanced by metal ions. Place and Duration of Study: Food Microbiology and Biotechnology Laboratory, North Carolina A&T State University, Greensboro, NC, USA, between September 2012 and May 2013. Methodology: Lactobacillus strains were grown in SPM and MRS at 37ºC for 16 h. At the end of incubation, bacterial population (log CFU/mL) was determined by plating and enzymatic activity was determined spectrophotometrically using the corresponding substrate. Results: Lactobacillus strains continue to grow in SPM and MRS and reached averages of 10.98±0.49 and 10.92±0.55 log CFU/mL respectively. Growth of Lactobacillus strains in SPM led to higher β-glucosidase, acid phosphatase, and phytase activity than MRS. Strains of L. reuteri (CF2-7F and SD2112) grown in SPM showed the highest acid phosphatase (15.84±1.05 and 20.56±1.49 Ph U/mL), and phytase (0.66±0.14 and 0.65±0.11 Ph U/mL) respectively. The highest β-glucosidase (36.04±3.16 Glu U/mL) activity was obtained from L. delbrueckii subsp. bulgaricus SR35 grown in SPM. In addition, acid phosphatase and phytase produced by L. reuteri CF2-7F growing in SPM were further increased by the addition of Mn2+ (70.1 and 41.8%) or Mg2+ (94.7 and 20.9%) respectively. β-glucosidase activity of L. reuteri was increased in a range of 4.1 to 130.6% due to the addition of metal ions. Conclusion: Components in sweet potatoes could increase enzymatic activity of Lactobacillus and the addition of metal ions could further produce an enhanced level of these enzymes.

Determination of K+, Na+and Ca2+in Miorodialysis of Apoplast of Poplar Stems by Atomic Absorption Spectrometry with Microdialysis Method / 分析化学

The dialysis for three species of poplar stems apoplast was obtained by microdialysis method, and then the concentration of Na+, K+, Ca2+ in the dialysis sample was directly measured by graphite furnace atomic absorption spectrometry ( GF-AAS) . The flow rate of perfusate was 1μL/min and the cut-off molecular weight of probe was 30 kDa. The real-time and non-destructive test technique established for the detection of ion concentration could be applied in research of poplar biochemical physiology. The recovery of the proposed method was 95. 8%-103. 1%. The contents of sodium ion in Populus wutunensis, Populus simonii and Salix matsudana were 1034-1156 μg/L, 1493-1611 μg/L and 1586-1703 μg/L; potassium ion were 1012-1237 μg/L, 941-964 μg/L and 1095-1201 μg/L; calcium ion were 4976-5237 μg/L, 4786-5042 μg/L and 5893-6142 μg/L. The method could provide reliable data for the study of ion concentration changes of plant response to adapt to all kinds of external environment.

Purification and characterization of 6-phosphogluconate dehydrogenase (6-PGD) from grass carp (Ctenopharyngodon idella) hepatopancreas.

6-Phosphogluconate dehydrogenase (6-PGD, E.C.: 1.1.1.44) was purified and characterized from the hepatopancreas of grass carp (Ctenopharyngodon idella) for the first time. Grass carp represents the second largest aquaculture industry in the world after silver carp, constituting 14.7% of the world aquaculture production, with an average annual increase of 14% in China, mainly as a source of food. The purification procedure involved a single 2’, 5’-ADP-Sepharose 4B affinity chromatographic step by using different elution buffers. The enzyme was purified 309-fold with a specific activity of 5.259 U/mg protein and yield of 68%. The purity and subunit molecular weights of the 6-PGD were checked on SDS-PAGE and purified enzyme showed a single band on the gel. The subunit molecular mass was 57 kDa, with an optimum pH, temperature and ionic strength at 7.96, 50oC and 100 mM Tris-HCl, respectively. The Km values of 6-PGA and NADP+ were 0.019 and 0.0052 mM, respectively, while Vm of 6-PGA and NADP+ was 0.69 U/ml. Dissociation constants (Ki) for 6-PGA and NADP+ were 2.05 and 0.12 mM, respectively. NADPH inhibited the enzyme in a competitive manner and its Ki value was 0.032 mM. The Cu2+, Zn2+, Cd2+ and Al3+ showed inhibitory effects on the enzyme with IC50 values of 0.293, 0.099, 0.045 and 1.526 mM, respectively. All tested metals inhibited the enzyme in a competitive manner, indicating that these metals might be toxic even at low concentrations for the 6-PGD. As the fish is one of valuable foodstuff of animal sources for human consumption, under certain environmental conditions, metal ions accumulated in fish up to a lethal concentration may be harmful for human health. Therefore, it is impending to reduce the concentration of metal ions in contaminated lakes and rivers for fishery and also for human health.

Biophysical Methods for the Elucidation of the S-Layer Proteins/Metal Interaction.

Surface-layers (S-layers) are macromolecular paracrystalline arrays of proteins or glycoproteins that can self-assemble into 2-dimensional semi-permeable meshworks to overlay the cell surface of many bacteria and archaea. They usually assemble into lattices with oblique, square or hexagonal symmetry and serve as an interface between the bacterial cell and the environment. Isolated S-layers can recrystallize into two-dimensional regular arrays in suspension or on various surfaces, thus being an appropriate material for several bionanotechnological purposes. Promising applications of S-layers include their use as biotemplates for the capture of metal ions or the synthesis of metal nanoclusters.

Metal-on-metal Articulation of Total Hip Replacement / 대한고관절학회지

Metal-on-metal (MoM) total hip replacement (THR) and hip resurfacing have an advantage of low wear rate and greater stability by larger head size and different characteristics of wear mechanism, tribology, lubrication or generating wear debris compared to conventional metal-on-polyethylene THR. Although the mid- or long term clinical reports of second generation MoM THR were excellent, concerns about local and systemic effect by metal particles or metal ions were remained. Recently, reports have emerged of abnormal soft-tissue reactions to metal particles or metal ions and some hip resurfacing implants were expelled from the market due to high revision rate. This article includes the history of MoM THR, tribology, the biologic effect of metal particles and ions, the clinical results of MoM THR and the issues regarding the problems associated with hip resurfacing.

Effects of chemical composition on the corrosion of dental alloys

The aim of this study was to determine the effect of the oral environment on the corrosion of dental alloys with different compositions, using electrochemical methods. The corrosion rates were obtained from the current-potential curves and electrochemical impedance spectroscopy (EIS). The effect of artificial saliva on the corrosion of dental alloys was dependent on alloy composition. Dissolution of the ions occurred in all tested dental alloys and the results were strongly dependent on the general alloy composition. Regarding the alloys containing nickel, the Ni-Cr and Ni-Cr-Ti alloys released 0.62 mg/L of Ni on average, while the Co-Cr dental alloy released ions between 0.01 and 0.03 mg/L of Co and Cr, respectively.The open-circuit potential stabilized at a higher level with lower deviation (standard deviation: Ni-Cr-6Ti = 32 mV/SCE and Co-Cr = 54 mV/SCE). The potenciodynamic curves of the dental alloys showed that the Ni-based dental alloy with >70 wt% of Ni had a similar curve and the Co-Cr dental alloy showed a low current density and hence a high resistance to corrosion compared with the Ni-based dental alloys. Some changes in microstructure were observed and this fact influenced the corrosion behavior for the alloys. The lower corrosion resistance also led to greater release of nickel ions to the medium. The quantity of Co ions released from the Co-Cr-Mo alloy was relatively small in the solutions. In addition, the quantity of Cr ions released into the artificial saliva from the Co-Cr alloy was lower than Cr release from the Ni-based dental alloys.

O objetivo deste estudo foi determinar o efeito do ambiente bucal na corrosão de diferentes ligas odontológicas, utilizando métodos eletroquímicos. Os índices de corrosão foram obtidos por meio das curvas de corrente-potencial e impedância eletroquímica (EIS). O efeito de saliva artificial na corrosão de ligas odontológicas foi dependente da composição. A dissolução dos íons ocorreu em todas as amostras e os resultados foram dependentes da composição da liga. Algumas mudanças na microestrutura foram observadas durante o estudo e influenciou o comportamento corrosivo das ligas investigadas. As ligas de Ni-Cr e Ni-Cr-Ti libertaram quantidade de 0,62 mg/L de íons Ni enquanto a liga de Co-Cr liberou entre 0,01 e 0,03 mg/L. As curvas potenciodinâmicas das ligas odontológicas mostraram que as ligas a base >70 wt% de Ni obtiveram curvas similares e a liga de Co-Cr apresentou a menor densidade de corrente e em consequência uma resistência alta a corrosão quando comparada as ligas à base de Ni. A baixa resistência à corrosão também levou a maior libertação de íons de níquel para o meio e a quantidade de Co liberado pela liga de Co-Cr-Mo foi relativamente pequena nas soluções. As quantidades de Cr liberada na saliva artificial pela liga de Co-Cr foi menor que a libertação de Cr pela liga à base de Ni.