Nitric oxide metabolism in heart mitochondria

Normal cardiac function is accomplished through a continuous energy supply provided by mitochondria. Heart mitochondria are the major source of reactive oxygen and nitrogen species: superoxide anion (O₂-) and nitric oxide (NO). NO production by mitochondrial NOS (mtNOS) is modified by metabolic state and shows an exponential dependence on Δψ. The interaction between mtNOS and complexes I and IV might be a mechanism involved in the regulation of mitochondrial NO production. NO exerts a high affinity, reversible and physiological inhibition of cytochrome c oxidase activity. A second effect of NO on the respiratory chain is accomplished through its interaction with ubiquinol-cytochrome c oxidoreductase. The ability of mtNOS to regulate mitochondrial O₂ uptake and O₂- and H₂O₂ productions through the interaction of NO with the respiratory chain is named mtNOS functional activity. Together, heart mtNOS allows NO to optimize the balance between cardiac energy production and utilization, and to regulate the steady-state concentrations of other oxygen and nitrogen species.     

Nitric oxide alleviates cadmium-impeded growth by limiting ROS accumulation in pea seedlings

Cadmium (Cd) causes oxidative stress, which leads to the oxidation of various biomolecules by the production of reactive oxygen species (ROS) to facilitate programmed cell death (PCD). The antioxidant defense system fails to detoxify ROS when it is produced in excess. Nitric oxide (NO), a gaseous free radical and a phytohormone, regulates various physiological processes of plants. Therefore, this work was undertaken to study the effects of the application of exogenous sodium nitroprusside (SNP, a NO donor) on growth parameters, oxidative stress, accumulation of secondary metabolites, and activities of antioxidant enzymes under Cd stress. Mild (50 µM) and severe (200 µM) Cd stress were applied to hydroponically grown pea (Pisum sativum L.) plants with or without 50 µM SNP. Severe Cd stress had a substantial impact on the plants. The effectiveness of NO in reducing Cd-induced negative effects on plant height, fresh weight, dry weight, protein content, nitrite content, nitrate reductase (NR) activity, catalase activity, and peroxidase activity were investigated. Seedling development, protein content, nitrite content, nitrate reductase (NR) activity, antioxidant defense systems disruption, overproduction of reactive oxygen species, and oxidative damage were observed. The antioxidant defense system (catalase and peroxidase activities) was activated by NO, which resulted in lower lipid peroxidation and lower hydrogen peroxide (H₂O₂) levels in Cd-exposed plants. SNP treatment boosted endogenous NO levels and NR activity in Cd-stressed plants while also enhanced proline levels to preserve osmotic equilibrium. The presence of total phenols and flavonoids increased after SNP treatment, indicating that SNP enhanced stress recovery and boosted plant development in Cd-stressed plants.

     

Imaging of reactive oxygen species burst from mitochondria using laser scanning confocal microscopy

Objective: Although several methods have been used to detect the intracellular reactive oxygen species (ROS) generation, it is still difficult to determine where ROS generate from. This study aimed to demonstrate whether ROS generate from mitochondria during oxidative stress induced mitochondria damage in cardiac H9c2 cells by laser scanning confocal microscopy (LSCM). Methods: Cardiac H9c2 cells were exposed to H₂O₂ (1200μM) to induce mitochondrial oxidant damage. Mitochondrial membrane potential (ΔΨm) was measured by staining cells with tetramethylrhodamine ethyl ester (TMRE); ROS generation was measured by staining cells with dichlorodihydrofluorescein diacetate (H₂DCFDA). Results: A rapid/transient ROS burst from mitochondria was induced in cardiac cells treated with H₂O₂ compared with the control group, suggesting that mitochondria are the main source of ROS induced by oxidative stress in H9c2 cells. Meanwhile, the TMRE fluorescence intensity of mitochondria which had produced a great deal of ROS decreased significantly, indicating that the burst of ROS induces the loss of ΔΨm. In addition, the structure of mitochondria was damaged seriously after ROS burst. However, we also demonstrated that the TMRE fluorescence intensity might be affected by H₂DCFDA. Conclusions: Mitochondria are the main source of ROS induced by oxidative stress in H9c2 cells and these findings provide a new method to observe whether ROS generate from mitochondria by LSCM. However, these observations also suggested that it is inaccurate to test the fluorescence intensities of cells stained with two or more different fluorescent dyes which should be paid more attention to. Microsc. Res. Tech. 76:612–617, 2013. © 2013 Wiley Periodicals, Inc.     

Field emission techniques for studying surface reactions: applying them to NO-H2 interaction with Pd tips

The adsorption of NO and its reaction with H₂ over Pd tips were investigated by means of field ion microscopy (FIM) and pulsed field desorption mass spectrometry (PFDMS) in the 10⁻³ Pa pressure range and at sample temperatures between 400 and 600 K. By varying the H₂ partial pressure while keeping the other control parameters constant, the NO+H₂ reaction over Pd crystallites is shown to exhibit a strong hysteresis effect. The hysteresis region narrows with increase in temperature and the H₂ pressures delimiting this hysteresis decrease as well. Abrupt transformations of the micrographs are observed by FIM from bright to dark patterns and vice versa. These transformations define the hysteresis region. The collected data allow establishing a novel kinetic phase diagram of the NO+H₂/Pd system within the range of temperatures and pressures indicated. The observed features are correlated with a local chemical analysis by means of field pulses. NO⁺ seems to be the dominating imaging species under all conditions. At high relative H₂ pressures (the “hydrogen-side”), H atoms seem to diffuse subsurface. This process is blocked at lower H₂ pressure (the “NO-side”) due to NO_ad and O_ad accumulation on the surface. Probe-hole measurements with field pulses indicate that the Pd surface undergoes oxidation as revealed by the occurrence of PdO₂⁺ species in the mass spectra.     

A kinetic model for the reduction of nitric oxide by hydrazine

A chemical kinetic model is developed for the non-catalytic reduction of nitric oxide (NO) by hydrazine (N₂H₄). Since the reduction of NO was observed in an experimental reaction with N₂H₄, the hydrazine has been suggested as a new reductant of NO in addition to the conventional ammonia, urea and isocyanic acid. In the proposed kinetic model, a set of fifty one chemical reactions that includes the various branching reactions of N₂H₄ to NH₂ and the wellknown reaction NO+NH₂→N₂+H₂O is simultaneously considered with the usual partial equilibrium assumptions. The NO reduction is estimated to occur at a temperature range between 700K and 1400 K, which is wider and lower than in the conventional Thermal DeNOx process. The maximum amount of the reduced NO is slightly less than that in the Thermal DeNOx. The effects of the other input parameter on the NO reduction rate also discussed.     

Elemental sulfur upregulated testicular testosterone biosynthesis by associating with altered gut microbiota in mice

Elemental sulfur has been used as a traditional Chinese medicine to treat the late-onset hypogonadism and impotence without a clarified mechanism for many hundreds of years. In the present study, mice were received sulfur or distilled water for 35 days by daily intragastric gavage at a dose of 250 mg/kg body weight. Then, the serum testosterone level and genes associated with testicular testosterone biosynthesis (TTB) were detected. The gut microbiota was also analyzed by 16S rRNA gene sequencing. Serum testosterone level was significantly increased by 291.1% in sulfur-treated mice. The H₂S levels in serum and feces were significantly increased. The expression of genes associated with TTB including StAR, p450c17, 3β-HSD, and P450scc in testes were significantly upregulated by Sulfur and NaHS, suggesting that sulfur promotes TTB depending on H₂S. In addition, sulfur increased the diversity of gut microbiota and the abundance of several bacteria associated with sulfur metabolism, including genus Prevotella, which might be positively associated with serum level of testosterone in boys. Five pathways including bile secretion, carotenoid biosynthesis, lipid biosynthesis proteins, propanoate metabolism, and biosynthesis of type II polyketide products, were identified to associate with sulfur. Together, our results suggested that sulfur upregulated testicular testosterone biosynthesis via H₂S, which was associated with alteration of gut microbiota in mice. Our study highlights a mechanism for the treatment of late-onset hypogonadism and impotence by sulfur.     

Hydrogen peroxide staining to visualize intracellular bacterial infections of seedling root cells

Visualization of bacteria in living plant cells and tissues is often problematic due to lack of stains that pass through living plant cell membranes and selectively stain bacterial cells. In this article, we report the use of 3,3′‐diaminobenzidine tetrachloride (DAB) to stain hydrogen peroxide associated with bacterial invasion of eukaryotic cells. Tissues were counterstained with aniline blue/lactophenol to stain protein in bacterial cells. Using this staining method to visualize intracellular bacterial (Burkholderia gladioli) colonization of seedling roots of switch grass (Panicum virgatum), we compared bacterial free seedling roots and those inoculated with the bacterium. To further assess application of the technique in multiple species of vascular plants, we examined vascular plants for seedling root colonization by naturally occurring seed‐transmitted bacteria. Colonization by bacteria was only observed to occur within epidermal (including root hairs) and cortical cells of root tissues, suggesting that bacteria may not be penetrating deeply into root tissues. DAB/peroxidase with counter stain aniline blue/lactophenol was effective in penetration of root cells to selectively stain bacteria. Furthermore, this stain combination permitted the visualization of the bacterial lysis process. Before any evidence of H₂O₂ staining, intracellular bacteria were seen to stain blue for protein content with aniline blue/lactophenol. After H₂O₂ staining became evident, bacteria were often swollen, without internal staining by aniline blue/lactophenol; this suggests loss of protein content. This staining method was effective for seedling root tissues; however, it was not effective at staining bacteria in shoot tissues due to poor penetration. Microsc. Res. Tech. 77:566–573, 2014. © 2014 Wiley Periodicals, Inc.     

Insight into 5-aminolevulinic acid-induced modulation of cellular antioxidant metabolism to confer salinity and drought tolerance in maize

The current study investigated the comparative oxidative damage in two maize seedlings induced by saline, drought, and combined stress and the ameliorative role of two different doses (20 and 80 µM) of 5-aminolevulinic acid (ALA) against the above-mentioned stresses. Hydroponically grown 10-day-old maize (Zea mays, var. BARI Hybrid Maize-7 (BHM-7) and BARI Hybrid Maize-9 (BHM-9)) seedlings were exposed to 12 dS/m of saline solution, 200 mM mannitol-induced drought stress alone and their combined stress for 7 days. Result revealed that individual stresses retard the plant growth to some degrees; however, their combined stress has more detrimental effects, which might be correlated with lipid peroxidation (MDA)-induced oxidative stress in seedlings, enhanced Na⁺ /K⁺ ratio, and augmented generation of superoxide (O₂^•− ) and hydrogen peroxide (H₂O₂). In contrast, exogenous ALA supplementation at 20 µM concentration markedly recovered from chlorosis and growth inhibition, substantially scavenged reactive oxygen species (ROS) and MDA by preserving ionhomeostasis and relaxing oxidative stress; also, by boosting catalase (CAT) and glutathione S-transferase (GST), and exclusively via depressing the activity of lipoxygenase (LOX) antioxidant enzyme. On the contrary, 80 µM ALA made things worse; nevertheless, higher activities shown by other antioxidant enzymes; like, superoxide dismutase (SOD), ascorbate peroxidase (APX), peroxidase (POD), and glutathione peroxidase (GPX), which were related to lessen the oxidative damage by highly produced O₂^•− and H₂O₂ under combined stress. Non-denaturing gel electrophoresis was done for further confirmation. However, ALA importantly increased the photosynthetic pigment contents in both genotypes irrespective of doses. Nevertheless, GST might have assisted the plants to escape from the herbicidal effect by detoxification. However, in the combined stress condition, high ALA concentration may have some positive role to play. Our findings also showed that BHM-9 performed better than BHM-7. Therefore, ALA at lower concentration was effective for single stress of saline and drought, while higher concentration can improve plant survival under combined stress.     

Effects of additive and preheat on the partially premixed CH4-air counter flow flames considering non-gray gas radiation

Detailed structures of the counterflow flames formed for different inlet fluid temperatures and different amount of additives are studied numerically. The detailed chemical reactions are modeled by using the CHEMKIN-II code. The discrete ordinates method and the narrow band based WSGGM with a gray gas regrouping technique (WSGGM-RG) are applied for modeling the radiative transfer through non-homogeneous and non-isothermal combustion gas mixtures generated by the counterflow flames. The results compared with those obtained by using the SNB model show that the WSGGM-RG is very successful in modeling the counterflow flames with non-gray gas mixture. The numerical results also show that the addition of CO₂ or H₂O to the oxidant lowers the peak temperature and the NO concentration in flame. But preheat of fuel or oxidant raises the flame temperature and the NO production rates. O₂ enrichment also causes to raise the temperature distribution and the NO production in flame. And it is found that the O₂ enrichment and the fuel preheat were the major parameters in affecting the flame width.     

Inhibition of H₂O₂-induced apoptosis of GC2-spg cells by functionalized selenium nanoparticles with lentinan through ROS-mediated ERK/p53 signaling pathways

A H₂O₂-induced oxidative stress injury cell model was established to investigate the antioxidant effect of nano-selenium on mouse spermatocyte lines and the regulation mechanism of the expression level and activity of selenium-containing antioxidant enzymes induced by oxidative stress. A safe and effective nano-drug system of functionalized selenium-containing nanoparticles (SeNPs) was developed with lentinan (LNT) (SeNPs@LNT). Mice spermatocyte line GC2-spg cells were treated with SeNPs@LNT (1, 2, 4, 8, 16, 32 μM) for 24–72 h to evaluate the cytotoxicity of selenium. GC2-spg cells were randomly divided into the following groups: control, hydrogen peroxide (H₂O₂), SeNPs@LNT, and H₂O₂+SeNPs@LNT groups. H₂O₂+SeNPs@LNT group was pretreated with SeNPs@LNT 4 μM for 12 h, followed by H₂O₂ 600 μM for 8 h. The cell viability decreased in the H₂O₂ group and increased significantly in the SeNPs@LNT group. Compared with the H₂O₂ group, the SeNPs@LNT+H₂O₂ group exhibited obvious red fluorescence, indicating a higher level of mitochondrial membrane potential. The content of intracellular reactive oxygen species (ROS) in the SeNPs@LNT group reduced significantly, and the intensity of green fluorescence in the SeNPs@LNT+H₂O₂ group decreased significantly compared with the H₂O₂ group, indicating the inhibitory effect of SeNPs@LNT on the generation of ROS-induced oxidative stress. The activity of GPx and SOD increased significantly in the SeNPs@LNT group. The expression of p53 decreased significantly under the intervention of nano-selenium, and GPx1 expression increased. In the oxidative stress group, the expressions of DNA damage-related proteins and apoptosis-related proteins were higher than those in other groups. Thus, SeNPs@LNT can promote GC2-spg cell proliferation, improve GPx and SOD activities, remove intracellular ROS, and reduce mitochondrial damage and functional abnormalities caused by oxidative stress by regulating the ERK and p53 protein levels. SeNPs@LNT has good biological activity and antioxidant effect, which can be used to protect the male reproductive system from oxidative stress.     

Microscopic and phytochemical techniques as a tool for authentication of herbal drug chiraita: Swertia cordata (G. Don) C.B. Clarke

Swertia cordata (G. Don) C.B. Clarke is one of the potential medicinal plants extensively used in eastern traditional medicine such as Unani, Ayurveda, Siddha, and in traditional Tibetan and Chinese medicine. S. paniculata is the common adulterant of S. cordata at herbal shops and markets but S. paniculata is also used in number of herbal formulations. The present study was conducted to use microscopic, pharmacognostic, and phytochemical techniques as a tool for the authentication of herbal drug chiraita (S. cordata). In herbal markets, mixing, adulteration, and use of spurious materials as substitute have become a major concern for herbal practitioners, local user, and industry for reasons of safety and efficacy. Therefore, authentication of medicinal plants is of utmost importance at each level of drug research. In the present study, anatomical features of two species showed a great diversity, as irregular epidermal cells and nonglandular, unicellular trichomes were found in S. cordata while in S. paniculata epidermal cells were hexagonal in shape and trichomes were A‐shaped. Antioxidant activity of two species showed a great variation where IC₅₀ value recorded for S. cordata was 208 μg/mL, while for S. paniculata IC₅₀ was 624 μg/mL. The study can serve as an important source of information to achieve the authenticity and to evaluate the quality and purity of the plant material in accordance to WHO guidelines. As this species is greatly exploited, so conservation is highly recommended.     

Environmental effects on the friction of hydrogenated DLC films

We have investigated environmental effects on hydrogenated diamond-like carbon (H-DLC) films under various pressures of H₂O, O₂, and N₂ by ultrahigh vacuum (UHV) tribometry. The H-DLC film exhibits an ultralow coefficient of friction (μ = 0.004 in UHV). The μ value increases with increasing pressure of H₂O and O₂. Specifically, μ increases up to 0.07 under 10 Torr of H₂O, and up to 0.03 under 150 Torr of O₂; these are typical H₂O and O₂ contents respectively in ambient air. Our results are consistent with similar environmental effects previously reported. But, we have also discovered that these friction changes are reversible, returning to the ultralow value when UHV is restored. The reversibility of the friction behavior in both environments, coupled with the lack of evidence of tribochemical changes by Auger electron spectroscopy, suggest that the observed friction changes are due to the weakly adsorbed gas molecules that influence the friction property by physically separating the H-DLC interface. Speed-dependent tribometry also supports this argument. In addition, two DLC films with different hydrogen contents and with widely different friction coefficients in UHV are shown to exhibit identical μ values under humid environments, further demonstrating that the frictional properties of these DLC films are essentially determined by the surface layer of adsorbed gas molecules.     

ROS-hormone interaction in regulating integrative défense signaling of plant cell

The elaborate redox network of the cell, comprising of events like turnover of reactive oxygen species (ROS), redox sensing, signaling, expression of redox-sensitive genes, etc., often orchestrates with other bonafide hormonal signaling pathways through their synergistic or antagonistic action in the plant cell. The redox cue generated in plant cells under fluctuating environmental conditions can significantly influence other hormonal biosynthetic or signaling mechanisms, thereby modulating physiology towards stress acclimation and defense. There is also strong evidence of the recruitment of ROS as a ‘second messenger’ in different hormonal signaling pathways under stress. Moreover, the retrograde signaling initiated by ROS also found to strongly influence hormonal homeostasis and signaling. The present review, in this aspect, is an effort towards understanding the regulatory roles of ROS in integrating and orchestrating other hormonal signaling pathways or vice versa so as to unfold the relationship between these two signaling episodes of plant cells under environmental odds. We also accentuate the significance of understanding the utterly complex interactions, which occur both at metabolic and genetic levels between ROS and phytohormones during stress combinations. Furthermore, the significant and decisive role of ROS turnover, particularly the contribution of RBOH (respiratory burst oxidase homologs) in the synergism of redox and hormone signaling during systemic acquired acclimation under stress is also discussed.     

Cell viability in the cadmium-stressed cell suspension cultures of tobacco is regulated by extracellular ATP,possibly by a reactive oxygen species-associated mechanism

Cadmium (Cd) is one of the most widespread and toxic heavy metals to plants. Extracellular ATP (exATP) is thought to be an extracellular effector in regulating the physiological responses of plant cells to environmental stresses. However, the function of exATP in Cd-stressed plant cells is much unknown. The present work showed that treating tobacco (Nicotiana tabacum L. cv. Bright Yellow-2) cell-suspension cultures with exogenous CdCl₂ reduced the cell viability, exATP level, and Mg content. However, the production of reactive oxygen species (ROS), Cd content, and electrolyte leakage of the cells were enhanced by exogenous CdCl₂. When the Cd-induced accumulation of ROS was decreased by the supplement with DMTU (dimethylthiourea, a scavenger of ROS), the Cd-induced increases of the electrolyte leakage and Cd content were alleviated, and the Cd-induced reductions of cell viability were partly rescued, suggesting that Cd-induced reduction of cell viability could be related to the ROS accumulation. Under the condition of Cd stress, when the reduction of exATP level was partly rescued by exogenous ATP (20 μM), the increases of ROS production, electrolyte leakage, and Cd content were attenuated, and the reduction of cell viability was also alleviated. These observations indicate that exATP can regulate the cell viability in the Cd–stressed plant cells possibly by an ROSassociated mechanism.     

Analysis of reactive oxygen species in the guard cell of wheat stoma with confocal microscope

Recently, the laser‐scanning confocal microscope has become a routine technique and indispensable tool for cell biological studies. Previous studies indicated that reactive oxygen species (ROS) were generated in tobacco epidermal cells with confocal microscope. In the present studies, the probe 2′,7′‐dichlorof luorescein diacetate (H₂DCF‐DA) was used to research the change of ROS in the guard cell of wheat stoma, and catalase (CAT) was used to demonstrate that ROS had been labeled. The laser‐scanning mode of confocal microscope was XYT, and the time interval between two sections was 1.6351 s. Sixty optical sections were acquired with the laser‐scanning confocal microscope, and CAT (60,000 U mg^?1) was added after four optical sections were scanned. Furthermore, the region of interest (ROI) was circled and the fluorescence intensity of ROS was quantified with Leica Confocal Software. The quantitative data were exported and the trend chart was made with software Excell. The results indicated that ROS were produced intracellularly in stomatal guard cells, and the quantified fluorescence intensity of ROS was declined with CAT added. It is a good method to research the instantaneous change of ROS in plant cells with confocal microscope and fluorescence probe H₂DCF‐DA. Microsc. Res. Tech., 2011. © 2010 Wiley‐Liss, Inc.     

Detection of sulfur in fixed and embedded rat peritoneal mast cell granules by X-ray energy dispersive spectroscopy

Purified rat peritoneal mast cells contained 3.3 × 10^?5 gm SO₄ and 2.2 × 10^?8 gm Ca/10⁶ cells. The molar ratio of S/Ca in the whole cell was 600:1. Frozen thin sections of unfixed mast cells contained only sulfur (S) in the granules when examined by X-ray energy dispersive spectroscopy (EDS). Mast cells fixed in 3% glutaraldehyde and 1.5% formaldehyde in 75% ethanol (Et/Ald) or in mixed buffered aldehydes and embedded in Epon 812 or the low viscosity resin diepoxyoctane (DEO) contained S in all granules and Ca in some of the granules measured. Neither element was found in the nucleus, cytoplasm, or resin. Isolated, Et/Ald fixed and embedded granules also contained S. The presence of Ca in the granules was artifactual in that the Ca was absorbed from water in the trough of the diamond knife and/or from the filter paper used to blot the sections dry. This phenomenon was investigated further. Sections of Et/Ald fixed and embedded mast cells were incubated with 5 × 10^?6 to 10^?2 M CaCl₂. Ca was detectable in 100% of the granules incubated at concentrations ≥ 10^?4 M and reached a constant S/Ca ratio of 2.0 at concentrations ≥ 10^?3 M. Ca was not detectable in the nucleus, cytoplasm, or resin at 10^?2 M. A plot of S versus Ca counts from the granules of cells incubated with 10^?2 M CaCl₂ was linear with a slope of 2.0 and a correlation coefficient of 0.88. Et/Ald fixed cells incubated with distilled H₂O had fewer granules containing Ca, 10%, than unincubated cells, 77%. Further, H₂O removed all Ca from Et/Ald fixed cells embedded in DEO. These studies show that S, which is present as SO₄ on the proteoglycan heparin, is readily detectable by X-ray EDS in fixed and embedded cells. An artifact of the technique is that weak anionic sites, which are most probably carboxyl groups on the proteoglycan, can bind the divalent cation Ca and cause spurious localization.     

Analysis of deformable distortion in the architecture of leaf xylary vessel elements of Carthamus oxycantha caused by heavy metals stress using image registration

Anatomical study of leaf xylary vessel elements of Carthamus oxycantha under various intensities of lead (Pb) and nickel (Ni) stress (200, 400, 600, and 800 mg Pb(NO₃)₂, NiCl₂·6H₂O/kg of the soil) was conducted. The deformations caused due to metal stress were detected using point‐based image registration technique. Initially, a set of corresponding feature points called landmarks was selected for warping of two‐dimensional microscopic images of deformed/source vessel (stressed) to its normal/target (unstressed) counterpart. The results show that the target registration error is less than 3 mm using real plant image datasets. The stress caused alterations mainly in diameter, size, and shape of the cells. Average cell diameter and average wall diameter of vessels were measured with “Image J.” The range of decrease in average cell diameter from 18.566 to 13.1 μm and the range of increase in average wall diameter was from 5.166 to 10.1 μm, with increase in stress factor through 200, 400, 600, and 800 mg Pb(NO₃)₂, NiCl₂·6H₂O/kg of the soil. We noted large deformation in the form of shrinkage in cell size and diminution in its diameter. The diminution in diameter and the shrinkage in cell size of vessel cells may be due to the deposition of wall materials. It can be a possible strategy to limit the water flow to overcome the rapid mobility and transportation of the excess amount of metals to safeguard the cellular components from unpleasant consequences of metallic stress.     

Novel method for fabrication of polyaniline-CdS sensor for H2S gas detection

In this paper, we report on the performance of a H₂S sensor based on polyaniline-CdS nanocomposites fabricated by a simple spin coating technique. The nanocomposites showed the sensitivity to H₂S gas at room temperature (300 K). The resistance of polyaniline-CdS nanocomposites showed a considerable change when exposed to various concentrations of H₂S. Maximum response up to 48% was achieved for 100 ppm H₂S for PANi-CdS sensor. Depending on the concentration of H₂S, the response time was in the range of 41 and 71 s, whereas the recovery time was in the range of 345-518 s.