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61.
The interaction of zinc oxide nanoparticles (ZnO NPs) with human haemoglobin (Hb) is studied for the biologically safe application of ZnO NPs in the human body. The Hb corona is formed around the ZnO nanoparticles, directly observed from high‐resolution transmission electron microscopy (HRTEM) images. Hb formed ‘hard corona' on the surface of ZnO NPs from an exponential association mechanism over a very short duration, as well as unfolding of Hb that occurred over a long lifetime. Dynamic light scattering measurements demonstrated that the ZnO NPs were completely covered by Hb with shell thickness of c. 6 nm that formed a ‘hard corona'. Zeta potential measurements represented that the ZnO NPs were fully covered by Hb molecules using an exponential association mechanism. Tryptophans (TRY), as well as heme‐porphyrin moieties of Hb, are the major binding sites for ZnO NPs. The nature of the interaction between ZnO NPs and Hb was analysed from the fluorescence quenching of TRYs. Electrostatic interaction, along with the hydrophobic interaction between ZnO NPs and Hb, is responsible for the conformational change in Hb due to increase in the percentage of β‐sheets together with a decrease in α‐helices. 相似文献
62.
AbstractAzo dyes are recalcitrant compounds used as a colorant in various industries. The pollution caused by their extensive usage has adversely affected the environment for years. The existing physicochemical methods for dye pollution remediation are rather inefficient and hence there is a dearth of low-cost, potential systems capable of dye degradation. The current research studies the biodegradation potential of immobilized bacterial cells against azo dyes Reactive Orange 16 (RO-16) and Reactive Blue 250 (RB-250). Two indigenous dye degrading bacteria Bacillus sp. VITAKB20 and Lysinibacillus sp. KPB6 was isolated from textile sludge sample. Free cells of Bacillus. sp. VITAKB20 degraded 92.38% of RO-16 and that of Lysinibacillus sp. KPB6 degraded 95.36% of RB-250 within 72?h under static conditions. Upon immobilization with calcium alginate, dye degradation occurred rapidly. Bacillus. sp. VITAKB20 degraded 97.5% of RO-16 and Lysinibacillus sp. KPB6 degraded 98.2% of RB-250 within 48?h under shaking conditions. Further, the nature of dye decolorization was biodegradation as evident by high-performance liquid chromatography (HPLC), and Fourier-transform infrared spectroscopy (FTIR) results. Phytotoxicity and biotoxicity assays revealed that the degraded dye products were less toxic in nature than the pure dyes. Thus, immobilization proved to be a highly likely alternative treatment for dye removal. 相似文献
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ZnO nanostructures of different morphology (nanorods, nano‐leaf, nanotubes) were favourably grown using a chemical precipitation process. The prepared ZnO nanostructures were characterized systematically using absorption spectroscopy, emission spectroscopy, X‐ray diffraction (XRD), scanning electron microscopy (SEM) and Fourier transform infrared studies. XRD results showed the hexagonal wurtzite phase of the synthesized ZnO nanostructures. Structural properties such as average crystallite size, lattice constants, volume of the unit cell, atomic fraction, and structural bonds were also studied. The optical band gap of the synthesized ZnO nanocrystals varied from 3.52 eV to 3.69 eV with high quantum yield of the blue emission (~420 nm). Urbach energy for ZnO nanocrystals was calculated to be 0.702 eV, 0.901 eV, and 0.993 eV for nanorods, nano‐leaf, and tube like ZnO crystals, respectively. Morphology of the fabricated nanostructures was investigated using SEM. Photocatalytic degradation of rhodamine B (Rh B) in solution under UV irradiation was explored with different ZnO morphology. Photocatalytic experiments showed that ZnO nano‐leaf had a higher degradation rate of photocatalytic activity of photodegrading Rh B compared with the other tube shape and rods shape nanostructures. The Rh B dye degraded considerably by ~79.05%, 74.41%, and 69.8% within 120 min in the presence of the as‐fabricated fern nano‐leaf, nanotubes, and nanorods of the ZnO nanocrystals at room temperature. 相似文献
66.
Papita Das Saha 《Bioremediation Journal》2013,17(1):52-60
ABSTRACT The effluents coming from the dye industries are colored and polluted, and the disposal of these wastes into receiving waters causes damage to the water as well as the environment. The use of rice husk for the removal of dye from wastewater has been explored in a stir tank reactor. The effects of operation variables such as adsorbent dosage, contact time, dye concentration, initial pH, and agitation on the removal of safranin were investigated in a stirred tank reactor. The combined effect of various process parameters on dye removal were analyzed using response surface methodology (RSM), and the modeling of the process parameter had been done using the artificial neural network simulation method. It was observed that response surface methodology can determine the optimization of the process parameters and the model derived from the simulation of the artificial neural network (ANN) (deviation from experimental results was ~0.09%) described the process variable efficiently. It was observed that at the initial solution pH of 6.28 and adsorbent dosage of 15.63 g L?1, dye removal of safranin was 97%. 相似文献
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Jayanta Saha Ruth M. Ruprecht Andre Rosowsky 《Nucleosides, nucleotides & nucleic acids》2013,32(7):1465-1475
Abstract A convenient general method of synthesis of 5′-O-(alkoxycarbonyl)phosphonate esters of 2′,3′-dideoxyribonucleosides is presented, using the 5′-O-(methoxycarbonyl)phosphinyl, 5′-0-(ethoxycarbonyl)phosphinyl, and 5′-O-(cholesterylcarbonyl)phosphinyl derivatives of 3′-azido-3′-deoxythymidine (AZT) and the 5′-0-(ethoxycarbonyl)phosphinyl derivative of 2′,3′-dideoxycytidine (ddC) as examples. Reaction of trimethyl phosphonoformate, methyl phosphonoformate, or dimethyl cholesterylcarbonylphosphonate with phosphorus pentachloride in carbon tetrachloride, followed by direct condensation of the resulting phosphonyl chloride with the nucleoside, gave the fully esterified phosphonoformate derivatives, which on treatment with sodium iodide in tetrahydrofuran underwent selective cleavage of the P-OMe or P-OEt groups, leaving the carboxylate esters intact. The resulting products were converted from sodium salts to ammonium salts by ion-exchange chromatography. 相似文献
69.
Minakshi Mazumdar Arghya Adhikary Samik Chakraborty Shravanti Mukherjee Argha Manna Shilpi Saha Suchismita Mohanty Amrita Dutta Pushpak Bhattacharjee Pallab Ray Sreya Chattopadhyay Shuvomoy Banerjee Juni Chakraborty Arun K. Ray Gaurisankar Sa Tanya Das 《Apoptosis : an international journal on programmed cell death》2013,18(5):589-604
Mutations in REarranged during Transfection (RET) receptor tyrosine, followed by the oncogenic activation of RET kinase is responsible for the development of medullary thyroid carcinoma (MTC) that responds poorly to conventional chemotherapy. Targeting RET, therefore, might be useful in tailoring surveillance of MTC patients. Here we showed that theaflavins, the bioactive components of black tea, successfully induced apoptosis in human MTC cell line, TT, by inversely modulating two molecular pathways: (i) stalling PI3K/Akt/Bad pathway that resulted in mitochondrial transmembrane potential (MTP) loss, cytochrome-c release and activation of the executioner caspases-9 and -3, and (ii) upholding p38MAPK/caspase-8/caspase-3 pathway via inhibition of Ras/Raf/ERK. Over-expression of either constitutively active myristoylated-Akt-cDNA (Myr-Akt-cDNA) or dominant-negative-caspase-8-cDNA (Dn-caspase-8-cDNA) partially blocked theaflavin-induced apoptosis, while co-transfection of Myr-Akt-cDNA and Dn-caspase-8-cDNA completely eradicated the effect of theaflavins thereby negating the possibility of existence of other pathways. A search for the upstream signaling revealed that theaflavin-induced disruption of lipid raft caused interference in anchorage of RET in lipid raft that in turn stalled phosphorylation of Ras and PI3Kinase. In such anti-survival cellular micro-environment, pro-apoptotic signals were triggered to culminate into programmed death of MTC cell. These findings not only unveil a hitherto unexplained mechanism underlying theaflavin-induced MTC death, but also validate RET as a promising and potential target for MTC therapy. 相似文献
70.
Nury M. Steuerwald David M. Foureau H. James Norton Jie Zhou Judith C. Parsons Naga Chalasani Robert J. Fontana Paul B. Watkins William M. Lee K. Rajender Reddy Andrew Stolz Jayant Talwalkar Timothy Davern Dhanonjoy Saha Lauren N. Bell Huiman Barnhart Jiezhun Gu Jose Serrano Herbert L. Bonkovsky 《PloS one》2013,8(12)
Drug-induced liver injury (DILI) is the most common cause of acute liver failure in the United-States. The aim of the study was to describe serum immune profiles associated with acute DILI, to investigate whether there are profiles associated with clinical features or types of DILI and/or with prognosis, and to assess temporal changes in levels. Twenty-seven immune analytes were measured in the sera of 78 DILI subjects in the Drug-Induced Liver Injury Network (DILIN) and compared with 40 healthy controls. Immune analytes (14 cytokines, 7 chemokines and 6 growth factors) were measured by BioPlex multiplex ELISA at DILI onset and after 6 months. A modeling process utilizing immune principles was used to select a final set of variables among 27 immune analytes and several additional clinical lab values for prediction of early death (within 6 months of DILI onset). Nineteen of the 27 immune analytes were differentially expressed among healthy control, DILI onset and 6-month cohorts. Disparate patterns of immune responses, especially innate and adaptive cellular (mostly TH17) immunity were evident. Low values of four immune analytes (IL-9, IL-17, PDGF-bb and RANTES) and serum albumin are predictive of early death [PPV = 88% (95% CI, 65%-100%), NPV = 97% (95% CI, 93%-100%), accuracy = 96% (95% CI, 92%-100%)].