查看更多>>摘要：Microbial electrochemical system (MES) is a favorable tool for CO2 emission reduction. Microbial cathode is one of the core components of the system, and its surface energy transfer characteristics can greatly affect the yield of organic matter from MES. In order to solve the problem that the energy transfer characteristics of microbial cathode are not clear, the mathematical model of MES was constructed on the basis of the preliminary experiment with an electrode made of copper foam modified with the reduced graphene oxide, analyzing the current and substrate concentration in the biofilm with conductivity, cathode potential and porosity of the biofilm. The results show that when the cathode potential is higher than -0.8 V (VS SHE), the substrate concentration and current density in the biofilm are related to the cathode potential. However, when the cathode potential decreased to -0.8 V (vs SHE), the ability of biofilm to reduce CO2 basically reached saturation. Low conductivity (<10(-3) S/m) will lead to the formation of significant potential difference in the biofilm, which will reduce the substrate utilization rate and seriously affect the performance of microbial cathode. The current density is highest, when the porosity of the biofilm is about 0.35. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Microbiologically influenced corrosion (MIC) is a complex process involving the cooperative effect of different bacterial species that coexist in the biofilm. Early studies focused on the MIC of single bacterial communities. However, in natural and industrial fields, biofilms are mostly composed of a variety of species. In this work, the effect of interspecific interaction on corrosion of X65 steel was investigated through the mixed culture of sulfate reducing bacteria (SRB) and iron oxidizing bacteria (IOB). Results demonstrated that the mixed microbial consortia created a cooperative effect to aggravate the local corrosion of X65 steel. Compared with the single species, the presence of IOB increased the growth activity of SRB cells and promoted the role of SRB in steel corrosion. The corrosion form on the surface of X65 steel gradually changed to annular pits induced by anaerobic SRB. The succession of dominant bacteria and the development of mixed species biofilm led to an increase in corrosion rate and local corrosion. The corrosion mechanism of X65 steel by mixed species biofilm at different stages was carefully elucidated. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Cold Atmospheric Plasma (CAP) is an emerging physical approach displaying encouraging antitumor and wound healing effects both in vitro and in vivo. In this study, we assessed the potential of direct CAP to remodel skin collagens using an original tissue-engineered human dermal substitute model rich in endogenous extracellular matrix (ECM) covered with 600 ml of culture medium and treated with CAP for 30 and 120 s. Our results indicated that Reactive Oxygen and Nitrogen Species (RONS) such as H2O2, NO3- and NO2- were produced in the medium during treatment. It appeared that in the CAP-treated dermal substitutes 1) cell viability was not altered, 2) pro-collagen I secretion was not modified over 48 h of culture after treatment, 3) global activity of matrix metalloproteinases MMPs was not mod-ulated over 48 h after treatment, and 4) no change in hydroxyproline content was observed over 5 days after treatment. In order to confirm the efficiency of our device, we showed that the plasma-activated culture medium induced cell apoptosis and growth delay using a 3D human tumor spheroid model. In conclusion, no effect of direct CAP treatment was monitored on dermal ECM production and degradation, indicating that CAP does not stimulate collagen remodeling at the tissue scale. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The presence of bio-active compounds in Stachys byzantina (SB) extract has made it a powerful source of green inhibitors in controlling steel corrosion. In this study, it has been attempted to create a highly durable corrosion protective film on the surface of the metal with SB and divalent zinc (II) cations and investigated them by Electrochemical Impedance Spectroscopy (EIS) and Potentiodynamic polarization (PP) tests, and surface analysis methods. EIS results show that after 24 h of placing the steel samples in 3.5% NaCl solution containing 700 SB -300 ZN, the synergistic corrosion inhibition behavior was about 92%. Besides, the results of the PP demonstrated a significant reduction of the i(corr). Furthermore, surface analyses such as Field Emission Scanning Electron Microscopy/Energy Dispersive X-ray Spectroscopy (FE-SEM/EDS) and Atomic Force Microscopy (AFM) images illustrated the low metal surface degradation, which indicates that the mix of SB and Zn caused a protective layer creation on the surface, especially for SB 700 - Zn 300. Also, new compounds of graphitic materials' structure were made using SB extract which is a natural-based chemical, and investigated by Fourier-Transform Infrared Spectroscopy (FTIR) test, Grazing Incidence X-ray Diffraction (GIXRD) technique, Ultraviolet-visible spectroscopy (UV-Vis) analysis, and Raman spectroscopy. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：In this work, we design an immunosensor for zearalenone (ZEN) detection with PEI-rGO/Pt@Au NRs nanocomposite as the modification material. PEI-rGO/Pt@Au NRs nanocomposite have good stability, conductivity and a large specific surface area, so they are chosen as the substrate material for the mod-ified electrode, which is beneficial in improving the detection performance of the sensor. When antibody binds to ZEN, the current signal decreases, and the response signal changes after ZEN incubation, recorded by differential pulse voltammetry (DPV) methods. Under the optimised conditions, the electro-chemical response of the constructed immunosensor shows a linear relation to a wide concentration range from 1 pg/mL to 1 x 10(6) pg/mL with a detection limit of 0.02 pg/mL. Additionally, the proposed electrochemical immunosensor has high selectivity, good stability and great potential for the trace detection of ZEN in real samples. (C) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：The diagnosis of hepatitis B virus (HBV) and monitoring of the vaccination efficiency against HBV require real-time analysis. The presence of antibody against hepatitis B virus surface antigen (anti-HBsAg) as a result of HBV infection and/or immunization may indicate individual immune status towards HBV. This study investigated the ability of a bio-nanogate-based displacement immunosensing strategy in detecting anti-HBsAg antibody, via nonspecific-binding between polyamidoamine dendrimers encapsu-lated gold nanoparticles (PAMAM-Au) and the 'antigenic determinant' region (aD) of HBsAg. For this pur -pose, maltose binding protein harbouring the aD region (MBP-aD) was synthesized as a bioreceptor and immobilized on the screen-printed carbon electrode (SPCE). Following that, PAMAM-Au was deposited on MBP-aD, forming the 'gate' and was used as a monitoring agent. Under optimal conditions, the high speci-ficity of anti-HBsAg antibody towards MBP-aD displaced PAMAM-Au causing the decrement of anodic peak in differential pulse voltammetry (DPV) analysis. The signal changes were proportionally related to the concentration of anti-HBsAg antibody, in a range of 1 -1000 mIU/mL with a limit of detection (LOD) of 2.5 mIU/mL. The results also showed high specificity and selectivity of the immunosensor plat-form in detecting anti-HBsAg antibody both in spiked buffer and human serum samples. (c) 2021 Elsevier B.V. All rights reserved.
查看更多>>摘要：Flavonoids, alkaloids, glucosides and tannins with good corrosion inhibition are the main natural components in plants. In this work, procyanidin B2 (PCB2), a natural flavonoid, was firstly isolated from Uncaria laevigata. Corrosion inhibition, chemical reactivity and adsorption of PCB2 on Q235 carbon steel were described by experimental and theoretical studies. The inhibition performance of PCB2 as a green corrosion inhibitor was evaluated by electrochemical and gravimetric tests. The binding active sites and activities thereof on the steel surface were illustrated by quantum chemistry, and the equilibrium configuration was predicted by molecular dynamics simulation. PCB2 exhibits good corrosion inhibition on Q235 steel over a wide temperature range. The electrochemical results show that PCB2 is a mixed inhibitor, and its inhibition efficiency increases with the addition of PCB2 concentration. Moreover, the protective film is formed on the steel and the active corrosion sites are blocked significantly by surface analysis. Additionally, the theoretical calculation proves a strong interaction between PCB2 molecule and carbon steel. Besides, the antimicrobial activity was also preliminarily studied. This suggests that PCB2 exhibits better antimicrobial activity against many Gram-positive and Gram-negative bacteria. As a novel green corrosion inhibitor and antimicrobial agent, PCB2 is worthy of further exploitation. (c) 2021 Elsevier B.V. All rights reserved.
Krust, DamarisGusbeth, ChristianMueller, Alexander S. K.Scherer, Daniel...
14页
查看更多>>摘要：Compared to mechanical extraction methods, pulsed electric field (PEF) treatment provides an energy efficient and gentle alternative. However, the biological processes involved are poorly understood. The unicellular green microalga Chlorella vulgaris was used as model organism to investigate the effect of PEF treatment on biological cells. A viability assay using fluorescein diacetate measured by flow cytometry was established. The influence of developmental stage on viability could be shown in synchronised cultures when applying PEF treatment with very low specific energies where one part of cells undergoes cell death, and the other part stays viable after treatment. Reactive oxygen species generation after similar low-energy PEF treatment could be shown, indicating that PEFs could act as abiotic stress signal. Most importantly, a cell-death inducing factor could be extracted. A water-soluble extract derived from microalgae suspensions incubated for 24 h after PEF treatment caused the recipient microalgae to die, even though the recipient cells had not been subjected to PEF treatment directly. The working model assumes that low-energy PEF treatment induces programmed cell death in C. vulgaris while specifically releasing a cell-death inducing factor. Low-energy PEF treatment with subsequent incubation period could be a novel biotechnological strategy to extract soluble proteins and lipids in cascade process. (c) 2021 The Authors. Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).
查看更多>>摘要：An electrochemical biosensor is presented that directly reflects the metabolic activity of prokaryotic and eukaryotic cells. This biosensor can be used measure the biological activity of bacteria, yeasts and mammalian cells. This makes the sensor interesting for various applications in industry and science. A possible application is bioprocess control, monitor activities from yeasts, bacteria and fungi to increase the yield. Other applications are starter culture quality studies in the food industry and cytoxicological evaluation with mammalian cells. Our latest investigations additionally indicate the applicability of the electrochemical biosensor to measure algae and cyanobacteria. In our investigations, we were able to show that it was also possible to detect photosynthetic organisms with the electrochemical measurement method, used for investigations on prokaryotic and eukaryotic organisms before. Therefore, this the present study demonstrates an alternative to using this electrochemical biosensor equipped with alga and cyanobacteria for toxicological investigations based on selected test chemicals. The results of this study show a good correlation with those from reference methods, such as the Algal Growth Inhibition Test and the Microtox Test. The advantages of the new electrochemical biosensor are easy handling and shorter measurement time by using different types of test organisms. The evaluation of the sensor signal is based on the current-time curves of a potentiostatic measurement produced by the detection of microbially reduced mediator molecules immobilized in a gel structure. The mediator molecules are reduced during the measurement process. The reduced mediator molecules produce a current signal, which rapidly provides information about the vigor and vitality of living bacteria, yeasts, fungi or cells. (c) 2021 Published by Elsevier B.V.
查看更多>>摘要：Cytochrome c (Cyt c) is a multifunctional protein that, in its native conformation, shuttles electrons in the mitochondrial respiratory chain. Conformational transitions that involve replacement of the heme distal ligand lead to the gain of alternative peroxidase activity, which is crucial for membrane permeabilization during apoptosis. Using a time-resolved SERR spectroelectrochemical approach, we found that the key physicochemical parameters that characterize the electron transfer (ET) canonic function and those that determine the transition to alternative conformations are strongly correlated and are modulated by local electric fields (LEF) of biologically meaningful magnitude. The electron shuttling function is optimized at moderate LEFs of around 1 V nm(-1). A decrease of the LEF is detrimental for ET as it rises the reorganization energy. Moreover, LEF values below and above the optimal for ET favor alternative conformations with peroxidase activity and downshifted reduction potentials. The underlying proposed mechanism is the LEF modulation of the flexibility of crucial protein segments, which produces a differential effect on the kinetic ET and conformational parameters of Cyt c. These findings might be related to variations in the mitochondrial membrane potential during apoptosis, as the basis for the switch between canonic and alternative functions of Cyt c. Moreover, they highlight the possible role of variable LEFs in determining the function of other moonlighting proteins through modulation of the protein dynamics. (C) 2021 Elsevier B.V. All rights reserved.
NSTL
Elsevier