On the role of gold nanoparticles in the selective photooxidation of 2-propanol over Au/TiO2

2015 ◽  
Vol 17 (16) ◽  
pp. 10391-10397 ◽  
Author(s):  
Alexander Lüken ◽  
Martin Muhler ◽  
Jennifer Strunk
Keyword(s):  
Gold Nanoparticles ◽  
Electron Transfer ◽  
Reaction Mechanism ◽  
Conduction Band ◽  
Electron Acceptor ◽  
Au Nanoparticles ◽  
Hole Capture ◽  
Insight Into

Partial insight into the reaction mechanism of the photooxidation of 2-propanol over Au/TiO2. 2-Propanol is activated by hole capture and converted to acetone requiring the presence of O2 as an electron acceptor. The deposited Au nanoparticles are assumed to facilitate the electron transfer from the TiO2 conduction band to adsorbed O2.

scholarly journals Bacterial microcompartments linked to the flavin-based extracellular electron transfer drives anaerobic ethanolamine utilization in Listeria monocytogenes

2020 ◽  
Author(s):  
Zhe Zeng ◽  
Sjef Boeren ◽  
Varaang Bhandula ◽  
Samuel H. Light ◽  
Eddy J. Smid ◽  
...  
Keyword(s):  
Electron Transfer ◽  
Listeria Monocytogenes ◽  
Electron Acceptor ◽  
Cell Membranes ◽  
Anaerobic Growth ◽  
Extracellular Electron Transfer ◽  
Severe Illness ◽  
Redox Imbalance ◽  
Bacterial Microcompartments

AbstractEthanolamine (EA) is a valuable microbial carbon and nitrogen source derived from phospholipids present in cell membranes. EA catabolism is suggested to occur in so-called bacterial microcompartments (BMCs) and activation of EA utilization (eut) genes is linked to bacterial pathogenesis. Despite reports showing that activation of eut in Listeria monocytogenes is regulated by a vitamin B12-binding riboswitch and that upregulation of eut genes occurs in mice, it remains unknown whether EA catabolism is BMC dependent. Here, we provide evidence for BMC-dependent anaerobic EA utilization via metabolic analysis, proteomics and electron microscopy. First, we show B12-induced activation of the eut operon in L. monocytogenes coupled to uptake and utilization of EA thereby enabling growth. Next, we demonstrate BMC formation in conjunction to EA catabolism with the production of acetate and ethanol in a molar ratio of 2:1. Flux via the ATP generating acetate branch causes an apparent redox imbalance due to reduced regeneration of NAD+ in the ethanol branch resulting in a surplus of NADH. We hypothesize that the redox imbalance is compensated by linking eut BMC to anaerobic flavin-based extracellular electron transfer (EET). Using L. monocytogenes wild type, a BMC mutant and a EET mutant, we demonstrate an interaction between BMC and EET and provide evidence for a role of Fe3+ as an electron acceptor. Taken together, our results suggest an important role of anaerobic BMC-dependent EA catabolism in the physiology of L. monocytogenes, with a crucial role for the flavin-based EET system in redox balancing.IMPORTANCEListeria monocytogenes is a food-borne pathogen causing severe illness and, as such, it is crucial to understand the molecular mechanisms contributing to pathogenicity. One carbon source that allows L. monocytogenes to grow in humans is ethanolamine (EA), which is derived from phospholipids present in eukaryotic cell membranes. It is hypothesized that EA utilization occurs in bacterial microcompartments (BMCs), self-assembling subcellular proteinaceous structures and analogs of eukaryotic organelles. Here, we demonstrate that BMC-driven utilization of EA in L. monocytogenes results in increased energy production essential for anaerobic growth. However, exploiting BMCs and the encapsulated metabolic pathways also requires balancing of oxidative and reductive pathways. We now provide evidence that L. monocytogenes copes with this by linking BMC activity to flavin-based extracellular electron transfer (EET) using iron as an electron acceptor. Our results shed new light on an important molecular mechanism that enables L. monocytogenes to grow using host-derived phospholipid degradation products.

New Insight into the Role of Gold Nanoparticles in Au@CdS Core-Shell Nanostructures for Hydrogen Evolution

Small ◽  
2014 ◽  
Vol 10 (22) ◽  
pp. 4664-4670 ◽  
Author(s):  
Xiang Ma ◽  
Kun Zhao ◽  
Hongjie Tang ◽  
Ying Chen ◽  
Chenguang Lu ◽  
...  
Keyword(s):  
Gold Nanoparticles ◽  
Hydrogen Evolution ◽  
Core Shell ◽  
Shell Nanostructures ◽  
Insight Into

Electrochemical impedance spectroscopy study of electron transfer at poly(3,4-ethylenedioxythiophene) containing gold nanoparticles coating

2011 ◽  
Vol 76 (12) ◽  
pp. 1433-1445
Author(s):  
Stelian Lupu
Keyword(s):  
Gold Nanoparticles ◽  
Electron Transfer ◽  
Electrochemical Impedance Spectroscopy ◽  
Impedance Spectroscopy ◽  
Au Nanoparticles ◽  
Electrochemical Impedance ◽  
Electrochemical Polymerization ◽  
Composite Coatings ◽  
Supporting Electrolyte ◽  
Transfer Resistance

Electrochemical impedance spectroscopy (EIS) was used for characterization of electron transfer in various redox probes, such as the redox couple ferrocyanide-ferricyanide, ferrocene, ferrocenemethanol, and the poly(3,4-ethylenedioxythiophene) (PEDOT) conducting polymer containing gold nanoparticles. The PEDOT coating was deposited onto platinum (Pt) and glassy carbon (GC) electrodes by galvanostatic electrochemical polymerization from an aqueous solution containing 10–2 M EDOT and 10–1 M LiClO4 as supporting electrolyte. The PEDOT-Au nanoparticles composite coating was prepared by droplet deposition of Au nanoparticles on top of the Pt/PEDOT and GC/PEDOT modified electrodes. The pure PEDOT and PEDOT-Au nanoparticles composite coatings were investigated using EIS and cyclic voltammetry (CV) in 10–1 M LiClO4 solution containing various redox probes. The impedance spectra were recorded at the formal redox potential of the redox probes. The charge transfer resistance (Rct), solution resistance (Rs), exchange current density (i0), standard rate constant (k0), and double-layer capacitance (Cdl) were calculated from the EIS data.

scholarly journals Easy colorimetric detection of gadolinium ions based on gold nanoparticles: key role of phosphine-sulfonate ligands

2020 ◽  
Vol 2 (10) ◽  
pp. 4671-4681
Author(s):  
Marjorie Yon ◽  
Claire Pibourret ◽  
Jean-Daniel Marty ◽  
Diana Ciuculescu-Pradines
Keyword(s):  
Gold Nanoparticles ◽  
Au Nanoparticles ◽  
Colorimetric Detection ◽  
Specific Interactions

Specific interactions between sulfonate groups of phosphine-sulfonate ligands on the surface of Au nanoparticles and Gd3+ ions allow the colorimetric detection of Gd3+ ions at the μM level.

Photoreduction of Silver Salts Using Au Nanoparticles to Form a Core-Shell-Type Nanostructure: Insight into the Reaction Mechanism

Plasmonics ◽  
2014 ◽  
Vol 9 (4) ◽  
pp. 945-949 ◽  
Author(s):  
Xiaojuan Chen ◽  
Rui Wen ◽  
Lisheng Zhang ◽  
Abhishek Lahiri ◽  
Peijie Wang ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Au Nanoparticles ◽  
Core Shell ◽  
Silver Salts ◽  
Shell Type ◽  
Insight Into
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