Non-enzymatic degradation of carbon nanotubes in the presence of bacterial enzymes

2021 ◽  
Author(s):  
Katsutoshi Hori ◽  
Seira Takahashi ◽  
Fumiko Taguchi
Keyword(s):  
Carbon Nanotubes ◽  
Fenton Reaction ◽  
Enzymatic Degradation ◽  
Environmental Fate ◽  
Chelating Agent ◽  
Heme Enzymes ◽  
Optical Absorbance ◽  
Heme Enzyme ◽  
Metabolic Systems ◽  
Wide Range

The enzymatic degradation of carbon nanotubes (CNTs) by several enzymes has been reported. However, because organisms that possess these enzymes have limited habitats and distribution areas, it is unclear whether CNTs can be degraded in the general environment. The investigation of CNTs degradation by enzymes derived from bacteria, which inhabit a wide range of environments and have diverse metabolic systems, is inevitable for predicting the environmental fate of CNTs. In this study, the degradation of oxidized (carboxylated) single-walled CNTs (O-SWCNTs) by mt2DyP, a dye-decolorizing peroxidase of Pseudomonas putida mt-2, a common soil bacterium, was investigated. Suspensions of O-SWCNTs gradually became transparent and their optical absorbance decreased during 30 d of incubation in the presence of mt2DyP produced by a recombinant Brevibacillus choshinensis strain and its substrate, H2O2. The degradation was enhanced by higher H2O2 concentrations. The measurement of Raman spectra revealed the complete degradation of O-SWCNTs after 30 d of incubation with 100 mM H2O2. However, surprisingly, this heme enzyme was inactivated within 60 min of the incubation with O-SWCNTs, which suggested that the degradation of O-SWCNTs was not catalyzed by the enzyme. The inactivation of mt2DyP was accompanied by the release of iron, which suggested that the degradation of the O-SWCNTs was owing to the Fenton reaction caused by the iron released from mt2DyP and the supplied H2O2. A chelating agent, diethylenetriaminepentaacetic acid, significantly inhibited the O-SWCNTs degradation, proving the degradation by the Fenton reaction. These phenomena were also observed with another heme enzyme, Cytochrome P450. These results are important for predicting the fate of CNTs in a wide range of environments, as heme enzymes are secreted by many bacteria in the environment. This study also shows that the effect of the Fenton reaction should be considered to validate the degradation of CNTs by heme enzymes.

scholarly journals A New Method for Dispersing Pristine Carbon Nanotubes Using Regularly Arranged S-Layer Proteins

Nanomaterials ◽  
2021 ◽  
Vol 11 (5) ◽  
pp. 1346
Author(s):  
Andreas Breitwieser ◽  
Uwe B. Sleytr ◽  
Dietmar Pum
Keyword(s):  
Carbon Nanotubes ◽  
Covalent Modification ◽  
Silica Layer ◽  
Medical Sciences ◽  
Lysinibacillus Sphaericus ◽  
Wide Range ◽  
Catalytic Sites ◽  
Multi Walled Carbon Nanotubes ◽  
Pristine Mwnts ◽  
Walled Carbon Nanotubes

Homogeneous and stable dispersions of functionalized carbon nanotubes (CNTs) in aqueous solutions are imperative for a wide range of applications, especially in life and medical sciences. Various covalent and non-covalent approaches were published to separate the bundles into individual tubes. In this context, this work demonstrates the non-covalent modification and dispersion of pristine multi-walled carbon nanotubes (MWNTs) using two S-layer proteins, namely, SbpA from Lysinibacillus sphaericus CCM2177 and SbsB from Geobacillus stearothermophilus PV72/p2. Both the S-layer proteins coated the MWNTs completely. Furthermore, it was shown that SbpA can form caps at the ends of MWNTs. Reassembly experiments involving a mixture of both S-layer proteins in the same solution showed that the MWNTs were primarily coated with SbsB, whereas SbpA formed self-assembled layers. The dispersibility of the pristine nanotubes coated with SbpA was determined by zeta potential measurements (−24.4 +/− 0.6 mV, pH = 7). Finally, the SbpA-coated MWNTs were silicified with tetramethoxysilane (TMOS) using a mild biogenic approach. As expected, the thickness of the silica layer could be controlled by the reaction time and was 6.3 +/− 1.25 nm after 5 min and 25.0 +/− 5.9 nm after 15 min. Since S-layer proteins have already demonstrated their capability to bind (bio)molecules in dense packing or to act as catalytic sites in biomineralization processes, the successful coating of pristine MWNTs has great potential in the development of new materials, such as biosensor architectures.

scholarly journals Metal Organic Frameworks Derived Fe-N-C Nanostructures as High-Performance Electrodes for Sodium Ion Batteries and Electromagnetic Interference (EMI) Shielding

Molecules ◽  
2021 ◽  
Vol 26 (4) ◽  
pp. 1018
Author(s):  
Vadahanambi Sridhar ◽  
Inwon Lee ◽  
Hyun Park
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Electromagnetic Interference ◽  
Sodium Ion ◽  
Iron Nitride ◽  
Sodium Ion Batteries ◽  
Nitrogen Doped ◽  
Wide Range ◽  
Metal Organic ◽  
Nitrogen Doped Carbon

Metal organic framework (MOF)-derived carbon nanostructures (MDC) synthesized by either calcinations or carbonization or pyrolysis are emerging as attractive materials for a wide range of applications like batteries, super-capacitors, sensors, water treatment, etc. But the process of transformation of MOFs into MDCs is time-consuming, with reactions requiring inert atmospheres and reaction time typically running into hours. In this manuscript, we report the transformation of 1,4-diazabicyclo[2.2.2]octane, (DABCO)-based MOFs into iron nitride nanoparticles embedded in nitrogen-doped carbon nanotubes by simple, fast and facile microwave pyrolysis. By using graphene oxide and carbon fiber as microwave susceptible surfaces, three-dimensional nitrogen-doped carbon nanotubes vertically grown on reduced graphene oxide (MDNCNT@rGO) and carbon fibers (MDCNT@CF), respectively, were obtained, whose utility as anode material in sodium-ion batteries (MDNCNT@rGO) and for EMI (electromagnetic interference) shielding material (MDCNT@CF) is reported.

Fungal melanins: a review

1998 ◽  
Vol 44 (12) ◽  
pp. 1115-1136 ◽  
Author(s):  
M J Butler ◽  
A W Day
Keyword(s):  
Molecular Biology ◽  
Analytical Methods ◽  
Enzymatic Degradation ◽  
Fundamental Properties ◽  
Wide Range ◽  
Lignin Peroxidases ◽  
Fungal Melanin ◽  
Relationship Of ◽  
The Relationship ◽  
Fungal Melanins

The relationship of polyketide melanogenesis molecular biology to that of nonmelanin-producing pathways in a wide range of fungi and other organisms is discussed. Analytical methods and fundamental properties of melanins are discussed and fungal melanin properties are compared with those of animal and bacterial melanins. The enzymatic degradation of melanins by lignin peroxidases is described.Key words: fungal melanin, polyketide melanin, DHN melanin, melanin degradation, melanin properties, melanin analysis.

scholarly journals Environmental fate of multiwalled carbon nanotubes and graphene oxide across different aquatic ecosystems

NanoImpact ◽  
2019 ◽  
Vol 13 ◽  
pp. 1-12 ◽  
Author(s):  
Brian Avant ◽  
Dermont Bouchard ◽  
Xiaojun Chang ◽  
Hsin-Se Hsieh ◽  
Brad Acrey ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Graphene Oxide ◽  
Multiwalled Carbon Nanotubes ◽  
Aquatic Ecosystems ◽  
Environmental Fate ◽  
Multiwalled Carbon

scholarly journals An investigation into the free vibrations of carbon nanotubes using analytical and finite element methods

2021 ◽  
Author(s):  
Ishan Ali Khan
Keyword(s):  
Carbon Nanotubes ◽  
Finite Element ◽  
Eigenvalue Problem ◽  
Natural Frequencies ◽  
Nonlinear Eigenvalue Problem ◽  
Dynamic Stiffness ◽  
Free Vibrations ◽  
Mode Shapes ◽  
Wide Range ◽  
Walled Cnts

Since their discovery, immense attention has been given to carbon nanotubes (CNTs), due to their exceptional thermal, electronic and mechanical properties and, therefore, the wide range of applications in which they are, or can be potentially, employed. Hence, it is important that all the properties of carbon nanotubes are studied extensively. This thesis studies the vibrational frequencies of double-walled and triple-walled CNTs, with and without an elastic medium surrounding them, by using Finite Element Method (FEM) and Dynamic Stiffness Matrix (DSM) formulations, considering them as Euler-Bernoulli beams coupled with van der Waals interaction forces. For FEM modelling, the linear eigenvalue problem is obtained using Galerkin weighted residual approach. The natural frequencies and mode shapes are derived from eigenvalues and eigenvectors, respectively. For DSM formulation of double-walled CNTs, a nonlinear eigenvalue problem is obtained by enforcing displacement and load end conditions to the exact solution of single equation achieved by combining the coupled governing equations. The natural frequencies are obtained using Wittrick-Williams algorithm. FEM formulation is also applied to both double and triple-walled CNTs modelled as nonlocal Euler-Bernoulli beam. The natural frequencies obtained for all the cases, are in agreement with the values provided in literature.

The Multifunctional Composite on the Base of Carbon Nanotubes Network and its Use as a Passive Antenna and Gas Sensing Element

2014 ◽  
Vol 605 ◽  
pp. 322-325
Author(s):  
Robert Olejnik ◽  
Jiri Matyas ◽  
Petr Slobodian ◽  
Karel Vlcek
Keyword(s):  
Carbon Nanotubes ◽  
Gas Sensing ◽  
Aqueous Suspension ◽  
Multiwall Carbon Nanotubes ◽  
Sensing Element ◽  
Vapor Detection ◽  
Filtration Method ◽  
Wide Range ◽  
Passive Antenna ◽  
Nonpolar Organic

Carbon nanotubes in the form of entangled network can be used as a multifunctional composite material for a wide range of using. A new and perspective usage is a passive antenna and gas sensing element. The antenna works well at 1.284 GHz. The local reflection minimum is 11.48 dB. The reflection coefficient r=0.2667. The transmission power in this frequency is 93%. Multiwall carbon nanotubes (MWCNT) network Buckypaper was made by the vacuum filtration method of MWCNT aqueous suspension. The sensitivity of multi-wall carbon nanotube (MWCNT) networks of randomly entangled pure and HNO3 oxidized nanotubes to polar and nonpolar organic vapors (ethanol, heptane), has been investigated by resistance measurements. The results demonstrate that the network electrical resistance increases when exposed to organic solvent vapors, and a reversible reaction is observed when the sample is removed from the vapors. The investigated MWCNT networks could be potentially used as sensing elements for sensitive and selective organic vapor detection.

Understanding enzymatic degradation of single-walled carbon nanotubes triggered by functionalization using molecular dynamics simulation

2017 ◽  
Vol 4 (3) ◽  
pp. 720-727 ◽  
Author(s):  
Ming Chen ◽  
Guangming Zeng ◽  
Piao Xu ◽  
Yi Zhang ◽  
Danni Jiang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Molecular Dynamics ◽  
Molecular Dynamics Simulation ◽  
Horseradish Peroxidase ◽  
Enzymatic Degradation ◽  
Single Walled Carbon Nanotubes ◽  
Dynamics Simulation ◽  
Single Walled Carbon ◽  
Degrading Enzymes ◽  
Walled Carbon Nanotubes

Interactions of SWCNTs with their degrading enzymes (horseradish peroxidase and lactoperoxidase) during biodegradation.

Relationship between soil composition and retention capacity of terbumeton onto chalky soils

2009 ◽  
Vol 6 (3) ◽  
pp. 245 ◽  
Author(s):  
Achouak El Arfaoui ◽  
Stéphanie Sayen ◽  
Eric Marceau ◽  
Lorenzo Stievano ◽  
Emmanuel Guillon ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Properties ◽  
Environmental Fate ◽  
Organic Matter Content ◽  
Calcareous Soils ◽  
Matter Content ◽  
Soil Composition ◽  
Retention Capacity ◽  
Wide Range ◽  
Soil Components

Environmental context. The wide use of pesticides for pest and weed control contributes to their presence in underground and surface waters, which has led to a continuously growing interest in their environmental fate. Soils play a key role in the transfer of these compounds from the sprayer to the water as a result of their capacity to retain pesticides depending on the soil components. The knowledge of soil composition should enable one to predict pesticide behaviour in the environment. Abstract. Eight calcareous soils of Champagne vineyards (France) were studied to investigate the adsorption of the herbicide terbumeton (TER). A preliminary characterisation of the soil samples using X-ray diffraction (XRD), elemental and textural analyses, revealed a wide range of soil properties for the selected samples. The adsorption isotherms of TER were plotted for all samples. The determination of soil properties, which significantly correlated with the Kd distribution coefficient, allowed identification of organic matter and CaCO3 as the two main soil components that govern the retention of the herbicide. Organic matter was the predominant phase involved in the retention but its role was limited by the presence of calcite. Finally, the ratio of CaCO3 content to organic matter content was proposed as a useful parameter to predict the adsorption of terbumeton in chalky soils. The evolution of Kd as a function of this ratio was successfully described using an empirical model.

Cytochemische Untersuchungen zur Reproduktion des Tabakmosaikvirus

1961 ◽  
Vol 16 (8) ◽  
pp. 520-538 ◽  
Author(s):  
Hendrik Zech
Keyword(s):  
Electric Fields ◽  
Uv Light ◽  
Refraction Index ◽  
Optical Measurements ◽  
Uv Spectrophotometry ◽  
X Rays ◽  
Optical Absorbance ◽  
Wide Range ◽  
Light Losses

Crystalline or paracrystalline tobacco mosaic virus (TMV) inclusions are known to be composed mainly of densely packed TMV-rods. These inclusions were studied in situ within infected tobacco leaf hair cells by scanning UV-microspectrophotometry. Comparative measurements in the macroand micro ranges of the instruments were carried out on purified TMV at low and high concentrations, on its separated and reconstituted RNA and protein parts and on isolated TMV-crystals, to permit the interpretation of the optical properties of TMV inclusions in situ. The optical absorbance of TMV in solution and in dried concentrates at room temperature could in part be attributed to distribution inhomogeneities caused by local particle aggregations being oriented to differing degrees. The resulting non-uniform electric fields around and within such unevenly distributed particle complexes caused local jumps of the refraction index and thereby unspecific light losses, chiefly through scattering. The apparent deviation from Beers law was found to be greatest at particle concentrations of 1 - 2 per cent. At higher concentrations the contribution of scatter to light losses was found to decrease again, probably because of increasing order of particles within the aggregates. On the other hand the specific absorbance of the chromophores of TMV over a wide range of concentration was not affected to a measurable degree by changing the distances between the rods. There was no indication that the charged groups of the RNA-cores within intact particles interacted with charged groups of other particles however great their proximity. The ribose phosphate backbone of the RNA strand, deeply embedded within the protein helix, may account for this phenomenon. However, isolated TMV-RNA reacted strongly to changes of the surrounding electric fields when concentrations were varied, and showed pronounced hypochromicity at higher concentrations and following prolonged irridation by x-rays and UV-light. RNA in dried and irradiated droplets was characterized by up to 55% lower extinction coefficients than freshly prepared RNA in solution. The hyprochromic effects caused by irradiation were shown to be almost, but not completely reversible. Hypochromicity increased towards the shorter wavelengths, diminishing the ratio E260/E280 from about 2.0 for diluted RNA to 1.4 for concentrated specimens. Mixing TMV-protein subunits with RNA before drying, leading to partial reconstitution of TMV particles, diminished the hypochromic effect resulting from irradiation of the concentrate. High UV-radiation doses applied to concentrated TMV solutions led to a marked splitting of RNA from protein, as revealed by UV-spectrophotometry of the supernatants and pellets of centrifuged irradiated specimens. Model measurements of intracellular and subsequently isolated TMV crystals combined with empirically derived parameters led to the construction of a correction curve, permitting interpretations of optical measurements on in situ TMV inclusion bodies.

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