scholarly journals Superior operational stability of immobilized l-asparaginase over surface-modified carbon nanotubes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Mafalda R. Almeida ◽  
Raquel O. Cristóvão ◽  
Maria A. Barros ◽  
João C. F. Nunes ◽  
Rui A. R. Boaventura ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Operating Conditions ◽  
Operational Stability ◽  
Free Form ◽  
Consecutive Reaction ◽  
Multi Walled Carbon Nanotubes ◽  
Activity Loss ◽  
Surface Modified ◽  
Modified Carbon Nanotubes ◽  
Functionalized Mwcnts

Abstractl-asparaginase (ASNase, EC 3.5.1.1) is an enzyme that catalyzes the l-asparagine hydrolysis into l-aspartic acid and ammonia, being mainly applied in pharmaceutical and food industries. However, some disadvantages are associated with its free form, such as the ASNase short half-life, which may be overcome by enzyme immobilization. In this work, the immobilization of ASNase by adsorption over pristine and modified multi-walled carbon nanotubes (MWCNTs) was investigated, the latter corresponding to functionalized MWCNTs through a hydrothermal oxidation treatment. Different operating conditions, including pH, contact time and ASNase/MWCNT mass ratio, as well as the operational stability of the immobilized ASNase, were evaluated. For comparison purposes, data regarding the ASNase immobilization with pristine MWCNT was detailed. The characterization of the ASNase-MWCNT bioconjugate was addressed using different techniques, namely Transmission Electron Microscopy (TEM), Thermogravimetric Analysis (TGA) and Raman spectroscopy. Functionalized MWCNTs showed promising results, with an immobilization yield and a relative recovered activity of commercial ASNase above 95% under the optimized adsorption conditions (pH 8, 60 min of contact and 1.5 × 10–3 g mL−1 of ASNase). The ASNase-MWCNT bioconjugate also showed improved enzyme operational stability (6 consecutive reaction cycles without activity loss), paving the way for its use in industrial processes.

scholarly journals Covalent Immobilization of Tyrosinase onto Multi-walled Carbon Nanotubes and Its Potential Use In Phenol Biosensing

2014 ◽  
Vol 7 (1) ◽  
Author(s):  
Shafinaz Shahir ◽  
Boon Kai Tai ◽  
Zaiton Abdul Majid ◽  
Nor Aziah Buang
Keyword(s):  
Carbon Nanotubes ◽  
Covalent Immobilization ◽  
Limiting Current ◽  
Reduction Peak ◽  
Covalently Bonded ◽  
Amide Carbonyl ◽  
Multi Walled Carbon Nanotubes ◽  
Surface Modified ◽  
Walled Carbon Nanotubes ◽  
Functionalized Mwcnts

The possibility of modifying the surface properties of multi-walled carbon nanotubes (MWCNTs) has stimulated increasing interest in their application as components in biosensors. In this sense, it is possible to employ surface modified MWCNTs as support to immobilize biomaterials such as enzymes. In this study the enzyme tyrosinase was immobilized onto functionalized MWCNTs (fMWCNTs) via covalent bonding and activity of immobilized tyrosinase was measured via electrochemical detection of phenol. MWCNTs were first treated with sulphuric acid and nitric acid with ratio 1 : 3 at 70ºC to introduce carboxylated groups (-COOH). The carboxyl moieties were then activated by treatment with a cross-linker, 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide (EDC) to enable tyrosinase immobilization via amide bonding. FTIR spectra of tyrosinase immobilized fMWCNTs showed the presence of peaks attributing to aliphatic C-N (1382 cm-1) and amide carbonyl (1639 cm-1) vibrations which confirmed successful covalent immobilization of tyrosinase onto fMWCNTs. Electrochemical measurements using tyrosinase-fMWCNTS-CPE revealed increasing limiting current values of reduction peak with increasing phenol concentrations at -200mV. The appearance of the reduction current indicates that the immobilization process retained the biological activity of the covalently bonded tyrosinase on fMWCNTs surface. This study has demonstrated the potential of using MWCNTs as support for enzyme immobilization and their application in biosensor technology.

A strategy for improving peroxidase stability via immobilization on surface modified multi-walled carbon nanotubes

2015 ◽  
Vol 90 (9) ◽  
pp. 1570-1578 ◽  
Author(s):  
Renato M Azevedo ◽  
João B Costa ◽  
Philippe Serp ◽  
José M Loureiro ◽  
Joaquim L Faria ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Multi Walled Carbon Nanotubes ◽  
Surface Modified ◽  
Walled Carbon Nanotubes

scholarly journals Multifunctional Ionogels Incorporated with Lanthanide (Eu3+, Tb3+) Complexes Covalently Modified Multi-Walled Carbon Nanotubes

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1099 ◽  
Author(s):  
Qiuping Li
Keyword(s):  
Carbon Nanotubes ◽  
Ionic Liquids ◽  
Uv Light ◽  
Green Emission ◽  
Sem Images ◽  
Hybrid Gels ◽  
Multi Walled Carbon Nanotubes ◽  
Electric Materials ◽  
Walled Carbon Nanotubes ◽  
Functionalized Mwcnts

Ionogels refer to an emerging composite material made from the confinement of ionic liquids within some specific cross-linked network matrices. They have potential applications in areas such as electrochemical and optical-electric materials. Incorporation of lanthanide (Eu3+, Tb3+) complexes covalently functionalized multi-walled carbon nanotubes (MWCNTs) in ionogels provide new ideas to design and synthesize novel luminescent hybrid materials that have excellent characteristics of luminescence and ionic conductivity. Here, the multifunctional ionogels were synthesized by confining an ionic liquid and the rare earth functionalized MWCNTs in the cross-linked polymethyl methacrylate (PMMA) networks, resulting in a novel optical/electric multifunctional hybrid material. The SEM images and digital photographs suggest that the lanthanide functionalized MWCNTs are evenly dispersed in the hybrid matrices, thus leading to a certain transparency bulky gel. The resulting ionogels exhibit certain viscosity and flexibility, and display an intense red/green emission under UV-light irradiation. The intrinsic conductibility of the embedded ionic liquids and carbon nanotubes in conjunction with the outstanding photoluminescent properties of lanthanide complexes makes the soft hybrid gels a material with great potential and valuable application in the field of optical-electric materials.

A novel strategy for the synthesis of sulfur-doped carbon nanotubes as a highly efficient Pt catalyst support toward the methanol oxidation reaction

2017 ◽  
Vol 5 (36) ◽  
pp. 19467-19475 ◽  
Author(s):  
Jing-Jing Fan ◽  
You-Jun Fan ◽  
Rui-Xiang Wang ◽  
Sheng Xiang ◽  
Hua-Guo Tang ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Oxidation Reaction ◽  
Catalyst Support ◽  
Pt Nanoparticles ◽  
Pt Catalyst ◽  
Methanol Oxidation Reaction ◽  
Multi Walled Carbon Nanotubes ◽  
Novel Strategy ◽  
Walled Carbon Nanotubes ◽  
Functionalized Mwcnts

Sulfur-doped multi-walled carbon nanotubes (S-MWCNTs) derived from PEDOT-functionalized MWCNTs can significantly improve the dispersion of supported Pt nanoparticles and enhance their electrocatalytic performance for the MOR.

scholarly journals Application of Functionalized Multi-Walled Carbon Nanotubes for Growth Enhancement of Mustard Seed Germination

2019 ◽  
Vol 20 (1) ◽  
pp. 120
Author(s):  
Agus Subagio ◽  
Erma Prihastanti ◽  
Ngadiwiyana Ngadiwiyana
Keyword(s):  
Carbon Nanotubes ◽  
Mustard Seed ◽  
Growth Enhancement ◽  
Beneficial Effects ◽  
Carboxylic Groups ◽  
Multi Walled Carbon Nanotubes ◽  
Inner Diameter ◽  
Walled Carbon Nanotubes ◽  
Functionalized Mwcnts ◽  
Mustard Seeds

Multi-walled carbon nanotubes (MWCNTs) are one of the nanomaterials that can be applied to agriculture. This work investigates the beneficial effects of MWCNT function on mustard plants. In this study, the material of MWCNTs is functionalized with nitric acid to attach the carboxylic group onto the tube wall. The functionalized MWCNTs were characterized by SEM, TEM, XRD, and FTIR. The MWCNT diameter produced ranges from 20 to 50 nm and the inner diameter is 5 to 10 nm at the pyrolysis temperature of 900 °C. It was found that crystallites of the MWCNTs have (002) and (100) directions. There is a weak peak in MWCNTs prior to the functionalization process due to the presence of metal carbide (Fe3C), which serves as an active catalyst. FTIR results clearly indicate the presence of hydroxyl and carboxylic groups. These functionalized MWCNTs were dispersed into distilled water with various concentrations at 25, 50 and 75 µg/mL. By utilizing an immersion time of 24 h, mustard (Brassica juncea) seeds were soaked in each functionalized and non-functionalized MWCNT solution. Functionalized MWCNT solution at a concentration of 50 µg/mL was found to affect the growth of mustard seeds more significantly.

Pebax-1657 mixed matrix membrane containing surface modified multi-walled carbon nanotubes for gas separation

RSC Advances ◽  
2016 ◽  
Vol 6 (83) ◽  
pp. 79563-79577 ◽  
Author(s):  
S. A. Habibiannejad ◽  
A. Aroujalian ◽  
A. Raisi
Keyword(s):  
Carbon Nanotubes ◽  
Carbon Nanotube ◽  
Functional Groups ◽  
Gas Separation ◽  
Mixed Matrix Membrane ◽  
Mixed Matrix ◽  
Multi Walled Carbon Nanotubes ◽  
Surface Modified ◽  
Walled Carbon Nanotubes

In this study different functional groups on the surface of carbon nanotube enhanced the performance of Pebax 1657/MWNTs.

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