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<span style="font-size:15.0pt;mso-bidi-font-size: 14.0pt;mso-bidi-font-weight:bold" lang="EN-US">Immobilization of cellulase on TiO<sub>2 </sub>nanoparticles by physical and covalent methods: A comparative study </span>

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Title Immobilization of cellulase on TiO2 nanoparticles by physical and covalent methods: A comparative study
 
Creator Ahmad, Razi
Sardar, Meryam
 
Subject Cellulase
Adsorption
Covalent attachment
Aminopropyltriethoxysilane
TiO2 nanoparticles
 
Description 314-320
Immobilization of cellulase from Aspergillus niger on
TiO2 nanoparticles was studied by two different
approaches — physical adsorption and covalent coupling. A. niger was
selected, as it is generally non-pathogenic, is found in nature in the broad
range of habitats and produces cellulase extracellulary. For covalent method,
TiO2 nanoparticles were modified with aminopropyltriethoxysilane
(APTS). The adsorbed and covalently immobilized enzymes showed 76% and 93%
activity, respectively, as compared to the free enzyme. The catalytic
efficiency Vmax/Km increased from
0.4 to 4.0 after covalent attachment, whereas in adsorption method, it
increased slightly from 0.4 to 1.2. The covalently-immobilized and adsorbed
cellulase lost only 25% and 50% of their activity, respectively after 60 min of
incubation at 75°C. The reusability and operational stability data also showed
that covalent coupling increased the stability of the enzyme. The presence of
enzyme on TiO2 nanoparticles was confirmed by Fourier-transform
infrared spectroscopy. The high-resolution transmission electron microscopy (HR-TEM)
and atomic force microscopy (AFM) studies indicated aggregation of enzyme when
adsorbed on TiO2 surface and a monolayer of enzyme in covalent
attachment. In conclusion, covalently attached cellulase retained good activity
and thermal stability, as compared to physically adsorbed enzyme. The lower
amount of enzyme activity and thermal stability in case of physically adsorbed
immobilized enzyme was due to aggregation of the enzyme after adsorption on TiO2
nanoparticles, as revealed by HR-TEM and AFM. Thus, TiO2
nanoparticles could be suitable candidates for immobilization of cellulase for
industrial applications like paper, textile, detergent and food industries.
 
Date 2014-09-03T04:21:53Z
2014-09-03T04:21:53Z
2014-08
 
Type Article
 
Identifier 0975-0959 (Online); 0301-1208 (Print)
http://hdl.handle.net/123456789/29326
 
Language en_US
 
Rights CC Attribution-Noncommercial-No Derivative Works 2.5 India
 
Publisher NISCAIR-CSIR, India
 
Source IJBB Vol.51(4) [August 2014]