scholarly journals Covalent Immobilization of β-Glucosidase into Mesoporous Silica Nanoparticles from Anhydrous Acetone Enhances Its Catalytic Performance

Nanomaterials ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 108 ◽  
Author(s):  
Filomena Sannino ◽  
Aniello Costantini ◽  
Francesco Ruffo ◽  
Antonio Aronne ◽  
Virginia Venezia ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Conformational Changes ◽  
Mesoporous Silica Nanoparticles ◽  
Covalent Binding ◽  
Cellulose Hydrolysis ◽  
Catalytic Performance ◽  
Covalent Immobilization ◽  
Free Enzyme ◽  
Anhydrous Acetone ◽  
Km Value

An immobilization protocol of a model enzyme into silica nanoparticles was applied. This protocol exploited the use of the bifunctional molecule triethoxysilylpropylisocyanate (TEPI) for covalent binding through a linker of suitable length. The enzyme β-glucosidase (BG) was anchored onto wrinkled silica nanoparticles (WSNs). BG represents a bottleneck in the conversion of lignocellulosic biomass into biofuels through cellulose hydrolysis and fermentation. The key aspect of the procedure was the use of an organic solvent (anhydrous acetone) in which the enzyme was not soluble. This aimed to restrict its conformational changes and thus preserve its native structure. This approach led to a biocatalyst with improved thermal stability, characterized by high immobilization efficiency and yield. It was found that the apparent KM value was about half of that of the free enzyme. The Vmax was about the same than that of the free enzyme. The biocatalyst showed a high operational stability, losing only 30% of its activity after seven reuses.

Facile One-Step Dialysis Strategy for Preparation of Porous Silica Nanoparticles with Rough Surface

NANO ◽  
2020 ◽  
Vol 15 (03) ◽  
pp. 2050038
Author(s):  
Zhe Chen ◽  
Jiaqiong Xu ◽  
Xuechen Xiang ◽  
Dongfang Ren ◽  
Ning Chen ◽  
...  
Keyword(s):  
Silica Nanoparticles ◽  
Rough Surface ◽  
Mesoporous Silica Nanoparticles ◽  
Porous Silica ◽  
Catalytic Performance ◽  
Ammonia Solution ◽  
Type Iv ◽  
Organic Surfactant ◽  
One Step ◽  
Adsorption Desorption

In this study, porous silica nanoparticles were fabricated in the absence of organic surfactant template at room temperature by a facile one-step dialysis method. By using a dialysis system comprising an ammonia solution as the dialysate, a series of porous silica nanoparticles with a rough surface (e.g., raspberry-like) were obtained by the initiation of a homogeneous ternary tetraethylsilicate-water-ethanol system with different ammonia solution concentrations. The specific surface area and pore volume of porous nanoparticles were regulated by changing the dialysate concentrations. N2 adsorption–desorption measurements revealed that the porous silica nanoparticles owned both mesopores and micropores and exhibited a type IV isotherm, hence, these nanoparticles can be used as mesoporous silica nanoparticles (MSNs). The Au@MSN nanocomposite can be used as a catalyst for the typical reduction of 4-nitrophenol to 4-aminophenol by NaBH4 and exhibited excellent catalytic performance.

Three-phase partitioning and immobilization of Bacillus methylotrophicus Y37 cellulase on organo-bentonite and its kinetic and thermodynamic properties

Clay Minerals ◽  
2020 ◽  
Vol 55 (2) ◽  
pp. 120-131
Author(s):  
Yonca Avci Duman ◽  
A. Uğur Kaya ◽  
Çiğdem Yağci
Keyword(s):  
Immobilized Enzyme ◽  
Maximum Velocity ◽  
Catalytic Performance ◽  
Covalent Immobilization ◽  
Single Step ◽  
Free Enzyme ◽  
Phase Partitioning ◽  
Bacillus Methylotrophicus ◽  
Three Phase ◽  
First Time

AbstractIn this study, for the first time Bacillus methylotrophicus Y37 cellulase was purified and recovered in a single step by three-phase partitioning (TPP). The optimal purification parameters for TPP were 40% ammonium sulfate saturation (m/v) with a 1.0:1.0 (v/v) ratio of crude extract:t-butanol, which gave 5.8-fold purification with 155% recovery of cellulase. Non-covalent immobilization of the partitioned cellulase was performed using bentonite as a support material. The activity observed in the 20th experiment was 100%. The optimal pH values and temperatures determined for the free enzyme and the immobilized enzyme were 5.0 and 6.0 and 45°C and 50°C, respectively. The Arrhenius activation energy (Ea) of the immobilized enzyme was lower than that of the free enzyme, whereas the Michaelis–Menten constant (Km) and maximum velocity (Vm) of the immobilized enzyme increased. The turnover number (kcat) and the catalytic performance (kcat/Km) demonstrated the improved catalytic properties of the immobilized enzyme compared to the free enzyme. Immobilization of cellulase is thermodynamically preferred.

scholarly journals The effect of pore morphology on the catalytic performance of β-glucosidase immobilized into mesoporous silica

2019 ◽  
Vol 91 (10) ◽  
pp. 1583-1592 ◽  
Author(s):  
Valeria Califano ◽  
Aniello Costantini ◽  
Brigida Silvestri ◽  
Virginia Venezia ◽  
Stefano Cimino ◽  
...  
Keyword(s):  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Mesoporous Silica Nanoparticles ◽  
Catalytic Performance ◽  
Morphological Characterization ◽  
Transmission Electron ◽  
Cellobiose Hydrolysis ◽  
Two Samples ◽  
Bet Method ◽  
Key Factor

Abstract β-Glucosidase (BG) was immobilized by adsorption on wrinkled silica nanoparticles (WSNs) and on tannic acid-templated mesoporous silica nanoparticles (TA-MSNPs). The effect induced by a different morphology of the pores of the sorbent on the catalytic performance of β-glucosidase was investigated. A complete textural and morphological characterization of the two samples was performed by Brunauer–Emmett–Teller (BET) method, Fourier Transform Infrared (FT-IR) and transmission electron microscopy (TEM). The results demonstrated that the catalytic performance of the immobilized enzyme depends on the pores size of sorbent but a key factor is the pores morphology. In fact, the BG immobilized on WSNs and TA-MSNPs (BG/WSNs and BG/TA-MSNPs) shows in both cases good catalytic performances in cellobiose hydrolysis, but the catalyst with the best performance is BG/WSNs, in which the support exhibits a central-radial pore structure and a hierarchical trimodal micro-mesoporous pore size. This peculiar morphology allows the enzyme to settle in a place where the interactions with the walls are maximized, increasing its conformational rigidity. Furthermore, the enzyme is prevalently collocated in the interior of pore so that the pores are not completely capped.

scholarly journals Immobilization of Cellulolytic Enzymes in Mesostructured Silica Materials

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 706 ◽  
Author(s):  
Valeria Califano ◽  
Aniello Costantini
Keyword(s):  
Silica Nanoparticles ◽  
Enzyme Stability ◽  
Mesoporous Silica Nanoparticles ◽  
Renewable Energy Sources ◽  
Hydrolytic Enzymes ◽  
Catalytic Efficiency ◽  
Catalytic Performance ◽  
Cellulolytic Enzymes ◽  
Mesostructured Silica ◽  
Enzyme Molecules

Mesostructured silica nanoparticles offer a unique opportunity in the field of biocatalysis thanks to their outstanding properties. The tunable pore size in the range of mesopores allows for immobilizing bulky enzyme molecules. The large surface area improves the catalytic efficiency by increasing enzyme loading and finely dispersing the biocatalyst molecules. The easily tunable pore morphology allows for creating a proper environment to host an enzyme. The confining effect of mesopores can improve the enzyme stability and its resistance to extreme pH and temperatures. Benefits also arise from other peculiarities of nanoparticles such as Brownian motion and easy dispersion. Fossil fuel depletion and environmental pollution have led to the need for alternative sustainable and renewable energy sources such as biofuels. In this context, lignocellulosic biomass has been considered as a strategic fuel source. Cellulases are a class of hydrolytic enzymes that convert cellulose into fermentable sugars. This review is intended to survey the immobilization of cellulolytic enzymes (cellulases and β-glucosidase) onto mesoporous silica nanoparticles and their catalytic performance, with the aim to give a contribution to the urgent action required against climate change and its impacts, by biorefineries’ development.

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