Preparation of Functionalized Mesoporous Silica as a Novel Carrier and Immobilization of Laccase

Abstract

Amino modi ed mesoporous silica (SBA-15-NH 2 ) was prepared by hydrothermal method, which is a kind of excellent carrier for enzyme immobilization. The structure of SBA-15 was characterized by SEM and FTIR, which proved that amino group was successfully attached to the surface of SBA-15. The carrier had good mesoporous structure by nitrogen adsorption and desorption test. Using SBA-15-NH 2 as the carrier, the optimal conditions of laccase immobilization by two different cross-linking methods were explored.At the same time, the properties of immobilized enzyme and free enzyme were compared. The results showed that the activity of immobilized laccase by two-step method (2977.5 U/g) was much higher than that by one-step method (239.5 U/g). The optimal conditions were as follows: free laccase (35℃, pH = 4.5), two-step immobilized laccase (40℃, pH = 4.0), one-step immobilized laccase (35℃, pH = 4.0). The two-step method was more adaptable to temperature. The pH adaptation range of immobilized enzyme was wider, and the thermal stability was greatly enhanced. After ve cycles of repeated reaction, the residual enzyme activity of two-step and one-step methods were 56% and 43% of the original. The treatment of simulated wastewater containing 2,4-dichlorophenol (2,4-DCP) by immobilized laccase was also studied. Under the optimum conditions (40℃, pH = 5.0, 20 mg/L), the removal of 2,4-DCP can reach 89.06%.

Applications and immobilization strategies of the copper-centred laccase enzyme; a review

“…For the case of pesticides and other organic pollutants, bisphenols (A,B and F) [ 183 , 219 , 220 ], chlorophenols [ 22 , 221 , 222 ], triclosan [ 64 , 147 , 195 ], anthracene [ 77 , 223 , 224 ], and other phenolic compounds such as naphthalene [ 17 ], catechol [ 225 ], phenol [ 226 ], and aminophenols [ 227 ]. Other pesticides explored include pyrometryn, atrazine [ 228 ], indole [ 223 ] and chlorpyrifos [ 192 ].…”

“…For large pore sizes, the silanol groups on the surface of the OMS can be activated with functional groups to strengthen the van der Waals interactions or serve as anchoring points for covalent immobilization [ 405 , 461 ]. For example, Yang et al [ 222 ], introduced amino functional groups in the pores of mesoporous silica using APTES and then crosslinked the activated carrier with GA prior to reaction with laccase solution.…”

Expression, characterization, and immobilization of a novel SGNH esterase Est882 and its potential for pyrethroid degradation

“…Physical adsorption has simple operation, low cost and maintenance of high enzyme activity, but can very easily desorb enzymes because of the dependence on the weak force between enzymes and the carrier ( Cai et al, 2016 ). Covalent binding usually requires a modifiable and highly stable carrier with more chemical groups, but the operation process is complex ( Yang et al, 2021 ). Although embedding is to fix the enzyme molecules in the grid structure of a porous carrier, and proceeds under mild reaction conditions, the substrate can hardly react with the enzyme due to the influence of the embedding structure.…”

“…Although embedding is to fix the enzyme molecules in the grid structure of a porous carrier, and proceeds under mild reaction conditions, the substrate can hardly react with the enzyme due to the influence of the embedding structure. Cross-linking can effectively improve enzyme leakage, but the immobilized enzyme prepared by simple crosslinking has poor mechanical properties, and therefore usually integrated with other methods to strengthen and improve the immobilization effect ( Cai et al, 2016 ; Ke et al, 2018 ; Yang et al, 2021 ). Hence, for the success of enzyme immobilization, the selection of appropriate methods is required ( He et al, 2015 ; Cai et al, 2016 ; Yang et al, 2021 ).…”

“…Cross-linking can effectively improve enzyme leakage, but the immobilized enzyme prepared by simple crosslinking has poor mechanical properties, and therefore usually integrated with other methods to strengthen and improve the immobilization effect ( Cai et al, 2016 ; Ke et al, 2018 ; Yang et al, 2021 ). Hence, for the success of enzyme immobilization, the selection of appropriate methods is required ( He et al, 2015 ; Cai et al, 2016 ; Yang et al, 2021 ). Appropriate immobilization methods are capable of immobilizing free enzymes on a recoverable carrier, so as to reduce production costs and broaden the applications of enzymes ( Mogharabi et al, 2012 ).…”