Mesoporous silicas with tunable morphology for the immobilization of laccase

Purification and immobilization of β-glucosidase using surface modified mesoporous silica Santa Barbara Amorphous 15 for eco-friendly preparation of sagittatoside A

Functionalized mesoporous materials have become a promising carrier for enzyme immobilization. In this study, Santa Barbara Amorphous 15 (SBA-15) was modified by N-aminoethyl-γ-aminopropyl trimethoxy (R). R-SBA-15 was employed to purify and immobilize recombinant β-glucosidase from Terrabacter ginsenosidimutans (BgpA) in one step for the first time. Optimum pH of the constructed R-SBA-15@BgpA were 7.0, and it has 20 ℃ higher optimal temperature than free enzyme. Relative activity of R-SBA-15@BgpA still retained > 70% at 42 ℃ after 8-h incubation. The investigation on organic reagent resistance revealed that the immobilized enzyme can maintain strong stability in 15% DMSO. In leaching test and evaluation of storage stability, only trace amount of protein was detected in buffer of the immobilized enzyme after storage at 4 ℃ for 33 days, and the immobilized BgpA still maintained > 50% relative activity. It also demonstrated good reusability, with 76.1% relative activity remaining after fourteen successive enzymatic hydrolyses of epimedin A to sagittatoside A. The newly proposed strategy is an effective approach for the purification and immobilization of BgpA concurrently. In addition, R-SBA-15@BgpA was demonstrated to have high efficiency and stability in this application, suggesting its great feasibility and potential to produce bioactive compounds such as secondary glycosides or aglycones from natural products.

Enhanced pollutant degradation via green-synthesized core-shell mesoporous Si@Fe magnetic nanoparticles immobilized with metagenomic laccase

With rapid industrial expansion, environmental pollution from emerging contaminants has increased, posing severe ecosystem threats. Laccases offer an eco-friendly solution for degrading hazardous substances, but their use as free-form biocatalysts face challenges. This study immobilized laccase (PersiLac1) on green-synthesized Si@Fe nanoparticles (MSFM NPs) to remove pollutants like Malachite Green-containing wastewater and degrade plastic films. Characterization techniques (FTIR, VSM, XRD, SEM, EDS, BET) confirmed the properties and structure of MSFM NPs, revealing a surface area of 31.297 m2.g-1 and a pore diameter of 12.267 nm. The immobilized PersiLac1 showed enhanced activity across various temperatures and pH levels, retaining over 82 % activity after 15 cycles at 80°C with minimal leaching. It demonstrated higher stability, half-life, and decimal reduction time than free laccase. Under 1 M NaCl, its activity was 1.8 times higher than the non-immobilized enzyme. The immobilized laccase removed 98.11 % of Malachite Green-containing wastewater and retained 82.92 % activity over twenty cycles of dye removal. Additionally, FTIR and SEM confirmed superior plastic degradation under saline conditions. These findings suggest that immobilizing PersiLac1 on magnetic nanoparticles enhances its function and potential for contaminant removal. Future research should focus on scalable, cost-effective laccase immobilization methods for large-scale environmental applications.

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

Laccase is a multi-copper enzyme widely expressed in fungi, higher plants, and bacteria which facilitates the direct reduction of molecular oxygen to water (without hydrogen peroxide production) accompanied by the oxidation of an electron donor. Laccase has attracted attention in biotechnological applications due to its non-specificity and use of molecular oxygen as secondary substrate. This review discusses different applications of laccase in various sectors of food, paper and pulp, waste water treatment, pharmaceuticals, sensors, and fuel cells. Despite the many advantages of laccase, challenges such as high cost due to its non-reusability, instability in harsh environmental conditions, and proteolysis are often encountered in its application. One of the approaches used to minimize these challenges is immobilization. The various methods used to immobilize laccase and the different supports used are further extensively discussed in this review.

Magnetic thermosensitive polymer composite carrier with target spacing for enhancing immobilized enzyme performance

A novel magnetic thermosensitive polymer composite carrier with target spacing was developed. In this strategy, thermosensitive polymer grafted on magnetic Fe₃O₄ for enhancing immobilized penicillin G acylase (PGA) performance and introduce immobilized target spacing into magnetic carriers for the first time. Fe₃O₄ nanoparticles were synthesized by a reverse microemulsion method. The modifier used was the silane coupling agent γ-methylacryloxypropyl trimethoxysilane (KH570) and then reacting with a reversible-adaptive fragmentation chain transfer (RAFT) reagent, 2-cyano-2-propyldodecyl trithiocarbonate (CPDTC). The thermo-sensitive nanoparticle-composite carrier of Fe₃O₄-grafted-poly N, N-diethyl acrylamide-block-poly β-Hydroxyethyl methacrylate-block-random copolymer of glycidyl methacrylate and methyl methacrylate (Fe₃O₄-g-PDEA-b-PHEMA-b-P(MMA-co-GMA)) were synthesized by RAFT polymerization technique that used N, N-diethyl acrylamide (DEA), β-Hydroxyethyl methacrylate (HEMA), Glycidyl methacrylate (GMA) and Methyl methacrylate (MMA) as monomer, then which were employed as functional carriers for the immobilization of PGA. Within the carrier, the epoxy group of GMA segment was a target immobilization site for PGA and the introduction of MMA reflected the target space of immobilized PGA to improve catalytic activity and catalytic activity recovery rate of the immobilized PGA. Characterizations demonstrated that the triblock copolymers grafted Fe₃O₄ nanoparticles were successfully fabricated by the structure design. Besides, under these circumstances the enzyme activity (EA), enzyme loading capacity (ELC) and catalytic activity recovery ration (CAR) reached 31235 U/g, 128.39 mg/g and 93.32 %, respectively. The catalytic activity of immobilized PGA maintained 87.4 % of initial value and the recovery ratio (R) of immobilized PGA reached 96.22 % after recycling 12 times. Furthermore, the immobilized PGA exhibited advantages of low temperature homogeneous catalysis and magnetic separation, which indicated broad application prospects in the biocatalysts' field.

Surface Functionalization of a γ-Graphyne-like Carbon Material via Click Chemistry

Surface functionalization of carbon materials is of interest in many research fields, such as electrocatalysis, interfacial engineering, and supercapacitors. As an emerging carbon material, γ-graphyne has attracted broad attention. Herein, we report that the surface functionalization of a γ-graphyne-like carbon material (γ-G1) is achieved by immobilizing functional groups via the click chemistry. Texture analysis of aberration-corrected microscopy, X-ray photoelectron spectroscopy, and electrochemistry confirm the successful surface modification of γ-G1 through a strong covalent linkage 1,2,3-triazole. The direct linkage of functional groups on γ-G1 via the click chemistry represents a general method for preparing other functional materials by using γ-graphyne-like materials as a skeleton.

Protein recovery as a resource from waste specifically via membrane technology-from waste to wonder

Economic growth and the rapid increase in the world population has led to a greater need for natural resources, which in turn, has put pressure on said resources along with the environment. Water, food, and energy, among other resources, pose a huge challenge. Numerous essential resources, including organic substances and valuable nutrients, can be found in wastewater, and these could be recovered with efficient technologies. Protein recovery from waste streams can provide an alternative resource that could be utilized as animal feed. Membrane separation, adsorption, and microbe-assisted protein recovery have been proposed as technologies that could be used for the aforementioned protein recovery. This present study focuses on the applicability of different technologies for protein recovery from different wastewaters. Membrane technology has been proven to be efficient for the effective concentration of proteins from waste sources. The main emphasis of the present short communication is to explore the possible strategies that could be utilized to recover or restore proteins from different wastewater sources. The presented study emphasizes the applicability of the recovery of proteins from various waste sources using membranes and the combination of the membrane process. Future research should focus on novel technologies that can help in the efficient extraction of these high-value compounds from wastes. Lastly, this short communication will evaluate the possibility of integrating membrane technology. This study will discuss the important proteins present in different industrial waste streams, such as those of potatoes, poultry, dairy, seafood and alfalfa, and the possible state of the art technologies for the recovery of these valuable proteins from the wastewater.

Short-channel mesoporous SBA-15 silica modified by aluminum grafting as a support for CoRu Fischer–Tropsch synthesis catalysts

Highly ordered short-channel mesoporous silica SBA-15 with large pores (11.2 nm) was synthesized from tetramethyl orthosilicate, using the block copolymer Pluronic PE-10400 as structure-directing agent, and triisopropylbenzene as a swelling agent.

Controlling Particle Morphology and Pore Size in the Synthesis of Ordered Mesoporous Materials

Ordered mesoporous materials have attracted considerable attention due to their potential applications in catalysis, adsorption, and separation technologies, as well as biomedical applications. In the present manuscript, we aim at a rational design to obtain the desired surface functionality (Ti and/or hydrophobic groups) while obtaining short channels (short diffusion paths) and large pore size (>10 nm). Santa Barbara Amorphous material SBA-15 and periodic mesoporous organosilica PMO materials are synthesized using Pluronic PE 10400 (P104) surfactant under mild acidic conditions to obtain hexagonal platelet-like particles with very short mesochannels (300–450 nm). The use of expanders, such as 1, 3, 5-trimethylbenzene (TMB) and 1, 3, 5-triisopropylbenzene (TIPB) were tested in order to increase the pore size. TMB yielded in the formation of vesicles in all the syntheses attempted, whereas P104 combined with TIPB resulted both in expanded (E) E-SBA-15 and E-PMO with 12.3 nm pore size short channel particles in both cases. Furthermore, the synthesis method was expanded to the incorporation of small amount of Ti via co-condensation method using titanocene as titanium source. As a result, Ti-E-SBA-15 was obtained with 15.5 nm pore size and isolated Ti-sites maintaining platelet hexagonal morphology. Ti-PMO was obtained with 7.8 nm and short channels, although the pore size under the tried synthesis conditions could not be expanded further without losing the structural ordering.

Greener Routes to Biomass Waste Valorization: Lignin Transformation Through Electrocatalysis for Renewable Chemicals and Fuels Production

Lignin valorization is essential for biorefineries to produce fuels and chemicals for a sustainable future. Today's biorefineries pursue profitable value propositions for cellulose and hemicellulose; however, lignin is typically used mainly for its thermal energy value. To enhance the profit potential for biorefineries, lignin valorization would be a necessary practice. Lignin valorization is greatly advantaged when biomass carbon is retained in the fuel and chemical products and when energy quality is enhanced by electrochemical upgrading. Though lignin upgrading and valorization are very desirable in principle, many barriers involved in lignin pretreatment, extraction, and depolymerization must be overcome to unlock its full potential. This Review addresses the electrochemical transformation of various lignins with the aim of gaining a better understanding of many of the barriers that currently exist in such technologies. These studies give insight into electrochemical lignin depolymerization and upgrading to value-added commodities with the end goal of achieving a global low-carbon circular economy.

A novel Laccase gene from Litopenaeus vannamei is involved in the immune responses to pathogen infection and oxidative stress

Laccases (Lacs) are copper-containing oxidase enzymes that are found in various plants, fungi, and microorganisms. For invertebrates, particularly insects and crustaceans, Lacs have been shown to be involved in immune responses. In shrimp, a Lac gene has been cloned and functionally characterized, which revealed that it is involved in shrimp anti-pathogen infection. In the present study, a novel Lac gene (LvLac2) was cloned from Litopenaeus vannamei. Real-time RT-PCR analysis showed that LvLac2 is induced by white spot syndrome virus (WSSV)- or Vibrio alginolyticus infection. In addition, the downregulated expression of LvLac2 decreased the cumulative mortality of WSSV- or V. alginolyticus infected shrimps. Moreover, LvLac2 is also induced by oxidative stress. Knocking down the expression of LvLac2 decreased the severity of hepatopancreatic injury caused by oxidative stress, as well as reduced the cumulative shrimp mortality during oxidative stress. Furthermore, gene reporter assays showed that the expression of LvLac2 is regulated by NF-E2-related factor 2, which is the key transcription factor of the oxidative stress response signaling pathway. Our study revealed that LvLac2 not only participates in immune responses against infections in L. vannamei but is also involved in oxidative stress responses.

Magnetic nanoparticles encapsulated laccase nanoflowers: evaluation of enzymatic activity and reusability for degradation of malachite green

Magnetic laccase nanoflowers (MNFs-Lac) were successfully prepared through encapsulating Fe₃O₄ magnetic nanoparticles into the interior of laccase nanoflowers by grafting N-(phosphonomethyl)iminodiacetic acid (PMIDA) as an interconnecting bridge between the magnetic nanoparticles and copper ions. The characterizations by scanning electron microscopy and transmission electron microscopy showed that MNFs-Lac were spherical, porous and flower-like crystals with diameters of ∼10 μm, and Fe₃O₄ nanoparticles were encapsulated in the interior of MNFs-Lac evenly. The enzymatic activity and reusability of MNFs-Lac were evaluated based on the degradation efficiency for malachite green (MG). The degradation parameters, concerning initial MG concentration, dosage of MNFs-Lac, reaction temperature, pH value and reaction time, were optimized through single-factor experiments. Under the optimal conditions, 25 mg·L^-1 MG can be degraded almost completely by 1.5 g·L^-1 MNFs-Lac within 15 min. When the MNFs-Lac were reused for 18 times, the degradation efficiency of MG was still as high as 90%. These results suggested that the modified preparation method improved greatly the reusability of MNFs-Lac, which made them more suitable to degrade MG in a water environment.

Environmentally Friendly Enzyme Immobilization on MOF Materials

Metal-organic framework (MOF) materials have revolutionized the applications of nanoporous materials. They can be potentially used in separation, storage, and catalysis, among other applications. Since their discovery in 1999 (Li et al. Nature 402:276-279, 1999; Chui Science 283:1148-1150, 1999), more than 20,000 new structures have been synthesized thanks in part to their high compositional versatility. However, only some of them are really stable in water (both in liquid and vapor phase), which limits their employment in other applications. Furthermore, biocatalysis field has been demanding a "universal support" able to encapsulate/immobilize any type of enzyme in a straightforward methodology and, simultaneously, capable of keeping the enzymatic catalytic activity. This requisite set has been a big challenge considering the drastic synthesis conditions required for most of the MOF materials. Thus, a compromise between the development of a well-formed material support and an acceptable enzymatic activity had to be achieved in order to obtain active biocatalysts, ideally prepared in just one step and under sustainable conditions. In this chapter, we describe the protocols about how to synthesize MOF materials in water, under mild conditions and almost instantaneously in the presence of enzymes. The most successful support of these sustainable MOFs was the semicrystalline Fe-BTC MOF material (like the commercial Basolite F300) allowing the development of efficient active biocatalysts (97% with respect to the free enzyme in the case of CALB lipase). Particularly, this enzyme support improves the benefits given by some other MOF-based supports also described in this chapter, like NH₂-MIL-53(Al). Furthermore, we present the post-synthesis immobilization approach, which consists firstly in the synthesis or preparation of the respective MOF material (Fe-BTC or NH₂-MIL-53(Al)), followed by an enzyme immobilization protocol. As reported in bibliography, MOFs as enzyme supports combine together more active biocatalysts with lower enzyme leaching when compared to other conventional materials. Moreover, MOFs prepared in non-aqueous media (for instance, N,N-dimethylformamide) can also trap enzymes in an otherwise adverse media. These facts bring these biocatalysts closer to industrial employment in even more demanding applications.

Isolation of the (+)-Pinoresinol-Mineralizing Pseudomonas sp. Strain SG-MS2 and Elucidation of Its Catabolic Pathway

Pinoresinol is a dimer of two β-β'-linked coniferyl alcohol molecules. It is both a plant defense molecule synthesized through the shikimic acid pathway and a representative of several β-β-linked dimers produced during the microbial degradation of lignin in dead plant material. Until now, little has been known about the bacterial catabolism of such dimers. Here we report the isolation of the efficient (+)-pinoresinol-mineralizing Pseudomonas sp. strain SG-MS2 and its catabolic pathway. Degradation of pinoresinol in this strain is inducible and proceeds via a novel oxidative route, which is in contrast to the previously reported reductive transformation by other bacteria. Based on enzyme assays and bacterial growth, cell suspension, and resting cell studies, we provide conclusive evidence that pinoresinol degradation in strain SG-MS2 is initiated by benzylic hydroxylation, generating a hemiketal via a quinone methide intermediate, which is then hydrated at the benzylic carbon by water. The hemiketal, which stays in equilibrium with the corresponding keto alcohol, undergoes an aryl-alkyl cleavage to generate a lactone and 2-methoxyhydroquinone. While the fate of 2-methoxyhydroquinone is not investigated further, it is assumed to be assimilated by ring cleavage. The lactone is further metabolized via two routes, namely, lactone ring cleavage and benzylic hydroxylation via a quinone methide intermediate, as described above. The resulting hemiketal again exists in equilibrium with a keto alcohol. Our evidence suggests that both routes of lactone metabolism lead to vanillin and vanillic acid, which we show can then be mineralized by strain SG-MS2.IMPORTANCE The oxidative catabolism of (+)-pinoresinol degradation elucidated here is fundamentally different from the reductive cometabolism reported for two previously characterized bacteria. Our findings open up new opportunities to use lignin for the biosynthesis of vanillin, a key flavoring agent in foods, beverages, and pharmaceuticals, as well as various new lactones. Our work also has implications for the study of new pinoresinol metabolites in human health. The enterodiol and enterolactone produced through reductive transformation of pinoresinol by gut microbes have already been associated with decreased risks of cancer and cardiovascular diseases. The metabolites from oxidative metabolism we find here also deserve attention in this respect.

Oriented Coimmobilization of Oxidase and Catalase on Tailor-Made Ordered Mesoporous Silica

Mesoporous silica materials are promising carriers for enzyme immobilization in heterogeneous biocatalysis applications. By tailoring their pore structural framework, these materials are designable for appropriate enzyme binding capacity and internal diffusivity. To supply O₂ efficiently to solid-supported immobilized enzymes represents a core problem of heterogeneously catalyzed oxidative biotransformations. In this study, therefore, we synthesized and compared three internally well-ordered and two amorphous silica materials as enzyme carriers, each of those with pore sizes of ≥10 nm, to enable the coimmobilization of d-amino-acid oxidase (79 kDa) and catalase (217 kDa). Both enzymes were fused to the silica-binding module Z_basic2 to facilitate their selective and oriented immobilization directly from crude protein mixtures on native silica materials. Analyzing the effects of varied pore architecture and internal surface area on the performance of the immobilized bienzymatic system, we showed that a uniform pore structural framework was beneficial for enzyme loading (≥70 mg protein/g carrier), immobilization yield (≥90%), surface and pore volume filling without hindered adsorption, and catalytic effectiveness (≥60%) of the coimmobilizate. Using the best carrier LP-SBA-15, we obtained a solid oxidase-catalase preparation with an activity of 2000 μmol/(min g_material) that was recyclable and stable during oxidation of d-methionine. These results affirm a strategy of optimizing immobilized O₂-dependent enzymes via tunable internal structuring of the silica material used as carrier. They thus make a significant advance toward the molecular design of heterogeneous oxidation biocatalysts on mesoporous silica supports.

Laccase encapsulation in chitosan nanoparticles enhances the protein stability against microbial degradation

A novel concept with the result of enzyme stabilization against microbial degradation in real bioremediation processes was developed through the encapsulation of laccase in chitosan nanoparticles. Besides of abundant information on laccase-chitosan conjugates, we report the laccase encapsulation into nanoparticles based in chitosan. The chitosan-tripolyphosphate technique was applied for the production of morphologically homogeneous enzymatic nanoparticles, with high enzyme encapsulation efficiency, small asymmetric sizes (from 40 to 90 nm), and rough surfaces. Contrary to macroscopic immobilized enzymes, temperature and pH activity profiles of nano-sized laccase were similar to those of free enzyme. The substrate affinity constant (K M) of nano-encapsulated laccase was similar to these from free enzyme, while its activity rate constant (k cat) represented 60 % of these obtained with free enzyme. Importantly, stability of nano-encapsulated laccase against microbial degradation in soil, compost, and wastewater was significantly increased. After 24 h exposure to wastewater from a treatment plant, the laccase activity of the nanoparticles was 82.8 % of initial activity, compared with only 7.8 % retained activity for free enzyme. After 36 h incubation in compost extract, the laccase nanoparticles showed 72.4 % of the initial activity, while the free enzyme was almost completely inactivated. Finally, after 84 h incubation in soil extract, the nanoparticles and free preparations showed 57.9 and 17.3 % of the initial activity, respectively. Thus, the nanoencapsulation of enzymes able to transform pollutants is an alternative to improve the operational lifetime of enzymes in real environmental applications.

Nanobiocatalysis: Nanostructured materials – a minireview

The field of nanobiocatalysis has experienced a rapid growth due to recent advances in nanotechnology. However, biocatalytic processes are often limited by the lack of stability of the enzymes and their short lifetime. Therefore, immobilization is key to the successful implementation of industrial processes based on enzymes. Immobilization of enzymes on functionalized nanostructured materials could give higher stability to nanobiocatalysts while maintaining free enzyme activity and easy recyclability under various conditions. This review will discuss recent developments in nanobiocatalysis to improve the stability of the enzyme using various nanostructured materials such as mesoporous materials, nanofibers, nanoparticles, nanotubes, and individual nanoparticles enzymes. Also, this review summarizes the recent evolution of nanostructured biocatalysts with an emphasis on those formed with polymers. Based on the synthetic procedures used, established methods fall into two important categories: “grafting onto” and “grafting from”. The fundamentals of each method in enhancing enzyme stability and the use of these new nanobiocatalysts as tools for different applications in different areas are discussed.