Covalent organic framework in-situ immobilized laccase for the covalent polymerization removal of sulfamethoxazole in the presence of natural phenols: Prominent enzyme stability and activity

Bimetallic CuMn nanozyme-enzyme microsystem for efficient dimethyl phthalate degradation

Recently, the synthesis of nanozymes-enzyme microsystems with high catalytic stability provides new opportunities for treating diverse pollutants in complex aquatic systems. Herein, a carboxyl-functionalized CuMn bimetallic nanozyme-enzyme microsystem (CMAC@Lipase) was successfully constructed by combining copper‑manganese based aminoclays (CMAC) with lipase. This system exhibited laccase-like catalytic activity facilitated by CuMn electron transfer, while enhancing lipase stability via its carrier function. Under alkaline conditions at pH 10, CMAC@Lipase catalyzed the hydrolysis of p-NPP (280 nm) to produce p-NP (400 nm), and subsequently reduced p-NP to p-AP within 30 min with the assistance of NaBH4. Furthermore, it effectively degraded 72.8 % of dimethyl phthalate (DMP) at 40 mg·L-1 under alkaline conditions within 48 h, maintaining a 53.5 % degradation rate after 10 reuse cycles. This work provided a new strategy for the design of nanozyme-enzyme microsystems and a new research idea for the efficient treatment of contaminants in actual aqueous environments.

An overview of additive manufacturing strategies of enzyme-immobilized nanomaterials with application incatalysis and biomedicine

Meticulous and bespoke fabrication of structural materials with simple yet innovative outlines along with on-demand availability is the imperative aspiration for numerous fields. The alliance between nanotechnology and enzymes has led to the establishment of an inimitable and proficient class of materials. With the advancement in the field of additive manufacturing, the fabrication of some complex biological architects is achievable with similitude to the instinctive microenvironment of the biological tissue. Rendering these enzymes-linked nanomaterials through 3D printing for biosensing, catalytic, and biomedical applications is challenging due to the need for a precise controlled, regulated system with scaleup capability for commercialization. The current review highlights the importance of nanomaterials as a persuasive matrix for enzyme immobilization along with the key parameters that regulate the rate of immobilization and the activity of the concerned enzyme. Precise attention has been devoted to the different strategies for immobilizing enzymes in the nanomaterial's matrix. The present review offers a comprehensive discussion on the utility of 3D printing technology for enzyme-immobilized nanomaterials in biosensing, catalysis, and biomedical applications. The employment of 3D printing grants new developments and avenues in the vast field of enzyme- immobilized nanomaterials.

Evaluation of the immobilized enzymes function in soil remediation following polycyclic aromatic hydrocarbon contamination

The bioremediation of polycyclic aromatic hydrocarbon (PAHs) from soil utilizing microorganisms, enzymes, microbial consortiums, strains, etc. has attracted a lot of interest due to the environmentally friendly, and cost-effective features. Enzymes can efficiently break down PAHs in soil by hydroxylating the benzene ring, breaking the C-C bond, and catalyze the hydroxylation of a variety of benzene ring compounds via single-electron transfer oxidation. However, the practical application is limited by its instability and ease to loss function under harsh environmental conditions such as pH, temperature, and edaphic stress etc. Therefore, this paper focused on the techniques used to immobilize enzymes and remediate PAHs in soil. Moreover, previous research has not adequately covered this topic, despite the employment of several immobilized enzymes in aqueous solution cultures to remediate other types of organic pollutants. Bibliometric analysis further highlighted the research trends from 2000 to 2023 on this field of growing interest and identified important challenges regarding enzyme stability and interaction with soil matrices. The findings indicated that immobilized enzymes may catalyzed PAHs via oxidation of OH groups in benzene rings, and generate benzyl radicals (i.e., •OH and •O2) that undergo further reaction and release water. As a result, the intermediate products of PAHs further catalyze by enzyme and enzyme induced microbes producing carbon dioxide and water. Meanwhile efficiency, activity, lifetime, resilience, and sustainability of immobilized enzyme need to be further improved for the large-scale and field-scale clean-up of PAHs polluted soils. This could be possible by integrating enzyme-based with microbial and plant-based remediation strategies. It can be coupled with another line of research focused on using a new set of support materials that can be derived from natural resources.

Thiadiazol ligand-based laccase-like nanozymes with a high Cu+ ratio for efficient removal of tetracyclines through polymerization

A promising water treatment technology involves inducing the polymerization of organic pollutants to form corresponding polymers, enabling rapid, efficient, and low CO2 emission removal of these pollutants. However, there is currently limited research on utilizing polymerization treatment technology for removing tetracyclines from water. In this study, we synthesized a laccase-mimic nanozyme (Cu-ATZ) with a high Cu+ ratio using 2-amino-1,3,4-thiadiazole as a ligand inspired by natural laccase. The Cu-ATZ exhibited enhanced resistance to more severe application conditions and improved stability compared to natural laccase, thereby demonstrating a broader range of potential applications. The excellent catalytic properties of Cu-ATZ enabled the nanozyme to be used in the polymerization process to remove tetracyclines from water. In order to simulate actual antibiotic pollution of water bodies, tetracyclines were added to the water from sewage treatment plants. Following Cu-ATZ treatment of the water sample, the chemical oxygen demand (COD) content was found to have decreased by over 80 %. In conclusion, this study presented a novel approach for tetracycline elimination from water.

Preparation of highly stable immobilized Candida antarctica lipase B (CALB) through adjusting the surface properties of carrier: Preparation, characterization and performance evaluation

The stability of the immobilized lipase is the key factor that determines the economy and feasibility of its industrial application. Here, two robust immobilized Candida antarctica lipase B (CALB) were prepared through adjusting the surface properties of ECR1030 resin. Silane coupling agent (SCA) and dialdehyde cellulose (DAC) were employed to modify the carrier surface. Contact angle measurement showed that the hydrophobicity of the modified carrier increased first, and then decreased with the increase of the chain length of SCA. FTIR results showed that Si-O-Si bond and aldehyde group were attached to ECR1030, respectively, indicating that the ECR1030 resin was successfully modified. Meanwhile, the NH and CN bond were observed in the corresponding immobilized CALB, suggesting CALB was immobilized onto the modified carriers. The effects of immobilization conditions on CALB immobilization was further investigated, and the C8-ECR1030-CALB and DAC-ECR1030-CALB with the activity of 12,736 U/g and 11,962 U/g were obtained. Moreover, the stability of the immobilized lipases was evaluated and compared with the commercial Novozym 435. The C8-ECR1030-CALB and DAC-ECR1030-CALB exhibited comparable or superior stability to Novozym 435 and showed better deacidification effect than Novozym 435. This study paves road for further study involving preparation of highly stable immobilized lipase.

Contribution of complexed Fe(Ⅱ) oxygenation to norfloxacin humification and stabilization: Producing and trapping of more humified products

Organic pollutants polymerization in advanced oxidation processes or environmental matrices has attracted increasing attention, but little is known about stabilization of the polymerization products. The results in this work revealed the contribution of Fe(Ⅱ) oxygenation to stabilization of the products from norfloxacin (NOR) humification. It was found that upon oxygenation of Fe(Ⅱ) complexed by catechol (CT), NOR polymerized into the products with larger molecular weight through nucleophilic addition. Around 83.9-89.7 % organic carbon (OC) can be retained in the reaction solution and the precipitates at different Fe(II)/CT molar ratio. In this system with humification potential, the produced hydroxyl radical (HO•) dominantly modified, instead of decomposed, the structure of transformation products (TPs). TPs with diversified side chains were formed through hydroxylation and ring-opening, leading to the more humified products. In the subsequent Fe(Ⅱ) oxidative precipitation, Fe-TPs composites were formed as spherical particle clusters, which could steadily incorporate OC species with molecular fractionation. Specifically, lignin-like, tannins-like, condensed aromatic and high-molecular-weight TPs were preferentially preserved in the precipitates, while the recalcitrant aliphatic products mainly retained in the solution. These findings shed light on the role of Fe(Ⅱ) oxygenation in stabilizing the products from pollutants humification, which could strengthen both decontamination and organics sequestration.

Laccase immobilization and its degradation of emerging pollutants: A comprehensive review

The chronic lack of effective disposal of pollutants has resulted in the detection of a wide variety of EPs in the environment, with concentrations high enough to affect ecological health. Laccase, as a versatile oxidase capable of catalyzing a wide range of substrates and without producing toxic by-products, is a potential candidate for the biodegradation of pollutants. Immobilization can provide favorable protection for free laccase, improve the stability of laccase in complex environments, and greatly enhance the reusability of laccase, which is significant in reducing the cost of industrial applications. This study introduces the properties of laccase and subsequently elaborate on the different support materials for laccase immobilization. The research advances in the degradation of EDs, PPCPs, and PAHs by immobilized laccase are then reviewed. This review provides a comprehensive understanding of laccase immobilization, as well as the advantages of various support materials, facilitating the development of more economical and efficient immobilization systems that can be put into practice to achieve the green degradation of EPs.

Multifunctional Manganese-Nucleotide Laccase-Mimicking Nanozyme for Degradation of Organic Pollutants and Visual Assay of Epinephrine via Smartphone

As a natural green catalyst, laccase has extensive application in the fields of environmental monitoring and pollutant degradation. However, susceptibility to environmental influences and poor reusability seriously hinder its application. To address these concerns, for the first time, manganese ion replaced copper ion as the active center to coordinate with guanosine monophosphate (GMP) for synthesizing mimic laccase with high catalytic activity. Compared with natural laccase, the laccase-like nanozyme (Mn-GMPNS) demonstrated superior thermal stability, acid-base resistance, salt tolerance, reusability, and substrate universality. Benefiting from the high catalytic activity of Mn-GMPNS, epinephrine, a significant neurotransmitter and hormone associated with numerous diseases, was visually detected within 10 min and a portable assay by smartphone. More encouragingly, Mn-GMPNS can efficiently degrade dye pollutants, achieving a decolorization rate over 70% within 30 min. Thus, the coordination between manganese ion and nucleotide demonstrated the potential in rational design of nanozymes with high catalytic activity, low cost, good stability, and good biocompatibility.

Enhanced catalytic performance of penicillin G acylase by covalent immobilization onto functionally-modified magnetic Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles

With the emergence of penicillin resistance, the development of novel antibiotics has become an urgent necessity. Semi-synthetic penicillin has emerged as a promising alternative to traditional penicillin. The demand for the crucial intermediate, 6-aminopicillanic acid (6-APA), is on the rise. Enzyme catalysis is the primary method employed for its production. However, due to certain limitations, the strategy of enzyme immobilization has also gained prominence. The magnetic Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles were successfully prepared by a rapid-combustion method. Sodium silicate was used to modify the surface of the Ni0.4Cu0.5Zn0.1Fe2O4 nanoparticles to obtain silica-coated nanoparticles (Ni0.4Cu0.5Zn0.1Fe2O4-SiO2). Subsequently, in order to better crosslink PGA, the nanoparticles were modified again with glutaraldehyde to obtain glutaraldehyde crosslinked Ni0.4Cu0.5Zn0.1Fe2O4-SiO2-GA nanoparticles which could immobilize the PGA. The structure of the PGA protein was analyzed by the PyMol program and the immobilization strategy was determined. The conditions of PGA immobilization were investigated, including immobilization time and PGA concentration. Finally, the enzymological properties of the immobilized and free PGA were compared. The optimum catalytic pH of immobilized and free PGA was 8.0, and the optimum catalytic temperature of immobilized PGA was 50°C, 5°C higher than that of free PGA. Immobilized PGA in a certain pH and temperature range showed better catalytic stability. Vmax and Km of immobilized PGA were 0.3727 μmol·min-1 and 0.0436 mol·L-1, and the corresponding free PGA were 0.7325 μmol·min-1 and 0.0227 mol·L-1. After five cycles, the immobilized enzyme activity was still higher than 25%.