3D printed polylactide scaffolding for laccase immobilization to improve enzyme stability and estrogen removal from wastewater

From nature to applications: Laccase immobilization onto bio-based materials for eco-conscious environmental remediation

Biodegradable and sustainable materials utilized for laccase immobilization have garnered substantial scholarly interest owing to their capacity to enhance enzyme stability and reusability, which are paramount for effective bioremediation methodologies. Laccase, a versatile oxidase, possesses the ability to degrade a broad spectrum of environmental contaminants, thus rendering it an invaluable asset in bioremediation endeavours. The immobilization of laccase onto biodegradable substrates not only augments its operational stability but also resonates with sustainable environmental strategies. This article systematically investigates recent advancements in sustainable and eco-conscious methodologies aimed at immobilizing laccase. By integrating biodegradable and non-toxic components, we elucidated how these materials not only proficiently enhanced the operational stability of laccases, but also improved their biodegradation effectiveness. A comprehensive analysis revealed that these sustainable materials facilitate immobilized laccase-mediated efficient removal of hazardous chemicals. Furthermore, we highlight the challenges that persist despite the encouraging characteristics of sustainable and eco-friendly approaches to laccase immobilization and pollutant elimination, and engage in discourse regarding potential pathways for their broader application and scalable solutions. This review highlights the significance of incorporating green technologies into environmental remediation efforts, thereby fostering the development of more effective and ecologically sound solutions for sustainable laccase immobilization to mitigate environmental contaminants efficiently.

Innovative laccase-based hollow packed-bed reactor for continuous treatment of hospital wastewater

This study reports on laccase-mediated removal of trace organic compounds (TrOCs) from real hospital wastewater (HWW) in a packed-bed reactor (PBR). The reactor column consisted of a catalytic bed of amino-functionalized mesoporous silica microspheres attached to a hollow polyethylene packing on which a Trametes hirsuta laccase was immobilized. This bed material had the advantage of significantly limiting pressure drop, which is one of the major drawbacks of PBRs operating in continuous mode. The PBR was fed with HWW, previously filtered through a 0.45-µm PTFE filter. The HWW was used either unspiked or spiked at 1 µg L-1 with acetaminophen, ibuprofen, naproxen, ketoprofen, mefenamic acid, indomethacin, and carbamazepine. A kinetic model combining the substrate conversion (1st-order kinetic) and the biocatalyst inactivation (1st-order kinetic) was developed and implemented, using acetaminophen as a model phenolic compound. After validation, the model showed good fit with experimental data and robustness regarding extended time operation with real HWW under uncontrolled conditions (pH, unbuffered media, ambient temperature). After 6 h of contact time, more than 95% of acetaminophen and mefenamic acid were removed in the PBR. In addition, toxicity tests showed that the laccase-based treatment resulted in a reduction in toxicity to Daphnia magna. The treated HWW did not significantly affect the mobility of Daphnia magna, unlike untreated HWW.

Ultrafiltration and composite microfiltration biocatalytic membrane activity and steroid hormone micropollutant degradation at environmentally relevant concentrations

Biocatalytic degradation of micropollutants has been extensively explored in both batch and membrane reactors in µg/L to mg/L concentrations and variable water compositions. The degradation of micropollutants by biocatalytic membranes at environmentally relevant concentrations of ng/L range found in natural surface water matrices has not yet been investigated, presumably because of the challenging concentration analysis. This study investigated the limitations of biocatalytic degradation of estradiol (E2) micropollutant at environmentally relevant concentrations by a biocatalytic membrane. The contributions of solute flux, hydraulic residence time (HRT) and water matrix composition on reaction kinetics, the apparent rate of disappearance (or reaction rate) and enzyme activity were examined. Two biocatalytic membranes were used: i) laccase entrapped in an ultrafiltration (UF) membrane support (namely UF-SNPs) and, ii) laccase covalently bound to the nanofiber matrix of a composite microfiltration (MF) membrane. The three main findings are reported. Firstly, the apparent rate of E2 disappearance decreases significantly by four orders of magnitude at a low micropollutant concentration of 0.1 µg/L, resulting in undetectable degradation during filtration, irrespective of the biocatalytic membrane. Secondly, the solute mass transfer and HRT control the biocatalytic degradation through the membranes resulting in different E2 removal. For the UF-SNPs membrane, a removal of 31 % is achieved only by increasing the concentration to 3000 µg/L and at a flux of 60 L/m².h (HRT of 4.5 s) due to an increase in solute flux by an order of magnitude similar to the apparent rate of disappearance. In contrast, the nano-MF membrane is ineffective in achieving biocatalytic degradation regardless of E2 concentration, as the HRT is approximately seven times lower (0.6 s) than that of the UF-SNPs, and thus insufficient for E2 to reach the catalytic site. Thirdly, the composition of the aqueous matrix plays a crucial role in the control of laccase activity irrespective of the membrane. Indeed, laccase is inactivated predominantly by chloride ions in synthetic carbonate buffer, since the typical NaCl concentration is about two orders of magnitude higher than E2 concentration. This study highlights that the slower kinetics achieved in the biocatalytic UF-SNPs and MF membranes are ineffective in removing steroid hormone micropollutants at realistic concentrations in surface water matrices. Further research is suggested to accelerate the reaction kinetics at such low concentrations and prolong the residence time within the membrane.

Amino-functionalized cellulose beads supporting laccase: A dual-function catalyst for simultaneous adsorption and enzymatic conversion of tetracycline

In this study, a novel cellulose-derived support of amino-functionalized cellulose beads (ACBs) for laccase immobilization was successfully developed using cellulose beads (CBs) and polyethyleneimine by glutaraldehyde crosslinking reaction. The covalent immobilization of laccase on ACBs was achieved via a Schiff base reaction. The obtained enzyme catalysts (Lac-ACBs) were applied for simultaneous adsorption and enzymatic conversion of tetracycline (TC) from water. The structure and properties of all samples were characterized by SEM-EDS, FT-IR, XRD, BET, and EA. Furthermore, the Lac-ACBs exhibited excellent stability and reusability: after 15 cycles of catalysis, they maintained 72 % of their original activity. The Lac-ACBs were applied for the removal of TC from water with simultaneous adsorption and enzymatic conversion, achieving an 82 % removal efficiency. The enzymatic conversion products were examined to investigate the mechanism of the conversion. The data illustrated that oxidation, dehydrogenation, and demethylation are major reactions in that process.

Magnetic nanoparticles-immobilized phospholipase LM and phospholipase 3G: Preparation, characterization, and application on soybean crude oil degumming

Immobilization of enzymes improves their stability and recoverability and is therefore crucial for scientific research and industrial applications. In this study, phospholipase LM (PLLM) and phospholipase 3G (PL3G) were immobilized using Fe3O4@SiO2@CS-COOH polycarboxylated magnetic nanoparticles (MNPs-COOH) as carriers and then used for degumming soybean crude oil. The immobilization rates and relative enzyme activities of these immobilized phospholipases were evaluated to determine the optimal immobilization parameters. The enzyme activities of PLLM-MNPs-COOH and PL3G-MNPs-COOH were 2830.87 and 1162.25 U/g, respectively. Enzymatic properties of the free and immobilized enzymes were compared. Both immobilized phospholipases exhibited higher condition tolerance and stability after immobilization. After 30-day storage at 4 °C, both immobilized phospholipases retained approximately 1.3 times the residual activity of the corresponding free phospholipases. When the degumming conditions were optimized, the residual phosphorus contents of the PLLM-MNPs-COOH- and PL3G-MNPs-COOH-degummed oils were 4.91 and 7.41 mg/kg, respectively, which were consistent with the safety standards for oil products. After 6 cycles, PLLM-MNPs-COOH and PL3G-MNPs-COOH continued to preserve 71.88 % and 70.00 % of their initial activities, respectively. The immobilized phospholipases are thus suitable for degumming soybean crude oil, and the mixed enzymes exhibited better degumming potential.

Artificial antibody-antigen-directed immobilization of α-amylase to hydrolyze starch for cascade reduction of 2-nitro-4-methylphenol to 2-amino-4-methylphenol

Nitrophenol is a hazardous substance that poses a threat to the environment and human health, and its treatment has attracted widespread attention. The purpose of this study is to establish an environmentally friendly α-amylase system for the hydrolysis of starch to reduce nitrophenol to aminophenol through cascade reactions. The α-amylase system was obtained through artificial antibody-antigen-directed immobilization, including the synthesis of artificial antibodies, synthesis of artificial antigens, and affinity assembly. In this process, catechol and protocatechuic aldehyde were used to prepare artificial antibodies and artificial antigens respectively through polymerization and Schiff base reactions. Then, artificial antibodies captured the catechol in the artificial antigen structure to form immobilized α-amylases. Compared with free α-amylase, the immobilized α-amylase showed a good reusability and excellent regenerative ability. Subsequently, the immobilized α-amylase were used in the reaction of catalyzing starch hydrolysis to synthesize 2-amino-4-methylphenol, and the yield of 2-amino-4-methylphenol was 58.88 ± 0.19 %. After 5 consecutive catalytic reactions, a yield of 47.61 ± 1.27 % can still be achieved.

Nucleobase-modulated copper nanomaterials with laccase-like activity for high-performance degradation and detection of phenolic pollutants

Laccases are the most commonly used agents for the treatment of phenolic pollutants. To address the instability and high cost of natural laccases, we investigated nucleobase-modulated copper nanomaterial with laccase-like activity. Various nucleobases, including adenine, guanine, cytosine, and thymine, were investigated as templates for Cu2+ reduction and copper nanomaterials formation due to their coordination capacity. By comparing structure and catalytic activity, the cytosine-mediated copper nanomaterial (C-Cu) had the best laccase-like activity and other nucleobase-templated copper nanomaterials exhibited low catalytic activity under the same conditions. The mechanism of nucleobase regulation of the catalytic activity of copper nanomaterials was further analyzed using X-ray photoelectron spectroscopy and density functional theory. The possible catalytic mechanisms of C-Cu, including substrate adsorption, substrate oxidation, oxygen binding, and oxygen reduction, were proposed. Remarkably, nucleobase-modulated copper nanozymes showed high stability and catalytic oxidation performance at various pH values, temperatures, long-term storage, and high salinity. In combination with electrochemical techniques, a portable electrochemical sensor for measuring phenolic pollutants was developed. This novel sensor exhibited a good linear response to catechol (10-1000 μM) with a limit of detection of 1.8 μM and excellent selectivity and anti-interference ability. This study provides not only a new strategy for the regulation of the laccase-like activity of copper nanomaterials but also a novel tool for the effective removal and low-cost detection of phenolic pollutants.

Stabilization of Eversa® Transform 2.0 lipase with sorbitol to enhance the efficiency of ultrasound-assisted biodiesel production

Ultrasound technology has emerged as a promising tool for enhancing enzymatic biodiesel production, yet the cavitation effect induced can compromise enzyme stability. This study explored the efficiency of polyols in enhancing lipase stability under ultrasound conditions to further improve biodiesel yield. The incorporation of sorbitol resulted in the highest fatty acid methyl ester (FAME) content in the ultrasound-assisted biodiesel production catalyzed by Eversa® Transform 2.0 among the investigated polyols. Furthermore, sorbitol enhanced the stability of the lipase, allowing it to tolerate up to 100 % ultrasound amplitude, compared to 60 % amplitude in its absence. Enzyme activity assays revealed that sorbitol preserved 99 % of the lipase activity, in contrast to 84 % retention observed without sorbitol under an 80 % ultrasound amplitude. Circular dichroism (CD) and fluorescence spectroscopy analyses confirmed that sorbitol enhanced lipase rigidity and preserved its conformational structure under ultrasound exposure. Furthermore, employing a stepwise methanol addition strategy in ultrasound-assisted reactions with sorbitol achieved an 81.2 wt% FAME content in 8 h with only 0.2 wt% enzyme concentration. This promising result highlights the potential of sorbitol as a stabilizing agent in ultrasound-assisted enzymatic biodiesel production, offering a viable approach for enhancing biodiesel yield and enzyme stability in industrial applications.

Microbial Immobilized Enzyme Biocatalysts for Multipollutant Mitigation: Harnessing Nature's Toolkit for Environmental Sustainability

The ever-increasing presence of micropollutants necessitates the development of environmentally friendly bioremediation strategies. Inspired by the remarkable versatility and potent catalytic activities of microbial enzymes, researchers are exploring their application as biocatalysts for innovative environmental cleanup solutions. Microbial enzymes offer remarkable substrate specificity, biodegradability, and the capacity to degrade a wide array of pollutants, positioning them as powerful tools for bioremediation. However, practical applications are often hindered by limitations in enzyme stability and reusability. Enzyme immobilization techniques have emerged as transformative strategies, enhancing enzyme stability and reusability by anchoring them onto inert or activated supports. These improvements lead to more efficient pollutant degradation and cost-effective bioremediation processes. This review delves into the diverse immobilization methods, showcasing their success in degrading various environmental pollutants, including pharmaceuticals, dyes, pesticides, microplastics, and industrial chemicals. By highlighting the transformative potential of microbial immobilized enzyme biocatalysts, this review underscores their significance in achieving a cleaner and more sustainable future through the mitigation of micropollutant contamination. Additionally, future research directions in areas such as enzyme engineering and machine learning hold immense promise for further broadening the capabilities and optimizing the applications of immobilized enzymes in environmental cleanup.

Artificial antibody-antigen-directed immobilization of lipase for consecutive catalytic synthesis of ester: Benzyl acetate case study

A strategy based on artificial antibody-antigen recognition was proposed for the specific directed immobilization of lipase. The artificial antibody was synthesized using catechol as a template, α-methacrylic acid as a functional monomer, and Fe3O4 as the matrix material. Lipase was modified with 3,4-dihydroxybenzaldehyde as an artificial antigen. The artificial antibody can specifically recognize catechol fragment in the enzyme structure to achieve the immobilization of lipase. The immobilization amount, yield, specific activity, and immobilized enzyme activity were 13.2 ± 0.2 mg/g, 78.9 ± 0.4 %, 7.9 ± 0.2 U/mgprotein, and 104.6 ± 1.7 U/gcarrier, respectively. Moreover, the immobilized lipase exhibited strong reusability and regeneration ability. Additionally, the immobilized lipase successfully catalyzed the synthesis of benzyl acetate and demonstrated robust continuous catalytic activity. These results fully demonstrate the feasibility of the proposed artificial antibody-antigen-directed immobilization of lipase.

One stone two birds: Recycling of an agri-waste to synthesize laccase-immobilized hierarchically porous magnetic biochar for efficient degradation of aflatoxin B1 in aqueous solutions and corn oil

Aflatoxin B1 (AFB1) contamination of oils is a serious concern for the safety of edible oil consumers. Enzyme-assisted detoxification of AFB1 is an efficient and safe method for decontaminating oils, but pristine enzymes are unstable in oils and require modifications before use. Therefore, we designed a novel and magnetically separable laccase-carrying biocatalyst containing spent-mushroom-substrate (SMS)-derived biochar (BF). Laccase was immobilized on NH2-activated magnetic biochar (BF-NH2) through covalent crosslinking, which provided physicochemical stability to the immobilized enzyme. After 30 days of storage at 4 °C, the immobilized laccase (product named "BF-NH2-Lac") retained ~95 % of its initial activity, while after five repeated cycles of ABTS oxidation, ~85 % activity retention was observed. BF-NH2-Lac was investigated for the oxidative degradation of AFB1, which exhibited superior performance compared to free laccase. Among many tested natural compounds as mediators, p-coumaric acid proved the most efficient in activating laccase for AFB1 degradation. BF-NH2-Lac demonstrated >90 % removal of AFB1 within 5.0 h, while the observed degradation efficiency in corn oil and buffer was comparable. An insight into the adsorptive and degradative removal of AFB1 revealed that AFB1 removal was governed mainly by degradation. The coexistence of multi-mycotoxins did not significantly affect the AFB1 degradation capability of BF-NH2-Lac. Investigation of the degradation products revealed the transformation of AFB1 into non-toxic AFQ1, while corn oil quality remained unaffected after BF-NH2-Lac treatment. Hence, this study holds practical importance for the research, knowledge-base and industrial application of newly proposed immobilized enzyme products.

Co-Immobilization of Alcalase/Dispase for Production of Selenium-Enriched Peptide from Cardamine violifolia

Enzymatically derived selenium-enriched peptides from Cardamine violifolia (CV) can serve as valuable selenium supplements. However, the industrial application of free enzyme is impeded by its limited stability and reusability. Herein, this study explores the application of co-immobilized enzymes (Alcalase and Dispase) on amino resin for hydrolyzing CV proteins to produce selenium-enriched peptides. The successful enzyme immobilization was confirmed through scanning electron microscopy (SEM), energy dispersive X-ray (EDX), and Fourier-transform infrared spectroscopy (FTIR). Co-immobilized enzyme at a mass ratio of 5:1 (Alcalase/Dispase) exhibited the smallest pore size (7.065 nm) and highest activity (41 U/mg), resulting in a high degree of hydrolysis of CV protein (27.2%), which was obviously higher than the case of using free enzymes (20.7%) or immobilized Alcalase (25.8%). In addition, after a month of storage, the co-immobilized enzyme still retained a viability level of 41.93%, showing fairly good stability. Encouragingly, the selenium-enriched peptides from co-immobilized enzyme hydrolysis exhibited uniform distribution of selenium forms, complete amino acid fractions and homogeneous distribution of molecular weight, confirming the practicality of using co-immobilized enzymes for CV protein hydrolysis.

Transformative applications of additive manufacturing in biomedical engineering: bioprinting to surgical innovations

This paper delves into the diverse applications and transformative impact of additive manufacturing (AM) in biomedical engineering. A detailed analysis of various AM technologies showcases their distinct capabilities and specific applications within the medical field. Special emphasis is placed on bioprinting of organs and tissues, a revolutionary area where AM has the potential to revolutionize organ transplantation and regenerative medicine by fabricating functional tissues and organs. The review further explores the customization of implants and prosthetics, demonstrating how tailored medical devices enhance patient comfort and performance. Additionally, the utility of AM in surgical planning is examined, highlighting how printed models contribute to increased surgical precision, reduced operating times, and minimized complications. The discussion extends to the 3D printing of surgical instruments, showcasing how these bespoke tools can improve surgical outcomes. Moreover, the integration of AM in drug delivery systems, including the development of innovative drug-loaded implants, underscores its potential to enhance therapeutic efficacy and reduce side effects. It also addresses personalized prosthetic implants, regulatory frameworks, biocompatibility concerns, and the future potential of AM in global health and sustainable practices.

Bioremediation of Hazardous Pollutants Using Enzyme-Immobilized Reactors

Bioremediation uses the degradation abilities of microorganisms and other organisms to remove harmful pollutants that pollute the natural environment, helping return it to a natural state that is free of harmful substances. Organism-derived enzymes can degrade and eliminate a variety of pollutants and transform them into non-toxic forms; as such, they are expected to be used in bioremediation. However, since enzymes are proteins, the low operational stability and catalytic efficiency of free enzyme-based degradation systems need improvement. Enzyme immobilization methods are often used to overcome these challenges. Several enzyme immobilization methods have been applied to improve operational stability and reduce remediation costs. Herein, we review recent advancements in immobilized enzymes for bioremediation and summarize the methods for preparing immobilized enzymes for use as catalysts and in pollutant degradation systems. Additionally, the advantages, limitations, and future perspectives of immobilized enzymes in bioremediation are discussed.

Co-immobilized multi-enzyme biocatalytic system on reversible and soluble carrier for saccharification of corn straw cellulose

Herein, three enzymes (cellulase, β-glucosidase, and pectinase) with synergistic effects were co-immobilized on the Eudragit L-100, and the recovery of co-immobilized enzymes from solid substrates were achieved through the reversible and soluble property of the carrier. The optimization of enzyme ratio overcomed the problem of inappropriate enzyme activity ratio caused by different immobilization efficiencies among enzymes during the preparation process of co-immobilized enzymes. The co-immobilized enzymes were utilized to catalytically hydrolyze cellulose from corn straw into glucose, achieving a cellulose conversion rate of 74.45% under conditions optimized for their enzymatic characteristics and hydrolytic reaction conditions. As a result of the reversibility and solubility of the carrier, the co-immobilized enzymes were recovered from the solid substrate after five cycles, retaining 54.67% of the enzyme activity. The aim of this study is to investigate the potential of co-immobilizing multiple enzymes onto the Eudragit L-100 carrier for the synergistic degradation of straw cellulose.

3D bioprinting in bioremediation: a comprehensive review of principles, applications, and future directions

Bioremediation is experiencing a paradigm shift by integrating three-dimensional (3D) bioprinting. This transformative approach augments the precision and versatility of engineering with the functional capabilities of material science to create environmental restoration strategies. This comprehensive review elucidates the foundational principles of 3D bioprinting technology for bioremediation, its current applications in bioremediation, and the prospective avenues for future research and technological evolution, emphasizing the intersection of additive manufacturing, functionalized biosystems, and environmental remediation; this review delineates how 3D bioprinting can tailor bioremediation apparatus to maximize pollutant degradation and removal. Innovations in biofabrication have yielded bio-based and biodegradable materials conducive to microbial proliferation and pollutant sequestration, thereby addressing contamination and adhering to sustainability precepts. The review presents an in-depth analysis of the application of 3D bioprinted constructs in enhancing bioremediation efforts, exemplifying the synergy between biological systems and engineered solutions. Concurrently, the review critically addresses the inherent challenges of incorporating 3D bioprinted materials into diverse ecological settings, including assessing their environmental impact, durability, and integration into large-scale bioremediation projects. Future perspectives discussed encompass the exploration of novel biocompatible materials, the automation of bioremediation, and the convergence of 3D bioprinting with cutting-edge fields such as nanotechnology and other emerging fields. This article posits 3D bioprinting as a cornerstone of next-generation bioremediation practices, offering scalable, customizable, and potentially greener solutions for reclaiming contaminated environments. Through this review, stakeholders in environmental science, engineering, and technology are provided with a critical appraisal of the current state of 3D bioprinting in bioremediation and its potential to drive forward the efficacy of environmental management practices.

Immobilizing white-rot fungi laccase: Toward bio-derived supports as a circular economy approach in organochlorine removal

Despite their high persistence in the environment, organochlorines (OC) are widely used in the pharmaceutical industry, in plastics, and in the manufacture of pesticides, among other applications. These compounds and the byproducts of their decomposition deserve attention and efficient proposals for their treatment. Among sustainable alternatives, the use of ligninolytic enzymes (LEs) from fungi stands out, as these molecules can catalyze the transformation of a wide range of pollutants. Among LEs, laccases (Lac) are known for their efficiency as biocatalysts in the conversion of organic pollutants. Their application in biotechnological processes is possible, but the enzymes are often unstable and difficult to recover after use, driving up costs. Immobilization of enzymes on a matrix (support or solid carrier) allows recovery and stabilization of this catalytic capacity. Agricultural residual biomass is a passive environmental asset. Although underestimated and still treated as an undesirable component, residual biomass can be used as a low-cost adsorbent and as a support for the immobilization of enzymes. In this review, the adsorption capacity and immobilization of fungal Lac on supports made from residual biomass, including compounds such as biochar, for the removal of OC compounds are analyzed and compared with the use of synthetic supports. A qualitative and quantitative comparison of the reported results was made. In this context, the use of peanut shells is highlighted in view of the increasing peanut production worldwide. The linkage of methods with circular economy approaches that can be applied in practice is discussed.