Production of a robust nanobiocatalyst for municipal wastewater treatment

Green nanobiocatalysts: enhancing enzyme immobilization for industrial and biomedical applications

Nanobiocatalysts (NBCs), which merge enzymes with nanomaterials, provide a potent method for improving enzyme durability, efficiency, and recyclability. This review highlights the use of eco-friendly synthesis methods to create sustainable nanomaterials for enzyme transport. We investigate different methods of immobilization, such as adsorption, ionic and covalent bonding, entrapment, and cross-linking, examining their pros and cons. The decreased environmental impact of green-synthesized nanomaterials from plants, bacteria, and fungi is emphasized. The review exhibits the various uses of NBCs in food industry, biofuel production, and bioremediation, showing how they can enhance effectiveness and eco-friendliness. Furthermore, we explore the potential impact of NBCs in biomedicine. In general, green nanobiocatalysts are a notable progression in enzyme technology, leading to environmentally-friendly and effective biocatalytic methods that have important impacts on industrial and biomedical fields.

Green synthesis of iron nanoparticles: Sources and multifarious biotechnological applications

Green synthesis of iron nanoparticles is a highly fascinating research area and has gained importance due to reliable, sustainable and ecofriendly protocol for synthesizing nanoparticles, along with the easy availability of plant materials and their pharmacological significance. As an alternate to physical and chemical synthesis, the biological materials, like microorganisms and plants are considered to be less costly and environment-friendly. Iron nanoparticles with diverse morphology and size have been synthesized using biological extracts. Microbial (bacteria, fungi, algae etc.) and plant extracts have been employed in green synthesis of iron nanoparticles due to the presence of various metabolites and biomolecules. Physical and biochemical properties of biologically synthesized iron nanoparticles are superior to that are synthesized using physical and chemical agents. Iron nanoparticles have magnetic property with thermal and electrical conductivity. Iron nanoparticles below a certain size (generally 10-20 nm), can exhibit a unique form of magnetism called superparamagnetism. They are non-toxic and highly dispersible with targeted delivery, which are suitable for efficient drug delivery to the target. Green synthesized iron nanoparticles have been explored for multifarious biotechnological applications. These iron nanoparticles exhibited antimicrobial and anticancerous properties. Iron nanoparticles adversely affect the cell viability, division and metabolic activity. Iron nanoparticles have been used in the purification and immobilization of various enzymes/proteins. Iron nanoparticles have shown potential in bioremediation of various organic and inorganic pollutants. This review describes various biological sources used in the green synthesis of iron nanoparticles and their potential applications in biotechnology, diagnostics and mitigation of environmental pollutants.

Utilization of laccase immobilized CdO nanoparticles in synthesis of industrially potent organics and their molecular docking studies

In the present study, Tricholoma giganteum AGHP laccase was immobilized on amino-functionalized cadmium oxide nanoparticles (CdO NPs) which was carried out by glutaraldehyde. The synthesized CdO NPs were characterized by using transmission electron microscopy (TEM), Energy dispersive X-ray analysis (EDXA) and X-ray diffraction (XRD) analysis which reflected the NPs had an average size of 35 nm with hexagonal and irregular shapes. Fourier transform infra-red (FTIR) study of laccase with amino-functionalized CdO (lac-CdO) NPs confirmed the crosslinking of laccase with CdO NPs. With immobilized laccase, a shift in pH (5.5) and temperature (35 ℃) optima was observed, when compared to free laccase (pH 4.5, 30 ℃). Lac-CdO NPs displayed 1.15 times higher stability (90 ± 0.47%) than free laccase (78 ± 0.69%) at optimum pH of 5.5. Immobilized laccase showed 1.19-fold improvement in thermal stability and 2.25-fold increment in half-life after 3 h of incubation at 50 ℃ as compared to free laccase. Recycling capability study demonstrated that lac-CdO NPs were able to retain 85 ± 0.68% of relative activity at the end of 20th 2,2-azinobis-3-ethylbenzthiozoline-6-sulfonic acid (ABTS) oxidation cycle. In addition, lac-CdO NPs showed remarkable reusability in catalysing various organic synthesis reactions even after several cycle of catalysis. Furthermore, the interactions of organic synthesis reactions and interacted residues were observed by assessing the molecular docking poses of T. giganteum laccase with substrates. The obtained results would be advantageous to develop a biocatalyst over a chemical catalyst for effective synthesis of potent organics having industrial importance.

Expanding the Scope of Nanobiocatalysis and Nanosensing: Applications of Nanomaterial Constructs

The synergistic interaction between advanced biotechnology and nanotechnology has allowed the development of innovative nanomaterials. Those nanomaterials can conveniently act as supports for enzymes to be employed as nanobiocatalysts and nanosensing constructs. These systems generate a great capacity to improve the biocatalytic potential of enzymes by improving their stability, efficiency, and product yield, as well as facilitating their purification and reuse for various bioprocessing operating cycles. The different specific physicochemical characteristics and the supramolecular nature of the nanocarriers obtained from different economical and abundant sources have allowed the continuous development of functional nanostructures for different industries such as food and agriculture. The remarkable biotechnological potential of nanobiocatalysts and nanosensors has generated applied research and use in different areas such as biofuels, medical diagnosis, medical therapies, environmental bioremediation, and the food industry. The objective of this work is to present the different manufacturing strategies of nanomaterials with various advantages in biocatalysis and nanosensing of various compounds in the industry, providing great benefits to society and the environment.

Molecularly imprinted polymers via reversible addition-fragmentation chain-transfer synthesis in sensing and environmental applications

Molecularly imprinted polymers (MIP) have shown their potential as artificial and selective receptors for environmental monitoring. These materials can be tailor-made to achieve a specific binding event with a template through a chosen mechanism. They are capable of emulating the recognition capacity of biological receptors with superior stability and versatility of integration in sensing platforms. Commonly, these polymers are produced by traditional free radical bulk polymerization (FRP) which may not be the most suitable for enhancing the intended properties due to the poor imprinting performance. To improve the imprinting technique and the polymer capabilities, controlled/living radical polymerization (CRP) has been used to overcome the main drawbacks of FRP. Combining CRP techniques such as RAFT (reversible addition-fragmentation chain transfer) with MIP has achieved higher selectivity, sensitivity, and sorption capacity of these polymers when implemented as the transductor element in sensors. The present work focuses on RAFT-MIP design and synthesis strategies to enhance the binding affinities and their implementation in environmental contaminant sensing applications.

Immobilized fungal enzymes: Innovations and potential applications in biodegradation and biosynthesis

Microbial enzymes catalyze various reactions inside and outside living cells. Among the widely studied enzymes, fungal enzymes have been used for some of the most diverse purposes, especially in bioremediation, biosynthesis, and many nature-inspired commercial applications. To improve their stability and catalytic ability, fungal enzymes are often immobilized on assorted materials, conventional as well as nanoscale. Recent advances in fungal enzyme immobilization provide effective and sustainable approaches to achieve improved environmental and commercial outcomes. This review aims to provide a comprehensive overview of commonly studied fungal enzymes and immobilization technologies. It also summarizes recent advances involving immobilized fungal enzymes for the degradation or assembly of compounds used in the manufacture of products, such as detergents, food additives, and fossil fuel alternatives. Furthermore, challenges and future directions are highlighted to offer new perspectives on improving existing technologies and addressing unexplored fields of applications.

Determination of conjugated protein on nanoparticles by an adaptation of the Coomassie blue dye method

A new accurate spectrophotometric method for protein determination on nanoparticles is described. The method is based on the Coomassie blue dye that binds to the basic and aromatic amino acid residues of proteins, especially arginine and lysine. A known amount of reagent dye was mixed with a variety of protein-loaded nanoparticles. Thereafter the unconjugated reagent was mixed with excess protein (bovine serum albumin) and titrated. In this method, the reacted dye on the protein coating of nanoparticle is directly determined, in opposite to the conventional method, in which the conjugated protein is determined as the difference between the non-conjugated protein found in the supernatant after centrifugation, and the total amount of protein originally used. This method is able to measure amounts of coated protein lower than 1 ppm.

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Simple and accurate method especially adapted for protein-coated nanoparticles.

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The amino acid residues of protein in the nanoparticle surface react with Coomassie brilliant blue dye.

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The unreacted dye is titrated with an excess of a standard protein.

Developments in support materials for immobilization of oxidoreductases: A comprehensive review

Bioremediation, a biologically mediated transformation or degradation of persistent chemicals into nonhazardous or less-hazardous substances, has been recognized as a key strategy to control levels of pollutants in water and soils. The use of enzymes, notably oxidoreductases such as laccases, tyrosinases, various oxygenases, aromatic dioxygenases, and different peroxidases (all of EC class 1) is receiving significant research attention in this regard. It should be stated that immobilization is emphasized as a powerful tool for enhancement of enzyme activity and stability as well as for protection of the enzyme proteins against negative effects of harsh reaction conditions. As proper selection of support materials for immobilization and their performance is overlooked when it comes to comparing performance of immobilized enzyme in academic studies, this review summarizes the current state of knowledge regarding the materials used for enzyme immobilization of these oxidoreductase enzymes for environmental applications. In the presented study, thorough physicochemical characteristics of the support materials was presented. Moreover, various types of reactions and notably operational modes of enzymatic processes for biodegradation of harmful pollutants are summarized, and future trends in use of immobilized oxidoreductases for environmental applications are discussed. Our goal is to provide an improved foundation on which new technological advancements can be made to achieve efficient enzyme-assisted bioremediation.

Characterisation of electron beam irradiation-immobilised laccase for application in wastewater treatment

Laccase from Phoma sp. UHH 5-1-03 was cross-linked to polyvinylidene fluoride membranes by electron beam irradiation. Immobilised laccase displayed a higher stability than the non-immobilised enzyme with respect to typical wastewater temperatures, and pH at a range of 5 to 9. Batch tests addressed the removal of pharmaceutically active compounds (PhACs; applied as a mixture of acetaminophen, bezafibrate, indometacin, ketoprofen, mefenamic acid, and naproxen) by both immobilised and non-immobilised laccase in municipal wastewater. High removal rates (>85%) of the most efficiently oxidised PhACs (acetaminophen and mefenamic acid) indicated a high efficiency of the immobilised laccase in wastewater. Continuous elimination of the aforementioned PhACs by the immobilised enzyme in a continuously operated diffusion basket reactor yielded a PhAC removal pattern qualitatively similar to those observed in batch tests. Clearly higher apparent V_max values and catalytic efficiencies (in terms of both V_max/S_0.5 as well as V_max/K_m values obtained from data fitting according to the Hill and the Michaelis-Menten model, respectively) observed for acetaminophen oxidation by the immobilised compared to the non-immobilised enzyme are in support of a considerably higher functional stability of the immobilised laccase especially in wastewater. The potential influence of acetaminophen on the removal of comparatively less laccase-oxidisable water pollutants such as the antimicrobial triclosan (TCS) was investigated. TCS was increasingly removed upon increasing the initial acetaminophen concentration in immobilised as well as non-immobilised laccase reaction systems until saturation became evident. Acetaminophen was consumed and not recycled during laccase reactions, which was accompanied by the formation of various acetaminophen-TCS cross-coupling products. Nevertheless, the simultaneous presence of acetaminophen (and potentially even more pollutant removal-enhancing laccase substrates) and more recalcitrant pollutants in wastewater represents an interesting option for the efficiency enhancement of enzyme-based wastewater treatment approaches.

Assessing the use of nanoimmobilized laccases to remove micropollutants from wastewater

Enzymes immobilization is a useful way to allow enzyme reuse and increase their stability. A high redox potential laccase from Trametes versicolor (TvL) and a low redox potential, but commercially available low-cost laccase from Myceliophthora thermophila (MtL), were successfully immobilized and co-immobilized onto fumed silica nanoparticles (fsNP). Enzyme loads of 1.78 ± 0.07, 0.69 ± 0.03, and 1.10 ± 0.01 U/mg fsNP were attained for the optimal doses of TvL, MtL, and co-immobilized laccases, respectively. In general, the laccase-fsNP conjugates showed a higher resistance against an acidic pH value (i.e., pH 3), and a higher storage stability than free enzymes. In addition, immobilized enzymes exhibited a superior long-term stability than free laccases when incubated in a secondary effluent from a municipal wastewater treatment plant (WWTP). For instance, the residual activity after 2 weeks for the co-immobilized laccases and the mixture of free laccases were 40.2 ± 2.5% and 16.8 ± 1.0%, respectively. The ability of the laccase-fsNP to remove a mixture of (14)C-bisphenol A (BPA) and (14)C-sodium diclofenac (DCF) from spiked secondary effluents was assessed in batch experiments. The catalytic efficiency was highly dependent on both the microbial source and state of the biocatalyst. The high redox potential TvL in free form attained a four-fold higher percentage of BPA transformation than the free MtL. Compared to free laccases, immobilized enzymes led to much slower rates of BPA transformation. For instance, after 24 h, the percentages of BPA transformation by 1000 U/L of a mixture of free laccases or co-immobilized enzymes were 67.8 ± 5.2 and 27.0 ± 3.9%, respectively. Nevertheless, the use of 8000 U/L of co-immobilized laccase led to a nearly complete removal of BPA, despite the unfavorable conditions for laccase catalysis (pH ~ 8.4). DCF transformation was not observed for any of the enzymatic systems, showing that this compound is highly recalcitrant toward laccase oxidation under realistic conditions.

Laccases to take on the challenge of emerging organic contaminants in wastewater

The removal of emerging organic contaminants from municipal wastewater poses a major challenge unsatisfactorily addressed by present wastewater treatment processes. Enzyme-catalyzed transformation of emerging organic contaminants (EOC) has been proposed as a possible solution to this major environmental issue more than a decade ago. Especially, laccases gained interest in this context in recent years due to their broad substrate range and since they only need molecular oxygen as a cosubstrate. In order to ensure the stability of the enzymes and allow their retention and reuse, either immobilization or insolubilization of the biocatalysts seems to be the prerequisite for continuous wastewater treatment applications. The present review summarizes the research conducted on EOC transformation with laccases and presents an overview of the possible immobilization techniques. The goal is to assess the state of the art and identify the next necessary steps that have to be undertaken in order to implement laccases as a tertiary wastewater treatment process in sewage treatment plants.

Hybrid membrane with TiO2 based bio-catalytic nanoparticle suspension system for the degradation of bisphenol-A

The removal of micropollutant in wastewater treatment has become a key environmental challenge for many industrialized countries. One approach is to use enzymes such as laccase for the degradation of micropollutants such as bisphenol-A. In this work, laccase was covalently immobilized on APTES modified TiO2 nanoparticles, and the effects of particle modification on the bio-catalytic performance were examined and optimized. These bio-catalytic particles were then suspended in a hybrid membrane reactor for BPA removal with good BPA degradation efficiency observed. Substantial improvement in laccase stability was achieved in the hybrid system compared with free laccase under simulated harsh industrial wastewater treatment conditions (such as a wide range of pH and presence of inhibitors). Kinetic study provided insight of the effect of immobilization on the bio-degradation reaction.

Electron beam-induced immobilization of laccase on porous supports for waste water treatment applications

The versatile oxidase enzyme laccase was immobilized on porous supports such as polymer membranes and cryogels with a view of using such biocatalysts in bioreactors aiming at the degradation of environmental pollutants in wastewater. Besides a large surface area for supporting the biocatalyst, the aforementioned porous systems also offer the possibility for simultaneous filtration applications in wastewater treatment. Herein a "green" water-based, initiator-free, and straightforward route to highly reactive membrane and cryogel-based bioreactors is presented, where laccase was immobilized onto the porous polymer supports using a water-based electron beam-initiated grafting reaction. In a second approach, the laccase redox mediators 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) and syringaldehyde were cross-linked instead of the enzyme via electron irradiation in a frozen aqueous poly(acrylate) mixture in a one pot set-up, yielding a mechanical stable macroporous cryogel with interconnected pores ranging from 10 to 50 µm in size. The membranes as well as the cryogels were characterized regarding their morphology, chemical composition, and catalytic activity. The reactivity towards waste- water pollutants was demonstrated by the degradation of the model compound bisphenol A (BPA). Both membrane- and cryogel-immobilized laccase remained highly active after electron beam irradiation. Apparent specific BPA removal rates were higher for cryogel- than for membrane-immobilized and free laccase, whereas membrane-immobilized laccase was more stable with respect to maintenance of enzymatic activity and prevention of enzyme leakage from the carrier than cryogel-immobilized laccase. Cryogel-immobilized redox mediators remained functional in accelerating the laccase-catalyzed BPA degradation, and especially ABTS was found to act more efficiently in immobilized than in freely dissolved state.

Advanced enzymatic elimination of phenolic contaminants in wastewater: a nano approach at field scale

The removal of recalcitrant chemicals in wastewater treatment systems is an increasingly relevant issue in industrialized countries. The elimination of persistent xenobiotics such as endocrine-disrupting chemicals (EDCs) emitted by municipal and industrial sewage treatment plants remains an unsolved challenge. The existing efficacious physico-chemical methods, such as advanced oxidation processes, are resource-intensive technologies. In this work, we investigated the possibility to remove phenolic EDCs [i.e., bisphenol A (BPA)] by means of a less energy and chemical consuming technology. To that end, cheap and resistant oxidative enzymes, i.e., laccases, were immobilized onto silica nanoparticles. The resulting nanobiocatalyst produced at kilogram scale was demonstrated to possess a broad substrate spectrum regarding the degradation of recalcitrant pollutants. This nanobiocatalyst was applied in a membrane reactor at technical scale for tertiary wastewater treatment. The system efficiently removed BPA and the results of long-term field tests illustrated the potential of fumed silica nanoparticles/laccase composites for advanced biological wastewater treatment.

Determination of oxidoreductase activity using a high-throughput microplate respiratory measurement

High-throughput multiparallel activity profiling for oxygen consuming cell layers has been recently developed for extracellular flux analysis. This technology has great potential for determining the enzymatic activity of oxidoreductases (i.e., laccase) both in vivo and in vitro, which is usually measured using photometrical tests monitoring the colored oxidation products. Improvements in terms of sample throughput, comparability, and gain of information (i.e., stoichiometry, electron transfer rate) can be achieved by means of a multiwell plate-based fluorimetric oxygen sensor. In the present study, various laccases have been applied to develop protocols that allow the multiparallel measurement of O(2)-consumption by enzymatic reactions. The developed and validated method enables the comparative quantitation of laccase characteristics (i.e., profiles of activity at various pH values) and minimizes the time it usually takes to collect respiratory data of oxygen-consuming enzymes. Furthermore, the possibility to assess differences between single and multisubstrate kinetics of laccases has been demonstrated.