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.

Nanotherapy to Reshape the Tumor Microenvironment: A New Strategy for Prostate Cancer Treatment

Prostate cancer (PCa) is the second most common cancer in males worldwide. Androgen deprivation therapy (ADT) is the primary treatment method used for PCa. Although more effective androgen synthesis and antiandrogen inhibitors have been developed for clinical practice, hormone resistance increases the incidence of ADT-insensitive prostate cancer and poor prognoses. The tumor microenvironment (TME) has become a research hotspot with efforts to identify treatment targets based on the characteristics of the TME to improve prognosis. Herein, we introduce the basic characteristics of the PCa TME and the side effects of traditional prostate cancer treatments. We further highlight the emergence of novel nanotherapy strategies, their therapeutic mechanisms, and their effects on the PCa microenvironment. With further research, clinical applications of nanotherapy for PCa are expected in the near future. Collectively, this Review provides a valuable resource regarding the various nanotherapy types, demonstrating their broad clinical prospects to improve the quality of life in patients with PCa.

An enzymatic continuous-flow reactor based on a pore-size matching nano- and isoporous block copolymer membrane

Continuous-flow biocatalysis utilizing immobilized enzymes emerged as a sustainable route for chemical synthesis. However, inadequate biocatalytic efficiency from current flow reactors, caused by non-productive enzyme immobilization or enzyme-carrier mismatches in size, hampers its widespread application. Here, we demonstrate a general-applicable and robust approach for the fabrication of a high-performance enzymatic continuous-flow reactor via integrating well-designed scalable isoporous block copolymer (BCP) membranes as carriers with an oriented and productive immobilization employing material binding peptides (MBP). Densely packed uniform enzyme-matched nanochannels of well-designed BCP membranes endow the desired nanoconfined environments towards a productive immobilized phytase. Tuning nanochannel properties can further regulate the complex reaction process and fortify the catalytic performance. The synergistic design of enzyme-matched carriers and efficient enzyme immobilization empowers an excellent catalytic performance with >1 month operational stability, superior productivity, and a high space-time yield (1.05 × 105 g L-1 d-1) via a single-pass continuous-flow process. The obtained performance makes the designed nano- and isoporous block copolymer membrane reactor highly attractive for industrial applications.

Mesocellular Silica Foam as Immobilization Carrier for Production of Statin Precursors

The employment of 2-deoxyribose-5-phosphate aldolase (DERA) stands as a prevalent biocatalytic route for synthesizing statin side chains. The main problem with this pathway is the low stability of the enzyme. In this study, mesocellular silica foam (MCF) with different pore sizes was used as a carrier for the covalent immobilization of DERA. Different functionalizing and activating agents were tested and kinetic modeling was subsequently performed. The use of succinic anhydride as an activating agent resulted in an enzyme hyperactivation of approx. 140%, and the stability almost doubled compared to that of the free enzyme. It was also shown that the pore size of MCF has a decisive influence on the stability of the DERA enzyme.

Biofluid-Activated Biofuel Cells, Batteries, and Supercapacitors: A Comprehensive Review

Recent developments in wearable and implanted devices have resulted in numerous, unprecedented capabilities that generate increasingly detailed information about a user's health or provide targeted therapy. However, options for powering such systems remain limited to conventional batteries which are large and have toxic components and as such are not suitable for close integration with the human body. This work provides an in-depth overview of biofluid-activated electrochemical energy devices, an emerging class of energy sources judiciously designed for biomedical applications. These unconventional energy devices are composed of biocompatible materials that harness the inherent chemistries of various biofluids to produce useable electrical energy. This work covers examples of such biofluid-activated energy devices in the form of biofuel cells, batteries, and supercapacitors. Advances in materials, design engineering, and biotechnology that form the basis for high-performance, biofluid-activated energy devices are discussed. Innovations in hybrid manufacturing and heterogeneous integration of device components to maximize power output are also included. Finally, key challenges and future scopes of this nascent field are provided.

Glucose Oxidase Loading in Ordered Porous Aluminosilicates: Exploring the Potential of Surface Modification for Electrochemical Glucose Sensing

Enzymatic electrochemical sensors have become the leading glucose detection technology due to their rapid response, affordability, portability, selectivity, and sensitivity. However, the performance of these sensors is highly dependent on the surface properties of the electrode material used to store glucose oxidase and its ability to retain enzymatic activity under variable environmental conditions. Mesoporous thin films have recently attracted considerable attention as promising candidates for enzyme storage and activity preservation due to their well-defined nanoarchitecture and tunable surface properties. Herein, we systematically compare pathways for the immobilization of glucose oxidase (GOx) and their effectiveness in electrochemical glucose sensing, following modification protocols that lead to the electrostatic attraction (amino functionalization), covalent bonding (aldehyde functionalization), and electrostatic repulsion (oxygen plasma treatment) of the ordered porous aluminosilicate-coated electrodes. By direct comparison using a quartz crystal microbalance, we demonstrate that glucose oxidase can be loaded in a nanoarchitecture with a pore size of ∼50 nm and pore interconnections of ∼35 nm using the native aluminosilicate surface, as well as after amino or aldehyde surface modification, while oxygen plasma exposure of the native surface inhibits glucose oxidase loading. Despite a variety of routes for enzyme loading, quantitative electrochemical glucose sensing between 0 and 20 mM was only possible when the porous surface was functionalized with amino groups, which we relate to the role of surface chemistry in accessing the underlying substrate. Our results highlight the impact of rational surface modification on electrochemical biosensing performance and demonstrate the potential of tailoring porous nanoarchitecture surfaces for biosensing applications.

Fabrication of a Floatable Micron-Sized Enzyme Device Using Diatom Frustules

Immobilization of enzymes has been widely reported due to their reusability, thermal stability, better storage abilities, and so on. However, there are still problems that immobilized enzymes do not have free movements to react to substrates during enzyme reactions and their enzyme activity becomes weak. Moreover, when only the porosity of support materials is focused, some problems such as enzyme distortion can negatively affect the enzyme activity. Being a solution to these problems, a new function "floatability" of enzyme devices has been discussed. A "floatable" micron-sized enzyme device was fabricated to enhance the free movements of immobilized enzymes. Diatom frustules, natural nanoporous biosilica, were used to attach papain enzyme molecules. The floatability of the frustules, evaluated by macroscopic and microscopic methods, was significantly better than that of four other SiO2 materials, such as diatomaceous earth (DE), which have been widely used to fabricate micron-sized enzyme devices. The frustules were fully suspended at 30 °C for 1 h without stirring, although they settled at room temperature. When enzyme assays were performed at room temperature, 37, and 60 °C with or without external stirring, the proposed frustule device showed the highest enzyme activity under all conditions among papain devices similarly prepared using other SiO2 materials. It was confirmed by the free papain experiments that the frustule device was active enough for enzyme reactions. Our data indicated that the high floatability of the reusable frustule device, and its large surface area, is effective in maximizing enzyme activity due to the high probability to react to substrates.

Developing Enzyme Immobilization with Fibrous Membranes: Longevity and Characterization Considerations

Fibrous membranes offer broad opportunities to deploy immobilized enzymes in new reactor and application designs, including multiphase continuous flow-through reactions. Enzyme immobilization is a technology strategy that simplifies the separation of otherwise soluble catalytic proteins from liquid reaction media and imparts stabilization and performance enhancement. Flexible immobilization matrices made from fibers have versatile physical attributes, such as high surface area, light weight, and controllable porosity, which give them membrane-like characteristics, while simultaneously providing good mechanical properties for creating functional filters, sensors, scaffolds, and other interface-active biocatalytic materials. This review examines immobilization strategies for enzymes on fibrous membrane-like polymeric supports involving all three fundamental mechanisms of post-immobilization, incorporation, and coating. Post-immobilization offers an infinite selection of matrix materials, but may encounter loading and durability issues, while incorporation offers longevity but has more limited material options and may present mass transfer obstacles. Coating techniques on fibrous materials at different geometric scales are a growing trend in making membranes that integrate biocatalytic functionality with versatile physical supports. Biocatalytic performance parameters and characterization techniques for immobilized enzymes are described, including several emerging techniques of special relevance for fibrous immobilized enzymes. Diverse application examples from the literature, focusing on fibrous matrices, are summarized, and biocatalyst longevity is emphasized as a critical performance parameter that needs increased attention to advance concepts from lab scale to broader utilization. This consolidation of fabrication, performance measurement, and characterization techniques, with guiding examples highlighted, is intended to inspire future innovations in enzyme immobilization with fibrous membranes and expand their uses in novel reactors and processes.

Renewable, sustainable, and natural lignocellulosic carriers for lipase immobilization: A review

It is well-known that enzymes are molecules particularly susceptible to pH and temperature variations. Immobilization techniques may overcome this weakness besides improving the reusability of the biocatalysts. Given the strong push toward a circular economy, the use of natural lignocellulosic wastes as supports for enzyme immobilization has been increasingly attractive in recent years. This fact is mainly due to their high availability, low costs, and the possibility of reducing the environmental impact that can occur when they are improperly stored. In addition, they have physical and chemical characteristics suitable for enzyme immobilization (large surface area, high rigidity, porosity, reactive functional groups, etc.). This review aims to guide readers and provide them with the tools necessary to select the most suitable methodology for lipase immobilization on lignocellulosic wastes. The importance and the characteristics of an increasingly interesting enzyme, such as lipase, and the advantages and disadvantages of the different immobilization methods will be discussed. The various kinds of lignocellulosic wastes and the processing required to make them suitable as carriers will be also reported.

On the Sensitivity and Affinity of Gold, Silver, and Platinum Surfaces against the SARS-CoV-2 Virus: A Comparative Computational Study

The novel coronavirus disease and its complications have motivated the design of new sensors with the highest sensitivity, and affinity for the detection of the SARS-CoV-2 virus is considered in many research studies. In this research article, we employ full atomistic molecular dynamics (MD) models to study the interactions between the receptor binding domain (RBD) and spike protein of the coronavirus and different metals such as gold (Au), platinum (Pt), and silver (Ag) to analyze their sensitivity against this virus. The comparison between the RBD interactions with ACE2 (angiotensin-converting enzyme 2) and different metals indicates that metals have remarkable effects on the structural features and dynamical properties of the RBD. The binding site of the RBD has more affinity to the surfaces of gold, platinum, and silver than to the other parts of the protein. Moreover, the initial configuration of the RBD relative to the metal surface plays an important role in the stability of metal complexes with the RBD. The binding face of the protein to the metal surface has been changed in the presence of different metals. In other words, the residues of the RBD that participate in RBD interactions with the metals are different irrespective of the initial configurations in which the [Asn, Thr, Tyr], [Ser, Thr, Tyr], and [Asn, Asp, Tyr] residues of the protein have a greater affinity to Ag, Au, and Pt, respectively. The corresponding metals have a considerable affinity to the RBD, which due to strong interactions with the protein can change the secondary structure and structural features. Based on the obtained results during the complexation process between the protein and metals, the helical structure of the protein changes to the bend and antiparallel β-sheets. The calculated binding energies for the RBD complexes with silver, gold, and platinum are -95.03, -138.03, and -133.96 kcal·mol-1, respectively. The adsorption process of the spike protein on the surfaces of different metals represents similar results and indicates that the entire spike protein of the coronavirus forms a more stable complex with the gold surface compared with other metals. Moreover, the RBD of the spike protein has more interactions with the surfaces than with the other parts of the protein. Therefore, it is possible to predict the properties of the coronavirus on the metal surface based on the dynamical behavior of the RBD. Overall, our computational results confirm that the gold surface can be considered as an outstanding substrate for developing new sensors with the highest sensitivity against SARS-CoV-2.

3D Printed Porous Nanocellulose-Based Scaffolds As Carriers for Immobilization of Glycosyltransferases

Biocatalysis is increasingly becoming an alternative method for the synthesis of industrially relevant complex molecules. This can be realized by using enzyme immobilized polysaccharide-based 3D scaffolds as compatible carriers, with defined properties. Especially, immobilization of either single or multiple enzymes on a 3D printed polysaccharide scaffold, exhibiting well-organized interconnected porous structure and morphology, is a versatile approach to access the performance of industrially important enzymes. Here, we demonstrated the use of nanocellulose-based 3D porous scaffolds for the immobilization of glycosyltransferases, responsible for glycosylation in natural biosynthesis. The scaffolds were produced using an ink containing nanofibrillated cellulose (NFC), carboxymethyl cellulose (CMC), and citric acid. Direct-ink-writing 3D printing followed by freeze-drying and dehydrothermal treatment at elevated temperature resulted in chemically cross-linked scaffolds, featuring tunable negative charges (2.2-5.0 mmol/g), pore sizes (10-800 μm), fluid uptake capacity, and exceptional dimensional and mechanical stability in the wet state. The negatively charged scaffolds were applied to immobilize two sugar nucleotide-dependent glycosyltransferases (C-glycosyltransferase, Z_basic2-CGT; sucrose synthase, Z_basic2-SuSy), each harboring a cationic binding module (Z_basic2) to promote charge-based enzyme adsorption. Both enzymes were immobilized at ∼30 mg of protein/g of dry carrier (∼20% yield), independent of the scaffold used. Their specific activities were 0.50 U/mg (Z_basic2-CGT) and 0.19 U/mg (Z_basic2-SuSy), corresponding to an efficacy of 37 and 18%, respectively, compared to the soluble enzymes. The glycosyltransferases were coimmobilized and shown to be active in a cascade reaction to give the natural C-glycoside nothofagin from phloretin (1.0 mM; ∼95% conversion). All enzyme bound scaffolds showed reusability of a maximum of 5 consecutive reactions. These results suggest that the 3D printed and cross-linked NFC/CMC-based scaffolds could present a class of solid carriers for enzyme (co)-immobilization, with promising applications in glycosyltransferase-catalyzed synthesis and other fields of biocatalysis.

Protein Condensation at Nanopore Entrances as Studied by Differential Scanning Calorimetry and Small-Angle Neutron Scattering

The condensation of globular myoglobin (Mb) at the pore entrances of mesoporous silica (MPS) with a series of pore diameters (4.2, 6.4, 7.7, and 9.0 nm) was examined by differential scanning calorimetry (DSC) and contrast-matching small-angle neutron scattering (CM-SANS) experiments. The DSC measurements were performed to estimate the amount of Mb adsorbed at two different adsorption sites, namely, the pore interior and the pore entrance regions. The CM-SANS measurements were conducted to observe condensation of Mb molecules at the pore entrance regions. Notably, the nanopore entrance with a diameter close to twice that of the Mb diameter was found to be the specific cavity to facilitate the condensation of globular Mb. The Mb condensation occurred at the entrances of the 6.4 nm pore during the adsorption uptake from concentrated Mb solutions, whereas the adsorption uptake from diluted Mb solutions induced the condensation of Mb at the entrances of the 7.7 nm pore.

Nano-fibrillated cellulose-based scaffolds for enzyme (co)-immobilization: Application to natural product glycosylation by Leloir glycosyltransferases

Polysaccharide-based scaffolds are promising carriers for enzyme immobilization. Here, we demonstrate a porous scaffold prepared by direct-ink-writing 3D printing of an ink consisting of nanofibrillated cellulose, carboxymethyl cellulose and citric acid for immobilization application. Negative surface charge introduced by the components made the scaffold amenable for an affinity-like immobilization via the cationic protein module Z_basic2. Z_basic2 fusions of two sugar nucleotide-dependent glycosyltransferases (C-glycosyltransferase, Z-CGT; sucrose synthase, Z-SuSy) were immobilized individually, or co-immobilized, and applied to synthesize the natural C-glycoside nothofagin. The cascade reaction involved β-C-glycosylation of phloretin (10 mM, ~90 % conversion) from UDP-glucose, provided from sucrose and catalytic amounts of UDP (1.0 mM). Enzymes were co-immobilized at ~65 mg protein/g carrier to receive activities of 9.5 U/g (Z-CGT) and 4.5 U/g (Z-SuSy) in 22-33 % yield (protein) and an effectiveness of 23 % (Z-CGT) and 13 % (Z-SuSy). The scaffold-bound enzymes were recyclable for 5 consecutive reactions.

Tri-templating Synthesis of Multilevel Mesoporous Silica Microspheres with a Complex Interior Structure for Efficient CO2 Capture and Catalysis

Multilevel porous architectures with microscopic shape control and tailor-made complex structures offer great potential for various innovative applications, but their elaborate design and synthesis have remained a scientific and technological challenge. Herein, we report a simple and effective tri-templating method, in which microscale Pickering droplets, nanoscale polystyrene colloids (PS), and molecular cetyltrimethylammonium chloride micelles are synchronously employed, for the fabrication of such micro-nanohierarchical mesoporous silica microspheres. In this protocol, Pickering droplet-directed interfacial sol-gel growth and its spatially confined surfactant assembly-directed sol-gel coating on PS suspensions are coupled together, enabling the successful formation of structured mesoporous silica that consists of numerous nanocompartments enclosed by a permeable shell. By varying the quantity of PS colloidal templates, rational regulation of the complex interior structure is achieved. Also, ascribed to the multilevel arrangement, this peculiar architecture not only shows desirable fast mass transport of external molecules but also possesses easy handling ability. After loading with tetraethylenepentamine or enzyme species, the yielded microspherical CO₂ sorbents or immobilized biocatalysts, respectively, exhibit enhanced CO₂ capture capacity and enzymatic catalysis efficiency. Notably, taking advantage of their microscopic characteristics, the immobilized biocatalysts could be ideally packed in a fixed-bed reactor for long-term continuous-flow enzymatic reactions. This tri-templating strategy provides a new synthetic route to access other multilevel microscopic materials with fascinating complex structures and paves a way to promote their practical applications.

The emergence of nanoporous materials in lung cancer therapy

Lung cancer is one of the most common cancers, affecting more than 2.1 million people across the globe every year. A very high occurrence and mortality rate of lung cancer have prompted active research in this area with both conventional and novel forms of therapies including the use of nanomaterials based drug delivery agents. Specifically, the unique physico-chemical and biological properties of porous nanomaterials have gained significant momentum as drug delivery agents for delivering a combination of drugs or merging diagnosis with targeted therapy for cancer treatment. This review focuses on the emergence of nano-porous materials for drug delivery in lung cancer. The review analyses the currently used nanoporous materials, including inorganic, organic and hybrid porous materials for delivering drugs for various types of therapies, including chemo, radio and phototherapy. It also analyses the selected research on stimuli-responsive nanoporous materials for drug delivery in lung cancer before summarizing the various findings and projecting the future of emerging trends. This review provides a strong foundation for the current status of the research on nanoporous materials, their limitations and the potential for improving their design to overcome the unique challenges of delivering drugs for the treatment of lung cancer.

Complementary Powerful Techniques for Investigating the Interactions of Proteins with Porous TiO2 and Its Hybrid Materials: A Tutorial Review

Understanding the adsorption and interaction between porous materials and protein is of great importance in biomedical and interface sciences. Among the studied porous materials, TiO₂ and its hybrid materials, featuring distinct, well-defined pore sizes, structural stability and excellent biocompatibility, are widely used. In this review, the use of four powerful, synergetic and complementary techniques to study protein-TiO_2-based porous materials interactions at different scales is summarized, including high-performance liquid chromatography (HPLC), atomic force microscopy (AFM), surface-enhanced Raman scattering (SERS), and Molecular Dynamics (MD) simulations. We expect that this review could be helpful in optimizing the commonly used techniques to characterize the interfacial behavior of protein on porous TiO₂ materials in different applications.

Enzyme Immobilization and Co-Immobilization: Main Framework, Advances and Some Applications

Enzymes are outstanding (bio)catalysts, not solely on account of their ability to increase reaction rates by up to several orders of magnitude but also for the high degree of substrate specificity, regiospecificity and stereospecificity. The use and development of enzymes as robust biocatalysts is one of the main challenges in biotechnology. However, despite the high specificities and turnover of enzymes, there are also drawbacks. At the industrial level, these drawbacks are typically overcome by resorting to immobilized enzymes to enhance stability. Immobilization of biocatalysts allows their reuse, increases stability, facilitates process control, eases product recovery, and enhances product yield and quality. This is especially important for expensive enzymes, for those obtained in low fermentation yield and with relatively low activity. This review provides an integrated perspective on (multi)enzyme immobilization that abridges a critical evaluation of immobilization methods and carriers, biocatalyst metrics, impact of key carrier features on biocatalyst performance, trends towards miniaturization and detailed illustrative examples that are representative of biocatalytic applications promoting sustainability.

Sources, purification, immobilization and industrial applications of microbial lipases: An overview

Microbial lipase is looking for better attention with the fast growth of enzyme proficiency and other benefits like easy, cost-effective, and reliable manufacturing. Immobilized enzymes can be used repetitively and are incapable to catalyze the reactions in the system continuously. Hydrophobic supports are utilized to immobilize enzymes when the ionic strength is low. This approach allows for the immobilization, purification, stability, and hyperactivation of lipases in a single step. The diffusion of the substrate is more advantageous on hydrophobic supports than on hydrophilic supports in the carrier. These approaches are critical to the immobilization performance of the enzyme. For enzyme immobilization, synthesis provides a higher pH value as well as greater heat stability. Using a mixture of immobilization methods, the binding force between enzymes and the support rises, reducing enzyme leakage. Lipase adsorption produces interfacial activation when it is immobilized on hydrophobic support. As a result, in the immobilization process, this procedure is primarily used for a variety of industrial applications. Microbial sources, immobilization techniques, and industrial applications in the fields of food, flavor, detergent, paper and pulp, pharmaceuticals, biodiesel, derivatives of esters and amino groups, agrochemicals, biosensor applications, cosmetics, perfumery, and bioremediation are all discussed in this review.

Recent Advances in Nanozymes for Bacteria-Infected Wound Therapy

Bacterial-infected wounds are a serious threat to public health. Bacterial invasion can easily delay the wound healing process and even cause more serious damage. Therefore, effective new methods or drugs are needed to treat wounds. Nanozyme is an artificial enzyme that mimics the activity of a natural enzyme, and a substitute for natural enzymes by mimicking the coordination environment of the catalytic site. Due to the numerous excellent properties of nanozymes, the generation of drug-resistant bacteria can be avoided while treating bacterial infection wounds by catalyzing the sterilization mechanism of generating reactive oxygen species (ROS). Notably, there are still some defects in the nanozyme antibacterial agents, and the design direction is to realize the multifunctionalization and intelligence of a single system. In this review, we first discuss the pathophysiology of bacteria infected wound healing, the formation of bacterial infection wounds, and the strategies for treating bacterially infected wounds. In addition, the antibacterial advantages and mechanism of nanozymes for bacteria-infected wounds are also described. Importantly, a series of nanomaterials based on nanozyme synthesis for the treatment of infected wounds are emphasized. Finally, the challenges and prospects of nanozymes for treating bacterial infection wounds are proposed for future research in this field.

DNase I functional microgels for neutrophil extracellular trap disruption

Neutrophil extracellular traps (NETs) are web-like chromatin structures produced and liberated by neutrophils under inflammatory conditions which also promote the activation of the coagulation cascade and thrombus formation. The formation of NETs is quite prominent when blood comes in contact with artificial surfaces like extracorporeal circuits, oxygenator membranes, or intravascular grafts. DNase I as a factor of the host defense system, digests the DNA backbone of NETs, which points out its treatment potential for NET-mediated thrombosis. However, the low serum stability of DNase I restricts its clinical/therapeutic applications. To improve the bioavailability of the enzyme, DNase I was conjugated to the microgels (DNase I MG) synthesized from highly hydrophilic N-(2-hydroxypropyl) methacrylamide (HPMA) and zwitterionic carboxybetaine methacrylamide (CBMAA). The enzyme was successfully conjugated to the microgels without any alternation to its secondary structure. The K_m value representing the enzymatic activity of the conjugated DNase I was calculated to be 0.063 μM demonstrating a high enzyme-substrate affinity. The DNase I MGs were protein repellant and were able to digest NETs more efficiently compared to free DNase in a biological media, remarkably even after long-term exposure to the stimulated neutrophils continuously releasing NETs. Overall, the conjugation of DNase I to a non-fouling microgel provides a novel biohybrid platform that can be exploited as non-thrombogenic active microgel-based coatings for blood-contacting surfaces to reduce the NET-mediated inflammation and microthrombi formation.

Intraparticle Kinetics Unveil Crowding and Enzyme Distribution Effects on the Performance of Cofactor-Dependent Heterogeneous Biocatalysts

Multidimensional kinetic analysis of immobilized enzymes is essential to understand the enzyme functionality at the interface with solid materials. However, spatiotemporal kinetic characterization of heterogeneous biocatalysts on a microscopic level and under operando conditions has been rarely approached. As a case study, we selected self-sufficient heterogeneous biocatalysts where His-tagged cofactor-dependent enzymes (dehydrogenases, transaminases, and oxidases) are co-immobilized with their corresponding phosphorylated cofactors [nicotinamide adenine dinucleotide phosphate (NAD(P)H), pyridoxal phosphate (PLP), and flavin adenine dinucleotide (FAD)] on porous agarose microbeads coated with cationic polymers. These self-sufficient systems do not require the addition of exogenous cofactors to function, thus avoiding the extensive use of expensive cofactors. To comprehend the microscopic kinetics and thermodynamics of self-sufficient systems, we performed fluorescence recovery after photobleaching measurements, time-lapse fluorescence microscopy, and image analytics at both single-particle and intraparticle levels. These studies reveal a thermodynamic equilibrium that rules out the reversible interactions between the adsorbed phosphorylated cofactors and the polycations within the pores of the carriers, enabling the confined cofactors to access the active sites of the immobilized enzymes. Furthermore, this work unveils the relationship between the apparent Michaelis-Menten kinetic parameters and the enzyme density in the confined space, eliciting a negative effect of molecular crowding on the performance of some enzymes. Finally, we demonstrate that the intraparticle apparent enzyme kinetics are significantly affected by the enzyme spatial organization. Hence, multiscale characterization of immobilized enzymes serves as an instrumental tool to better understand the in operando functionality of enzymes within confined spaces.

Recent Developments in the Immobilization of Laccase on Carbonaceous Supports for Environmental Applications - A Critical Review

Τhe ligninolytic enzyme laccase has proved its potential for environmental applications. However, there is no documented industrial application of free laccase due to low stability, poor reusability, and high costs. Immobilization has been considered as a powerful technique to enhance laccase's industrial potential. In this technology, appropriate support selection for laccase immobilization is a crucial step since the support could broadly affect the properties of the resulting catalyst system. Through the last decades, a large variety of inorganic, organic, and composite materials have been used in laccase immobilization. Among them, carbon-based materials have been explored as a support candidate for immobilization, due to their properties such as high porosity, high surface area, the existence of functional groups, and their highly aromatic structure. Carbon-based materials have also been used in culture media as supports, sources of nutrients, and inducers, for laccase production. This study aims to review the recent trends in laccase production, immobilization techniques, and essential support properties for enzyme immobilization. More specifically, this review analyzes and presents the significant benefits of carbon-based materials for their key role in laccase production and immobilization.

Biodiesel Production Using Homogeneous, Heterogeneous, and Enzyme Catalysts via Transesterification and Esterification Reactions: a Critical Review

The excessive utilization of petroleum resources leads to global warming, crude oil price fluctuations, and the fast depletion of petroleum reserves. Biodiesel has gained importance over the last few years as a clean, sustainable, and renewable energy source. This review provides knowledge of biodiesel production via transesterification/esterification using different catalysts, their prospects, and their challenges. The intensive research on homogeneous chemical catalysts points to the challenges in using high free fatty acids containing oils, such as waste cooking oils and animal fats. The problems faced are soap formation and the difficulty in product separation. On the other hand, heterogeneous catalysts are more preferable in biodiesel synthesis due to their ease of separation and reusability. However, in-depth studies show the limited activity and selectivity issues. Using biomass waste-based catalysts can reduce the biodiesel production cost as the materials are readily available and cheap. The use of an enzymatic approach has gained precedence in recent times. Additionally, immobilization of these enzymes has also improved the statistics because of their excellent functional properties like easy separation and reusability. However, free/liquid lipases are also growing faster due to better mass transfer with reactants. Biocatalysts are exceptional in good selectivity and mild operational conditions, but attractive features are veiled with the operational costs. Nanocatalysts play a vital role in heterogeneous catalysis and lipase immobilization due to their excellent selectivity, reactivity, faster reaction rates owing to their higher surface area, and easy recovery from the products and reuse for several cycles.

Alternative Activation of Macrophages through Interleukin-13-Loaded Extra-Large-Pore Mesoporous Silica Nanoparticles Suppresses Experimental Autoimmune Encephalomyelitis

Multiple sclerosis (MS) treatment via cytokine-mediated immunomodulation has been hampered by the difficulty with which cytokines can be stably and noninvasively delivered to the central nervous system. Here, we show that interleukin (IL)-13 packaged in extra-large-pore mesoporous silica nanoparticles (XL-MSNs) is protected from degradation and directs the alternative activation of macrophages both in vitro and in vivo. Furthermore, the noninvasive intranasal delivery of IL-13-loaded XL-MSNs ameliorated the symptoms of experimental autoimmune encephalomyelitis, a murine model of MS, accompanied by the induction of chemokines orchestrating immune cell infiltration. These results demonstrate the therapeutic potential of IL-13-loaded XL-MSNs for MS patients.

Leloir glycosyltransferases enabled to flow synthesis: Continuous production of the natural C-glycoside nothofagin

C‐glycosyltransferase (CGT) and sucrose synthase (SuSy), each fused to the cationic binding module Z_basic2, were co‐immobilized on anionic carrier (ReliSorb SP400) and assessed for continuous production of the natural C‐glycoside nothofagin. The overall reaction was 3ʹ‐C‐β‐glycosylation of the polyphenol phloretin from uridine 5ʹ‐diphosphate (UDP)‐glucose that was released in situ from sucrose and UDP. Using solid catalyst optimized for total (∼28 mg/g) as well as relative protein loading (CGT/SuSy = ∼1) and assembled into a packed bed (1 ml), we demonstrate flow synthesis of nothofagin (up to 52 mg/ml; 120 mM) from phloretin (≥95% conversion) solubilized by inclusion complexation in hydroxypropyl β‐cyclodextrin. About 1.8 g nothofagin (90 ml; 12–26 mg/ml) were produced continuously over 90 reactor cycles (2.3 h/cycle) with a space‐time yield of approximately 11 mg/(ml h) and a total enzyme turnover number of up to 2.9 × 10³ mg/mg (=3.8 × 10⁵ mol/mol). The co‐immobilized enzymes exhibited useful effectiveness (∼40% of the enzymes in solution), with limitations on the conversion rate arising partly from external liquid–solid mass transfer of UDP under packed‐bed flow conditions. The operational half‐life of the catalyst (∼200 h; 30°C) was governed by the binding stability of the glycosyltransferases (≤35% loss of activity) on the solid carrier. Collectively, the current study shows integrated process technology for flow synthesis with co‐immobilized sugar nucleotide‐dependent glycosyltransferases, using efficient glycosylation from sucrose via the internally recycled UDP‐glucose. This provides a basis from engineering science to promote glycosyltransferase applications for natural product glycosides and oligosaccharides.

Tailoring metal-organic frameworks-based nanozymes for bacterial theranostics

Nanozymes are next-generation artificial enzymes having distinguished features such as cost-effective, enhanced surface area, and high stability. However, limited selectivity and moderate activity of nanozymes in the biochemical environment hindered their usage and encouraged researchers to seek alternative catalytic materials. Recently, metal-organic frameworks (MOFs) characterized by distinct crystalline porous structures with large surface area, tunable pores, and uniformly dispersed active sites emerged, that filled the gap between natural enzymes and nanozymes. Moreover, by selecting suitable metal ions and organic linkers, MOFs can be designed for effective bacterial theranostics. In this review, we briefly presented the design and fabrication of MOFs. Then, we demonstrated the applications of MOFs in bacterial theranostics and their safety considerations. Finally, we proposed the major obstacles and opportunities for further development in research on the interface of nanozymes and MOFs. We expect that MOFs based nanozymes with unique physicochemical and intrinsic enzyme-mimicking properties will gain broad interest in both fundamental research and biomedical applications.

Oxidation of 2,5-diformfylfuran to 2,5-furandicarboxylic acid catalyzed by Candida antarctica Lipase B immobilized in a cyclodextrin-templated mesoporous silica. The critical role of pore characteristics on the catalytic performance

HYPOTHESIS

Porous silica has been extensively used as suitable carrier for the immobilization of various enzymes. Randomly Methylated β-Cyclodextrin (RaMeβCD) has surface active properties and very high solubility in water and could therefore be used as template in the fabrication of silica particles with tunable pore size.

EXPERIMENTS

Silica particles were prepared by sol-gel process in alkaline medium with and without use of RaMeβCD. Lipase Bfrom Candida antarctica (CALB) was either incorporated within the pores of RaMeβCD-derived support or covalently attached on the surface of CD-free silica particles and its catalytic performance was assayed in the oxidation of 2,5-diformylfuran (DFF) to 2,5-furandicarboxylic acid (FDCA). Enzymatic reactors were characterized by N₂-adsorption analysis, small angle XRD, TG/DSC experiments, ATR-FTIR spectroscopy, HR-TEM and LSCM, while reaction products were determined based on ¹H NMR spectroscopy combined with HPLC.

FINDINGS

Results showed that the use of RaMeβCD as structure directing agent led to mesoporous silica composed of uniform 8 nm-sized particles with 11 nm-sized mesopores compatible with the dimensions of CALB (3.0 nm × 4.0 nm × 5.0 nm). Incorporation of CALB within the pores of RaMeβCD-derived silica caused almost a two-fold increase in specific activity after 7 h at 40 °C when compared to lipase immobilized on the surface of CD-free silica particles (33.2 μmol g^-1 min^-1vs. 14.4 μmol g^-1 min^-1). Moreover, the RaMeβCD-derived biocatalyst demonstrated enhanced operational stability during the recycling experiments, retaining more than 90% of its initial activity after five 24 h-reaction cycles. These findings open up new avenues for future research on the use of cyclodextrins in the development of enzyme-based nanoreactors.

Nature Inspired Multienzyme Immobilization: Strategies and Concepts

In a biological system, the spatiotemporal arrangement of enzymes in a dense cellular milieu, subcellular compartments, membrane-associated enzyme complexes on cell surfaces, scaffold-organized proteins, protein clusters, and modular enzymes have presented many paradigms for possible multienzyme immobilization designs that were adapted artificially. In metabolic channeling, the catalytic sites of participating enzymes are close enough to channelize the transient compound, creating a high local concentration of the metabolite and minimizing the interference of a competing pathway for the same precursor. Over the years, these phenomena had motivated researchers to make their immobilization approach naturally realistic by generating multienzyme fusion, cluster formation via affinity domain-ligand binding, cross-linking, conjugation on/in the biomolecular scaffold of the protein and nucleic acids, and self-assembly of amphiphilic molecules. This review begins with the discussion of substrate channeling strategies and recent empirical efforts to build it synthetically. After that, an elaborate discussion covering prevalent concepts related to the enhancement of immobilized enzymes' catalytic performance is presented. Further, the central part of the review summarizes the progress in nature motivated multienzyme assembly over the past decade. In this section, special attention has been rendered by classifying the nature-inspired strategies into three main categories: (i) multienzyme/domain complex mimic (scaffold-free), (ii) immobilization on the biomolecular scaffold, and (iii) compartmentalization. In particular, a detailed overview is correlated to the natural counterpart with advances made in the field. We have then discussed the beneficial account of coassembly of multienzymes and provided a synopsis of the essential parameters in the rational coimmobilization design.

Specific immobilization of lipase on functionalized 3D printing scaffolds via enhanced hydrophobic interaction for efficient resolution of racemic 1-indanol

Lipase immobilization with hydrophobic interaction is of interesting exploration, and some functionalized groups on supports are special for activity increasing. To achieved a good performance of cost-effective immobilization on macro-supports for feasible usage and recycle, eco-friendly PLA-based 3D printing macro-scaffolds with fabrication was designed, and phenyl groups with different length of linkers and combined two kinds of groups were anchored for lipase YCJ01 binding with improving payload, the highest enzyme expression of 2227.5 U/g, activity recovery of 137.3%, and increasing specific activity of 815.9 U/mg were attained by using PLA@AMTS-C7-Ph/PLA@AMTS-C9-Ph scaffolds as carries. The immobilized lipase YCJ01 on bifunctionalized 3D printing scaffolds was further applied to the efficient resolution of racemic 1-indanol (267 mM) with high stereoselectivity using a binary solvent system. The immobilized lipase YCJ01 could control the over transesterification of (S)-1-indanol and exhibit good operational stability of repetitive usage for 9 cycles. This is beneficial to obtain the high enantiomerical pure product by feasible separation of immobilized biocatalyst without rigorous operation.

Covalent organic frameworks as emerging host platforms for enzyme immobilization and robust biocatalysis - A review

In recent years, the synthesis and application of green and sustainable products have become global ecological and societal issues. Based on the principles of green chemistry, the application of different biocatalysts not only produce target products and decreases side effects but also enhances the selectivity and activity. Enzyme-based biocatalysts are very interesting due to their high catalytic performance, eco-friendly reaction systems, and selectivity. Immobilization is demonstrated as a favorable approach to improve the stability and recyclability of enzymes. Among different supports, porous and crystalline materials, covalent organic frameworks (COFs), represent an interesting class of support matrices for the immobilization of different enzymes. Owing to tunable physicochemical characteristics, a high degree of crystallinity, large specific surface area, superior adsorption capacity, pre-designable structure and marked stability, COFs might consider as perfect host materials for improving the desirable properties of enzymes, such as poor stability, low operational range, lack of repeatability, and products/by-products inhibition for large-scale applications. The enzyme-incorporated COFs have emerged as one of the hopeful ways to constitute tailor-made biocatalytic systems, which can be employed in an array of reactions. Highly porous nature of many COFs led to increased process output in contrast to other micro/nanoparticles. The enzymes can be integrated into COFs through different techniques, including physical adsorption and direct covalent attachment between the enzyme molecules and COFs or through a cross-linking agent. Herein, we discuss and highlight the synthesis methods, properties, and functionalization of COFs and the recent literature for the application of these materials in enzymes immobilization. Main approaches for immobilization of enzymes into COFs and the catalytic applications of these materials are also presented. This study offers new avenues to address the limitations of traditional enzyme immobilization supports as well as delivers new possibilities to construct smart biocatalytic systems for diverse biotechnological applications.

Status of the application of exogenous enzyme technology for the development of natural plant resources

Exogenous enzymes are extraneous enzymes that are not intrinsic to the subject. The exogenous enzyme industry has been rapidly developing recently. Successful application of recombinant DNA amplification, high-efficiency expression, and immobilization technology to genetically engineered bacteria provides a rich source of enzymes. Amylase, cellulase, protease, pectinase, glycosidase, tannase, and polyphenol oxidase are among the most widely used such enzymes. Currently, the application of exogenous enzyme technology in the development of natural plant resources mainly focuses on improving the taste and flavor of the product, enriching the active ingredient contents, deriving and transforming the structure of a chosen compound, and enhancing the biological activity and utilization of the functional ingredient. In this review, we discuss the application status of exogenous enzyme technology for the development of natural plant resources using typical natural active ingredients from plant, such as resveratrol, steviosides, catechins, mogrosides, and ginsenosides, as examples, to provide basis for further exploitation and utilization of exogenous enzyme technology.

Excellent Protein Immobilization and Stability on Heterogeneous C-TiO2 Hybrid Nanostructures: A Single Protein AFM Study

Enhancing molecular interaction is critical for improving the immobilization and stability of proteins on TiO₂ surfaces. In this work, mesoporous TiO₂ materials with varied pore geometries were decorated with phenyl phosphoric acid (PPA), followed by a thermal treatment to obtain chemically heterogeneous C-TiO₂ samples without changing the geometry and crystalline structure, which can keep the advantages of both carbon and TiO₂. The molecular interaction force between the protein and the surfaces was measured using atomic force microscopy by decomposing from the total adhesion forces, showing that the surface chemistry determines the interaction strength and depends on the amount of partial carbon coverage on the TiO₂ surface (∼40-80%). Samples with 58.3% carbon coverage provide the strongest molecular interaction force, consistent with the observation from the detected friction force. Surface-enhanced Raman scattering and electrochemical biosensor measurements for these C-TiO₂ materials were further conducted to illustrate their practical implications, implying their promising applications such as in protein detection and biosensing.

The Immobilization of Lipases on Porous Support by Adsorption and Hydrophobic Interaction Method

Four major enzymes commonly used in the market are lipases, proteases, amylases, and cellulases. For instance, in both academic and industrial levels, microbial lipases have been well studied for industrial and biotechnological applications compared to others. Immobilization is done to minimize the cost. The improvement of enzyme properties enables the reusability of enzymes and facilitates enzymes used in a continuous process. Immobilized enzymes are enzymes physically confined in a particularly defined region with retention to their catalytic activities. Immobilized enzymes can be used repeatedly compared to free enzymes, which are unable to catalyze reactions continuously in the system. Immobilization also provides a higher pH value and thermal stability for enzymes toward synthesis. The main parameter influencing the immobilization is the support used to immobilize the enzyme. The support should have a large surface area, high rigidity, suitable shape and particle size, reusability, and resistance to microbial attachment, which will enhance the stability of the enzyme. The diffusion of the substrate in the carrier is more favorable on hydrophobic supports instead of hydrophilic supports. The methods used for enzyme immobilization also play a crucial role in immobilization performance. The combination of immobilization methods will increase the binding force between enzymes and the support, thus reducing the leakage of the enzymes from the support. The adsorption of lipase on a hydrophobic support causes the interfacial activation of lipase during immobilization. The adsorption method also causes less or no change in enzyme conformation, especially on the active site of the enzyme. Thus, this method is the most used in the immobilization process for industrial applications.

Glycoside hydrolase (PelAh) immobilization prevents Pseudomonas aeruginosa biofilm formation on cellulose-based wound dressing

Bacterial cellulose (BC) is recognized as a wound dressing material well-suited for chronic wounds; however, it has no intrinsic antimicrobial activity. Further, the formation of biofilms can limit the effectiveness of the pre-saturation of BC with antimicrobial agents. Here, to hinder biofilm formation by P. aeruginosa, we immobilized the hydrolytic domain of PelA (a glycohydrolase involved in the synthesis of biofilm polysaccharide Pel) on the surface of BC. The immobilization of 32.35 ± 1.05 mg PelA_h per g BC membrane resulted in an eight-fold higher P. aeruginosa cell detachment from BC membrane, indicating reduced biofilm matrix stability. Further, 1D and 2D infrared spectroscopy analysis indicated systematic reduction of polysaccharide biofilm elements, confirming the specificity of immobilized PelA_h. Importantly, BC-PelA_h was not cytotoxic towards L929 fibroblast cells. Thus, we conclude that PelA_h can be used in BC wound dressings for safe and specific protection against biofilm formation by P. aeruginosa.

Effect of eggshell membrane as porogen on the physicochemical structure and protease immobilization of chitosan-based macroparticles

Chitosan-based macroparticle is a common carrier for enzyme immobilization applied in food industry. Driven by the requirement of large carrier pores for the biomacromolecular substrates such as protein, the eggshell membrane powder (ESMP) was employed as multifunctional porogen to improve the physicochemical structure of chitosan-based macroparticles. The prepared macroparticles were characterized by SEM, XRD, FTIR, Raman spectroscopy, nitrogen adsorption-desorption isotherms, and thermogravimetric analysis. The results showed that an increase of ESMP percentage could improve the porosity of macro holes in macroparticles, and it also enlarged the size of mesopores. Moreover, the ESMP significantly increased (P < 0.05) the amount of papain immobilization, whereas the specific activity of immobilized papain achieved a maximum value of 871.95 U/mg at CSESM2 and then declined with the increase of ESMP. Therefore, the inclusion of 20 % ESMP in chitosan-based macroparticles gave the highest activity of its immobilized protease.