All Wrapped up: Stabilization of Enzymes within Single Enzyme Nanoparticles

Exploring Enzyme-Mimicking Metal-Organic Frameworks for CO2 Conversion through Vibrational Spectra-Based Machine Learning

In pursuing the benefits of natural enzyme catalysts while overcoming their limitations, we find metal-organic frameworks (MOFs), renowned for their highly tunable functionalities, stand out in biomimetic applications. We used unsupervised machine learning on density functional theory-computed vibrational infrared and Raman spectral features to screen 300 Zn-MOFs for CO2 conversion, similar to carbonic anhydrase (CA). Our findings confirmed that MOFs with spectroscopic attributes closely resembling those of CA hold the potential for replicating CA's electronic and catalytic properties. Unlike previous studies that relied on heuristic or trial-and-error methods and focused on geometric configurations, our research uses vibrational spectral features to explore structure-property relationships, making them more accessible through spectroscopy. Moreover, we highlight vibrational spectral features as efficient carriers for highly dimensional chemical information, enabling the simultaneous optimization of multiple performance parameters. These findings pave the way for pioneering designs of enzyme-mimetic MOFs and concurrently expand the application scope of spectroscopic tools in biomimetic catalysis.

Assessment of Fungal Lytic Enzymatic Extracts Produced Under Submerged Fermentation as Enhancers of Entomopathogens' Biological Activity

The application of enzymes in agricultural fields has been little explored. One potential application of fungal lytic enzymes (chitinases, lipases, and proteases) is as an additive to current biopesticides to increase their efficacy and reduce the time of mortality. For this, a screening of lytic overproducer fungi under submerged fermentation with a chemical-defined medium was performed. Then, the enzymatic crude extract (ECE) was concentrated and partially characterized. This characterization consisted of measuring the enzymatic activity (lipase, protease and, chitinase) and determining the enzyme stability after storage at temperatures of - 80, - 20 and, 4 °C. And lastly, the application of these concentrated enzymatic crude extracts (C-ECE) as an enhancer of spores-based fungal biopesticide was proven. Beauveria were not as good producers of lytic enzymes as the strains from Trichoderma and Metarhizium. The isolate M. robertsii Mt015 was selected for the co-production of chitinases and proteases; and the isolate T. harzianum Th180 for co-production of chitinases, lipases, and proteases. The C-ECE of Mt015 had a protease activity of 18.6 ± 1.1 U ml-1, chitinase activity of 0.28 ± 0.01 U ml-1, and no lipase activity. Meanwhile, the C-ECE of Th180 reached a chitinase activity of 0.75 U ml-1, lipase activity of 0.32 U ml-1, and protease activity of 0.24 U ml-1. Finally, an enhancing effect of the enzymatic extracts of M. robertsii (66.7%) and T. harzianum (43.5%) on the efficacy of B. bassiana Bv064 against Diatraea saccharalis larvae was observed. This work demonstrates the non-species-specific enhancing effect of enzymatic extracts on the insecticidal activity of conidial-based biopesticides, which constitutes a contribution to the improvement of biological control agents' performance.

Dual Enzyme-Encapsulated Materials for Biological Cascade Chemistry and Synergistic Tumor Starvation

Framework and polymeric nanoreactors (NRs) have distinct advantages in improving chemical reaction efficiency in the tumor microenvironment (TME). Nanoreactor-loaded oxidoreductase enzyme is activated by tumor acidity to produce H2O2 by increasing tumor oxidative stress. High levels of H2O2 induce self-destruction of the vesicles by releasing quinone methide to deplete glutathione and suppress the antioxidant potential of cancer cells. Therefore, the synergistic effect of the enzyme-loaded nanoreactors results in efficient tumor ablation via suppressing cancer-cell metabolism. The main driving force would be to take advantage of the distinct metabolic properties of cancer cells along with the high peroxidase-like activity of metalloenzyme/metalloprotein. A cascade strategy of dual enzymes such as glucose oxidase (GOx) and nitroreductase (NTR) wherein the former acts as an O2-consuming agent such as overexpression of NTR and further amplified NTR-catalyzed release for antitumor therapy. The design of cascade bioreductive hypoxia-responsive drug delivery via GOx regulates NTR upregulation and NTR-responsive nanoparticles. Herein, we discuss tumor hypoxia, reactive oxygen species (ROS) formation, and the effectiveness of these therapies. Nanoclusters in cascaded enzymes along with chemo-radiotherapy with synergistic therapy are illustrated. Finally, we outline the role of the nanoreactor strategy of cascading enzymes along with self-synergistic tumor therapy.

Multivariate Silicification-Assisted Single Enzyme Structure Augmentation for Improved Enzymatic Activity-Stability Trade-Off

The ability to finely tune/balance the structure and rigidity of enzymes to realize both high enzymatic activity and long-term stability is highly desired but highly challenging. Herein, we propose the concept of the "silicazyme", where solid inorganic silica undergoes controlled hybridization with the fragile enzyme under moderate conditions at the single-enzyme level, thus enabling simultaneous structure augmentation, long-term stability, and high enzymatic activity preservation. A multivariate silicification approach was utilized and occurred around individual enzymes to allow conformal coating. To realize a high activity-stability trade-off the structure flexibility/rigidity of the silicazyme was optimized by a component adjustment ternary (CAT) plot method. Moreover, the multivariate organosilica frameworks bring great advantages, including surface microenvironment adjustability, reversible modification capability, and functional extensibility through the rich chemistry of silica. Overall silicazymes represent a new class of enzymes with promise for catalysis, separations, and nanomedicine.

Cell-Free Protein Expression in Polymer Materials

While synthetic biology has advanced complex capabilities such as sensing and molecular synthesis in aqueous solutions, important applications may also be pursued for biological systems in solid materials. Harsh processing conditions used to produce many synthetic materials such as plastics make the incorporation of biological functionality challenging. One technology that shows promise in circumventing these issues is cell-free protein synthesis (CFPS), where core cellular functionality is reconstituted outside the cell. CFPS enables genetic functions to be implemented without the complications of membrane transport or concerns over the cellular viability or release of genetically modified organisms. Here, we demonstrate that dried CFPS reactions have remarkable tolerance to heat and organic solvent exposure during the casting processes for polymer materials. We demonstrate the utility of this observation by creating plastics that have spatially patterned genetic functionality, produce antimicrobials in situ, and perform sensing reactions. The resulting materials unlock the potential to deliver DNA-programmable biofunctionality in a ubiquitous class of synthetic materials.

Bidirectional Regulation of Intracellular Enzyme Activity Using Light-Driven Nano-Inhibitors

Photochemical regulation provides precise control over enzyme activities with high spatiotemporal resolution. A promising approach involves anchoring "photoswitches" at enzyme active sites to modulate substrate recognition. However, current methods often require genetic mutations and irreversible enzyme modifications for the site-specific anchoring of "photoswitches", potentially compromising the enzyme activities. Herein, we present a pioneering reversible nano-inhibitor based on molecular imprinting technique for bidirectional regulation of intracellular enzyme activity. The nano-inhibitor employs a molecularly imprinted polymer nanoparticle as its body and azobenzene-modified inhibitors ("photoswitches") as the arms. By using a target enzyme as the molecular template, the nano-inhibitor acquires oriented binding sites on its surface, resulting in a high affinity for the target enzyme and non-covalently firm anchoring of the azobenzene-modified inhibitor to the enzyme active site. Harnessing the reversible isomerization of azobenzene units upon exposure to ultraviolet and visible light, the nano-inhibitor achieves bidirectional enzyme activity regulation by precisely docking and undocking inhibitor at the active site. Notably, this innovative approach enables the facile in situ regulation of intracellular endogenous enzymes, such as carbonic anhydrase. Our results represent a practical and versatile tool for precise enzyme activity regulation in complex intracellular environments.

Data-Driven Design of Polymer-Based Biomaterials: High-throughput Simulation, Experimentation, and Machine Learning

Polymers, with the capacity to tunably alter properties and response based on manipulation of their chemical characteristics, are attractive components in biomaterials. Nevertheless, their potential as functional materials is also inhibited by their complexity, which complicates rational or brute-force design and realization. In recent years, machine learning has emerged as a useful tool for facilitating materials design via efficient modeling of structure-property relationships in the chemical domain of interest. In this Spotlight, we discuss the emergence of data-driven design of polymers that can be deployed in biomaterials with particular emphasis on complex copolymer systems. We outline recent developments, as well as our own contributions and takeaways, related to high-throughput data generation for polymer systems, methods for surrogate modeling by machine learning, and paradigms for property optimization and design. Throughout this discussion, we highlight key aspects of successful strategies and other considerations that will be relevant to the future design of polymer-based biomaterials with target properties.

Metal-pyrimidine nanocubes immobilized enzymes with pH-switchable multienzyme-like activity for broad-pH-responsive sensing assay for organophosphorus pesticides

Peroxidase (POD)-like can only function in acidic environments and the pH mismatch restricts the application of enzyme-nanozyme cascade catalytic sensing platforms in the broad-pH-responsive assay for organophosphorus pesticides (OPs). Herein, the metal-pyrimidine nanocubes (MPNCs) with intrinsic pH-switchable POD-like and catalase (CAT)-like properties were synthesized via the coordination of pyrimidin-2-ol with Cu2+. Meanwhile, acetylcholinesterase (AChE) and choline oxidase (CHO) were simultaneously encapsulated in MPNCs to construct an enzyme-nanozyme cascade catalytic platform (AChE/CHO@MPNCs). AChE/CHO@MPNCs could catalyze the hydrolysis of acetylcholine to choline, which was subsequently converted to H2O2. The POD-like activity of MPNCs was dominant under acidic conditions, while the CAT-like activity prevailed under neutral and alkaline conditions, which could catalyze H2O2 to •OH and O2, respectively, then oxidizing dopamine (DA) to polydopamine quantum dots (PDA QDs) with different fluorescence characteristics. Consequently, OPs could be detected in a linear range from 0.05 to 1000 nM with a LOD of 0.015 nM in acidic environments and a linear range from 0.05 to 500 nM with a LOD of 0.023 nM in alkaline environments. Overall, our work expands the horizon of constructing enzyme@MOFs composites with high catalytic activity. Meanwhile, the intrinsic pH-switchable multienzyme-like property opens avenues to construct sensing platforms with broad-pH-responsive for OPs and other analytes detection.

Covalent Organic Frameworks for the Purification of Recombinant Enzymes and Heterogeneous Biocatalysis

Recombinant enzymes have gained prominence due to their diverse functionalities and specificity and are often a greener alternative in biocatalysis. This context makes purifying recombinant enzymes from host cells and other impurities crucial. The primary goal is to isolate the pure enzyme of interest and ensure its stability under ambient conditions. Covalent organic frameworks (COFs), renowned for their well-ordered structure and permeability, offer a promising approach for purifying histidine-tagged (His-tagged) enzymes. Furthermore, immobilizing enzymes within COFs represents a growing field in heterogeneous biocatalysis. In this study, we have developed a flow-based technology utilizing a nickel-infused covalent organic framework (Ni-TpBpy COF) to combine two distinct processes: the purification of His-tagged enzymes and the immobilization of enzymes simultaneously. Our work primarily focuses on the purification of three His-tagged enzymes β-glucosidase, cellobiohydrolase, and endoglucanase as well as two proteins with varying molecular weights, namely, green fluorescent protein (27 kDa) and BG Rho (88 kDa). We employed Ni-TpBpy as a column matrix to showcase the versatility of our system. Additionally, we successfully obtained a Ni-TpBpy COF immobilized with enzymes, which can serve as a heterogeneous catalyst for the hydrolysis of p-nitrophenyl-β-d-glucopyranoside and carboxymethylcellulose. These immobilized enzymes demonstrated catalytic activity comparable to that of their free counterparts, with the added advantages of recyclability and enhanced stability under ambient conditions for an extended period, ranging from 60 to 90 days. This contrasts with the free enzymes, which do not maintain their activity as effectively over time.

Engineering a hierarchically micro-/nanostructured Si@Au-based artificial enzyme with improved accessibility of active sites for enhanced catalysis

The active site accessibility and high loading of gold nanoparticles (AuNPs) are key factors affecting the catalytic activity of supported AuNP-based catalysts. However, the preparation of supported AuNP-based catalysts with highly accessible active sites still remains a challenge. Herein, sphere-on-sphere (SoS) silica microspheres with a hierarchical structure, good dispersion and high surface density of thiol groups (10 SH nm-2) are prepared and used as a platform for the growth of high-density AuNPs. The obtained hierarchical Si@Au micro-/nanostructure consisting of 0.55 μm SoS silica microspheres and 7.3 nm AuNPs (SoS-0.55@Au-7.3) is found to show excellent peroxidase-mimicking activity (Km = 0.033 mM and Vmax = 34.6 × 10-8 M s-1) with merits of high stability and good reusability. Furthermore, the as-obtained SoS-0.55@Au-7.3-based system can sensitively detect hydrogen peroxide (H2O2) with a low detection limit of 1.6 μM and a wide linear range from 2.5 μM to 1.0 mM. The high catalytic activity, excellent stability and good reusability of SoS-0.55@Au-7.3 imply its great prospects in biosensing and biomedical analysis.

Construction of molecular enrichment accelerators via assembly of enzyme surface grafted polymer and cyclodextrin achieving rapid and stable ester catalysis for biodiesel synthesis

Efficient and stable catalysis has always been the core concept of enzyme catalysis in industrial processes for manufacturing. Here, we constructed molecular enrichment accelerators to synergistically enhance enzyme activity and stability by assembling enzyme surface grafted polymer and cyclodextrin. At 40 °C, the enzyme activity of CalB-PNIPAM212/β-CD was 2.9 times that of CalB-PNIPAM212. The enzyme activity of CalB-PNIPAM428/γ-CD had reached 1.61 times that of CalB. At the same time, the stability of CalB-PNIPAM212/β-CD and CalB-PNIPAM428/γ-CD are slightly better than that of CalB under high temperature, organic solution and extreme pH conditions. The synergistic increase in activity and stability of the lipase-polymer assembly was achieved due to the structure of assembly, in which the role of cyclodextrin could enrich substrate affecting molecular diffusion. In addition, the lipase-polymer assembly proved to be an efficient catalyst for biodiesel synthesis, with a biodiesel conversion 1.4 times that of CalB at 60 °C. Therefore, this simple and low-cost lipase-polymer assembly provides new possibilities for the construction of high-efficiency industrial biocatalytic catalysts.

Bionanofabrication of Cupric oxide catalyst from Water hyacinth based carbohydrate and its impact on cellulose deconstructing enzymes production under solid state fermentation

One of the most important properties of cellulolytic enzyme is its ability to convert cellulosic polymer into monomeric fermentable sugars which are carbohydrate by nature can efficiently convert into biofuels. However, higher production costs of these enzymes with moderate activity-based stability are the main obstacles to making cellulase-based applications sustainably viable, and this has necessitated rigorous research for the economical availability of this process. Using water hyacinth (WH) waste leaves as the substrate for cellulase production under solid state fermentation (SSF) while treating the fermentation production medium with CuO (cupric oxide oxide) bionanocatalyst have been examined as ways to make fungal cellulase production economically feasible. Herein, a sustainable green synthesis of CuO bionanocatalyst has been performed by using waste leaves of WH. Through XRD, FT-IR, SEM, and TEM analysis, the prepared CuO bionanocatalyst's physicochemical properties have been evaluated. Furthermore, the effect of CuO bionanocatalyst on the temperature stability of raw cellulases was observed, and its half-life stability was found to be up to 9 h at 65 °C. The results presented in the current investigation may have broad scope for mass trials for various industrial applications, such as cellulosic biomass conversion.

Biomimetic Metal-Pyrimidine Nanoflowers: Enzyme Immobilization Platforms with Boosted Activity

For the enzyme immobilization platform, enhancing enzyme activity retention while improving enzyme stability remains a challenge for sensitive sensing analysis. Herein, an in situ biomimetic immobilized enzyme carrier (metal-pyrimidine nanoflowers, MPNFs) synthesized by the coordination of DNA base derivative (2-aminopyrimidine) with Zn2+ in the aqueous phase at room temperature is developed. The biocompatibility of 2-aminopyrimidine and the hydrophilicity and green synthetic conditions of MPNFs allows the immobilized enzymes to retain above 91.2% catalytic activity. On this basis, a cascade catalytic platform is constructed by simultaneously immobilizing acetylcholinesterase (AChE), choline oxidase (CHO), and horseradish peroxidase (HRP) in MPNFs (AChE/CHO/HRP@MPNFs) for organophosphorus pesticides (OPs) colorimetric biosensing detection. The assay could specifically detect parathion-methyl within 13 min with a wider linear range (0.1-1000.0 nm) and a lower limit of detection (LOD) (0.032 nm). The remarkable stability of the immobilized enzymes is also achieved under harsh environments, room temperature storage, and recycling. Furthermore, a portable and cost-effective biosensing platform is developed by integrating AChE/CHO/HRP@MPNFs with a smartphone-assisted paper device for the on-site detection of OPs. Overall, the high catalytic activity retention and the enhanced detection performance demonstrate that MPNF is a robust carrier in enzyme immobilization and holds great promise in biosensing and other field applications.

Transglutaminase in Foods and Biotechnology

Stabilization and reusability of enzyme transglutaminase (TGM) are important goals for the enzymatic process since immobilizing TGM plays an important role in different technologies and industries. TGM can be used in many applications. In the food industry, it plays a role as a protein-modifying enzyme, while, in biotechnology and pharmaceutical applications, it is used in mediated bioconjugation due to its extraordinary crosslinking ability. TGMs (EC 2.3.2.13) are enzymes that catalyze the formation of a covalent bond between a free amino group of protein-bound or peptide-bound lysine, which acts as an acyl acceptor, and the γ-carboxamide group of protein-bound or peptide-bound glutamine, which acts as an acyl donor. This results in the modification of proteins through either intramolecular or intermolecular crosslinking, which improves the use of the respective proteins significantly.

Alginate-based materials for enzyme encapsulation

Enzymes are widely used in industry due to their high efficiency and selectivity. However, their low stability during certain industrial processes can result in a significant loss of catalytic activity. Encapsulation is a promising technique that can stabilize enzymes by protecting them from environmental stresses such as extreme temperature and pH, mechanical force, organic solvents, and proteases. Alginate and alginate-based materials have emerged as effective carriers for enzyme encapsulation due to their biocompatibility, biodegradability, and ability to form gel beads through ionic gelation. This review presents various alginate-based encapsulation systems for enzyme stabilization and explores their applications in different industries. We discuss the preparation methods of alginate encapsulated enzymes and analyze the release mechanisms of enzymes from alginate materials. Additionally, we summarize the characterization techniques used for enzyme-alginate composites. This review provides insights into the use of alginate encapsulation as a means of stabilizing enzymes and highlights the potential benefits for various industrial applications.

Molecular Modeling Insights into Metal-Organic Frameworks (MOFs) as a Potential Matrix for Immobilization of Lipase: An In Silico Study

CRL is a highly versatile enzyme that finds extensive utility in numerous industries, which is attributed to its selectivity and catalytic efficiency, which have been impeded by the impracticality of its implementation, leading to a loss of native catalytic activity and non-reusability. Enzyme immobilization is a necessary step for enabling its reuse, and it provides methods for regulating the biocatalyst's functional efficacy in a synthetic setting. MOFs represent a novel category of porous materials possessing distinct superlative features that make MOFs an optimal host matrix for developing enzyme-MOF composites. In this study, we employed molecular modeling approaches, for instance, molecular docking and MD simulation, to explore the interactions between CRL and a specific MOF, ZIF-8. The present study involved conducting secondary structural analysis and homology modeling of CRL, followed by docking ZIF-8 with CRL. The results of the molecular docking analysis indicate that ZIF-8 was situated within the active site pocket of CRL, where it formed hydrogen bonds with Val-81, Phe-87, Ser-91, Asp-231, Thr-132, Lue-297, Phe-296, Phe-344, Thr-347, and Ser-450. The MD simulation analysis revealed that the CRL and ZIF-8 docked complex exhibited stability over the entire simulation period, and all interactions presented in the initial docked complex were maintained throughout the simulation. The findings derived from this investigation could promote comprehension of the molecular mechanisms underlying the interaction between CRL and ZIF-8 as well as the development of immobilized CRL for diverse industrial purposes.

Mucoadhesive gellan gum-based and carboxymethyl cellulose -based hydrogels containing gemcitabine and papain for bladder cancer treatment

Local treatment of bladder cancer faces several limitations such as short residence time or low permeation through urothelium tissue. The aim of this work was to develop patient-friendly mucoadhesive gel formulations combining gemcitabine and the enzyme papain for improved intravesical chemotherapy delivery. Hydrogels based on two different polysaccharides, gellan gum and sodium carboxymethylcellulose (CMC), were prepared with either native papain or papain nanoparticles (nanopapain) to explore for the first time their use as permeability enhancers through bladder tissue. Gel formulations were characterized regarding enzyme stability, rheological behavior, retention on bladder tissue and bioadhesion, drug release properties, permeation capacity, and biocompatibility. After 90 days of storage, the enzyme loaded in the CMC gels retained up to 83.5 ± 4.9 % of its activity in the absence of the drug, and up to 78.1 ± 5.3 with gemcitabine. The gels were mucoadhesive and the enzyme papain showed mucolytic action, which resulted in resistance against washing off from the urothelium and enhanced permeability of gemcitabine in the ex vivo tissue diffusion tests. Native papain shortened lag-time tissue penetration to 0.6 h and enhanced 2-fold drug permeability All formulations demonstrated pseudoplastic behavior and no irritability. Overall, the developed formulations have potential as an upgraded alternative to intravesical therapy for bladder cancer treatment.

Carbonic Anhydrase Enhanced UV-Crosslinked PEG-DA/PEO Extruded Hydrogel Flexible Filaments and Durable Grids for CO2 Capture

In this study, poly (ethylene glycol) diacrylate/poly (ethylene oxide) (PEG-DA/PEO) interpenetrating polymer network hydrogels (IPNH) were extruded into 1D filaments and 2D grids. The suitability of this system for enzyme immobilization and CO₂ capture application was validated. IPNH chemical composition was verified spectroscopically using FTIR. The extruded filament had an average tensile strength of 6.5 MPa and elongation at break of 80%. IPNH filament can be twisted and bent and therefore is suitable for further processing using conventional textile fabrication methods. Initial activity recovery of the entrapped carbonic anhydrase (CA) calculated from esterase activity, showed a decrease with an increase in enzyme dose, while activity retention of high enzyme dose samples was over 87% after 150 days of repeated washing and testing. IPNH 2D grids that were assembled into spiral roll structured packings exhibited increased CO₂ capture efficiency with increasing enzyme dose. Long-term CO₂ capture performance of the CA immobilized IPNH structured packing was tested in a continuous solvent recirculation experiment for 1032 h, where 52% of the initial CO₂ capture performance and 34% of the enzyme contribution were retained. These results demonstrate the feasibility of using rapid UV-crosslinking to form enzyme-immobilized hydrogels by a geometrically-controllable extrusion process that uses analogous linear polymers for both viscosity enhancement and chain entanglement purposes, and achieves high activity retention and performance stability of the immobilized CA. Potential uses for this system extend to 3D printing inks and enzyme immobilization matrices for such diverse applications as biocatalytic reactors and biosensor fabrication.

Enzyme-Polymer Conjugates for Tuning, Enhancing, and Expanding Biocatalytic Activity

Combining polymers with functional proteins is an approach that has brought several successful stories in the field of biomedicine with PEGylated therapeutic proteins. The latest advances in polymer chemistry have facilitated the expansion of protein-polymer hybrids to other research areas such as biocatalysis. Polymers can impart stability and novel functionalities to the enzyme of interest, thereby improving the catalytic performance of a given reaction. In this review, we have revisited the main methodologies currently used for the synthesis of enzyme-polymer hybrids, unveiling the interplay between the configuration and the composition of the assembled structure and the eventual traits of the hybrid. Finally, the latest advances, such as the assembly of polymer-based chemoenzymatic nanoreactors and the use of deep learning methodologies to achieve the most suitable polymer compositions for catalysis, are discussed.

Using Defect Control To Break the Stability-Activity Trade-Off in Enzyme Immobilization via Competitive Coordination

Immobilization of enzymes within metal-organic frameworks is a powerful strategy to enhance the long-term usability of labile enzymes. However, the thus-confined enzymes suffer from the trade-off between enhanced stability and reduced activity because of the contradiction between the high crystallinity and the low accessibility. Here, by taking laccase and zeolitic imidazolate framework-8 (ZIF-8) as prototypes, we disclosed an observation that the stability-activity trade-off could be solved by controlling the defects via competitive coordination. Owing to the presence of competitive coordination between laccase and the ligand precursor of ZIF-8, there existed a three-stage process in the de novo encapsulation: nucleation-crystallization-recrystallization. Our results show that the biocomposites collected before the occurrence of recrystallization possessed both increased activity and enhanced stability. The findings here shed new light on the control of defects through the subtle use of competitive coordination, which is of great significance for the engineering application of biomacromolecules.

Stable Enzymatic Nanoparticles from Nucleases, Proteases, Lipase and Antioxidant Proteins with Substrate-Binding and Catalytic Properties

Limited membrane permeability and biodegradation hamper the intracellular delivery of the free natural or recombinant enzymes necessary for compensatory therapy. Nanoparticles (NP) provide relative protein stability and unspecific endocytosis-mediated cellular uptake. Our objective was the fabrication of NP from 7 biomedicine-relevant enzymes, including DNase I, RNase A, trypsin, chymotrypsin, catalase, horseradish peroxidase (HRP) and lipase, the analysis of their conformation stability and enzymatic activity as well as possible toxicity for eukaryotic cells. The enzymes were dissolved in fluoroalcohol and mixed with 40% ethanol as an anti-solvent with subsequent alcohol evaporation at high temperature and low pressure. The shapes and sizes of NP were determined by scanning electron microscopy (SEM), atomic force microscopy (AFM) and dynamic light scattering (DLS). Enzyme conformations in solutions and in NP were compared using circular dichroism (CD) spectroscopy. The activity of the enzymes was assayed with specific substrates. The cytotoxicity of the enzymatic NP (ENP) was studied by microscopic observations and by using an MTT test. Water-insoluble ENP of different shapes and sizes in a range 50-300 nm consisting of 7 enzymes remained stable for 1 year at +4 °C without any cross-linking. CD spectroscopy of the ENP permitted us to reveal changes in proportions of α-helixes, β-turns and random coils in comparison with fresh enzyme solutions in water. Despite the minor conformation changes of the proteins in the ENP, the enzymes retained their substrate-binding and catalytic properties. Among the studied bioactive ENP, only DNase NP were highly toxic for 3 cell lines with granulation in 1 day posttreatment, whereas other NP were less toxic (if any). Taken together, the enzymes in the stable ENP retained their catalytic activity and might be used for intracellular delivery.

Air-Stable Radical Organic Cages as Cascade Nanozymes for Enhanced Catalysis

The pursuit of single-assembled molecular cage reactors for complex tandem reactions is a long-standing target in biomimetic catalysis but still a grand challenge. Herein, nanozyme-like organic cages are reported by engineering air-stable radicals into the skeleton upon photoinduced electron transfer. The generation of radicals is accompanied by single-crystal structural transformation and exhibits superior stability over six months in air. Impressively, the radicals throughout the cage skeleton can mimic the peroxidase of natural enzymes to decompose H₂ O₂ into OH· and facilitate oxidation reactions. Furthermore, an integrated catalyst by encapsulating Au clusters (glucose oxidase mimics) into the cage has been developed, in which the dual active sites (Au cluster and radical) are spatially isolated and can work as cascade nanozymes to prominently promote the enzyme-like tandem reaction via a substrate channeling effect.

Advances in the One-Step Approach of Polymeric Materials Using Enzymatic Techniques

The formulation in which biochemical enzymes are administered in polymer science plays a key role in retaining their catalytic activity. The one-step synthesis of polymers with highly sequence-controlled enzymes is a strategy employed to provide enzymes with higher catalytic activity and thermostability in material sustainability. Enzyme-catalyzed chain growth polymerization reactions using activated monomers, protein-polymer complexation techniques, covalent and non-covalent interaction, and electrostatic interactions can provide means to develop formulations that maintain the stability of the enzyme during complex material processes. Multifarious applications of catalytic enzymes are usually attributed to their efficiency, pH, and temperature, thus, progressing with a critical structure-controlled synthesis of polymer materials. Due to the obvious economics of manufacturing and environmental sustainability, the green synthesis of enzyme-catalyzed materials has attracted significant interest. Several enzymes from microorganisms and plants via enzyme-mediated material synthesis have provided a viable alternative for the appropriate synthesis of polymers, effectively utilizing the one-step approach. This review analyzes more and deeper strategies and material technologies widely used in multi-enzyme cascade platforms for engineering polymer materials, as well as their potential industrial applications, to provide an update on current trends and gaps in the one-step synthesis of materials using catalytic enzymes.

Traceless pH-Sensitive Antibody Conjugation Inspired by Citraconic Anhydride

We introduce a pH-sensitive amide bond, inspired by citraconic anhydride, for the reversible conjugation of polymers to the lysine residues of proteins and antibodies. The pH sensitivity arises from a conformation lock at the end of the polymer, which we introduce by means of a Diels-Alder reaction, that positions a carboxylic acid close to the amide after conjugation occurs. The amide is stable over weeks at pH 7.4 but sensitive to hydrolysis at pH 5.5 and below, returning the amine to its original state. The pH sensitivity can be tuned by positioning secondary amide groups nearby. We use this approach to PEGylate an antibody to human serum albumin at high dilution and demonstrate successful recovery of the activity after hydrolysis at pH 5.5. These results offer a convenient and traceless approach to protein and antibody functionalization.

Noncovalent Enzyme Nanogels via a Photocleavable Linkage

Enzyme nanogels (ENGs) offer a convenient method to protect therapeutic proteins from in vivo stressors. Current methodologies to prepare ENGs rely on either covalent modification of surface residues or the noncovalent assembly of monomers at the protein surface. In this study, we report a new method for the preparation of noncovalent ENGs that utilizes a heterobifunctional, photocleavable monomer as a hybrid approach. Initial covalent modification with this monomer established a polymerizable handle at the protein surface, followed by radical polymerization with poly(ethylene glycol) methacrylate monomer and ethylene glycol dimethacrylate crosslinker in solution. Final photoirradiation cleaved the linkage between the polymer and protein to afford the noncovalent ENGs. The enzyme phenylalanine ammonia lyase (PAL) was utilized as a model protein yielding well-defined nanogels 80 nm in size by dynamic light scattering (DLS) and 76 nm by atomic force microscopy. The stability of PAL after exposure to trypsin or low pH was assessed and was found to be more stable in the noncovalent nanogel compared to PAL alone. This approach may be useful for the stabilization of active enzymes.

Instability Challenges and Stabilization Strategies of Pharmaceutical Proteins

Maintaining the structure of protein and peptide drugs has become one of the most important goals of scientists in recent decades. Cold and thermal denaturation conditions, lyophilization and freeze drying, different pH conditions, concentrations, ionic strength, environmental agitation, the interaction between the surface of liquid and air as well as liquid and solid, and even the architectural structure of storage containers are among the factors that affect the stability of these therapeutic biomacromolecules. The use of genetic engineering, side-directed mutagenesis, fusion strategies, solvent engineering, the addition of various preservatives, surfactants, and additives are some of the solutions to overcome these problems. This article will discuss the types of stress that lead to instabilities of different proteins used in pharmaceutics including regulatory proteins, antibodies, and antibody-drug conjugates, and then all the methods for fighting these stresses will be reviewed. New and existing analytical methods that are used to detect the instabilities, mainly changes in their primary and higher order structures, are briefly summarized.

Angiotensin-Converting Enzyme 2-Based Biosensing Modalities and Devices for Coronavirus Detection

Rapid and cost-effective diagnostic tests for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are a critical and valuable weapon for the coronavirus disease 2019 (COVID-19) pandemic response. SARS-CoV-2 invasion is primarily mediated by human angiotensin-converting enzyme 2 (hACE2). Recent developments in ACE2-based SARS-CoV-2 detection modalities accentuate the potential of this natural host-virus interaction for developing point-of-care (POC) COVID-19 diagnostic systems. Although research on harnessing ACE2 for SARS-CoV-2 detection is in its infancy, some interesting biosensing devices have been developed, showing the commercial viability of this intriguing new approach. The exquisite performance of the reported ACE2-based COVID-19 biosensors provides opportunities for researchers to develop rapid detection tools suitable for virus detection at points of entry, workplaces, or congregate scenarios in order to effectively implement pandemic control and management plans. However, to be considered as an emerging approach, the rationale for ACE2-based biosensing needs to be critically and comprehensively surveyed and discussed. Herein, we review the recent status of ACE2-based detection methods, the signal transduction principles in ACE2 biosensors and the development trend in the future. We discuss the challenges to development of ACE2-biosensors and delineate prospects for their use, along with recommended solutions and suggestions.

Multiscale simulation-guided design of enzyme bioconjugates with enhanced catalysis

Biopolymer-scaffold modification is widely used to enhance enzyme catalysis. A central challenge is predicting the effects of scaffold position on enzyme properties. Here, we use a computational-experimental approach to develop a model for the effects of DNA scaffold position on enzyme kinetics. Using phosphotriesterase modified with a 20bp dsDNA, we demonstrate that conjugation position is as important as the scaffold's chemistry and structure. Multiscale simulations predict the effective substrate concentration increases close to the scaffold, which has μM-strength binding to the substrate. Kinetic analysis shows that the effective concentration that the scaffold provides is best utilized when positioned next to, but not blocking, the active site. At ~5Å distance between scaffold and active site a 7-fold increase in k cat /K M was achieved. A model that accounts for the substrate concentration as well PTE-DNA geometry accurately captures the kinetic enhancements, enabling prediction of the effect across a range of DNA positions.

Controlled growth of redox polymer network on single enzyme molecule for stable and sensitive enzyme electrode

The electrochemical applications of enzymes are often hampered by poor enzyme stability and low electron conductivity. In this work, a novel enzyme nanogel based on atom transfer radical polymerization (ATRP) has been developed for highly sensitive detection of glucose based on ferrocene (Fc) embedded in crosslinked polymer network nanogel. Enzyme surfaces are successively modified with Br initiator, and then in situ atom transfer radical polymerization (ATRP) was performed to build up crosslinked polyacrylamide network. The resulting single enzyme nanogel (ATRP-SEG) is uniform in size fairly. ATRP-SEG reveals bi-phasic inactivation, and the half-life of stable ATRP-SEG after 18-day incubation at 50 °C is 47 days, which is 197 times longer than that of free Gox (5.7 h). By introducing a ferrocene (Fc) containing redox polymer, poly(acrylamide-co-vinylferrocene), the half-life of Fc-ATRP-SEG after 18-day incubation at 50 °C is 49 days. Fc-ATRP-SEG is used for preparation of glucose-sensing electrode, and the sensitivity of Fc-ATRP-SEG electrode is 111 μA cm^-2 mM^-1, which is 366 and 1270 times higher than those of free GOx (0.303 μA cm^-2 mM^-1) and ATRP-SEG (0.0874 μA cm^-2 mM^-1), respectively. Fc-ATRP-SEG electrode maintained 90% of initial current density under 4 °C storage condition and repetitive usages every day for 7 days. Even the electrode repeatedly used in continuous harsh condition (250 rpm, room temperature), the current density maintained 96% after 12 h incubation at operational condition.

Machine Learning on a Robotic Platform for the Design of Polymer-Protein Hybrids

Polymer-protein hybrids are intriguing materials that can bolster protein stability in non-native environments, thereby enhancing their utility in diverse medicinal, commercial, and industrial applications. One stabilization strategy involves designing synthetic random copolymers with compositions attuned to the protein surface, but rational design is complicated by the vast chemical and composition space. Here, a strategy is reported to design protein-stabilizing copolymers based on active machine learning, facilitated by automated material synthesis and characterization platforms. The versatility and robustness of the approach is demonstrated by the successful identification of copolymers that preserve, or even enhance, the activity of three chemically distinct enzymes following exposure to thermal denaturing conditions. Although systematic screening results in mixed success, active learning appropriately identifies unique and effective copolymer chemistries for the stabilization of each enzyme. Overall, this work broadens the capabilities to design fit-for-purpose synthetic copolymers that promote or otherwise manipulate protein activity, with extensions toward the design of robust polymer-protein hybrid materials.

Nano-biocatalysts for food applications; immobilized enzymes within different nanostructures

The rapid progress in modern technologies and paying more attention to food safety has prompted new green technologies superior than chemical methods in the food industry. In this regard, enzymes can decrease the usage of chemical reactions but they are sensitive to environmental effects (pH and temperature). In addition, enzymes are scarcely possible to be reused. Consequently, their application as natural catalysts is restricted. Using nanotechnology and the possibility of enzyme immobilization on nanomaterials has led to nanobiocatalysts, resulting from the integration of nanotechnology and biotechnology. Nanocarriers have individual features like nanoscale size, excellent surface/volume ratio, and diversity in construction to improve the activity, efficiency, stability, and storage stability of enzymes. Nanobiocatolysts have a wide range of applications in purification, extraction, clarification, production, and packaging of various products in the food industry. Furthermore, the application of nanobiocatalysts to identify specific components of food contaminants such as microorganisms or their metabolites, heavy metals, antibiotics, and residual pesticides has been successful due to the high accuracy of detection. This review investigates the integration of nanotechnology and food enzymes, the nanomaterials used to create nanobiocatalysts and their application, along with the possible risks and legal aspects of nanomaterials in food bioprocesses.

Polar Substitutions on the Surface of a Lipase Substantially Improve Tolerance in Organic Solvents

Biocatalysis in organic solvents (OSs) enables more efficient routes to the synthesis of various valuable chemicals. However, OSs often reduce enzymatic activity, which limits the use of enzymes in OSs. Herein, we report a comprehensive understanding of interactions between surface polar substitutions and DMSO by integrating molecular dynamics (MD) simulations of 45 variants from Bacillus subtilis lipase A (BSLA) and substitution landscape into a "BSLA-SSM" library. By systematically analyzing 39 structural-, solvation-, and interaction energy-based observables, we discovered that hydration shell maintenance, DMSO reduction, and decreased local flexibility simultaneously govern the stability of polar variants in OS. Moreover, the fingerprints of 1631 polar-related variants in three OSs demonstrated that substituting aromatic to polar amino acid(s) hold great potential to highly improve OSs resistance. Hence, surface polar engineering is a powerful strategy to generate OS-tolerant lipases and other enzymes, thereby adapting the catalyst to the desired reaction and process with OSs.

Machine-Assisted Discovery of Chondroitinase ABC Complexes toward Sustained Neural Regeneration

Among the many molecules that contribute to glial scarring, chondroitin sulfate proteoglycans (CSPGs) are known to be potent inhibitors of neuronal regeneration. Chondroitinase ABC (ChABC), a bacterial lyase, degrades the glycosaminoglycan (GAG) side chains of CSPGs and promotes tissue regeneration. However, ChABC is thermally unstable and loses all activity within a few hours at 37 °C under dilute conditions. To overcome this limitation, the discovery of a diverse set of tailor-made random copolymers that complex and stabilize ChABC at physiological temperature is reported. The copolymer designs, which are based on chain length and composition of the copolymers, are identified using an active machine learning paradigm, which involves iterative copolymer synthesis, testing for ChABC thermostability upon copolymer complexation, Gaussian process regression modeling, and Bayesian optimization. Copolymers are synthesized by automated PET-RAFT and thermostability of ChABC is assessed by retained enzyme activity (REA) after 24 h at 37 °C. Significant improvements in REA in three iterations of active learning are demonstrated while identifying exceptionally high-performing copolymers. Most remarkably, one designed copolymer promotes residual ChABC activity near 30%, even after one week and notably outperforms other common stabilization methods for ChABC. Together, these results highlight a promising pathway toward sustained tissue regeneration.

Atomically unveiling the structure-activity relationship of biomacromolecule-metal-organic frameworks symbiotic crystal

Crystallization of biomacromolecules-metal-organic frameworks (BMOFs) allows for orderly assemble of symbiotic hybrids with desirable biological and chemical functions in one voxel. The structure-activity relationship of this symbiotic crystal, however, is still blurred. Here, we directly identify the atomic-level structure of BMOFs, using the integrated differential phase contrast-scanning transmission electron microscopy, cryo-electron microscopy and x-ray absorption fine structure techniques. We discover an obvious difference in the nanoarchitecture of BMOFs under different crystallization pathways that was previously not seen. In addition, we find the nanoarchitecture significantly affects the bioactivity of the BMOFs. This work gives an important insight into the structure-activity relationship of BMOFs synthesized in different scenarios, and may act as a guide to engineer next-generation materials with excellent biological and chemical functions.

Biomolecule-metal-organic-frameworks allow for the creation of hybrid materials with desired biological and chemical function. Here, the authors refine the structure-function relationship by identifying the atomic-layer structure of the hybrids and show differences in structure upon different crystallisation pathways.

Leveraging multiomics approaches for producing lignocellulose degrading enzymes

Lignocellulosic materials form the building block of 50% of plant biomass comprising non-chewable agri-components like wheat straw, rice stubbles, wood shavings and other crop residues. The degradation of lignin, cellulose and hemicellulose is complicated and presently being done by chemical process for industrial application through a very energy intensive process. Lignin degradation is primarily an oxidative process where the enzyme lignin peroxidase digests the polymer into smaller fragments. Being a recalcitrant component, higher lignin content poses a challenge of lower recovery of product for industrial use. Globally, the scientists are working on leveraging fungal biotechnology for using the lignocellulose degrading enzymes secreted by actinomycetes and basidiomycetes fungal groups. Enzymes contributing to degradation of lignin are mainly performing the function of modifying the lignin and degrading the lignin. Ligninolytic enzymes do not act as an independent reaction but are vital to complete the degradation process. Microbial enzyme technology is an emerging green tool in industrial biotechnology for commercial application. Bioprocessing of lignocellulosic biomass is challenged by limitations in enzymatic and conversion process where pretreatment and separation steps are done to remove lignin and hydrolyze carbohydrate into fermentable sugars. This review highlights recent advances in molecular biotechnology, lignin valorization, sequencing, decipher microbial membership, and characterize enzyme diversity through 'omics' techniques. Emerging techniques to characterize the interwoven metabolism and spatial interactions between anaerobes are also reviewed, which will prove critical to developing a predictive understanding of anaerobic communities to guide in microbiome engineering This requires more synergistic collaborations from microbial biotechnologists, bioprocess engineers, enzymologists, and other biotechnological fields.

Bio-fabrication of thermozyme-based nano-biosensors: their components and present scenario

An amalgamation of microbiology, biocatalysis, recombinant molecular biology, and nanotechnology is crucial for groundbreaking innovation in developing nano-biomedicines and sensoristics. Enzyme-based nano-biosensor finds prospective applications in various sectors (environmental, pharmaceutical, food, biorefineries). These applications demand reliable catalytic efficiency and functionality of the enzyme under an extreme operational environment for a prolonged period. Over the last few years, bio-fabrication of nano-biosensors in conjunction with thermozymes from thermophilic microbes is being sought after as a viable design. Thermozymes are known for their robustness, are chemically resistant toward organic solvents, possess higher durability for constant use, catalytic ability, and stability at elevated temperatures. Additionally, several other attributes of thermozymes like substrate specificity, selectivity, and sensitivity make them desirable in developing a customized biosensor. In this review, crucial designing aspects of enzyme-based nano-biosensors like enzyme immobilization on an electrode surface, new materials derived from microbial sources (biopolymers based nanocomposites), improvisation measures for sensitivity, and selectivity have been addressed. It also covers microbial biosynthesis of nanomaterials used to develop sensoristic devices and its numerous applications such as wastewater treatment, biorefineries, and diagnostics. The knowledge will pave the way toward creating consistent eco-friendly, economically viable nanostructured-based technologies with broad applicability and exploitation for industrial use in the near future.

Reversible Regulating the Substrate Specificity of Enzymes in Microgels by a Phase Transition in Polymer Networks

Here, we report a distinct approach for regulating the substrate specificity of enzymes immobilized in microgels by a phase transition in polymer networks. The finding is demonstrated on glucose oxidase that is immobilized in thermoresponsive poly(N-isopropylacrylamide)-based microgels. Laser light scattering and enzymatic oxidation tests indicate that the broadened specificity appears at low temperatures, at which the gel matrix is in the relatively swollen state relative to its state at microgel synthesis temperature; upon heating to the relative higher temperatures, the gel matrix is not able to shrink further that offers a tight space in which the enzyme resides to retain high glucose specificity. It is proposed that polymer phase transition in the gel matrix mainly alter protein gates that control passage of substrates into active sites, making them open or close to a certain extent that enable reversible regulating the substrate specificity. The finding is also observed on bulk gels under a rational design, making it of potential interest in enzymatic biofuel cell applications.

Fluorescence enables high throughput screening of polyelectrolyte–protein binding affinities

Förster resonance energy transfer (FRET) in combination with high throughput controlled radical polymerisation allows quick identification of polymers that can bind strongly to enzymes such as glucose oxidase.

Highly Efficient Synergistic Biocatalysis Driven by Stably Loaded Enzymes within Hierarchically Porous Iron/Cobalt Metal-Organic Framework via Biomimetic Mineralization

The integration of multimodal chemo-/bio-catalysis for efficient cascade reactions has long provided broad prospects in the field of biotechnology for ages. In this work, we describe the synthesis of a...

Selective immobilization of his-tagged phosphomannose isomerase on Ni chelated nanoparticles with good reusability and activity

In this paper, self-stable precipitation polymerization was used to prepare the enzyme-immobilized microsphere composite. Phosphomannose isomerase (PMI) with His-tag was successfully immobilized on Ni 2+ charged pyridine-derived particles. The maximum amount of PMI immobilized on such particles was ~ 184 mg/g. Compared with the free enzymes, the activity of the immobilized enzymes has been significantly improved. In addition, the immoblized enzymes showed a much better thermostability than free enzymes. At the same time, the immobilized enzymes can be reused for multiple reaction cycles. We have observed that the enzyme activity did not decrease significantly after 6 cycles of repeating usages. We conclude that the pyridine-derived particles can be used to selectively immobilize His-tagged enzymes, which can couple the enzyme purification and catalysis steps and improve the efficiency of enzyme-catalyzed industrial processes.

Three-Dimensional Printable Enzymatically Active Plastics

Here, we describe a facile route to the synthesis of enzymatically active highly fabricable plastics, where the enzyme is an intrinsic component of the material. This is facilitated by the formation of an electrostatically stabilized enzyme-polymer surfactant nanoconstruct, which, after lyophilization and melting, affords stable macromolecular dispersions in a wide range of organic solvents. A selection of plastics can then be co-dissolved in the dispersions, which provides a route to bespoke 3D enzyme plastic nanocomposite structures using a wide range of fabrication techniques, including melt electrowriting, casting, and piston-driven 3D printing. The resulting constructs comprising active phosphotriesterase (arPTE) readily detoxify organophosphates with persistent activity over repeated cycles and for long time periods. Moreover, we show that the protein guest molecules, such as arPTE or sfGFP, increase the compressive Young's modulus of the plastics and that the identity of the biomolecule influences the nanomorphology and mechanical properties of the resulting materials. Overall, we demonstrate that these biologically active nanocomposite plastics are compatible with state-of-the-art 3D fabrication techniques and that the methodology could be readily applied to produce robust and on-demand smart nanomaterial structures.

Polymeric Micro/Nanocarriers and Motors for Cargo Transport and Phototriggered Delivery

Smart polymer-based micro/nanoassemblies have emerged as a promising alternative for transporting and delivering a myriad of cargo. Cargo encapsulation into (or linked to) polymeric micro/nanocarrier (PC) strategies may help to conserve cargo activity and functionality when interacting with its surroundings in its journey to the target. PCs for cargo phototriggering allow for excellent spatiotemporal control via irradiation as an external stimulus, thus regulating the delivery kinetics of cargo and potentially increasing its therapeutic effect. Micromotors based on PCs offer an accelerated cargo-medium interaction for biomedical, environmental, and many other applications. This review collects the recent achievements in PC development based on nanomicelles, nanospheres, and nanopolymersomes, among others, with enhanced properties to increase cargo protection and cargo release efficiency triggered by ultraviolet (UV) and near-infrared (NIR) irradiation, including light-stimulated polymeric micromotors for propulsion, cargo transport, biosensing, and photo-thermal therapy. We emphasize the challenges of positioning PCs as drug delivery systems, as well as the outstanding opportunities of light-stimulated polymeric micromotors for practical applications.