An ultrasensitive electrochemical aptasensor based on zeolitic imidazolate framework-67 loading gold nanoparticles and horseradish peroxidase for detection of aflatoxin B1

Aflatoxin B1 (AFB1) is one of the most toxic mycotoxins and poses a high risk to human health. Highly sensitive and rapid detection is one of the most effective preventive measures to avoid potential hazards. Herein, an electrochemical aptasensor based on DNA nanotetrahedron and zeolitic imidazolate framework-67 loading gold nanoparticles, horseradish peroxidase, and aptamers was designed for the ultrasensitive detection of AFB1. The high specific surface area and large pore volume of zeolitic imidazolate framework-67 can increase the loading capacity and further improve the detection sensitivity of electrochemical aptasensors. DNA nanotetrahedron can enhance the capture ability of AFB1 with steady immobilization. The developed aptasensor showed good analytical performance for AFB1 detection, with a detection limit of 3.9 pg mL-1 and a wide linear range of 0.01-100 ng mL-1. The aptasensor detected AFB1 in corn samples with recovery rates ranging from 94.19%-105.77% and has potential for use in food safety monitoring.

Metal-organic frameworks for biomedical applications: A review

Metal-organic frameworks (MOFs) are emergent materials in diverse prospective biomedical uses, owing to their inherent features such as adjustable pore dimension and volume, well-defined active sites, high surface area, and hybrid structures. The multifunctionality and unique chemical and biological characteristics of MOFs allow them as ideal platforms for sensing numerous emergent biomolecules with real-time monitoring towards the point-of-care applications. This review objects to deliver key insights on the topical developments of MOFs for biomedical applications. The rational design, preparation of stable MOF architectures, chemical and biological properties, biocompatibility, enzyme-mimicking materials, fabrication of biosensor platforms, and the exploration in diagnostic and therapeutic systems are compiled. The state-of-the-art, major challenges, and the imminent perspectives to improve the progressions convoluted outside the proof-of-concept, especially for biosensor platforms, imaging, and photodynamic therapy in biomedical research are also described. The present review may excite the interdisciplinary studies at the juncture of MOFs and biomedicine.

Ultrarobust stable ABTS radical cation prepared using Spore@Cu-TMA biocomposites for antioxidant capacity assay

Herein, spore@Cu-trimesic acid (TMA) biocomposites were prepared by self-assembling Cu-based metal-organic framework on the surface of Bacillus velezensis spores. The laccase-like activity of spore@Cu-TMA biocomposites was enhanced by 14.9 times compared with that of pure spores due to the reaction of Cu2+ ions with laccase on the spore surface and the microporous structure of Cu-TMA shell promoting material transport and increasing substrate accessibility. Spore@Cu-TMA rapidly oxidized and transformed 2,2'-azino-bis (3-ethylbenzthiazoline-6-sulfonic acid) (ABTS) into ABTS●+ without using H2O2. Under optimum conditions, the ABTS●+ could be stored for 21 days at 4 °C and 7 days at 37 °C without the addition of any stabilizers, allowing for the large-scale preparation and long-term storage of ABTS●+. The ultrarobust stable ABTS●+ obtained with the use of Cu-TMA could effectively reduce the "back reaction" by preventing the leaching of the metabolites released by the spores. On the basis of these findings, a rapid, low-cost, and eco-friendly colorimetric platform was successfully developed for the detection of antioxidant capacity. Determination of antioxidant capacity for several antioxidants such as caffeic acid, glutathione, and Trolox revealed their corresponding limits of detection at 4.83, 8.89, and 7.39 nM, respectively, with linear ranges of 0.01-130, 0.01-140, and 0.01-180 μM, respectively. This study provides a facile way to prepare ultrarobust stable ABTS●+ and presents a potential application of spore@Cu-TMA biocomposites in food detection and bioanalysis.

Active site-tuned high peroxidase-like activity nanozyme for on-the-spot detection of saliva total antioxidant capacity using smartphone devices

Metal-Organic Framework (MOF) based nanozymes with clear structure are beneficial for exploration of structural-performance and exhibit broad prospects in improving activity. In this study, the prepared bimetallic Fe3Ni-MOF nanozyme was superior to single metal MOF in the peroxidase-like activity. Subsequently, a derivative nanozyme (Fe3Ni-MOF-Ar) was prepared by pyrolysis using Fe3Ni-MOF as the precursor in argon atomoshere with controlled temperature. The investigated of Fe3Ni-MOF-Ar revealed that the irregular macroporous state and the presence of heterovalent FeIII/FeII sites of Fe3Ni-MOF-Ar enable the retention, exposure, and electronic structure regulation of active sites, promoting the dual mechanism (the generation of •OH and electron transfer mechanism) and significantly increasing the peroxidase-like activity. Fe3Ni-MOF-Ar exhibited a strong affinity for substrate H2O2, which is higher than horseradish peroxidase. Ascorbic acid and cysteine are typical substances of antioxidants. Fe3Ni-MOF-Ar was used for sensitive colorimetric detection of ascorbic acid and cysteine, and the detection limit was as low as 150 and 60 nM. In addition, the smartphone devices was used to detection of antioxidant equivalent ascorbic acid, with a detection range of 0.5-120 μM. Fe3Ni-MOF-Ar nanozyme is feasible for sensitive detection of saliva total antioxidant capacity.

Advanced materials for micro/nanorobotics

Autonomous micro/nanorobots capable of performing programmed missions are at the forefront of next-generation micromachinery. These small robotic systems are predominantly constructed using functional components sourced from micro- and nanoscale materials; therefore, combining them with various advanced materials represents a pivotal direction toward achieving a higher level of intelligence and multifunctionality. This review provides a comprehensive overview of advanced materials for innovative micro/nanorobotics, focusing on the five families of materials that have witnessed the most rapid advancements over the last decade: two-dimensional materials, metal-organic frameworks, semiconductors, polymers, and biological cells. Their unique physicochemical, mechanical, optical, and biological properties have been integrated into micro/nanorobots to achieve greater maneuverability, programmability, intelligence, and multifunctionality in collective behaviors. The design and fabrication methods for hybrid robotic systems are discussed based on the material categories. In addition, their promising potential for powering motion and/or (multi-)functionality is described and the fundamental principles underlying them are explained. Finally, their extensive use in a variety of applications, including environmental remediation, (bio)sensing, therapeutics, etc., and remaining challenges and perspectives for future research are discussed.

Irisin-Encapsulated Mitochondria-Targeted Biomimetic Nanotherapeutics for Alleviating Acute Kidney Injury

Acute kidney injury (AKI) is the sudden decrease in renal function that can be attributed to dysregulated reactive oxygen species (ROS) production and impaired mitochondrial function. Irisin, a type I membrane protein secreted by skeletal muscles in response to physical activity, has been reported to alleviate kidney damage through regulation of mitochondrial biogenesis and oxidative metabolism. In this study, a macrophage membrane-coated metal-organic framework (MCM@MOF) is developed as a nanocarrier for encapsulating irisin to overcome the inherent characteristics of irisin, including a short circulation time, limited kidney-targeting ability, and low membrane permeability. The engineered irisin-mediated biomimetic nanotherapeutics have extended circulation time and enhanced targeting capability toward injured kidneys due to the preservation of macrophage membrane proteins. The irisin-encapsulated biomimetic nanotherapeutics effectively mitigate acute ischemia-reperfusion injury by protecting mitochondrial function and modulating SOD2 levels in renal tubular epithelial cells. The present study provides novel insights to advance the development of irisin as a potential therapeutic approach for AKI.

Engineered E. coli for Long-Term Oral Enzyme Delivery

Intestinal flora shows excellent affinity in the gut, and the adhesive property is borrowed for oral drug delivery. A facile strategy for bacteria engineering has been successfully developed by introducing metal-organic framework (MOF) mineralization. The MOF exoskeleton serves as an extendable platform for accommodating various cargoes with good Escherichia coli morphology maintained. The artificial exoskeleton surrounding E. coli is employed for encapsulating macromolecules as a therapeutic cargo, maintaining good bioactivity with high immobilization efficiency (60%) after systematic optimization of the MOF precursor. Leveraging the natural affinity of E. coli in the gut, the in-vivo tracking of MOF-engineered E. coli in the gastrointestinal tract confirmed excellent adhesion to the GI mucosa and a 17.9-fold increase in the gut retention half-time, demonstrating significant advantages in retention capability. In comparison, the control group without E. coli equipment resulted in quick gut passage. Furthermore, the artificially engineered E. coli serves as an effective carrier for macromolecules without notable oral toxicity, as evidenced by biocompatibility evaluations in cells and animals. Overall, the MOF-engineered E. coli provides an extendable platform for loading on-demand cargoes in versatile therapeutic functions with promising clinical transnationality for long-term applications.

Stretchable ionic-electronic bilayer hydrogel electronics enable in situ detection of solid-state epidermal biomarkers

Continuous and in situ detection of biomarkers in biofluids (for example, sweat) can provide critical health data but is limited by biofluid accessibility. Here we report a sensor design that enables in situ detection of solid-state biomarkers ubiquitously present on human skin. We deploy an ionic-electronic bilayer hydrogel to facilitate the sequential dissolution, diffusion and electrochemical reaction of solid-state analytes. We demonstrate continuous monitoring of water-soluble analytes (for example, solid lactate) and water-insoluble analytes (for example, solid cholesterol) with ultralow detection limits of 0.51 and 0.26 nmol cm-2, respectively. Additionally, the bilayer hydrogel electrochemical interface reduces motion artefacts by a factor of three compared with conventional liquid-sensing electrochemical interfaces. In a clinical study, solid-state epidermal biomarkers measured by our stretchable wearable sensors showed a high correlation with biomarkers in human blood and dynamically correlated with physiological activities. These results present routes to universal platforms for biomarker monitoring without the need for biofluid acquisition.

Biomimetic functionalized metal organic frameworks as multifunctional agents: Paving the way for cancer vaccine advances

Biomimetic functionalized metal-organic frameworks (Fn-MOFs) represent a cutting-edge approach in the realm of cancer vaccines. These multifunctional agents, inspired by biological systems, offer unprecedented opportunities for the development of next-generation cancer vaccines. The vast surface area, tunable pore size, and diverse chemistry of MOFs provide a versatile scaffold for the encapsulation and protection of antigenic components, crucial for vaccine stability and delivery. This work delves into the innovative design and application of Fn-MOFs, highlighting their role as carriers for immune enhancement and their potential to revolutionize vaccine delivery. By mimicking natural processes, Fn-MOFs, with their ability to be functionalized with a myriad of chemical and biological entities, exhibit superior biocompatibility and stimuli-responsive behavior and facilitate targeted delivery to tumor sites. This review encapsulates the latest advancements in Fn-MOF technology, from their synthesis and surface modification to their integration into stimuli-responsive and combination therapies. It underscores the significance of biomimetic approaches in overcoming current challenges in cancer vaccine development, such as antigen stability and immune evasion. By leveraging the biomimetic nature of Fn-MOFs, this work paves the way for innovative strategies in cancer vaccines, aiming to induce potent and long-lasting immune responses against malignancies.

Encapsulation of Enzymes into Hydrophilic and Biocompatible Metal Azolate Framework: Improved Functions of Biocatalyst in Cascade Reactions and its Sensing Applications

Multiple enzyme-triggered cascade biocatalytic reactions are vital in vivo or vitro, considering the basic biofunction preservation in living organisms and signals transduction for biosensing platforms. Encapsulation of such enzymes into carrier endows a sheltering effect and can boost catalytic performance, although the selection and preparation of an appropriate carrier is still a concern. Herein, focusing on MAF-7, a category of metal azolate framework (MAF) with superiority against the topologically identical ZIF-8, this enzyme@MAF system can ameliorate the sustainability of encapsulating natural enzymes into carriers. The proposed biocatalyst composite AChE@ChOx@MAF-7/hemin is constructed via one-pot in situ coprecipitation method. Subsequently, MAF-7 is demonstrated to exhibit an excellent capacity of the carrier and protection against external factors in the counterpart of ZIF-8 through encapsulated and free enzymes. In addition, detections for specific substrates or inhibitors with favorable sensitivity are accomplished, indicating that the properties above expectation of different aspects of the established platform are successfully realized. This biofunctional composite based on MAF-7 can definitely provide a potential approach for optimization of cascade reaction and enzyme encapsulation.

Molecular simulations guide immobilization of lipase on nest-like ZIFs with regulatable hydrophilic/hydrophobic surface

The catalytic performance of immobilized lipase is greatly influenced by functional support, which attracts growing interest for designing supports to achieve their promotive catalytic activity. Many lipases bind strongly to hydrophobic surfaces where they undergo interfacial activation. Herein, the behavioral differences of lipases with distinct lid structures on interfaces of varying hydrophobicity levels were firstly investigated by molecular simulations. It was found that a reasonable hydrophilic/hydrophobic surface could facilitate the lipase to undergo interfacial activation. Building on these findings, a novel "nest"-like superhydrophobic ZIFs (ZIFN) composed of hydrophobic ligands was prepared for the first time and used to immobilize lipase from Aspergillus oryzae (AOL@ZIFN). The AOL@ZIFN exhibited 2.0-folds higher activity than free lipase in the hydrolysis of p-Nitrophenyl palmitate (p-NPP). Especially, the modification of superhydrophobic ZIFN with an appropriate amount of hydrophilic tannic acid can significantly improve the activity of the immobilized lipase (AOL@ZIFN-TA). The AOL@ZIFN-TA exhibited 30-folds higher activity than free lipase, and still maintained 82% of its initial activity after 5 consecutive cycles, indicating good reusability. These results demonstrated that nanomaterials with rational arrangement of the hydrophilic/hydrophobic surface could facilitate the lipase to undergo interfacial activation and improve its activity, displaying the potential of the extensive application.

Composites with Immobilized Bioactive Spirulina on an Inorganic Substrate (Yellow Clay, Hydroxyapatite, SiO2, TiO2, ZnO)

In order to improve the structural properties of clays and composites of powdered spirulina, clay, nanosilica, hydroxyapatite, TiO2 and ZnO were used as an additive for mechanical processing. As a result, composites with natural nanostructured materials (NNM) are prepared with improved structural properties and bioactivity. The mixtures based on NNM with crystalline kaolinite, clays and admixtures were processed in a knife mill. The materials were characterized using FTIR spectroscopy, nitrogen adsorption and desorption, SEM release of bioactive components (anthocyanin 0,004-0,07 mg/g; chlorophyll 20-29 mg/g), composite toxicity level (below 25%), particle size measurement and surface charge density, zeta potential. Adsorption enthalpies during the formation of an intermolecular complex during the interactions of an anthocyanin molecule with the appropriate component of the composite were also calculated. There are regularities in the characteristics depending on the type of NNM, particle morphology and textural features of solids. The morphological and structural properties of the components changed slighty in the blends because the processing was conducted under relatively low mechanical stress. The morphological, textural and structural characteristics of the composites as well as the transformation to a nanostructured state, assume great bioactive activity of the composites, interesting for practical applications in medicine and cosmetics.

Development of cross-linked glucose oxidase integrated Cu-nanoflower electrode for reusable and stable glucose sensing

The demand for glucose-sensing devices has increased along with the increasing diabetic population. Here, we aimed to construct a system with a glucose oxidase (GOx)-integrated Cu-nanoflower (Cu-NF) as the underlying electrode. This novel system was successfully developed by creating a cross-linked GOx within a Cu-NF matrix, forming a c-GOx@Cu-NF-coated film on a carbon screen-printed electrode (CSPE). A comparison of the stabilities of the cross-linking methods demonstrated enhanced durability, with an activity level of >88 % maintained after approximately 35 days of storage in room temperature buffer. Regarding the ability of the c-GOx@Cu-NF modified CSPE to detect glucose via electrochemical methods, the redox potential gap (ΔE) and peak current increased in the presence of GOx. In comparison to that of glucose, the sensitivity of c-GOx@Cu-NF was approximately 8 times greater than that of GOx@Cu-NF, with a detection limit of 0.649 μM and a linear range of 5-500 μM. It sustained an average relative activity of 80 % over 20 days. After 10 cycles of repeated use, the activity remained above 75 %. In terms of evaluating the electrode's specificity for glucose, the detection rate for individual similar substances was approximately 1 %. The introduction of a crosslinking strategy to Cu-NF, leading to enhanced mechanical stability and conductivity, improved the detection capability. Furthermore, this approach led to increased long-term storage stability and reusability, allowing for specific glucose detection. To our knowledge, this report represents the first demonstration of a c-GOx@Cu-NF system for integrating electrochemical biosensing devices into digital healthcare pathways, offering enhanced sensing accuracy and mechanical stability.

Immobilization of Bacillus thuringiensis Cry1Ac in metal-organic frameworks through biomimetic mineralization for sustainable pest management

Traditional chemical pesticide dosage forms and crude application methods have resulted in low pesticide utilization, increased environmental pollution, and the development of resistance. Compared to traditional pesticides, nanopesticides enhance the efficiency of pesticide utilization and reduce the quantity required, thereby decreasing environmental pollution. Herein, Cry1Ac insecticidal crystal protein from Bacillus thuringiensis Subsp. Kurstaki HD-73 was encapsulated in a metal-organic framework (zeolite imidazolate framework-8, ZIF-8) through biomimetic mineralization to obtain Cry1Ac@ZIF-8 nanopesticides. The Cry1Ac@ZIF-8 nanopesticides exhibited a dodecahedral porous structure, and the introduction of Cry1Ac did not affect the intrinsic crystal structure of ZIF-8. The indoor toxicity analysis revealed that the toxicity of Cry1Ac towards Ostrinia furnacalis (Guenée), Helicoverpa armigera Hubner, and Spodoptera litura Fabricius was not affected by ZIF-8 encapsulation. Surprisingly, Cry1Ac@ZIF-8 still exhibited excellent pest management efficacy even after exposure to heat, UV irradiation, and long-term storage. More importantly, the encapsulation of ZIF-8 significantly enhanced the internal absorption performance of Cry1Ac in maize leaves and extended its persistence period. Thus, ZIF-8 could potentially serve as a promising carrier for the preparation of nanopesticides with enhanced applicability, stability, and persistence period, providing a powerful strategy to improve the application of Cry1Ac in future agricultural pest management.

Immobilized Urease Vector System Based on the Dynamic Defect Regeneration Strategy for Efficient Urea Removal

The clearance of urea poses a formidable challenge, and its excessive accumulation can cause various renal diseases. Urease demonstrates remarkable efficacy in eliminating urea, but cannot be reused. This study aimed to develop a composite vector system comprising microcrystalline cellulose (MCC) immobilized with urease and metal-organic framework (MOF) UiO-66-NH2, denoted as MCC@UiO/U, through the dynamic defect generation strategy. By utilizing competitive coordination, effective immobilization of urease into MCC@UiO was achieved for efficient urea removal. Within 2 h, the urea removal efficiency could reach up to 1500 mg/g, surpassing an 80% clearance rate. Furthermore, an 80% clearance rate can also be attained in peritoneal dialyzate from patients. MCC@UiO/U also exhibits an exceptional bioactivity even after undergoing 5 cycles of perfusion, demonstrating remarkable stability and biocompatibility. This innovative approach and methodology provide a novel avenue and a wide range of immobilized enzyme vectors for clinical urea removal and treatment of kidney diseases, presenting immense potential for future clinical applications.

Design of Multivariate Biological Metal-Organic Frameworks: Toward Mimicking Active Sites of Enzymes

Mimicking enzymatic processes carried out by natural enzymes, which are highly efficient biocatalysts with key roles in living organisms, attracts much interest but constitutes a synthetic challenge. Biological metal-organic frameworks (bioMOFs) are potential candidates to be enzyme catalysis mimics, as they offer the possibility to combine biometals and biomolecules into open-framework porous structures capable of simulating the catalytic pockets of enzymes. In this work, we first study the catalase activity of a previously reported bioMOF, derived from the amino acid L-serine, with formula {CaIICuII6[(S,S)-serimox]3(OH)2(H2O)} · 39H2O (1) (serimox = bis[(S)-serine]oxalyl diamide), which is indeed capable to mimic catalase enzymes, in charge of preventing cell oxidative damage by decomposing, efficiently, hydrogen peroxide to water and oxygen (2H2O2 → 2 H2O + O2). With these results in hand, we then prepared a new multivariate bioMOF (MTV-bioMOF) that combines two different types of bioligands derived from L-serine and L-histidine amino acids with formula CaIICuII6[(S,S)-serimox]2[(S,S)-hismox]1(OH)2(H2O)}·27H2O (2) (hismox = bis[(S)-histidine]oxalyl diamide ligand). MTV-bioMOF 2 outperforms 1 degrading hydrogen peroxide, confirming the importance of the amino acid residue from the histidine amino acid acting as a nucleophile in the catalase degradation mechanism. Despite displaying a more modest catalytic behavior than other reported MOF composites, in which the catalase enzyme is immobilized inside the MOF, this work represents the first example of a MOF in which an attempt is made to replicate the active center of the catalase enzyme with its constituent elements and is capable of moderate catalytic activity.

Integration of multienzyme co-immobilization and biomimetic catalysis in magnetic metal-organic framework nanoflowers for α-amylase detection in fermentation samples

Multiple enzymes induce biological cascade catalysis is essential in nature and industrial production. However, the shortcomings of enzymes, including unsatisfactory stability, reusability, and sensitivity in harsh microenvironment, have restricted their broader use. Here, we report a facile method for fabricating a cascade system by combining the benefits of immobilized enzymes and biomimetic catalysis based on magnetic metal-organic framework nanoflowers (mMOFNFs). mMOFNFs prepared through the layered double hydroxide-derived strategy exhibited remarkable peroxidase-like activity and accessible amino interface, enabling it to serve not only as a reliable carrier for α-glucosidase and glucose oxidase fixation, but also as a nanozyme participating in cascade. On this basis, a colorimetric biosensor of excellent sensitivity and selectivity for α-amylase detection was constructed with a wide range (2-225 U L-1), low detection limit (2.48 U L-1), and rapid operation (30 min). This work provides a versatile strategy for establishing multi-enzyme cascade systems and rapid analysis of α-amylase.

Enzyme-Immobilized Porous Crystals for Environmental Applications

Developing efficient technologies to eliminate or degrade contaminants is paramount for environmental protection. Biocatalytic decontamination offers distinct advantages in terms of selectivity and efficiency; however, it still remains challenging when applied in complex environmental matrices. The main challenge originates from the instability and difficult-to-separate attributes of fragile enzymes, which also results in issues of compromised activity, poor reusability, low cost-effectiveness, etc. One viable solution to harness biocatalysis in complex environments is known as enzyme immobilization, where a flexible enzyme is tightly fixed in a solid carrier. In the case where a reticular crystal is utilized as the support, it is feasible to engineer next-generation biohybrid catalysts functional in complicated environmental media. This can be interpreted by three aspects: (1) the highly crystalline skeleton can shield the immobilized enzyme against external stressors. (2) The porous network ensures the high accessibility of the interior enzyme for catalytic decontamination. And (3) the adjustable and unambiguous structure of the reticular framework favors in-depth understanding of the interfacial interaction between the framework and enzyme, which can in turn guide us in designing highly active biocomposites. This Review aims to introduce this emerging biocatalysis technology for environmental decontamination involving pollutant degradation and greenhouse gas (carbon dioxide) conversion, with emphasis on the enzyme immobilization protocols and diverse catalysis principles including single enzyme catalysis, catalysis involving enzyme cascades, and photoenzyme-coupled catalysis. Additionally, the remaining challenges and forward-looking directions in this field are discussed. We believe that this Review may offer a useful biocatalytic technology to contribute to environmental decontamination in a green and sustainable manner and will inspire more researchers at the intersection of the environment science, biochemistry, and materials science communities to co-solve environmental problems.

Enhanced Interfacial Electron Transfer in Photocatalyst-Natural Enzyme Coupled Artificial Photosynthesis System: Tuning Strategies and Molecular Simulations

Laccase is capable of catalyzing a vast array of reactions, but its low redox potential limits its potential applications. The use of photocatalytic materials offers a solution to this problem by converting absorbed visible light into electrons to facilitate enzyme catalysis. Herein, MIL-53(Fe) and NH2-MIL-53(Fe) serve as both light absorbers and enzyme immobilization carriers, and laccase is employed for solar-driven chemical conversion. Electron spin resonance spectroscopy results confirm that visible light irradiation causes rapid transfer of photogenerated electrons from MOF excitation to T1 Cu(II) of laccase, significantly increasing the degradation rate constant of tetracycline (TC) from 0.0062 to 0.0127 min-1. Conversely, there is only minimal or no electron transfer between MOF and laccase in the physical mixture state. Theoretical calculations demonstrate that the immobilization of laccase's active site and its covalent binding to the metal-organic framework surface augment the coupled system's activity, reducing the active site accessible from 27.8 to 18.1 Å. The constructed photo-enzyme coupled system successfully combines enzyme catalysis' selectivity with photocatalysis's high reactivity, providing a promising solution for solar energy use.

Hierarchical Micro- and Mesoporous Zeolitic Imidazolate Framework-8-Based Enzyme Hybrid for Combination Antimicrobial by Lysozyme and Lactoferrin

Pathogenic bacteria have consistently posed a formidable challenge to human health, creating the critical need for effective antibacterial solutions. In response, enzyme-metal-organic framework (MOF) composites have emerged as a promising class of antibacterial agents. This study focuses on the development of an enzyme-MOF composite based on HZIF-8, incorporating the advantages of simple synthesis, ZIF-8 antibacterial properties, lysozyme hydrolysis, and high biological safety. Through a one-pot method, core-shell nanoparticles (HZIF-8) were synthesized. This structure enables efficient immobilization of lysozyme and lactoferrin within the HZIF-8, resulting in the formation of the lysozyme-lactoferrin@HZIF-8 (LYZ-LF@HZIF-8) composite. Upon exposure to light irradiation, HZIF-8 itself possessed antibacterial properties. Lysozyme initiated the degradation of bacterial peptidoglycan and lactoferrin synergistically enhanced the antibacterial effect of lysozyme. All of the above ultimately contributed to comprehensive antibacterial activity. Antibacterial assessments demonstrated the efficacy of the LYZ-LF@HZIF-8 composite, effectively eradicating Staphylococcus aureus at a cell density of 1.5 × 106 CFU/mL with a low dosage of 200 μg/mL and completely inactivating Escherichia coli at 400 μg/mL with the same cell density. The enzyme-MOF composite exhibited significant and durable antibacterial efficacy, with no apparent cytotoxicity in vitro, thereby unveiling expansive prospects for applications in the medical and food industries.

A dual recognition-based strategy employing Ni-modified metal-organic framework for in situ screening of SIRT1 inhibitors from Chinese herbs

Sirtuin1 (SIRT1), an NAD+-dependent histone deacetylase, plays a crucial role in regulating molecular signaling pathways. Recently, inhibition of SIRT1 rather than its activation shows the therapeutic potential for central nervous system disorder, however, the discovered SIRT1 inhibitors remains limited. In this work, a dual recognition-based strategy was developed to screen SIRT1 inhibitors from natural resources in situ. This approach utilized a Ni-modified metal-organic framework (Ni@Tyr@UiO-66-NH2) along with cell lysate containing an engineered His-tagged SIRT1 protein, eliminating the need for purified proteins, pure compounds, and protein immobilization. The high-performance Ni@Tyr@UiO-66-NH2 was synthesized by modifying the surface of UiO-66-NH2 with Ni2+ ions to specifically capture His-tagged SIRT1 while persevering its enzyme activity. By employing dual recognition, in which Ni@Tyr@UiO-66-NH2 recognized SIRT1 and SIRT1 recognized its ligands, the process of identifying SIRT1 inhibitors from complex matrix was vastly streamlined. The developed method allowed the efficient discovery of 16 natural SIRT1 inhibitors from Chinese herbs. Among them, 6 compounds were fully characterized, and suffruticosol A was found to have an excellent IC50 value of 0.95 ± 0.12 μM. Overall, an innovative dual recognition-based strategy was proposed to efficiently identify SIRT1 inhibitors in this study, offering scientific clues for the development of drugs targeting CNS disorders.

Encapsulation engineering of porous crystalline frameworks for delayed luminescence and circularly polarized luminescence

Delayed luminescence (DF), including phosphorescence and thermally activated delayed fluorescence (TADF), and circularly polarized luminescence (CPL) exhibit common and broad application prospects in optoelectronic displays, biological imaging, and encryption. Thus, the combination of delayed luminescence and circularly polarized luminescence is attracting increasing attention. The encapsulation of guest emitters in various host matrices to form host-guest systems has been demonstrated to be an appealing strategy to further enhance and/or modulate their delayed luminescence and circularly polarized luminescence. Compared with conventional liquid crystals, polymers, and supramolecular matrices, porous crystalline frameworks (PCFs) including metal-organic frameworks (MOFs), covalent-organic frameworks (COFs), zeolites and hydrogen-bonded organic frameworks (HOFs) can not only overcome shortcomings such as flexibility and disorder but also achieve the ordered encapsulation of guests and long-term stability of chiral structures, providing new promising host platforms for the development of DF and CPL. In this review, we provide a comprehensive and critical summary of the recent progress in host-guest photochemistry via the encapsulation engineering of guest emitters in PCFs, particularly focusing on delayed luminescence and circularly polarized luminescence. Initially, the general principle of phosphorescence, TADF and CPL, the combination of DF and CPL, and energy transfer processes between host and guests are introduced. Subsequently, we comprehensively discuss the critical factors affecting the encapsulation engineering of guest emitters in PCFs, such as pore structures, the confinement effect, charge and energy transfer between the host and guest, conformational dynamics, and aggregation model of guest emitters. Thereafter, we summarize the effective methods for the preparation of host-guest systems, especially single-crystal-to-single-crystal (SC-SC) transformation and epitaxial growth, which are distinct from conventional methods based on amorphous materials. Then, the recent advancements in host-guest systems based on PCFs for delayed luminescence and circularly polarized luminescence are highlighted. Finally, we present our personal insights into the challenges and future opportunities in this promising field.

A Synergetic Pore Compartmentalization and Hydrophobization Strategy for Synchronously Boosting the Stability and Activity of Enzyme

Spatial immobilization of fragile enzymes using a nanocarrier is an efficient means to design heterogeneous biocatalysts, presenting superior stability and recyclability to pristine enzymes. An immobilized enzyme, however, usually compromises its catalytic activity because of inevasible mass transfer issues and the unfavorable conformation changes in a confined environment. Here, we describe a synergetic metal-organic framework pore-engineering strategy to trap lipase (an important hydrolase), which confers lipase-boosted stability and activity simultaneously. The hierarchically porous NU-1003, featuring interconnected mesopore and micropore channels, is precisely modified by chain-adjustable fatty acids on its mesopore channel, into which lipase is trapped. The interconnected pore structure ensures efficient communication between trapped lipase and exterior media, while the fatty acid-mediated hydrophobic pore can activate the opening conformation of lipase by interfacial interaction. Such dual pore compartmentalization and hydrophobization activation effects render the catalytic center of trapped lipase highly accessible, resulting in 1.57-fold and 2.46-fold activities as native lipase on ester hydrolysis and enantioselective catalysis. In addition, the feasibility of these heterogeneous biocatalysts for kinetic resolution of enantiomer is also validated, showing much higher efficiency than native lipase.

Enhanced Enzymatic Performance of Immobilized Pseudomonas fluorescens Lipase on ZIF-8@ZIF-67 and Its Application to the Synthesis of Neryl Acetate with Transesterification Reaction

In this study, hybrid skeleton material ZIF-8@ZIF-67 was synthesized by the epitaxial growth method and then was utilized as a carrier for encapsulating Pseudomonas fluorescens lipase (PFL) through the co-precipitation method, resulting in the preparation of immobilized lipase (PFL@ZIF-8@ZIF-67). Subsequently, it was further treated with glutaraldehyde to improve protein immobilization yield. Under optimal immobilization conditions, the specific hydrolytic activity of PFL@ZIF-8@ZIF-67 was 20.4 times higher than that of the free PFL. The prepared biocatalyst was characterized and analyzed by scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR). Additionally, the thermal stability of PFL@ZIF-8@ZIF-67 at 50 °C was significantly improved compared to the free PFL. After 7 weeks at room temperature, PFL@ZIF-8@ZIF-67 retained 78% of the transesterification activity, while the free enzyme was only 29%. Finally, PFL@ZIF-8@ZIF-67 was applied to the neryl acetate preparation in a solvent-free system, and the yield of neryl acetate reached 99% after 3 h of reaction. After 10 repetitions, the yields of neryl acetate catalyzed by PFL@ZIF-8@ZIF-67 and the free PFL were 80% and 43%, respectively.

Nanomaterial-related hemoglobin-based oxygen carriers, with emphasis on liposome and nano-capsules, for biomedical applications: current status and future perspectives

Oxygen is necessary for life and plays a key pivotal in maintaining normal physiological functions and treat of diseases. Hemoglobin-based oxygen carriers (HBOCs) have been studied and developed as a replacement for red blood cells (RBCs) in oxygen transport due to their similar oxygen-carrying capacities. However, applications of HBOCs are hindered by vasoactivity, oxidative toxicity, and a relatively short circulatory half-life. With advancements in nanotechnology, Hb encapsulation, absorption, bioconjugation, entrapment, and attachment to nanomaterials have been used to prepare nanomaterial-related HBOCs to address these challenges and pend their application in several biomedical and therapeutic contexts. This review focuses on the progress of this class of nanomaterial-related HBOCs in the fields of hemorrhagic shock, ischemic stroke, cancer, and wound healing, and speculates on future research directions. The advancements in nanomaterial-related HBOCs are expected to lead significant breakthroughs in blood substitutes, enabling their widespread use in the treatment of clinical diseases.

MOFs for next-generation cancer therapeutics through a biophysical approach-a review

Metal-organic frameworks (MOFs) have emerged as promising nanocarriers for cancer treatment due to their unique properties. Featuring high porosity, extensive surface area, chemical stability, and good biocompatibility, MOFs are ideal for efficient drug delivery, targeted therapy, and controlled release. They can be designed to target specific cellular organelles to disrupt metabolic processes in cancer cells. Additionally, functionalization with enzymes mimics their catalytic activity, enhancing photodynamic therapy and overcoming apoptosis resistance in cancer cells. The controllable and regular structure of MOFs, along with their tumor microenvironment responsiveness, make them promising nanocarriers for anticancer drugs. These carriers can effectively deliver a wide range of drugs with improved bioavailability, controlled release rate, and targeted delivery efficiency compared to alternatives. In this article, we review both experimental and computational studies focusing on the interaction between MOFs and drug, explicating the release mechanisms and stability in physiological conditions. Notably, we explore the relationship between MOF structure and its ability to damage cancer cells, elucidating why MOFs are excellent candidates for bio-applicability. By understanding the problem and exploring potential solutions, this review provides insights into the future directions for harnessing the full potential of MOFs, ultimately leading to improved therapeutic outcomes in cancer treatment.

Selective Removal of Denatured Proteins Using MOF Nanopores

Here we present, for the first time, the selective adsorption of denatured proteins using a metal-organic framework (MOF), demonstrating promising potential for protein purification. Typical proteins, such as lysozyme and carbonic anhydrase B, enter the pores of MIL-101 through their narrow apertures when they are denatured to an unfolded state. Selective adsorption is achieved by finely tuning two key features: the sizes of the aperture and cage of the MOF nanopores, which are responsible for sorting unfolded polypeptide chains and inhibiting the translocation of the native form into the pores, respectively. By leveraging this selective adsorption, we successfully purified a mixture of native and denatured proteins by adding MOF to the mixture, achieving a native purity of over 99%.

Enhancing Chymotrypsin Activity and Stability of Capillary Immobilized Enzyme Microreactors Using Zeolitic Imidazolate Frameworks as Encapsulation Materials

Open-tubular immobilized enzyme microreactors (OT-IMERs) are some of the most widely used enzyme reaction devices due to the advantages of simple preparation and fast sample processing. However, the traditional approaches for OT-IMERs preparation had some defects such as limited enzyme loading amount, susceptibility to complex sample interference, and less stability. Here, we report a strategy for the preparation of highly active and stable OT-IMERs, in which the single-stranded DNA-enzyme composites were immobilized in capillaries and then encapsulated in situ in the capillaries via zeolitic imidazolate frameworks (ZIF-L). The phosphate groups of the DNA adjusted the surface potential of the enzyme to negative values, which could attract cations, such as Zn2+, to promote the formation of ZIF-L for enzyme encapsulation. Using chymotrypsin (ChT) as a model enzyme, the prepared ChT@ZIF-L-IMER has higher activity and better affinity than the free enzyme and ChT-IMER. Moreover, the thermal stability, pH stability, and organic solvent stability of ChT@ZIF-L-IMER were much higher than those of free enzyme and ChT-IMER. Furthermore, the activity of ChT@ZIF-L-IMER was much higher than that of ChT-IMER after ten consecutive reactions. To demonstrate the versatility of this preparation method, we replaced ChT with glucose oxidase (GOx). The stability of GOx@ZIF-L-IMER was also experimentally demonstrated to be superior to that of GOx and GOx-IMER. Finally, ChT@ZIF-L-IMER was used for proteolytic digestion analysis. The results showed that ChT@ZIF-L-IMER had a short digestion time and high digestive efficiency compared with the free enzyme. The present study broadened the synthesis method of OT-IMERs, effectively integrating the advantages of metal-organic frameworks and IMER, and the prepared OT-IMERs significantly improved enzyme stability. All of the results indicated that the IMER prepared by this method had a broad application prospect in capillary electrophoresis-based high-performance enzyme analysis.

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.

When nanozymes meet enzyme: Unlocking the dual-activity potential of integrated biocomposites

Integrating enzymes and nanozymes in various applications is a topic of significant interest. The researchers have explored the encapsulation of enzymes using diverse nanostructures to create nanomaterial-enzyme hybrids. These nanomaterials introduce unique properties that contribute to the additional activity along with the stabilization of enzymes in immobilized form, enabling a cascade of second-order reactions. This review centers on dual-activity nanozymes, providing insights into their applications in biosensors and biocatalysis. These applications leverage the enhanced catalytic activity and stability offered by dual-activity nanozymes. These nanozymes find promising applications in fields like bioremediation, offering eco-friendly solutions for mitigating environmental pollution while showing potential in medical diagnostics. The review delves into various techniques for creating enzyme-nanozyme hybrid catalysts, including adsorption, encapsulation, and incorporation methods. The review also addresses the challenges that must be overcome, such as overlapping catalytic surfaces and disparities in reaction rates in multi-enzyme cascade reactions. It concludes by presenting strategies to tackle these issues and offers insights into the field's promising future, suggesting that machine learning may drive further advancements in enzyme-nanozyme integration. This comprehensive exploration illuminates the present and charts a promising course for future innovations in the seamless integration of enzymes and nanozymes, heralding a new era of catalytic possibilities.

Artificial Intelligence-Guided Gut-Microenvironment-Triggered Imaging Sensor Reveals Potential Indicators of Parkinson's Disease

The gut-brain axis has recently emerged as a crucial link in the development and progression of Parkinson's disease (PD). Dysregulation of the gut microbiota has been implicated in the pathogenesis of this disease, sparking growing interest in the quest for non-invasive biomarkers derived from the gut for early PD diagnosis. Herein, an artificial intelligence-guided gut-microenvironment-triggered imaging sensor (Eu-MOF@Au-Aptmer) to achieve non-invasive, accurate screening for various stages of PD is presented. The sensor works by analyzing α-Syn in the gut using deep learning algorithms. By monitoring changes in α-Syn, the sensor can predict the onset of PD with high accuracy. This work has the potential to revolutionize the diagnosis and treatment of PD by allowing for early intervention and personalized treatment plans. Moreover, it exemplifies the promising prospects of integrating artificial intelligence (AI) and advanced sensors in the monitoring and prediction of a broad spectrum of diseases and health conditions.

Recent Advances in Pristine Iron Triad Metal-Organic Framework Cathodes for Alkali Metal-Ion Batteries

Pristine iron triad metal-organic frameworks (MOFs), i.e., Fe-MOFs, Co-MOFs, Ni-MOFs, and heterometallic iron triad MOFs, are utilized as versatile and promising cathodes for alkali metal-ion batteries, owing to their distinctive structure characteristics, including modifiable and designable composition, multi-electron redox-active sites, exceptional porosity, and stable construction facilitating rapid ion diffusion. Notably, pristine iron triad MOFs cathodes have recently achieved significant milestones in electrochemical energy storage due to their exceptional electrochemical properties. Here, the recent advances in pristine iron triad MOFs cathodes for alkali metal-ion batteries are summarized. The redox reaction mechanisms and essential strategies to boost the electrochemical behaviors in associated electrochemical energy storage devices are also explored. Furthermore, insights into the future prospects related to pristine iron triad MOFs cathodes for lithium-ion, sodium-ion, and potassium-ion batteries are also delivered.

Glucose Oxidase Energized Osmium with Dual-Active Centers and Triple Enzyme Activities for Infected Diabetic Wound Management

Diabetic wounds are susceptible to bacterial infections, largely linked to high blood glucose levels (hyperglycemia). To treat such wounds, enzymes like glucose oxidase (GOx) can be combined with nanozymes (nanomaterials mimic enzymes) to use glucose effectively for purposes. However, there is still room for improvement in these systems, particularly in terms of process simplification, enzyme activity regulation, and treatment effects. Herein, the approach utilizes GOx to directly facilitate the biomineralized growth of osmium (Os) nanozyme (GOx-OsNCs), leading to dual-active centers and remarkable triple enzyme activities. Initially, GOx-OsNCs use vicinal dual-active centers, enabling a self-cascaded mechanism that significantly enhances glucose sensing performance compared to step-by-step reactions, surpassing the capabilities of other metal sources such as gold and platinum. In addition, GOx-OsNCs are integrated into a glucose-sensing gel, enabling instantaneous visual feedback. In the treatment of infected diabetic wounds, GOx-OsNCs exhibit multifaceted benefits by lowering blood glucose levels and exhibiting antibacterial properties through the generation of hydroxyl free radicals, thereby expediting healing by fostering a favorable microenvironment. Furthermore, the catalase-like activity of GOx-OsNCs aids in reducing oxidative stress, inflammation, and hypoxia, culminating in improved healing outcomes. Overall, this synergistic enzyme-nanozyme blend is user-friendly and holds considerable promise for diverse applications.

Boosted Enzyme Activity via Encapsulation within Metal-Organic Frameworks with Pores Matching Enzyme Size and Shape

A novel and versatile approach called "physical imprinting" is introduced to modulate enzyme conformation using mesoporous materials, addressing challenges in achieving improved enzyme activity and stability. Metal-organic frameworks with tailored mesopores, precisely matching enzyme size and shape, are synthesized. Remarkably, enzymes encapsulated within these customized mesopores exhibit over 1670% relative activity compared to free enzymes, maintaining outstanding efficiency even under harsh conditions such as heat, exposure to organic solvents, wide-ranging pH extremes from acidic to alkaline, and exposure to a digestion cocktail. After 18 consecutive cycles of use, the immobilized enzymes retain 80% of their initial activity. Additionally, the encapsulated enzymes exhibit a substantial increase in catalytic efficiency, with a 14.1-fold enhancement in kcat/KM compared to native enzymes. This enhancement is among the highest reported for immobilized enzymes. The improved enzyme activity and stability are corroborated by solid-state UV-vis, electron paramagnetic resonance, Fourier-transform infrared spectroscopy, and solid-state NMR spectroscopy. The findings not only offer valuable insights into the crucial role of size and shape complementarity within confined microenvironments but also establish a new pathway for developing solid carriers capable of enhancing enzyme activity and stability.

Boosting humoral and cellular immunity with enhanced STING activation by hierarchical mesoporous metal-organic framework adjuvants

Vaccination is essential for preventing and controlling infectious diseases, along with reducing mortality. Developing safe and versatile adjuvants to enhance humoral and cellular immune responses to vaccines remains a key challenge in vaccine development. Here, we designed hierarchical mesoporous MOF-801 (HM801) using a Cocamidopropyl betaine (CAPB) and a Pluronics F127 in an aqueous phase system. Meanwhile, we synthesized a novel SARS-CoV-2 nanovaccine (R@M@HM801) with a high loading capacity for both the STING agonist (MSA-2) and the Delta receptor binding domain (Delta-RBD) antigen. R@M@HM801 enhanced MSA-2 and RBD utilization and effectively co-delivered MSA-2 and RBD antigens to antigen-presenting cells in the draining lymph nodes, thereby promoting the activation of both T and B cells. Lymphocyte single-cell analysis showed that R@M@HM801 stimulated robust CD11b+CD4+ T cells, CXCR5+CD4+ T follicular helper (Tfh), and durable CD4+CD44+CD62L-, CD8+CD44+CD62L- effector memory T cell (TEM) immune responses, and promoted the proliferative activation of CD26+ B cells in vivo. Meanwhile, R@M@HM801 induced stronger specific antibodies and neutralization of pseudovirus against Delta compared to the RBD + MAS-2 and RBD + MAS-2 + Alum vaccines. Our study demonstrated the efficacy of a hierarchical mesoporous HM801 and its potential immune activation mechanism in enhancing adaptive immune responses against viruses and other diseases.

Morphology Control of Zr-Based Luminescent Metal-Organic Frameworks for Aflatoxin B1 Detection

Metal-organic frameworks (MOFs) have gained significant prominence as sensing materials owing to their unique properties. However, understanding the correlation between the morphology, properties, and sensing performance in these MOF-based sensors remains a challenge, limiting their applications and potential for improvement. In this study, Zr-MOF was chosen as an ideal model to explore the impact of the MOF morphology on the sensing performance, given its remarkable stability and structural variability. Three luminescent MOFs (namely rod-like Zr-LMOF, prismoid-like Zr-LMOF, and ellipsoid-like Zr-LMOF) were synthesized by adjusting the quantities of the benzoic acid and the reaction time. More importantly, the sensing performance of these Zr-LMOFs in response to aflatoxin B1 (AFB1) was thoroughly examined. Notably, the ellipsoid-like Zr-LMOF exhibited significantly higher sensitivity compared to other Zr-LMOFs, attributed to its large specific surface area and pore volume. Additionally, an in-depth investigation into the detection mechanism of AFB1 by Zr-LMOFs was conducted. Building upon these insights, a ratiometric fluorescence sensor was developed by coordinating Eu3+ with ellipsoid-like Zr-LMOF, achieving a remarkably lower detection limit of 2.82 nM for AFB1. This study contributes to an improved comprehension of the relationship between the MOF morphology and the sensing characteristics while presenting an effective approach for AFB1 detection.

Amino Functionality Enables Aqueous Synthesis of Carboxylic Acid-Based MOFs at Room Temperature by Biomimetic Crystallization

Enzyme immobilization within metal-organic frameworks (MOFs) is a promising solution to avoid denaturation and thereby utilize the desirable properties of enzymes outside of their native environments. The biomimetic mineralization strategy employs biomacromolecules as nucleation agents to promote the crystallization of MOFs in water at room temperature, thus overcoming pore size limitations presented by traditional postassembly encapsulation. Most biomimetic crystallization studies reported to date have employed zeolitic imidazole frameworks (ZIFs). Herein, we expand the library of MOFs suitable for biomimetic mineralization to include zinc(II) MOFs incorporating functionalized terephthalic acid linkers and study the catalytic performance of the enzyme@MOFs. Amine functionalization of terephthalic acids is shown to accelerate the formation of crystalline MOFs enabling new enzyme@MOFs to be synthesized. The structure and morphology of the enzyme@MOFs were characterized by PXRD, FTIR, and SEM-EDX, and the catalytic potential was evaluated. Increasing the linker length while retaining the amino moiety gave rise to a family of linkers; however, MOFs generated with the 2,2'-aminoterephthalic acid linker displayed the best catalytic performance. Our data also illustrate that the pH of the reaction mixture affects the crystal structure of the MOF and that this structural transformation impacts the catalytic performance of the enzyme@MOF.

Protein-Integrated Hydrogen-Bonded Organic Frameworks: Chemistry and Biomedical Applications

Hydrogen-bonded organic frameworks (HOFs) are porous nanomaterials that offer exceptional biocompatibility and versatility for integrating proteins for biomedical applications. This minireview concisely discusses recent advancements in the chemistry and functionality of protein-HOF interfaces. It particularly focuses on strategic methodologies, such as the careful selection of building blocks and the genetic engineering of proteins, to facilitate protein-HOF interactions. We examine the role of enzyme encapsulation within HOFs, highlighting its capability to preserve enzyme function, a crucial aspect for applications in biosensing and disease diagnosis. Moreover, we discuss the emerging utility of nanoscale HOFs for intracellular protein delivery, illustrating their applicability as nanoreactors for intracellular catalysis and neuroprotective biorthogonal catalysis within cellular compartments. We highlight the significant advancement of designing biodegradable HOFs tailored for cytosolic protein delivery, underscoring their promising application in targeted cancer therapies. Finally, we provide a perspective viewpoint on the design of biocompatible protein-HOF assemblies, underlining their promising prospects in drug delivery, disease diagnosis, and broader biomedical applications.

Natural Polymer Encapsulated Zeolitic Imidazolate Framework-12 Composite toward Electrochemical Sensing of Antitumor Agent

Encapsulation of natural polymer pectin (Pec) into a zeolitic imidazolate framework-12 (ZIF-12) matrix via a simple chemical method toward anticancer agent gallic acid (GA) detection is reported in this work. GA, a natural phenol found in many food sources, has gained attention by its biological effects on the human body, such as an antioxidant and anti-inflammatory. Therefore, it is crucial to accurately and rapidly determine the GA level in humans. The encapsulation of Pec inside the ZIF-12 has been successfully confirmed from the physiochemical studies such as XRD, Raman, FTIR, and XPS spectroscopy along with morphological FESEM, BET, and HRTEM characterization. Under optimized conditions, the Pec@ZIF-12 composite exhibits wide linear range of 20 nM-250 μM with a detection limit of 2.2 nM; also, it showed excellent selectivity, stability, and reproducibility. Furthermore, the real sample analysis of food samples including tea, coffee, grape, and pomegranate samples shows exceptional recovery percentage in an unspiked manner. So far, there is little literature for encapsulating proteins, enzymes, metals, etc., that have been reported; here, we successfully encapsulated a natural polymer Pec inside the ZIF-12 cage. This encapsulation significantly enhanced the composite electrochemical performance, which could be seen from the overall results. All of these strongly suggest that the proposed Pec@ZIF-12 composite could be used for miniaturized device fabrication for the evaluation of GA in both home and industrial applications.

Boosting one-step degradation of shrimp shell waste to produce chitin oligosaccharides at smart nanoscale enzyme reactor with liquid-solid system

Chitin oligosaccharides (CTOS) possess potential applications in food, medicine, and agriculture. However, lower mass transfer and catalytic efficiency are the main kinetic limitations for the production of CTOS from shrimp shell waste (SSW) and crystalline chitin. Chemical or physical methods are usually used for pretreatment to improve chitinase hydrolysis efficiency, but this is not eco-friendly and cost-effective. To address this challenge, a chitinase nanoreactor with the liquid-solid system (BcChiA1@ZIF-8) was manufactured to boost the one-step degradation of SSW and crystalline chitin. Compared with free enzyme, the catalytic efficiency of BcChiA1@ZIF-8 on colloidal chitin was significantly improved to 142 %. SSW and crystalline chitin can be directly degraded by BcChiA1@ZIF-8 without any pretreatments. The yield of N, N'-diacetylchitobiose [(GlcNAc)2] from SSW and N-acetyl-D-glucosamine (GlcNAc) from crystalline chitin was 2 times and 3.1 times than that of free enzyme, respectively. The reason was that BcChiA1@ZIF-8 with a liquid-solid system enlarged the interface area, increased the collision frequency between enzyme and substrate, and improved the large-substrates binding activity of chitinase. Moreover, the biphasic system exhibited excellent stability, and the design showed universal applicability. This strategy provided novel guidance for other polysaccharide biosynthesis and the conversion of environmental waste into carbohydrates.

One-Pot Synthesis of 1,3,5-Trisubstitued Pyrazoles via Immobilized Thermomyces lanuginosus Lipase (TLL) on a Metal-Organic Framework

A regioselective enzyme-catalyzed system is selected for the synthesis of 1,3,5-trisubstituted pyrazole derivatives by adding phenyl hydrazines, nitroolefins, and benzaldehydes. The reaction is performed in a one-pot vessel with a yield ranging from 49 to 90%. TLL@MMI, immobilized Thermomyces lanuginosus lipase (TLL) on a multivariate of MOF-5/IRMOF-3 (MMI), showed good performance for the catalysis of this reaction. The prepared biocatalyst was characterized by FTIR, XRD, SEM, and EDX. The thermal and solvent stability of TLL@MMI was investigated in MeOH and EtOH after 24 h incubation. In the presence of 100% concentrations of EtOH, TLL@MMI has 80% activity.

Encapsulation of an enzyme-immobilized smart polymer membrane in a metal-organic framework for enhancement of catalytic performance

Encapsulation of enzymes within porous materials has shown great promise for protecting enzymes from denaturation, increasing their tolerance to harsh environments and promoting their industrialization. However, controlling the conformational freedom of the encapsulated enzymes to enhance their catalytic performance remains a great challenge. To address this issue, herein, following immobilization of GOx and HRP on a thermo-responsive porous poly(styrene-maleic-anhydride-N-isopropylacrylamide) (PSMN) membrane, a GOx-HRP@PSMN@HZIF-8 composite was fabricated by encapsulating GOx-HRP@PSMN in hollow ZIF-8 (HZIF-8) with liposome (L) as the sacrificial template. The improved conformational freedom for enzymes arising from the hollow cavity formed in ZIF-8 through the removal of L enhanced the mass transfer and dramatically promoted the catalytic activity of the composite. Interestingly, at high temperature, the coiled PN moiety in PSMN provided the confinement effect for GOx-HRP, which also significantly boosted the catalytic performance of the composites. Compared to the maximum catalytic reaction rates (Vmax) of GOx-HRP@PSMN@LZIF-8, the free enzyme and GOx-HRP@ZIF-8, the Vmax of the GOx-HRP@PSMN@HZIF-8 composite exhibited an impressive 17.8-fold, 10.8-fold and 6.0-fold enhancement at 37 °C, respectively. The proposed composites successfully demonstrated their potential as catalytic platforms for the colorimetric detection of glucose in a cascade reaction. This study paves a new way for overcoming the current limitations of immobilizing enzymes in porous materials and the use of smart polymers for the potential fabrication of enzyme@polymer@MOF composites with tunable conformational freedom and confinement effect.

Hypoxia-Responsive Hydrogen-Bonded Organic Framework-Mediated Protein Delivery for Cancer Therapy

The efficient delivery of therapeutic proteins to tumor sites is a promising cancer treatment modality. Hydrogen-bonded organic frameworks (HOFs) are successfully used for the protective encapsulation of proteins; however, easy precipitation and lack of controlled release of existing HOFs limit their further application for protein delivery in vivo. Here, a hypoxia-responsive HOF, self-assembled from azobenzenedicarboxylate/polyethylene glycol-conjugated azobenzenedicarboxylate and tetrakis(4-amidiniumphenyl)methane through charge-assisted hydrogen-bonding, is developed for systemic protein delivery to tumor cells. The newly generated HOF platform efficiently encapsulates representative cytochrome C, demonstrating good dispersibility under physiological conditions. Moreover, it can respond to overexpressed reductases in the cytoplasm under hypoxic conditions, inducing fast intracellular protein release to exert therapeutic effects. The strategy presented herein can be applied to other therapeutic proteins and can be expanded to encompass more intrinsic tumor microenvironment stimuli. This offers a novel avenue for utilizing HOFs in protein-based cancer therapy.

A wearable flexible electrochemical biosensor with CuNi-MOF@rGO modification for simultaneous detection of uric acid and dopamine in sweat

BACKGROUND

In health assessment and personalized medical services, accurate detection of biological markers such as dopamine (DA) and uric acid (UA) in sweat is crucial for providing valuable physiological information. However, there are challenges in detecting sweat biomarkers due to their low concentrations, variations in sweat yield among individuals, and the need for efficient sweat collection.

RESULTS

We synthesized CuNi-MOF@rGO as a high-activity electrocatalyst and investigated its feasibility and electrochemical mechanism for simultaneously detecting low-concentration biomarkers UA and DA. Interaction between the non-coordinating carboxylate group and the sample produces effective separation signals for DA and UA. The wearable biomimetic biosensor has a wide linear range of 1-500 μM, with a detection limit of 9.41 μM and sensitivity of 0.019 μA μM-1 cm-2 for DA, and 10-1000 μM, with a detection limit of 9.09 μM and sensitivity of 0.026 μA μM-1 cm-2 for UA. Thus, our sensor performs excellently in detecting low-concentration biomarkers. To improve sweat collection, we designed a microfluidic-controlled device with hydrophilic modification in the microchannel. Experimental results show optimal ink flow at 2% concentration. Overall, we developed an innovative and highly active electrocatalyst, successfully enabling simultaneous detection of low-concentration biomarkers UA and DA.

SIGNIFICANCE

This study provides a strategy for sweat analysis and health monitoring. Moreover, the sensor also showed good performance in detecting real sweat samples. This study has shown great potential in future advances in sweat analysis and health monitoring.

Nanocomposites Based on Magnetic Nanoparticles and Metal-Organic Frameworks for Therapy, Diagnosis, and Theragnostics

In the last two decades, metal-organic frameworks (MOFs) with highly tunable structure and porosity, have emerged as drug nanocarriers in the biomedical field. In particular, nanoscaled MOFs (nanoMOFs) have been widely investigated because of their potential biocompatibility, high drug loadings, and progressive release. To enhance their properties, MOFs have been combined with magnetic nanoparticles (MNPs) to form magnetic nanocomposites (MNP@MOF) with additional functionalities. Due to the magnetic properties of the MNPs, their presence in the nanosystems enables potential combinatorial magnetic targeted therapy and diagnosis. In this Review, we analyze the four main synthetic strategies currently employed for the fabrication of MNP@MOF nanocomposites, namely, mixing, in situ formation of MNPs in presynthesized MOF, in situ formation of MOFs in the presence of MNPs, and layer-by-layer methods. Additionally, we discuss the current progress in bioapplications, focusing on drug delivery systems (DDSs), magnetic resonance imaging (MRI), magnetic hyperthermia (MHT), and theragnostic systems. Overall, we provide a comprehensive overview of the recent advances in the development and bioapplications of MNP@MOF nanocomposites, highlighting their potential for future biomedical applications with a critical analysis of the challenges and limitations of these nanocomposites in terms of their synthesis, characterization, biocompatibility, and applicability.

Current status of controlled onco-therapies based on metal organic frameworks

Despite consecutive efforts devoted to the establishment of innovative therapeutics for cancer control, cancer remains as a primary global public health concern. Achieving controlled release of anti-cancer agents may add great value to the field of oncology that requires the involvement of nanotechnologies. Metal organic frameworks (MOFs) hold great promise in this regard owing to their unique structural properties. MOFs can act as superior candidates for drug delivery given their porous structure and large loading area, and can be prepared into anti-cancer therapeutics by incorporating stimuli-sensitive components into the ligands or nodes of the framework. By combing through chemical and physical features of MOFs favorable for onco-therapeutic applications and current cancer treatment portfolios taking advantages of these characteristics, this review classified MOFs feasible for establishing controlled anti-cancer modalities into 6 categories, outlined the corresponding strategies currently available for each type of MOF, and identified understudied areas and future opportunities towards innovative MOF design for improved or expanded clinical anti-cancer applications.

ZIF-8 encapsulated-enzymes integrated nanozyme cascade biocatalysis platform for the colorimetric sensing of glucose and lactose in milk

Cascade biocatalytic reactions have a wide range of applications, especially in the filed of food analysis. Herein, a multi-enzyme composite (ZGGPC) was prepared by in-situ synthesis of Zeolite imidazole framework-8 (ZIF-8) on Prussian blue (PB) modified carbon cloth (CC). The composite encapsulated both glucose oxidase and β-galactosidase simultaneously during the synthesis process. CC and ZIF-8 showed high loading capacity for PB and natural enzymes, respectively. And ZIF-8 also displayed excellent tolerance in protecting enzyme activity under extreme conditions. Based on the cascade biocatalysis, ZGGPC was used to detect glucose and lactose by colorimetric method with detection limits of 1.2 μM and 1.7 mM, respectively. Benefiting from the merits of low cost, easy preparation, and good stability, the sensing system was used to successfully determine glucose and lactose in different milk samples. The present cascade biocatalysis system is hopeful to develop simple and efficient sensing platforms for food analysis.

Phosphate Coordination to Metal-Organic Layer Secondary Building Units Prolongs Drug Retention for Synergistic Chemoradiotherapy

Chemoradiotherapy combines radiotherapy with concurrent chemotherapy to potentiate antitumor activity but exacerbates toxicities and causes debilitating side effects in cancer patients. Herein, we report the use of a nanoscale metal-organic layer (MOL) as a 2D nanoradiosensitizer and a reservoir for the slow release of chemotherapeutics to amplify the antitumor effects of radiotherapy. Coordination of phosphate-containing drugs to MOL secondary building units prolongs their intratumoral retention, allowing for continuous release of gemcitabine monophosphate (GMP) for effective localized chemotherapy. In the meantime, the MOL sensitizes cancer cells to X-ray irradiation and provides potent radiotherapeutic effects. GMP-loaded MOL (GMP/MOL) enhances cytotoxicity by 2-fold and improves radiotherapeutic effects over free GMP in vitro. In a colon cancer model, GMP/MOL retains GMP in tumors for more than four days and, when combined with low-dose radiotherapy, inhibits tumor growth by 98 %. The synergistic chemoradiotherapy enabled by GMP/MOL shows a cure rate of 50 %, improves survival, and ameliorates cancer-proliferation histological biomarkers.

GAA/(Au-Au/IrO2)@Cu(PABA) reactor with cascade catalytic activity for α-glucosidase inhibitor screening

BACKGROUND

In vitro screening strategies based on the inhibition of α-glucosidase (GAA) activity have been widely used for the discovery of potential antidiabetic drugs, but they still face some challenges, such as poor enzyme stability, non-reusability and narrow range of applicability. To overcome these limitations, an in vitro screening method based on GAA@GOx@Cu-MOF reactor was developed in our previous study. However, the method was still not satisfactory enough in terms of construction cost, pH stability, organic solvent resistance and reusability. Thence, there is still a great need for the development of in vitro screening methods with lower cost and wider applicability.

RESULTS

A colorimetric sensing strategy based on GAA/(Au-Au/IrO2)@Cu(PABA) cascade catalytic reactor, which constructed through simultaneous encapsulating Au-Au/IrO2 nanozyme with glucose oxidase-mimicking and peroxidase-mimicking activities and GAA in Cu(PABA) carrier with peroxidase-mimicking activity, was innovatively developed for in vitro screening of GAA inhibitors in this work. It was found that the reactor not only exhibited excellent thermal stability, pH stability, organic solvent resistance, room temperature storage stability, and reusability, but also possessed cascade catalytic performance, with approximately 12.36-fold increased catalytic activity compared to the free system (GAA + Au-Au/IrO2). Moreover, the in vitro GAA inhibitors screening method based on this reactor demonstrated considerable anti-interference performance and detection sensitivity, with a detection limit of 4.79 nM for acarbose. Meanwhile, the method owned good reliability and accuracy, and has been successfully applied to the in vitro screening of oleanolic acid derivatives as potential GAA inhibitors.

SIGNIFICANCE

This method not only more effectively solved the shortcomings of poor stability, narrow scope of application, and non-reusability of natural enzymes in the classical method compared with our previous work, but also broaden the application scope of Au-Au/IrO2 nanozyme with glucose oxidase and peroxidase mimicking activities, and Cu(PABA) carrier with peroxidase mimicking activity, which was expected to be a new generation candidate method for GAA inhibitor screening.

Metal-Organic Framework Based Nanozyme System for NLRP3 Inflammasome-Mediated Neuroinflammatory Regulation in Parkinson's Disease

Neuroinflammation is associated with a series of pathological symptoms in Parkinson's disease (PD), including α-synuclein aggregation and dopaminergic neuronal death. The NOD-like receptor protein 3 (NLRP3) inflammasome plays a crucial role in neuroinflammation at the lesion site and is a promising target for PD treatment. In this study, a nanoscale metal-organic framework (Zr-FeP MOF) based nanozyme is fabricated using Fe-5,10,15,20-tetra (4-carboxyphenyl) porphyrin (Fe-TCPP) and Zr6 cluster as ligands. The Zr-FeP MOF is subsequently encapsulated with mannitol (Man)-liposome, resulting in the formation of Zr-FeP MOF@Man liposome (MOF@Man Liposome) nanozyme system. The in vitro studies show that this nanozyme system is effective in relieving the formation of NLRP3 inflammasome and mitochondrial dysfunction. In mouse models of PD, the nanozyme system demonstrates a significant blood-brain barrier-crossing capability attributed to the Man-mediated brain targeting. Additionally, transcriptomic and biochemical studies show that the nanozyme system effectively inhibits the formation and assembly of inflammasome components, mitigating the activation of glial cells and neuroinflammatory response, and ultimately regulating the pathological symptoms of PD effectively.