Molybdenum disulfide-based materials with enzyme-like characteristics for biological applications

Recent advances in reactive oxygen species scavenging nanomaterials for wound healing

Reactive oxygen species play a crucial role in cell signaling pathways during wound healing phases. Treatment strategies to balance the redox level in the deep wound tissue are emerging for wound management. In recent years, reactive oxygen species scavenging agents including natural antioxidants, reactive oxygen species (ROS) scavenging nanozymes, and antioxidant delivery systems have been widely employed to inhibit oxidative stress and promote skin regeneration. Here, the importance of reactive oxygen species in different wound healing phases is critically analyzed. Various cutting-edge bioactive ROS nanoscavengers and antioxidant delivery platforms are discussed. This review also highlights the future directions for wound therapies via reactive oxygen species scavenging. This comprehensive review offers a map of the research on ROS scavengers with redox balancing mechanisms of action in the wound healing process, which benefits development and clinical applications of next-generation ROS scavenging-based nanomaterials in skin regeneration.

AgAu-modified quasi-MIL-53 hybrid nanozymes with triple enzyme-like activities for boosting biocatalytic disinfection

Metal-organic frameworks (MOFs) have great potential for combating pathogenic bacterial infections and are expected to become an alternative to antibiotics. However, organic linkers obstruct and saturate the inorganic nodes of MOF structures, making it challenging to utilize the applied potential of metal centers. Here, we combined controlled ligand decarboxylation with noble metal nanoparticles to rationally remodel MIL-53, resulting in a hybrid nanozyme (AgAu@QMIL-53, AAQM) with excellent multiple enzyme-like activities that both eradicate bacteria and promote diabetic wound healing. Specifically, benefitting from oxidase (OXD)-like and peroxidase (POD)-like activities, AAQM converts oxygen (O2) and hydrogen peroxide (H2O2) into superoxide anion radicals (O2-) and hydroxyl radicals (OH) to eradicate bacteria. In in vitro antibacterial experiments, AAQM exhibited favorable killing efficacy against Pseudomonas aeruginosa (P. aeruginosa) and methicillin-resistant Staphylococcus aureus (MRSA) (>99 %). Notably, due to its superoxide (SOD)-like activity and outstanding reactive nitrogen species (RNS) elimination capacity, AAQM can produce adequate O2 and alleviate oxidative stress in diabetic wounds. Benefiting from the rational modification of MIL-53, the synthesized hybrid nanozyme can effectively kill bacteria while alleviating oxidative stress and ultimately promote infected diabetic wound healing. Overall, this biomimetic enzyme-catalyzed strategy will bring enlightenment to the design of self-antibacterial agents for efficient disinfection and wound healing simultaneously.

Macrophage Membrane-Modified MoS2 Quantum Dots as a Nanodrug for Combined Multi-Targeting of Alzheimer's Disease

The complex pathological mechanism of Alzheimer's disease (AD) limits the efficacy of simple drug therapy, and drugs are difficult to penetrate the blood-brain barrier (BBB). Therefore, it is a breakthrough to enhance the therapeutic effect of AD by rationally using multiple therapeutic strategies to inhibit multiple pathological targets. In this study, macrophage membrane (MM) with active targeting inflammation function is used to functionalize molybdenum disulfide quantum dots (MoS2 QDs) with the properties of elimination of reactive oxygen species (ROS) and anti-Aβ1-42 deposition to form the nano drug (MoS2 QDs/MM), and play the role of multi-target combined therapy with NIR. The results show that MoS2 QDs/MM has a targeted therapeutic effect on ROS elimination and anti-deposition of Aβ1-42 . In addition, the combined therapy group effectively reduced Aβ1-42 mediated cytotoxicity. The modification of MM could effectively target the brain, and NIR irradiation could actively increase the cross of BBB of materials. In vivo behavioral study also show that APP/PS1 mice in the combined treatment group showed the similar exploration desire and learning ability to mice in the group of WT. MoS2 QDs/MM is an excellent nano drug with multiple effects, which has advantages in the field of neurological diseases with crisscross pathogenesis.

Nanozyme-Engineered Hydrogels for Anti-Inflammation and Skin Regeneration

Inflammatory skin disorders can cause chronic scarring and functional impairments, posing a significant burden on patients and the healthcare system. Conventional therapies, such as corticosteroids and nonsteroidal anti-inflammatory drugs, are limited in efficacy and associated with adverse effects. Recently, nanozyme (NZ)-based hydrogels have shown great promise in addressing these challenges. NZ-based hydrogels possess unique therapeutic abilities by combining the therapeutic benefits of redox nanomaterials with enzymatic activity and the water-retaining capacity of hydrogels. The multifaceted therapeutic effects of these hydrogels include scavenging reactive oxygen species and other inflammatory mediators modulating immune responses toward a pro-regenerative environment and enhancing regenerative potential by triggering cell migration and differentiation. This review highlights the current state of the art in NZ-engineered hydrogels (NZ@hydrogels) for anti-inflammatory and skin regeneration applications. It also discusses the underlying chemo-mechano-biological mechanisms behind their effectiveness. Additionally, the challenges and future directions in this ground, particularly their clinical translation, are addressed. The insights provided in this review can aid in the design and engineering of novel NZ-based hydrogels, offering new possibilities for targeted and personalized skin-care therapies.

Unveiling the antibacterial strategies and mechanisms of MoS2: a comprehensive analysis and future directions

Antibiotic resistance is a growing problem that requires alternative antibacterial agents. MoS2, a two-dimensional transition metal sulfide, has gained significant attention in recent years due to its exceptional photocatalytic performance, excellent infrared photothermal effect, and impressive antibacterial properties. This review presents a detailed analysis of the antibacterial strategies and mechanism of MoS2, starting with its morphology and synthesis methods and focusing on the different interaction stages between MoS2 and bacteria. The paper summarizes the main antibacterial mechanisms of MoS2, such as photocatalytic antibacterial, enzyme-like catalytic antibacterial, physical antibacterial, and photothermal-assisted antibacterial. It offers a comprehensive discussion focus on recent research studies of photocatalytic antibacterial mechanisms and categorizes them, guiding the application of MoS2 in the antibacterial field. Overall, the review provides an in-depth understanding of the antibacterial mechanisms of MoS2 and presents the challenges and future directions for the improvement of MoS2 in the field of high-efficiency antibacterial materials.

Oxygen-Generating Hydrogels as Oxygenation Therapy for Accelerated Chronic Wound Healing

Hypoxia in chronic wounds impairs the activities of reparative cells, resulting in tissue necrosis, bacterial infections, decreased angiogenesis, and delayed wound healing. To achieve effective oxygenation therapy and restore oxygen homeostasis, oxygen-generating hydrogels based on different oxygen sources have been developed to release dissolved oxygen in the wound bed, which not only alleviate hypoxia, but also accelerate chronic wound healing. This review first discusses the vital role of oxygen and hypoxia in the wound healing process. The advancements in oxygen-generating hydrogels, which produce oxygen through the decomposition of hydrogen peroxide, metal peroxides, glucose-activated cascade reactions, and photosynthesis of algae microorganisms for chronic wound healing, are discussed and summarized. The therapeutic effects and challenges of using oxygen-generating hydrogels for the clinical treatment of chronic wounds are concluded and prospected.

Enhancing diabetic wound healing with a pH-responsive nanozyme hydrogel featuring multi-enzyme-like activities and oxygen self-supply

Diabetic wound treating remains a challenging due to bacterial infections, oxidative stress, tissue hypoxia, and high glucose levels. Herein, a multi-enzyme-like activities nanocomposite (Mo,Fe/Cu,I-Ag@GOx) was designed and anchored to a multifunctional fluorescence hydrogel. The nanozyme gel, loaded with glucose-oxidase (GOx), exhibits intrinsic GOx, peroxidase (POD)-, oxidase (OXD)-, catalase (CAT)- and superoxide dismutase (SOD)-like activities with pH-switchable glucose-initiated cascade reaction for diabetic wound healing. In the first cascade-reaction, initiated by GOx, the nanozyme gel catalyzes glucose and O2 into gluconic acid and H2O2 to further generate superoxide anion radical (O2·-) and hydroxyl radicals (·OH) to eradicate bacteria. In the second cascade-reaction, as the wound pH changes alkalescent microenvironment, the nanozyme gel simulates SOD to transform O2·- into O2 and H2O2, and then decomposes endogenous and exogenous H2O2 into O2 via CAT-like activity to reduce oxidative stress and alleviate hypoxia. The gel by calcium ion (Ca2+) cross-linked sodium alginate (SA) and chitosan (CS) containing nanozyme was constructed with injectability, adhesion and fluorescence properties, as well as beneficial biocompatible. Importantly, the water/alcohol solubility of the nanozyme gel allows it to be used as a dressing without causing secondary injury to the wound. The multifunctional fluorescence hydrogel exhibits efficiently promote pro-angiogenesis and bacteria-infected wound healing.

Two-dimensional molybdenum disulfide nanosheets evoke nitric oxide-dependent antibacterial effects

Nanomaterials are currently being explored as novel antimicrobial agents. In this study, we first investigated the ability of two-dimensional (2D) molybdenum disulfide (MoS2) nanosheets to trigger neutrophil extracellular traps (NETs) using neutrophil-differentiated HL-60 cells as well as primary human peripheral blood neutrophils. We then addressed whether the MoS2 nanosheets themselves function as antibacterial agents. We found that MoS2 and Na2MoO4 both triggered NETs, as evidenced by the quantification of neutrophil elastase (NE) activity and immunofluorescence staining of extracellular NE, as well as scanning electron microscopy. The release of NETs was found to be nitric oxide (NO)-dependent. We also found that the MoS2 nanosheets but not the soluble salt prompted acellular NO production in the presence of NaNO2. The acellular generation of NO, suggestive of nanozyme properties of the MoS2 nanosheets, was demonstrated by electron paramagnetic resonance analysis. Electrochemical analysis using cyclic voltammetry confirmed the redox transition of the MoS2 nanosheets. Finally, MoS2 nanosheets inhibited the growth of Escherichia coli in the presence of sodium nitrate. Taken together, MoS2 nanosheets triggered cellular effects as well as acellular antibacterial effects, and we provided evidence for nitrite reductase-like properties of MoS2.

Modified TPP-MoS2 QD Blend as a Bio-Functional Model for Normalizing Microglial Dysfunction in Alzheimer's Disease

Alzheimer's disease (AD) is the most prevalent neurodegenerative disease of old age. Accumulation of β-amyloid peptide (Aβ) and mitochondrial dysfunction results in chronic microglial activation, which enhances neuroinflammation and promotes neurodegeneration. Microglia are resident macrophages of the brain and spinal cord which play an important role in maintaining brain homeostasis through a variety of phenotypes, including the pro-inflammatory phenotype and anti-inflammatory phenotypes. However, persistently activated microglial cells generate reactive species and neurotoxic mediators. Therefore, inhibitors of microglial activation are seen to have promise in AD control. The modified TPP/MoS2 QD blend is a mitochondrion-targeted nanomaterial that exhibits cytoprotective activities and antioxidant properties through scavenging free radicals. In the present study, the cell viability and cytotoxicity of the DSPE-PEG-TPP/MoS2 QD blend on microglial cells stimulated by Aβ were investigated. The levels of reactive oxygen species (ROS) and mitochondrial membrane potential (MMP) were also assessed. In addition, pro-inflammatory and anti-inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin-6 (IL-6), interleukin-1β (IL-1β), transforming growth factor beta (TGF-β), inducible nitric oxide synthase (iNOS) and arginase-1 (Arg-I) were measured in the presence or absence of the DSPE-PEG-TPP/MoS2 QD blend on an immortalized microglia cells activated by accumulation of Aβ. We found that the DSPE-PEG-TPP/MoS2 QD blend was biocompatible and nontoxic at specific concentrations. Furthermore, the modified TPP/MoS2 QD blend significantly reduced the release of free radicals and improved the mitochondrial function through the upregulation of MMP in a dose-dependent manner on microglial cells treated with Aβ. In addition, pre-treatment of microglia with the DSPE-PEG-TPP/MoS2 QD blend at concentrations of 25 and 50 μg/mL prior to Aβ stimulation significantly inhibited the release and expression of pro-inflammatory cytokines, such as IL-1β, IL-6, TNF-α, and iNOS. Nevertheless, the anti-inflammatory cytokines TGF-β and Arg-I were activated. These findings suggest that the modified TPP/MoS2 QD blend reduced oxidative stress, inflammation and improved the mitochondrial function in the immortalized microglial cells (IMG) activated by Aβ. Overall, our research shows that the DSPE-PEG-TPP/MoS2 QD blend has therapeutic promise for managing AD and can impact microglia polarization.

Inorganic nanoparticles as scaffolds for bioorthogonal catalysts

Bioorthogonal transition metal catalysts (TMCs) transform therapeutically inactive molecules (pro-drugs) into active drug compounds. Inorganic nanoscaffolds protect and solubilize catalysts while offering a flexible design space for decoration with targeting elements and stimuli-responsive activity. These "drug factories" can activate pro-drugs in situ, localizing treatment to the disease site and minimizing off-target effects. Inorganic nanoscaffolds provide structurally diverse scaffolds for encapsulating TMCs. This ability to define the catalyst environment can be employed to enhance the stability and selectivity of the TMC, providing access to enzyme-like bioorthogonal processes. The use of inorganic nanomaterials as scaffolds TMCs and the use of these bioorthogonal nanozymes in vitro and in vivo applications will be discussed in this review.

Clear-Box Machine Learning for Virtual Screening of 2D Nanozymes to Target Tumor Hydrogen Peroxide

Targeting tumor hydrogen peroxide (H₂ O₂ ) with catalytic materials has provided a novel chemotherapy strategy against solid tumors. Because numerous materials have been fabricated so far, there is an urgent need for an efficient in silico method, which can automatically screen out appropriate candidates from materials libraries for further therapeutic evaluation. In this work, adsorption-energy-based descriptors and criteria are developed for the catalase-like activities of materials surfaces. The result enables a comprehensive prediction of H₂ O₂ -targeted catalytic activities of materials by density functional theory (DFT) calculations. To expedite the prediction, machine learning models, which efficiently calculate the adsorption energies for 2D materials without DFT, are further developed. The finally obtained method takes advantage of both interpretability of physics model and high efficiency of machine learning. It provides an efficient approach for in silico screening of 2D materials toward tumor catalytic therapy, and it will greatly promote the development of catalytic nanomaterials for medical applications.

Hierarchical microtubes constructed using Fe-doped MoS2 nanosheets for biosensing applications

The structural design of multiple functional components could enhance the synergistic catalytic performance of MoS₂-based composites in enzyme-like catalysis. Herein, one-dimensional (1D) Fe-MoS₂ microtubes were designed to prepare tubular Fe-doped MoS₂ composites with MoO₃ microrods as self-sacrificing precursors. Remarkably, the results indicated that the generated ammonia released from the sulfidation process led to the dissolution of MoO₃ cores and the generation of a tubular structure. The Fe-MoS₂ composites integrated the synergistic effects of Fe-doped MoS₂ nanosheets (NSs) and the 1D tubular structure. Thus, a higher catalytic activity was observed in peroxidase-like catalysis than in other components, such as MoO₃@FeOOH, FeOOH and MoS₂ NSs. The peroxidase-like mechanism originated from the generation of the ˙OH radical. The Fe-MoS₂ microtube-based colorimetric assay was used to detect H₂O₂ with a detection limit (LOD) of 0.51 μM in a linear range from 1.25 to 50 μM. The colorimetric method was simple, selective, and sensitive for glutathione (GSH) detection in the range of 0.25-125 μM with a detection limit (LOD) of 0.12 μM. Thus, we provide a facile synthetic strategy for simultaneously integrating electronic modulation and structural design to develop an efficient MoS₂-based functional catalyst.

Nanomaterials in bioelectrochemical devices: on applications enhancing their positive effect

Electrochemical biosensors and biofuel cells are finding an ever-increasing practical application due to several advantages. Biosensors are miniature measuring devices, which can be used for on-the-spot analyses, with small assay times and sample volumes. Biofuel cells have dual benefits of environmental cleanup and electric energy generation. Application of nanomaterials in biosensor and biofuel-cell devices increases their functioning efficiency and expands spheres of use. This review discusses the potential of nanomaterials in improving the basic parameters of bioelectrochemical systems, including the sensitivity increase, detection lower-limit decrease, detection-range change, lifetime increase, substrate-specificity control. In most cases, the consideration of the role of nanomaterials links a certain type of nanomaterial with its effect on the bioelectrochemical device upon the whole. The review aims at assessing the effects of nanomaterials on particular analytical parameters of a biosensor/biofuel-cell bioelectrochemical device.

Ternary and Quaternary Nanocrystalline Cu-Based Sulfides as Perspective Antibacterial Materials Mechanochemically Synthesized in a Scalable Fashion

Twelve Cu-based ternary (Cu-Me₁-S, Me₁ = Fe, Sn, or Sb) and quaternary (Cu-Me₂-Sn-S, Me₂ = Fe, Zn, or V) nanocrystalline sulfides are shown as perspective antibacterial materials here. They were prepared from elemental precursors by a one-step solvent-free mechanochemical synthesis in a 100 g batch using scalable eccentric vibratory ball milling. Most of the products have shown strong antibacterial activity against Escherichia coli and Staphylococcus aureus bacteria. For instance, stannite Cu₂FeSnS₄ and mohite Cu₂SnS₃ were the most active against E. coli, whereas kesterite Cu₂ZnSnS₄ and rhodostannite Cu₂FeSn₃S₈ exhibited the highest antibacterial activity against S. aureus. In general, stannite has shown the best antibacterial properties out of all the studied samples. Five out of twelve products have been prepared using mechanochemical synthesis for the first time in a scalable fashion here. The presented synthetic approach is a promising alternative to traditional syntheses of nanomaterials suitable for biological applications and shows ternary and quaternary sulfides as potential candidates for the next-generation antibacterial agents.

Microporous surface containing flower-like molybdenum disulfide submicro-spheres of sulfonated polyimide with antibacterial effect and promoting bone regeneration and osteointegration

Implanted materials with both osteogenic and antibacterial functions are promising for facilitating osteointegration and preventing infection for orthopedic applications. In this work, we synthesized flower-like molybdenum disulfide (fMD) submicro-spheres containing nanosheets, which were incorporated onto the microporous surface of polyimide (PI) via concentrated sulfuric acid, suspending fMD contents of 5 wt% (SPM1) and 10 wt% (SPM2). Compared with sulfonated polyimide (SPM0), both SPM1 and SPM2 with microporous surfaces containing fMD exhibited nano-submicro-microporous surfaces, which improved the surface roughness, wettability, and surface energy. Due to there being more fMD submicro-spheres on the microporous surface, SPM2 revealed a better antibacterial effect than SPM1. In addition, compared with SPM1 and SPM0, SPM2 with more fMD significantly promoted rat bone marrow-derived stromal cell response in vitro. Moreover, SPM2 remarkably enhanced new bone formation and osteointegration in vivo. In summary, the combination of fMD with the microporous surface of SPM2 resulted in a nano-submicro-microporous surface with optimized surface performance, which possessed not only osteogenic bioactivity but also an antibacterial effect. As a bone implant, SPM2 with osteogenic and antibacterial functions may have enormous potential as a bone tissue substitute.

Nanomaterials alleviating redox stress in neurological diseases: mechanisms and applications

Overproduced reactive oxygen and reactive nitrogen species (RONS) in the brain are involved in the pathogenesis of several neurological diseases, such as Alzheimer's disease, Parkinson's disease, traumatic brain injury, and stroke, as they attack neurons and glial cells, triggering cellular redox stress. Neutralizing RONS, and, thus, alleviating redox stress, can slow down or stop the progression of neurological diseases. Currently, an increasing number of studies are applying nanomaterials (NMs) with anti-redox activity and exploring the potential mechanisms involved in redox stress-related neurological diseases. In this review, we summarize the anti-redox mechanisms of NMs, including mimicking natural oxidoreductase activity and inhibiting RONS generation at the source. In addition, we propose several strategies to enhance the anti-redox ability of NMs and highlight the challenges that need to be resolved in their application. In-depth knowledge of the mechanisms and potential application of NMs in alleviating redox stress will help in the exploration of the therapeutic potential of anti-redox stress NMs in neurological diseases.

Conducting molybdenum sulfide/graphene oxide/polyvinyl alcohol nanocomposite hydrogel for repairing spinal cord injury

A sort of composite hydrogel with good biocompatibility, suppleness, high conductivity, and anti-inflammatory activity based on polyvinyl alcohol (PVA) and molybdenum sulfide/graphene oxide (MoS₂/GO) nanomaterial has been developed for spinal cord injury (SCI) restoration. The developed (MoS₂/GO/PVA) hydrogel exhibits excellent mechanical properties, outstanding electronic conductivity, and inflammation attenuation activity. It can promote neural stem cells into neurons differentiation as well as inhibit the astrocytes development in vitro. In addition, the composite hydrogel shows a high anti-inflammatory effect. After implantation of the composite hydrogel in mice, it could activate the endogenous regeneration of the spinal cord and inhibit the activation of glial cells in the injured area, thus resulting in the recovery of locomotor function. Overall, our work provides a new sort of hydrogels for SCI reparation, which shows great promise for improving the dilemma in SCI therapy.

Recent Advances in Nanozymes for Bacteria-Infected Wound Therapy

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

Adaptive Hydrogels Based on Nanozyme with Dual-Enhanced Triple Enzyme-Like Activities for Wound Disinfection and Mimicking Antioxidant Defense System

Bacterial infection and oxidative stress are two critical problems for chronic infected wound healing. Here, molybdenum disulfide nanosheets (MoS₂ NSs) with triple enzyme-like activities are loaded onto carbon nanotubes (CNTs) and incorporated into multifunctional hydrogels aiming to eradicate bacteria and eliminate free radicals. The nanozyme activities of MoS₂ are significantly enhanced through CNTs and near-infrared irradiation. The hydrogel exhibits significant antibacterial performance attributed to the peroxidase-like activity (catalyzing hydrogen peroxide (H₂ O₂ ) into hydroxyl free radicals (•OH)) under acidic conditions, glutathione loss, and photothermal therapy. Additionally, the nanozyme can mimic the superoxide-like activity to transform the superoxide radicals (O₂ ^•- ) into H₂ O₂ and oxygen (O₂ ), then H₂ O₂ is further depleted into O₂ via the catalase-like activity, benefitting from which and •OH scavenging ability, the hydrogel shows excellent scavenging free radical ability in neutral environment and provides abundant O₂ for wound healing. The multifunctional hydrogel, crosslinked by dynamic boron ester bonds, exhibits adhesiveness, self-healing, and shape-adaptivity, which can fill the cavity of irregular wounds and promote the nanozyme to play the role with maximum efficiency. The hydrogels notably accelerate the skin reconstruction through killing bacteria, clearing ROS, promoting collagen deposition and angiogenesis.

Tribological Behavior of Novel CNTs-Based Lubricant Grease in Steady-State and Fretting Sliding Conditions

The tribological behavior of novel 7.5 wt% carbon nanotube-based lubricant greases in PAO (polyalphaolefin) oil with and without 1.0 wt% MoS2, together with several other commercial greases such as calcium, lithium, were studied. The test results showed a marked reduction of frictional coefficient achieved by the CNTs based grease samples with an average benefit of around 30% compared to conventional greases. The steady state test under 1.00 GPa average contact pressure in a mixed lubrication regime and the fretting test showed the best results in terms of friction reduction obtained by CNTs greases. Steady state tests at higher average contact pressure of 1.67 GPa proved to have a lower friction coefficient for CNTs grease containing MoS2; otherwise CNTs grease without MoS2 showed an average value of CoF comparable to calcium and lithium greases, both in a boundary and a mixed regime. The protection against wear, a considerable decrease (−60%) of reference parameter was measured with CNTs grease with MoS2 (NLGI 2) in comparison with the worst conventional grease and −22% in comparison with the best conventional grease. The data indicated that our novel carbon nanotube greases show superior tribological properties and will have promising applications in the corresponding industry.

Enzyme (Single and Multiple) and Nanozyme Biosensors: Recent Developments and Their Novel Applications in the Water-Food-Health Nexus

The use of sensors in critical areas for human development such as water, food, and health has increased in recent decades. When the sensor uses biological recognition, it is known as a biosensor. Nowadays, the development of biosensors has been increased due to the need for reliable, fast, and sensitive techniques for the detection of multiple analytes. In recent years, with the advancement in nanotechnology within biocatalysis, enzyme-based biosensors have been emerging as reliable, sensitive, and selectively tools. A wide variety of enzyme biosensors has been developed by detecting multiple analytes. In this way, together with technological advances in areas such as biotechnology and materials sciences, different modalities of biosensors have been developed, such as bi-enzymatic biosensors and nanozyme biosensors. Furthermore, the use of more than one enzyme within the same detection system leads to bi-enzymatic biosensors or multi-enzyme sensors. The development and synthesis of new materials with enzyme-like properties have been growing, giving rise to nanozymes, considered a promising tool in the biosensor field due to their multiple advantages. In this review, general views and a comparison describing the advantages and disadvantages of each enzyme-based biosensor modality, their possible trends and the principal reported applications will be presented.