MnO2 Research Articles

Unveiling the role of Atomic-Level “Pump-Driven” effect in MoS2/MnO2 for facilitating directional charge transfer in hybrid capacitive deionization

In addressing the limitations imposed by the inherently low electronic conductivity and substantial ion transfer resistance of transition metal oxides (TMOs) in hybrid capacitive deionization (HCDI) applications, this study delineates a pioneering approach through the fabrication of a MoS2/MnO2 heterostructure, leveraging manganese dioxide (MnO2) as a model system. The investigation underscores the essentiality of constructing high-quality interfaces to act as conduits for directional charge flow, a critical but formidable challenge for enhancing desalination efficacy in electrode materials. By harnessing an atomistic “pump-driven” mechanism, the MoS2/MnO2 heterostructure demonstrably facilitates the promotion of desalination processes, underscored by the establishment of a potent local electric field (IEF) aimed at commanding charge dynamics. Empirical and computational analyses coalesce to unveil the preferential electron transfer from MoS2 to MnO2, a phenomenon precipitated by charge redistribution. This orchestrated charge flow not only augments electronic and ionic transfer efficiencies but also emboldens the MoS2/MnO2 heterostructure with enhanced desalination capabilities. The results show that MoS2/MnO2 demonstrates superior HCDI performance compared to MnO2 in a 500 mg L-1 NaCl solution at 1.2 V, with SRC of 33.21 mg g-1 and SRR of 1.50 mg g-1 min-1. The elucidation of this charge-guided dynamic, achieved through meticulous manipulation of the electronic microstructure and the IEF at the atomic scale, presents a novel paradigm for material science. This research presents an innovative approach for realizing robust charge-guided dynamics through the deliberate manipulation of the electronic microstructure and IEF of materials, employing an atomic-level “pump-driven” effect. This strategy opens new avenues for extending these principles to a broad array of advanced materials.

Genetically engineered nanomodulators elicit potent immunity against cancer stem cells by checkpoint blockade and hypoxia relief

Rapid development of checkpoint inhibitors has provided significant breakthroughs for cancer stem cell (CSC) therapy, while the therapeutic efficacy is restricted by hypoxia-mediated tumor immune evasion, especially hypoxia-induced CD47 overexpression in CSCs. Herein, we developed a genetically engineered CSC membrane-coated hollow manganese dioxide (hMnO2@gCMs) to elicit robust antitumor immunity by blocking CD47 and alleviating hypoxia to ultimately achieve the eradication of CSCs. The hMnO2 core effectively alleviated tumor hypoxia by inducing decomposition of tumor endogenous H2O2, thus suppressing the CSCs and reducing the expression of CD47. Cooperating with hypoxia relief-induced downregulation of CD47, the overexpressed SIRPα on gCM shell efficiently blocked the CD47-SIRPα “don't eat me” pathway, synergistically eliciting robust antitumor-mediated immune responses. In a B16F10-CSC bearing melanoma mouse model, the hMnO2@gCMs showed an enhanced therapeutic effect in eradicating CSCs and inhibiting tumor growth. Our work presents a simple, safe, and robust platform for CSC eradication and cancer immunotherapy.

Assembly of manganese dioxide/polypyrrole electrode//activated carbon flexible asymmetric supercapacitor with excellent electrochemical performances

Manganese dioxide (MnO2) often suffers from a slow electron transport, and so improving the charge transport capability of MnO2 is imminent. In here, crossed MnO2 nanosheets grown on carbon cloth (CC) are fabricated firstly and subsequently coated with a layer of polypyrrole (PPy) to prepare CC/MnO2/PPy (CC/MP) electrode. At 1 A g−1, the prepared electrode is able to deliver a specific capacitance of 328 F g−1. The flexible asymmetric supercapacitor consists of CC/MP and CC/activated carbon (CC/AC) separately as positive and negative electrodes and PVA‐H2SO4 as gel electrolyte. The assembled device exhibits a specific capacitance of 123.96 F g−1 at 10 mV s−1, reaches a voltage window of 1.6 V, has a capacitance retention of 96.46% after 8000 cycles, and produces an energy density of 25.67 W h kg−1 at a power density of 401.79 W kg−1, as well as an energy density of 8.78 W h kg−1 at a power density of 3902.22 W kg−1. The two devices in series can illuminate 1.8 V red light‐emitting diode (LED) light. These excellent electrochemical properties are ascribed to the unique heterostructure of the electrode composite. The outcomes indicate that the prepared CC/MP electrode and the corresponding device have huge potential applications in next‐generation high‐performance supercapacitor devices.

A ferroptosis amplifier based on triple-enhanced lipid peroxides accumulation strategy for effective pancreatic cancer therapy

As an iron dependent regulatory cell death process driven by excessive lipid peroxides (LPO), ferroptosis is recognized as a powerful weapon for pancreatic cancer (PC) therapy. However, the tumor microenvironment (TME) with hypoxia and elevated glutathione (GSH) expression not only inhibits LPO production, but also induces glutathione peroxidase 4 (GPX4) mediated LPO clearance, which greatly compromise the therapeutic outcomes of ferroptosis. To address these issues, herein, a novel triple-enhanced ferroptosis amplifier (denoted as Zal@HM-PTBC) is rationally designed. After intravenous injection, the overexpressed H2O2/GSH in TME induces the collapse of Zal@HM-PTBC and triggers the production of oxygen and reactive oxygen species (ROS), which synergistically amplify the degree of lipid peroxidation (broaden sources). Concurrently, GSH consumption because of the degradation of the hollow manganese dioxide (HM) significantly weakens the activity of GPX4, resulting in a decrease in LPO clearance (reduce expenditure). Moreover, the loading and site-directed release of zalcitabine further promotes autophagy-dependent LPO accumulation (enhance effectiveness). Both in vitro and in vivo results validated that the ferroptosis amplifier demonstrated superior specificity and favorable therapeutic responses. Overall, this triple-enhanced LPO accumulation strategy demonstrates the ability to facilitate the efficacy of ferroptosis, injecting vigorous vitality into the treatment of PC.

Photodynamic-Controllable microneedle composite with Antibacterial, Antioxidant, and angiogenic effects to expedite infected diabetic wound healing

Effective treatment of infected diabetic wound (IDW) requires delivering therapeutic agents to both wound surface and deep layers, as well as improving the wound microenvironment through antibacterial actions, clearing excessive reactive oxygen species (ROS), and promoting vascular regeneration. Here, we present a novel inorganic nanosheet called MnO2/PDA@Cu, consisting of manganese dioxide (MnO2) with copper (Cu) ions loaded on its surface through in-situ polymerization, using polydopamine (PDA) as an intermediate. We then encapsulated the MnO2/PDA@Cu nanosheet into a methacrylated hyaluronic acid (HA) soluble microneedle patch, creating a photodynamic-controllable multifunctional MnO2/PDA@Cu-HA microneedle. We used this microneedle to treat IDWs in a rat full-thickness skin defect model. Results demonstrated that the MnO2/PDA@Cu-HA microneedle effectively delivered therapeutic agents to both wound surface and deep layers, where PDA's photodynamic therapy swiftly combated bacteria under 808 nm near-infrared irradiation. Simultaneously, MnO2 acted as a nanoenzyme, mitigating ROS levels and providing oxygen for wound healing. In addition, the photothermal effect of PDA further facilitated the release of Cu, promoting vascularization. The MnO2/PDA@Cu-HA microneedle significantly accelerated wound closure, re-epithelialization, and collagen deposition, enhancing IDW healing. In conclusion, our synthesized MnO2/PDA@Cu-HA microneedle represents a photodynamic-controllable multifunctional platform for IDW treatment, offering a promising approach for effective wound management.

High mass loading potassium ion stabilized manganese dioxide nanowire forests for rechargeable Zn batteries

Manganese dioxide (MnO2) represents an ideal cathode material for rechargeable aqueous Zn batteries due to its high theoretical capacity (308 mAh g−1), suitable potential (1.4 V vs. Zn2+/Zn), natural abundance, and negligible toxicity. However, the capacity and rate capability of MnO2 deteriorate significantly in thick electrodes owing to its low electrical and ionic conductivities. Herein, we report the design of high mass loading potassium ion stabilized α-MnO2 (K0.133MnO2) nanowire forests on carbon cloth through a seed-assisted hydrothermal method for Zn batteries. The vertically aligned K0.133MnO2 nanowire forests with uninterrupted charge transport afford a high area capacity of 3.54 mAh cm−2 and a capacity retention of 79.2% over 1000 cycles in aqueous electrolyte. Moreover, the high area capacity and cyclability can be readily transferred to quasi-solid-state devices.

The effect of copper doping in α-MnO2 as cathode material for aqueous Zinc-ion batteries

Copper-doped Manganese Dioxide has been synthesised through a simple hydrothermal method at different doping levels. The synthesised materials have been characterized by X-ray diffraction (XRD), and scanning electron microscopy (SEM) to determine the composition, structure, and morphology. All the Cu doped MnO2 are found to be single phased. Their electrochemical properties as cathode for Zinc-ion batteries are studied by cyclic voltammetry (CV), galvano-static charge / discharge (GCD) and electrochemical impedance spectroscopy (EIS), using 3 M ZnSO4 + 0.3 MnSO4 solution as the electrolyte. 3.8% Cu doped MnO2 has shown the highest initial capacity of 379.5 mAh g−1 at 0.02 A·g−1, and 304.4 mA h g−1 at 0.5 A g−1, but experienced fast fading with a poor capacity retention of 56.8% after 100 cycles. 7.4% Cu doping gives lower capacity, while 5.9% doping shows a higher discharging capacity (320.0 mAh·g−1 at 0.02 A·g−1 and 269.3 mAh·g−1 at 0.5 A·g−1) and improved stability (85.8% capacity retention after 100 cycles), better than non-doped MnO2 electrode (284.4 mAh g−1 at 0.02 A g−1 and 252.1 mAh·g−1 at 0.5 A g−1, capacity retention 76.7%). The samples show satisfactory capacity and rate capability while the cycling stability is not ideal, which may relate to the needle like morphology and nanoscale particle size. CV tests revealed that the electrochemical process is mainly diffusion controlled. The zinc ion diffusion coefficient is tested to be in the range of 10−12 cm2·s−1 from both CV and EIS tests and showed the same trend in their electrochemical capacity. Doping of Copper in MnO2 reduced the polarization on electrode, improved the electrochemical reversibility, as evidenced by the reduction of the redox peak potential difference from 0.31 to 0.24 V at 1.1 mV·s−1, and from 0.45 V to 0.31 V at 5 mV·s−1. Whilst the cell resistance of non-doped MnO2 increased from 1.78 Ω to 7.39 Ω after cycling, the cell resistances of all Cu-doped cathodes reduced, indicating improved electronic conductivities after cycling. These results indicate that Cu-doping is effective to increase the conductivity of the materials, reduce the polarization during charge and discharge, and improve the cycling stability of MnO2 cathode.

Recent development in addressing challenges and implementing strategies for manganese dioxide cathodes in aqueous zinc ion batteries

Safety issues of energy storage devices in daily life are receiving growing attention, together with resources and environmental concerns. Aqueous zinc ion batteries (AZIBs) have emerged as promising alternatives for extensive energy storage due to their ultra-high capacity, safety, and eco-friendliness. Manganese-based compounds are key to the functioning of AZIBs as the cathode materials thanks to their high operating voltage, substantial charge storage capacity, and eco-friendly characteristics. Despite these advantages, the development of high-performance Mn-based cathodes still faces the critical challenges of structural instability, manganese dissolution, and the relatively low conductivity. Primarily, the charge storage mechanism of manganese-based AZIBs is complex and subject to debate. In view of the above, this review focuses on the mostly investigated MnO2-based cathodes and comprehensively outlines the charge storage mechanisms of MnO2-based AZIBs. Current optimization strategies are systematically summarized and discussed. At last, the perspectives on elucidating advancing MnO2 cathodes are provided from the mechanistic, synthetic, and application-oriented aspects.

Ammonium Ion-Pre-Intercalated MnO2 on Carbon Cloth for High-Energy Density Asymmetric Supercapacitors.

With the continuous development of green energy, society is increasingly demanding advanced energy storage devices. Manganese-based asymmetric supercapacitors (ASCs) can deliver high energy density while possessing high power density. However, the structural instability hampers the wider application of manganese dioxide in ASCs. A novel MnO2-based electrode material was designed in this study. We synthesized a MnO2/carbon cloth electrode, CC@NMO, with NH4+ ion pre-intercalation through a one-step hydrothermal method. The pre-intercalation of NH4+ stabilizes the MnO2 interlayer structure, expanding the electrode stable working potential window to 0-1.1 V and achieving a remarkable mass specific capacitance of 181.4 F g-1. Furthermore, the ASC device fabricated using the CC@NMO electrode and activated carbon electrode exhibits excellent electrochemical properties. The CC@NMO//AC achieves a high energy density of 63.49 Wh kg-1 and a power density of 949.8 W kg-1. Even after cycling 10,000 times at 10 A g-1, the device retains 81.2% of its capacitance. This work sheds new light on manganese dioxide-based asymmetric supercapacitors and represents a significant contribution for future research on them.

A Smart Nitric Oxide (NO) Generating Immuno‐Trimetallic Nanocatalyst Triggering Chemodynamic Therapy in Breast Cancer Treatment

AbstractChemodynamic therapy (CDT) has great potential in cancer treatment, but its efficacy is limited due to non‐specificity, insufficient hydrogen peroxide (H2O2), and excessive glutathione (GSH) within the tumor microenvironment (TME). Here, an intelligent nanoplatform (Fe3O4@MnO2@NO@Au NPs, abbreviated as CD44FMNA) is reported for the treatment of breast cancer, which is constructed with Fe3O4 nanoparticles (NPs) as the core coated with manganese dioxide (MnO2) nanoshells encapsulating NO donors and gold nanoparticles (Au NPs) within the pores of MnO2, followed by the conjugation of targeting ligand anti‐CD44 mAb. The fabricated CD44FMNA initially remains inactive in normal cells, but after CD44 receptor ‐mediated MDA‐MB‐231 cell‐specific endocytosis, acidic TME can induce the decomposition of the MnO2 shell to release NO donors, thereby dually depleting the existing GSH in cells and enhancing the Fenton‐like reaction in a cascade manner. The generation of hydroxyl radicals (·OH) and the dual depletion of GSH can significantly weaken the GSH‐related antioxidant defense system (ADS) within MDA‐MB‐231 cells, accelerating apoptosis and cell death via the mitochondrial pathway. In addition, in vivo studies demonstrate that CD44FMNA can effectively inhibit tumor growth with good biosafety. Therefore, this nanoplatform may provide an effective therapy for the treatment of breast cancer.

Core@paratroopers Nanoassemblies with Catalytic Cascade for Efficient Tumor Starvation Therapy

AbstractThe catalytic therapy based on the nanozymes has received increasing interest in cancer treatment. However, the catalytic capabilities of standalone nanozymes are relatively limited, necessitating the development of a nano‐bio composite system that integrates both nanozymes and natural enzymes. This construction often inevitably leads to interference between natural enzyme and nanozymes, resulting in reduced synergistic performance. Herein, a cascade catalysis system featuring the “core@paratroopers” structure is proposed, wherein hollow manganese dioxide (HMnO2) serves as “core” and ultra‐small hybrid single‐micelle (H‐micelle) encapsulated with glucose oxidase (GOx) as “paratroopers” (H‐micelle‐GOx). The outer SiO2 layer of the H‐micelle can effectively protect the GOx. Under hypoxic conditions, HMnO2 reacts with endogenous H2O2 to produce O2, thereby enhancing the catalytic efficiency of GOx for starvation therapy. Simultaneously, the generated H2O2 boosts the catalytic efficiency of HMnO2, accelerating local O2 generation and alleviating tumor hypoxia. Additionally, this system exhibits rapid degradation in the tumor microenvironment characterized by high glutathione (GSH) expression, facilitating the release and deep penetration of the ultra‐small H‐micelle‐GOx “paratroopers” within the solid tumor.

Characterization and application of targeted MnO2/CS@ALA-MTX nano-radiosensitizers for boosting X-ray radiotherapy of brain tumors

The current study aimed to investigate the potential of methotrexate (MTX) functionalized, 5-aminolevulinic acid (5-ALA)-modified, chitosan-coated manganese dioxide (MnO2/CS) nanoparticles (NPs) as a targeted radiosensitizer for cancer therapy. The novelty of the current study lies in the development of the MnO2/CS@5-ALA-MTX NPs as a novel formulation with high encapsulation capacity, site specificity, and biosafety for targeted drug delivery. The study also emphasizes comprehensive in-vitro tests to understand the cell death mechanisms after radiosensitization. The effects of MnO2/CS@5-ALA-MTX NPs on U87MG cell lines treated with radiation were examined in-vitro and in-vivo. Mitochondrial function and reactive oxygen species (ROS) production were evaluated under normoxia and hypoxia conditions. The combination of MTX and 5-ALA provided tumor-targeting ability, while the CS coating prolonged the circulation time of the nano-system. The synthesized MnO2/CS@5-ALA-MTX NPs had an average size of 70 ± 9 nm, a Zeta potential of −6 ± 2 mV, and a polydispersity of 0.240. The loading efficiency and release profile of the drug delivery system were assessed and demonstrated its capacity for drug delivery. The MTT assay on U87MG cells revealed that MnO2/CS@5-ALA-MTX NPs reduced cell viability compared to MTX alone. Both in-vitro and in-vivo studies demonstrated tumor-enhanced radiosensitization using MTX functionalized MnO2/CS NPs. The mice receiving MnO2/CS@5-ALA-MTX NPs and subsequent radiation exposure exhibited significant tumor inhibition and increased survival ratios. Notably, tumor-bearing mice treated with MnO2/CS@5-ALA-MTX NPs and X-ray irradiation demonstrated more effective tumor rejection compared to the groups treated with X-ray alone or NPs alone. In conclusion, the results highlight the potential of MnO2/CS@5-ALA-MTX NPs as a targeted radiosensitizer for cancer therapy. The NPs exhibited promising tumor-inhibiting effects and enhanced radiosensitization both in-vitro and in-vivo, suggesting their potential as a valuable approach for cancer treatment in the future.

MnO2-based capacitive system enhances ozone inactivation of bacteria by disrupting cell membrane

The application of ozone (O3) disinfection has been hindered by its low solubility in water and the formation of disinfection by-products (DBPs). In this study, capacitive disinfection is applied as a pre-treatment for O3 oxidation, in which manganese dioxide with a rambutan-like hollow spherical structure is used as the electrode to increase the charge density on the electrode surface. When a voltage is applied, the negative-charged microbes are attracted to the electrodes and killed by electrical interactions. The contact between microbes and capacitive electrodes leads to changes in cell permeability and burst of reactive oxygen species, thereby promoting the diffusion of O3 into the cells. After O3 penetrates the cell membrane, it can directly attack the cytoplasmic constituents, accelerating fatal and irreversible damage to pathogens. As a result, the performance of the capacitance-O3 process is proved better than the direct sum of the two individual process efficiencies. The design of capacitance-O3 system is beneficial to reduce the ozone dosage and DBPs with a broader inactivation spectrum, which is conducive to the application of ozone in primary water disinfection.

3D Cryo‐Printed Hierarchical Porous Scaffolds Harmonized with Hybrid Nanozymes for Combinatorial Mitochondrial Therapy: Enhanced Diabetic Bone Regeneration via Micromilieu Remodeling

AbstractRegeneration of bone defects in diabetic patients has always been a significant challenge in clinical treatment. The pathologic diabetic micromilieu, characterized by mitochondrial dysfunction, excessive reactive oxygen species (ROS) accumulation, cellular senescence, and chronic inflammation, compromises innate bone healing capacity. 3D cryo‐printing technology is utilized in bone tissue engineering to fabricate hierarchical porous scaffolds that promote a conducive microenvironment for cellular adhesion, migration, proliferation, and nutrient exchange. Nanozymes are used as synthetic mimics of natural enzymes to scavenge ROS, addressing the limitations of natural antioxidative enzymes. To remodel the diabetic bone regeneration micromilieu, a 3D cryo‐printed polyaryletherketone with carboxyl groups (PAEK‐COOH) and 45S5 bioactive glass (BG) hierarchical porous scaffold (PBG scaffold), harmonized with hybrid nanozymes comprising SS31‐enhanced manganese dioxide (MnO2)‐ferritin biomimetic nanozyme (MF@S nanozyme), is developed for combinatorial mitochondrial therapy. The MF@S nanozyme specifically targets mitochondria to enhance mitochondrial function, scavenge ROS accumulated in mitochondria, and suppress mitochondrial ROS (mtROS) production, and thus rejuvenate aging cells, regulate macrophage polarization, and modulate differentiation of osteoblasts and osteoclasts. This 3D cryo‐printed PBG‐MF@S hierarchical porous scaffold combines with a combinatorial mitochondrial therapy system to remodel the diabetic micromilieu and presents a promising therapeutic approach for the regeneration of bone defects in diabetes.

Structural transformation investigations of δ to α manganese dioxides: Phosphate sorption and its mechanism

The elevation of environmental phosphate levels can negatively impact both the natural environment and human health. To address this issue, a series of MnO2 sorbents were investigated in this study. A facile one-pot synthesis method was employed to fabricate distinct morphologies and crystalline structures by controlling the hydrothermal duration. As the hydrothermal duration was prolonged, the samples demonstrated a pronounced enhancement of stability and crystalline phases, along with a corresponding increase in structural oxygen vacancies. A series of sorption performance tests were conducted, including pH effect, sorption isotherm, sorption kinetics, co-existing ions and sorption–desorption cycles experiments. It was revealed that manganese dissolution, the surface charge of the sorbents, and the phosphate species at different pH values collectively influenced the sorption process. The sorbent α-MnO2-120 h, with the highest oxygen vacancy ratio, exhibited the best sorption performance towards phosphate ions, with the maximum sorption capacity at pH 7. The highest removal rate and kd value were 82.63 % and 2.29 × 103 mL g−1, respectively, at the initial concentration of 30.7 mg PO4 g−1. The α-MnO2-120 h sorbent exhibited excellent selectivity in the presence of NO3−, SO42−, CO32−, and SiO32−. Furthermore, the regenerated material exhibited only a 6 % decrease in phosphate removal efficiency after five cycles, with no structural changes observed. A novel mechanism was proposed, highlighting the dominance of covalent chemical reactions in the sorption process. In particular, the participation of oxygen vacancies in sorbents contributed to enhancing the effective removal of phosphate ions. Overall, this study successfully demonstrated that synthesized α-MnO2 is a promising sorbent for phosphate removal.

Energy-efficient and advanced electrowinning of metallic manganese within a novel H+ exchange membrane cell using a Ti/IrO2−RuO2−SiO2 anode

Coated Titanium Anodes (CTAs) exhibit significant potential in addressing the high energy consumption challenge inherent in current manganese electrowinning processes. However, the electrodeposition of manganese dioxide (MnO2) at the anode limits the utilization of CTAs in conventional manganese electrolytic cells. Herein, a novel H+ exchange membrane (HEM) electrolytic cell was proposed and applied to manganese electrowinning employing Ti/IrO2 − RuO2 − SiO2 anode. The HEM electrolytic cell is a three-chamber electrolytic reactor consisting of cathode chamber, acidification chamber and anode chamber separated by woven terylene diaphragm and HEM. The results indicated that after 24 h of electrowinning, the cathodic current efficiency (CE) of 85.1 % was achieved, along with a specific energy consumption (EC) of 4189 kW·h/t. Compared to conventional industrial electrowinning technology, this represents an increase in CE by more than 15 % and a reduction in EC by over 1400 kW·h/t. The unique structure of the HEM electrolytic cell effectively prevents MnO2 deposition, ensuring the functionality of the CTAs and eliminating the generation of anode mud. Additionally, the H+ from the oxygen evolution reaction at the anode is collected and concentrated in the acidification chamber. This resulted in a spent electrolyte with 15.2 g/L H2SO4, enabling its reuse in extracting manganese ores. Employing the HEM electrolytic cell with a Ti/IrO2 − RuO2 − SiO2 anode for manganese electrowinning is therefore considered an energy-efficient and clean approach. It is highly recommended for saving energy and reducing carbon emissions in industrial processes.

Multi-Functional Nano-Doped Hollow Fiber from Microfluidics for Sensors and Micromotors.

Nano-doped hollow fiber is currently receiving extensive attention due to its multifunctionality and booming development. However, the microfluidic fabrication of nano-doped hollow fiber in a simple, smooth, stable, continuous, well-controlled manner without system blockage remains challenging. In this study, we employ a microfluidic method to fabricate nano-doped hollow fiber, which not only makes the preparation process continuous, controllable, and efficient, but also improves the dispersion uniformity of nanoparticles. Hydrogel hollow fiber doped with carbon nanotubes is fabricated and exhibits superior electrical conductivity (15.8 S m-1), strong flexibility (342.9%), and versatility as wearable sensors for monitoring human motions and collecting physiological electrical signals. Furthermore, we incorporate iron tetroxide nanoparticles into fibers to create magnetic-driven micromotors, which provide trajectory-controlled motion and the ability to move through narrow channels due to their small size. In addition, manganese dioxide nanoparticles are embedded into the fiber walls to create self-propelled micromotors. When placed in a hydrogen peroxide environment, the micromotors can reach a top speed of 615 μm s-1 and navigate hard-to-reach areas. Our nano-doped hollow fiber offers a broad range of applications in wearable electronics and self-propelled machines and creates promising opportunities for sensors and actuators.

Structural, chemical states, electrical properties and forward transport phenomena of Ti/MnO2/p-InP heterostructure with a transition metal oxide MnO2 interlayer

The study examines the surface topology, optical, structural and electrical characteristics of e-beam evaporated manganese dioxide (MnO2) films on p-InP using AFM, FESEM, UV–Vis, XRD, XPS and I–V procedures. The surface roughness of the MnO2 was smooth from AFM and FESEM analysis. The optical bandgap of MnO2 film was extracted from Tauc's plot. The outcomes endorse that the MnO2 layer deposited on InP. Then, the Ti/MnO2/p-InP heterostructure (HS) was created with an MnO2 interlayer to check the consequence of MnO2 on the electrical features of the Ti/p-InP Schottky diode (SD). The I–V results demonstrated that the higher Φb is acquired for the HS (0.90 eV) than the SD (0.84 eV), implying the MnO2 layer alters the Фb. Also, the Фb, ‘n’ and RS of the SD and HS can be determined by utilizing Cheung's and Norde's functions. The estimated Фb was almost similar, indicating the methodologies applied here are sturdy and effective. The determined NSS of the HS is lesser than the SD, implying that the MnO2 interlayer has a significant role in the decrease in NSS. The forward bias log (I)-log(V) plot of the SD and HS indicates that the ohmic behavior and space charge limited the conduction process at lower-bias and higher-bias segments, respectively. The study outcomes suggested that the transition metal oxide MnO2 layer would be favourable for creating MIS devices.

Manganese Dioxide-Based Nanomaterials for Medical Applications.

Manganese dioxide (MnO2) nanomaterials can react with trace hydrogen peroxide (H2O2) to produce paramagnetic manganese (Mn2+) and oxygen (O2), which can be used for magnetic resonance imaging and alleviate the hypoxic environment of tumors, respectively. MnO2 nanomaterials also can oxidize glutathione (GSH) to produce oxidized glutathione (GSSG) to break the balance of intracellular redox reactions. As a consequence of the sensitivity of the tumor microenvironment to MnO2-based nanomaterials, these materials can be used as multifunctional diagnostic and therapeutic platforms for tumor imaging and treatment. Importantly, when MnO2 nanomaterials are implanted along with other therapeutics, synergetic tumor therapy can be achieved. In addition to tumor treatment, MnO2-based nanomaterials display promising prospects for tissue repair, organ protection, and the treatment of other diseases. Herein, we provide a thorough review of recent progress in the use of MnO2-based nanomaterials for biomedical applications, which may be helpful for the design and clinical translation of next-generation MnO2 nanomaterials.

A facile cellulose finishing strategy through in-situ growth of sliver-doped manganese dioxide assisted by amine-quinone for improving indoor living quality

Nowadays, various harmful indoor pollutants especially including bacteria and residual formaldehyde (HCHO) seriously threaten human health and reduce the quality of public life. Herein, a universal substrate-independence finishing approach for efficiently solving these hybrid indoor threats is demonstrated, in which amine-quinone network (AQN) was employed as reduction agent to guide in-situ growth of Ag@MnO2 particles, and also acted as an adhesion interlayer to firmly anchor nanoparticles onto diverse textiles, especially for cotton fabrics. In contrast with traditional hydrothermal or calcine methods, the highly reactive AQN ensures the efficient generation of functional nanoparticles under mild conditions without any additional catalysts. During the AQN-guided reduction, the doping of Ag atoms onto cellulose fiber surface optimized the crystallinity and oxygen vacancy of MnO2, providing cotton efficient antibacterial efficiency over 90 % after 30 min of contact, companying with encouraging UV-shielding and indoor HCHO purification properties. Besides, even after 30 cycles of standard washing, the Ag@MnO2-decorated textiles can effectively degrade HCHO while well-maintaining their inherent properties. In summary, the presented AQN-mediated strategy of efficiently guiding the deposition of functional particles on fibers has broad application prospects in the green and sustainable functionalization of textiles.