MnO2 Nanoparticles Research Articles

Constructing superior rate-performance manganese-based anode for lithium-ion batteries by tuning interface effect

Interface engineering is an effective way to improve the electrochemical performance of electrode materials for LIBs. Point contact interfaces in composites are constructed by growing of Mn3O4 nanoparticles on the surface of acetylene black (AB). The prepared electrode materials exhibit excellent rate capability (355.7 mAh g−1 at 6.4 A g−1) and cycling stability (1386.7 mAh g−1 after 300 cycles at 1 A g−1). The presence of AB in the composite reduces the charge transfer resistance and improves the cycling stability of the electrode. Moreover, the interface between the composites increases the contribution of pseudocapacitance, which will facilitate the electrode kinetics. The construction of interfaces in the composites provides a promising perspective for the design of high-power density anode for LIBs. Highlights Construction of Mn3O4 nanoparticles on 0 D-AB spheres was proposed and synthesised by a facile and scalable strategy. The composite materials exhibit excellent electrochemical performance. The superior rate performance is mainly attributed to the interface effect of composite material.

Modified pine cone with MnO2 nanoparticles as a photoabsorber for highly efficient seawater desalination and wastewater treatment

Modified pine cone with MnO2 nanoparticles as a photoabsorber for highly efficient seawater desalination and wastewater treatment

Incorporation of thermally induced shaped and phases of manganese oxide nanoparticles into zein/PVA fiber blends

Incorporation of nanomaterials into polymers and their blend provide additional advantages to their use and structural support. Metals such as Ag, Cu, Ti, and Fe are often reported in their metallic or their oxide forms for applications in microbiological, water treatment, and biomedical fields. The integration of metal oxide nanoparticles into polymer fiber blends overcomes the mechanical instability and compatibility challenges of nanomaterials. Manganese-based oxides provide good stability and optical properties in their nanoscale useful in polymeric composite or fiber materials enhancement. MnO2 and Mn2O3 nanoparticles were synthesized at different calcination temperatures using the co-precipitation method and characterized a microscopic technique TEM, and TGA. TEM images and the XRD patterns confirmed that the manganese oxide nanoparticle were spheres and rod-shaped with corresponding cryptomelane and orthorhombic crystalline phases. Mn2O3 nanoparticles were successfully integrated into zein/PVA (80/20) fiber blends. SEM images confirmed that the inclusion of the nanoparticles into zein/PVA solutions increased the conductivity of the solutions which led to an improved morphology and increased surface area to volume ratio. XRD patterns and TGA showed that the incorporated nanoparticles were below the detection limit, therefore there was no significant change observed. Therefore, all characterization techniques illustrated that the effect of concentration significantly enhanced the morphology of the fiber blends.

Catechol-Modified and MnO2-Nanozyme-Reinforced Hydrogel with Improved Antioxidant and Antibacterial Capacity for Periodontitis Treatment.

Periodontitis is an inflammatory disease characterized by tooth loss and alveolar bone resorption. Bacteria are the original cause of periodontitis, and excess reactive oxygen species (ROS) encourage and intensify inflammation. In this study, a mussel-inspired and MnO2 NPs-reinforced adhesive hydrogel capable of alleviating periodontitis with improved antibacterial and antioxidant abilities was developed. The hydrogel was created by combining polyvinyl alcohol (PVA), 3,4-dihydroxy-d-phenylalanine (DOPA), and MnO2 nanoparticles (NPs) (named PDMO hydrogel). The hydrogel was demonstrated to be able to scavenge various free radicals (including total ROS─O2•- and OH•) and relieve the hypoxia in an inflammatory microenvironment by scavenging excess ROS and generating O2 due to its superoxide dismutase (SOD)/catalase (CAT)-like activity. Besides, under 808 nm near-infrared (NIR) light, the photothermal performance of the PDMO hydrogel displayed favorable antibacterial and antibiofilm effects toward Escherichia coli, Staphylococcus aureus, and Porphyromonas gingivalis (up to nearly 100% antibacterial rate). Furthermore, the PDMO hydrogel exhibited favorable therapeutic efficacy in alleviating gingivitis in Sprague-Dawley rats, even comparable to or better than the commercial PERIO. In addition, in the periodontitis models, the PDMO2 group showed the height of the residual alveolar bone and the smallest shadow area of low density among other groups, indicating the positive role of the PDMO2 hydrogel in bone regeneration. Finally, the biosafety of the PDMO hydrogel was comprehensively investigated, and the hydrogel was demonstrated to have good biocompatibility. Therefore, the developed PDMO hydrogel provided an effective solution to resolve biofilm recolonization and oxidative stress in periodontitis and could be a superior candidate for local drug delivery system in the clinical management of periodontitis with great potential for future clinical translation.

Bioinspired palladium-doped manganese oxide nanocorns: a remarkable antimicrobial agent targeting phyto/animal pathogens

Microbial pathogens are known for causing great environmental stress, owing to which emerging challenges like lack of eco-friendly remediation measures, development of drug-resistant and mutational microbial strains, etc., warrants novel and green routes as a stepping stone to serve such concerns sustainably. In the present study, palladium (Pd) doped manganese (II, III) oxide (Mn3O4) nanoparticles (NPs) were synthesized using an aqueous Syzygium aromaticum bud (ASAB) extract. Preliminary phytochemical analysis of ASAB extract indicates the presence of polyphenolics such as phenols, alkaloids, and flavonoids that can act as potential capping agents in NPs synthesis, which was later confirmed in FTIR analysis of pure and Pd-doped Mn3O4 NPs. XRD, Raman, and XPS analyses confirmed the Pd doping in Mn3O4 NPs. FESEM and HRTEM study reveals the mixed morphologies dominated by nanocorns appearance. Zeta potential investigation reveals high stability of the synthesized NPs in colloidal solutions. The developed Pd-doped Mn3O4 NPs were tested against two fungal phytopathogens, i.e., Sclerotinia sclerotiorum and Colletotrichum gloeosporioides, known for causing great economic losses in yield and quality of different plant species. The antifungal activity of synthesized Pd‐doped Mn3O4 NPs displayed a dose‐dependent response with a maximum of ~92%, and ~72% inhibition was recorded against S. sclerotiorum and C. gloeosporioides, respectively, at 1000 ppm concentration. However, C. gloeosporioides demonstrated higher sensitivity to Pd‐doped Mn3O4 NPs upto 500 ppm) treatment than S. sclerotiorum. The prepared NPs also showed significant antibacterial activity against Enterococcus faecalis. The Pd-doped Mn3O4 NPs were effective even at low treatment doses, i.e., 50–100 ppm, with the highest Zone of inhibition obtained at 1000 ppm concentration. Our findings provide a novel, eco-benign, and cost-effective approach for formulating a nanomaterial composition offering multifaceted utilities as an effective antimicrobial agent.

(Invited) Reduced Graphene Oxide Complexed to MnO2 Nanoparticles as Efficient Platform for Photothermal and Chemodynamic Combined Therapy

The intracellular cascade reactions triggered by nanomateraials are emerging as promising strategies to treat cancer more efficiently, by exploting the specific tumour microenvironment [1]. One of the mechanisms of cell ablation is based on depletion of glutathione (GSH) and generation of reactive oxygen species (ROS). We recently exploited reduced graphene oxide (rGO), one of the most popular form of graphene, in combination with manganese dioxide nanoparticles (MnO2 NPs) to design a multifunctional nanoplatform (rGO@MnO2) for efficient photothermal/chemodynamic combined therapies. Manganese-based NPs were bound onto the surface of rGO nanosheets (rGO NSs). These NPs are able to oxidize intracellular GSH, generating Mn2+ ions that convert H2O2 into hydroxyl radicals by Fenton reaction. In addition, rGO NSs mediated photothermal therapy (PTT) enhance the mortality of cancer cells. The high temperature caused by photothermal conversion increases the Fenton reaction rate, which enhances the efficiency of MnO2 NPs mediated chemodynamic therapy (CDT). Such type of hybrid materials has great potential in cancer therapy by exploiting the synergistic effect of PTT and CDT.[1] Ma, B.; Guo, S.; Nishina, Y.; Bianco, A. Reaction between Graphene Oxide and Intracellular Glutathione Affects Cell Viability and Proliferation. ACS Appl. Mater. Interfaces 2021, 13, 3528-3535. DOI:10.1021/acsami.0c17523[2] Ma, B.; Nishina, Y.; Bianco, A. A glutathione responsive nanoplatform made of reduced graphene oxide and MnO2 nanoparticles for photothermal and chemodynamic combined therapy. Carbon 2021, 178, 783-791. DOI:10.1016/j.carbon.2021.03.065

Superhydrophobic Photocatalytic Self‐Cleaning Nanocellulose‐Based Strain Sensor for Full‐Range Human Motion Monitoring

AbstractNanocellulose‐based strain sensor (NBSS) have been a subject of growing interest for wearable electronics. However, these electronic devices are susceptible to damage when they come into contact with water and organic contaminants. Recently, researchers have developed a superhydrophobic NBSS. Unfortunately, it does not treat organic pollutants in water when used in an underwater environment. In this paper, a new solution: a superhydrophobic photocatalytic self‐cleaning NBSS created through scrape coating and dip coating methods is proposed. This new method shows outstanding self‐cleaning capabilities against water and organic contaminants due to the synergistic effects of the superhydrophobicity and photocatalysis of MnO2 nanoparticles. Furthermore, the superhydrophobic photocatalytic self‐cleaning NBSS has an exceptional response time of 0.66 s, a fast recovery time of 0.81 s, a sensitivity ≈66.53 at a strain of 0.5%. It is expect that the superhydrophobic photocatalytic self‐cleaning NBSS can monitor human movements, including finger twists, wrist movements, elbow bends, and knee movements. Not only is the fabrication method cost‐effective and scalable, but the new NBSS holds great promise in a wide range of fields, including human‐machine interactive systems, smart systems, and human‐body monitoring. Overall, the study provides significant guidance for future designs for wearable strain sensors.

Improved Ethanol Sensing Performance of α-MnO2 Nanorods at Room Temperature Enabled through PPy Embedding.

Ethanol is a colorless, highly flammable, volatile organic compound and is a biomarker for fatty liver diseases. So, high-performance and reliable ethanol sensors are the need of the day for biomedical and environmental monitoring applications and drunken driving detection. In this work, we have reported a polypyrrole (PPy)-embedded α-MnO2 nanorod (NR)-based chemiresistive sensor for the selective detection of trace ethanol vapor at room temperature (25 °C). PPy-embedded α-MnO2 NR nanocomposites (MP25, MP50, and MP100) were synthesized by in situ chemical oxidative polymerization of pyrrole followed by mixing of α-MnO2 NR having different weight ratios. The prepared nanocomposites were characterized by various sophisticated instruments such as XRD, FTIR, Raman spectroscopy, BET, FESEM, TEM, EDX, UV-vis spectroscopy, and current-voltage (I-V) measurement. The as-prepared sensor, namely, PPy-embedded α-MnO2 nanorod (MP50), shows the highest response to ethanol vapor with a detection lower limit of 1 ppm at room temperature with rapid response (∼2.39 s) and recovery (∼37.08 s) times associated with at least 60 days stability, excellent selectivity, good repeatability, and reproducibility. The formation of a p-n heterojunction and transfer of charge carriers between PPy and MnO2 nanoparticles are attributed to the enhancement of sensing performance. Thus, the prepared sensor could be potentially applicable to detect ethanol content in alcoholic beverages, diagnose liver disease from exhale breath analysis, and drunken driving detection.

MnO2 nanoparticles and MnSO4 differentially affected hepatic lipid metabolism through miR-92a/acsl3-dependent de novo lipogenesis in yellow catfish Pelteobagrusfulvidraco

With the increasing production and use of MnO2 NPs and MnSO4 in various fields, their discharge into the aquatic environment is inevitable, which poses potential threats to aquatic organisms and humans. However, to date, few studies have been conducted to investigate the potential mechanism of the toxicity of MnO2 NPs, and a comprehensive understanding of the differences between this mechanism and the toxicity mechanism of inorganic Mn (MnSO4) is still lacking. Since lipid metabolism-relevant parameters have been widely recognized as novel biomarkers for risk assessment of environmental contaminants, the present study investigated the differential mechanisms of how MnO2 NPs and MnSO4 affect hepatic lipid metabolism in a freshwater fish yellow catfish. Compared to MnSO4, dietary MnO2 NPs caused liver injury, increased hepatic lipid accumulation and induced lipotoxicity, and up-regulated mRNA expression of de novo lipogenic genes. Moreover, MnO2 NPs downregulated the expression of miR-92a and miR-92b-3p, microRNAs involved in regulation of lipid metabolism, in the liver. Mechanistically, we found that acls3, an acetyl-coenzyme A synthetase, is target gene of miR-92a, and miR-92a-acsl3-dependent de novo lipogenesis contributes to lipid accumulation and lipotoxicity induced by MnO2 NPs. Collectively, these findings provided novel insights into mechanism whereby miRNAs mediate nanoparticles- and inorganic Mn-induced hepatic lipotoxicity and changes of lipid metabolism in vertebrates. Our findings also shed new perspective for ecotoxicity and ecological risk of MnO2 NPs and MnSO4 in aquatic environment.

Facile Synthesis of Ultrafine and Highly Dispersible MnO2 Nanoparticles for Energy Storage in Supercapacitors

AbstractManganese dioxide (MnO2) has been extensively investigated as an electrode material for supercapacitors because of its high theoretical capacitance, great abundance, and low toxicity. To obtain satisfactory capacitance performance, in recent years, many efforts have been dedicated to the fabrication of MnO2 nanoparticles that offer a larger specific surface area and an escalated chemical activity. Beyond them, the ideal dispersibility of nanoparticles in a liquid medium is also of vital importance when processing those powdery materials into slurry ones for some particular uses, such as editable and ink‐printing supercapacitor devices. In this study, the as‐synthesized ultrafine MnO2 nanoparticles having excellent dispersibility in water can be prepared via a facile one‐step hydrothermal route, with a uniform size in diameter of 200 nm exhibiting a large specific surface area of ~389.7 m2 g−1, and a high specific capacitance of 135.7 F g−1 at 5 mV s−1.

Mesoporous Nanosized Manganese Dioxides for Efficient Toluene Oxidation

An efficient approach to synthetize the sandwich-like graphene-supported manganese oxides nanosheets (G-MnO[Formula: see text] had been developed for catalytic combustion of toluene by employing sandwich-like graphene-silica nanosheets (G-silica) as intermediates. The as-prepared G-MnO2 not only inherited the two-dimensional structure of reduced graphene, high specific surface areas, the unique mesoporous structure, good dispersion, but also possessed numerous nanoparticles of crystalline MnO2 with the size of about 5[Formula: see text]nm on each nanosheet. Such unique features had enhanced significantly the catalytic performance and catalytic stability of MnO2 for toluene oxidation. As a consequence, with the help of sandwich-like G-silica intermediates, the T[Formula: see text] and T[Formula: see text] of G-MnO2 for toluene was 240[Formula: see text]C (3.92[Formula: see text][Formula: see text][Formula: see text]mol [Formula: see text]g[Formula: see text][Formula: see text]h[Formula: see text] and 262[Formula: see text]C (7.06[Formula: see text][Formula: see text][Formula: see text]h[Formula: see text] respectively, and even after 30[Formula: see text]h at 288[Formula: see text]C, the conversion of toluene could still be maintained at 99.7% (GHSV[Formula: see text]60[Formula: see text]000[Formula: see text]mL[Formula: see text]g[Formula: see text][Formula: see text]h[Formula: see text].

MnO2 nanoparticles decorated with Ag/Au nanotags for label-based SERS determination of cellular glutathione.

Anovel stimulus-responsive surface-enhanced Raman scattering (SERS) nanoprobe has been developed for sensitive glutathione (GSH) detection based on manganese dioxide (MnO2) core and silver/gold nanoparticles (Ag/Au NPs). TheMnO2 core isnot only capable to actas a scaffold to amplify the SERS signal via producing "hot spots",but also can be degraded in the presence of thetarget and thus greatly enhance the nanoprobe sensitivity for sensing of GSH. This approach enables a wide linear range from 1 to 100µM with a 2.95µM (3σ/m) detection limit. Moreover, the developed SERS nanoprobe represents great possibility in both sensitive detection of intracellular GSH and even can monitor the change of intracellular GSH level when the stimulant occurs. This sensing system not merely offers a novel strategy for sensitive sensing of GSH, but also provides a new avenue for other biomolecules detection.

Green synthesis of Plectranthus amboinicus leaf extract incorporated fine-tuned manganese dioxide nanoparticles: Antimicrobial and antioxidant activity

Plectranthus amboinicus Manganese dioxide (PA-MnO2) nanoparticles were synthesized by the reduction of potassium permanganate (KMnO4) using Plectranthus amboinicus (P. amboinicus) leaf extract at room temperature. A dark brown colour appeared after the addition of leaf extract to the solution of KMnO4. PA-MnO2 nanoparticles showed absorbance maximum at 324 nm. Scanning Electron Microscopy (SEM) study of particle size and morphology revealed that PA-MnO2 nanoparticles have spherical structures in shape. The electron dispersive X-ray spectroscopy confirmed the presence of Mn and O in the sample. Fourier Transforms infrared spectra of PA-MnO2 nanoparticles show the occurrence of O-Mn-O vibrational mode at around 515 cm-1. Based on the spectral and morphological data confirms the prepared compounds are nanometer in size. The structural investigation of MnO2 nanoparticles using the powder X-ray diffraction method reveals that the nanoparticles have a tetragonal configuration. Powder X-ray diffraction measurements were used to estimate crystallite grain diameter. The size of the crystalline grains is 7.5 nm. The PA-MnO2 nanoparticles demonstrated enhanced antibacterial activity against various gram positive bacteria like as S. aureus, S. pneumoniae, Stap. Pneumoniae and B. subtilis and various gram negative bacterial strains like as E. coli, K. pneumoniae, p. mirabilis and P. aeruginosa than standard drug ciprofloxacin. Antifungal activity of PA-MnO2 nanoparticles exhibited abnormal character against various fungal strains such as A. niger, C. albicans, C. tropicalis and M. campestris than the standard drug nystatin. Free radical scavenging study by DPPH assay showed enhanced activity by increasing the concentration of PA-MnO2. This study shows simple and eco-friendly synthesis of PA-MnO2 nanoparticles by plant extract. PA-MnO2 nanoparticles by green approach have potential to resolve emerging drug resistance against pathogenic diseases.

Tumor microenvironment-responsive delivery nanosystems reverse immunosuppression for enhanced CO gas/immunotherapy.

Carbon monoxide (CO) gas therapy demonstrates great potential to induce cancer cell apoptosis and antitumor immune responses, which exhibits tremendous potential in cancer treatment. However, the therapeutic efficacy of CO therapy is inhibited by the immunosuppressive tumor microenvironment (TME). Herein, a facile strategy is proposed to construct hollow-structured rough nanoplatforms to boost antitumor immunity and simultaneously reverse immunosuppression by exploring intrinsic immunomodulatory properties and morphological optimization of nanomaterials. The TME-responsive delivery nanosystems (M-RMH) are developed by encapsulating the CO prodrug within hollow rough MnO2 nanoparticles and the subsequent surface functionalization with hyaluronic acid (HA). Rough surfaces are designed to facilitate the intrinsic properties of HA-functionalized MnO2 nanoparticles (RMH) to induce dendritic cell maturation and M1 macrophage polarization by STING pathway activation and hypoxia alleviation through enhanced cellular uptake. After TME-responsive degradation of RMH, controlled release of CO is triggered at the tumor site for CO therapy to activate antitumor immunity. More importantly, RMH could modulate immunosuppressive TME by hypoxia alleviation. After the combination with aPD-L1-mediated checkpoint blockade therapy, robust antitumor immune responses are found to inhibit both primary and distant tumors. This work provides a facile strategy to construct superior delivery nanosystems for enhanced CO/immunotherapy through efficient activation of antitumor immune responses and reversal of immunosuppression.

A Versatile Glycopeptide Hydrogel Promotes Chronic Refractory Wound Healing Through Bacterial Elimination, Sustained Oxygenation, Immunoregulation, and Neovascularization

AbstractChronic refractory wounds have become a severe threat to public health and are characterized by repeated bacterial infections, persistent hypoxia, abnormal immune regulation, and obstruction of angiogenesis. However, current treatment strategies usually perform only one or two therapeutic functions and cannot satisfy the dynamic and complex demands of chronic wound healing. Herein, a versatile dynamic Schiff base and borate ester cross‐linked glycopeptide hydrogel is prepared from phenylboronic acid‐grafted ε‐polylysine (EPBA), epigallocatechin‐3‐gallate (EGCG), and oxidized alginate. Customized polydopamine‐coated honeycomb MnO2 nanoparticles loaded with herb‐derived salvianolic acid B (PHMS) are embedded into the hydrogel before gelation. Under the distinct acidic and oxidative microenvironment of chronic refractory wounds, the hydrogel gradually dissociates, and the released EPBA effectively eliminates bacteria, while the released EGCG and PHMS eradicates reactive oxygen and nitrogen species, promotes M2 polarization of macrophages, and continuously generates oxygen. Then PHMS further disintegrates, and the released salvianolic acid B promotes angiogenesis through the PI3K/Akt pathway. The versatile glycopeptide hydrogel accelerates Staphylococcus aureus‐infected diabetic cutaneous wound repair in vivo and is a promising candidate dressing for chronic refractory wound healing.

Facile synthesis of 2D/0D Bi2O3/MnO2 Z-scheme heterojunction for enhanced visible light-assisted photocatalytic degradation of acetaminophen

The construction of heterojunctions is a prominent strategy for improving the photocatalytic activity of semiconductor nanoparticles. In this study, a novel visible-light-driven 2D/0D Bi2O3/MnO2 (BMO) Z-scheme heterojunction was fabricated through a facile room-temperature solution-phase synthesis scheme to achieve enhanced photocatalytic degradation of acetaminophen (ACT). The BMO nanocomposite achieved 94.3% degradation efficiency at 0.0202 min−1 in 120 min, approximately 3.5 and 3.8 times higher than the degradation rate of the individual MnO2 and Bi2O3 photocatalysts, respectively. Based on electron paramagnetic resonance spectra and Mott-Schottky measurements, a Z-scheme heterojunction appeared between the Bi2O3 nanoflakes and MnO2 nanoparticles. The effective charge separation and electron transfer efficiency due to Z-scheme heterojunction and a narrow band gap of 2.10 eV were responsible for the enhanced photocatalytic performance. Further, the intermediates and end products of ACT degradation were identified, and plausible degradation pathways were established. Additionally, the performance of BMO in various real water matrices was evaluated. The degradation efficiency was highest in deionized water, followed by tap water, municipal, hospital, and pharmaceutical industry wastewater. Eventually, a mathematical model based on an artificial neural network has been developed to predict the photocatalytic process. Besides, the excellent photocatalytic performance of the BMO nanocomposite remained intact even after five consecutive cycles. The results of this study elicit crucial insights into synthesizing highly efficient and stable Z-scheme heterojunction photocatalysts to degrade emerging contaminants.

Construction of MoS2/TMO/GO nanocomposites for enhancing the thermal decomposition of AP and the combustion of AP/HTPB composite propellant

The novel MoS2/TMO/GO (MTG) nanocomposites (TMO = Co3O4, MnO2, CuO) were constructed by a two stage layer adding method. The characterization results proved that TMO nanoparticles were successfully loaded on the nanosheets composed by GO and MoS2. Especially after loading MnO2 nanoparticles, MTG-Mn nanocomposite exhibited a three-dimension network structure with a higher surface area (152.8 m2·g−1) and plenty of mesopore channels. For the thermal decomposition of ammonium perchlorate (AP), MTG-Co (2.0 wt%), MTG-Mn (2.0 wt%) and MTG-Cu (2.0 wt%) could highly decrease decomposition temperature by about 87.1 °C, 104.8 °C and 84.4 °C, respectively. Among the as-prepared catalysts, MTG-Mn could also enhance heat release of AP to 1592.8 J‧g−1, indicating the good catalytic activity of MTGMn. Under the action of MTG-Mn (2.0 wt%), Ea was highly decreased by about 123.8 kJ·mol−1 and the decomposition rate k increased by 228.9%. The ignition delay time of AP/HTPB propellant after adding MTG-Mn was shortened by 70.5% and the mass burning rate increased by 206.8%. These superior properties mainly come from the synergism of multi-components in MTG-Mn and make it act as a potential catalyst for improving the combustion property of AP-based propellants.

Three-Dimensional Nanoporous CNT@Mn3O4 Hybrid Anode: High Pseudocapacitive Contribution and Superior Lithium Storage

A composite electrode of carbon nanotube CNT@Mn3O4 nanocable was successfully synthesized via direct electrophoretic deposition onto a copper foil, followed by calcination. By uniformly depositing Mn3O4 nanoparticles on CNTs, a nanocable structure of CNT@Mn3O4 can be formed, where the CNT acts as a “highway” for electrons and ions to facilitate fast transportation. Moreover, capacitive energy storage processes play a crucial role in lithium (Li) storage, especially during high scan rates. The significant contribution of capacitance is highly advantageous for the rapid transfer of Li+ ions, which ultimately results in an improved reversible capacity and prolonged cycle stability of the battery. A high specific capacity of 1367 mAh g−1 was maintained over 300 charge–discharge cycles at a current density of 1 A g−1, indicating excellent capacity retention and an extended cycle life. Furthermore, the synthesis process was facile and cost-effective, obviating the need for complex procedures such as mixing and pasting. Additionally, no binder was required, thereby enhancing battery quality efficiency.

Preparation of a Novel Formaldehyde-Free Impregnated Decorative Paper Containing MnO2 Nanoparticles for Highly Efficient Formaldehyde Removal.

The loading of catalytic manganese dioxide (MnO2) nanoparticles onto an impregnated decorative paper has been an effective method for the removal of indoor formaldehyde (HCHO) pollutants. However, its preparation can present numerous challenges, including instability in dipping emulsions and leaching. In this investigation, a novel and stable formaldehyde-free polyacrylate dipping emulsion containing MnO2 particles was prepared and then back-coated on a decorative paper. To improve the dispersion and fixation, the MnO2 was modified with silane. HCHO can undergo physical adsorption on the cellulosic fibers present in the paper, while it can also undergo chemical degradation into CO2 within the MnO2 groups. The silane not only enhanced the interfacial adhesion to a polyacrylate resin but also increased the interlayer distance, thereby creating a larger space for HCHO absorption. The impregnated decorative paper back-coated with 10 wt % of silane-modified MnO2 exhibited a removal efficiency of approximately 90% for HCHO at 20 °C. The removal rate further improved to approximately 100% when the temperature was increased to 60 °C. Moreover, it is worth noting that the release of volatile organic compounds was exceptionally minimal. Additionally, the particleboard bonded with this impregnated decorative paper exhibited an extremely low emission of HCHO, with a value that approached 0 mg·L-1. Furthermore, the bonding strength of the surface remained unaffected. Therefore, this study provides a simple and eco-friendly method for effectively removing HCHO, which can enhance indoor air quality.

Exosome membrane-sheathed and multi-stimuli-responsive MnO2 nanoparticles with self-oxygenation and energy depletion abilities potentiate the sonodynamic therapy of hypoxic tumors

Sonodynamic therapy (SDT), which employs ultrasound (US) to activate sonosensitizers to generate reactive oxygen species (ROS), has emerged as an effective approach for treating deep-seated tumors. However, poor biocompatibility of sonosensitizers and hypoxic tumor microenvironments are significant challenges for in vivo SDT. Herein, hollow manganese dioxide nanoparticles (MnO2 NPs) encapsulating the sonosensitizer, indocyanine green (ICG), were developed for enhanced sonodynamic cancer therapy by high ICG loading and tumor hypoxia relief. A glycolysis inhibitor, FX11, was co-loaded into MnO2 NPs to boost SDT efficacy via FX11-induced energy depletion. Because of the high biocompatibility, low immunogenicity, and efficient intracellular delivery of exosomes, ICG- and FX11-loaded MnO2 NP [M(ICG/FX11)] was coated with exosome membranes for safe and efficient in vivo SDT. The exosome membrane-coated M(ICG/FX11) [Exo-M(ICG/FX11)] exhibited triple pH/H2O2/US-responsive drug release while avoiding premature drug leakage. Exo-M(ICG/FX11) was efficiently internalized by MCF-7 human breast cancer cells and catalyzed the endogenous H2O2 to generate O2 to relieve tumor hypoxia. Consequently, Exo-M(ICG/FX11) markedly boosted intracellular ROS levels upon US irradiation. Moreover, Exo-M(ICG/FX11) effectively inhibited glycolytic pathways, thereby potentiating the anticancer efficacy of SDT. An in vivo study using tumor-xenografted mice demonstrated that Exo-M(ICG/FX11) effectively accumulated in tumors and alleviated tumor hypoxia. Notably, Exo-M(ICG/FX11) combined with US substantially suppressed tumors in mice without causing systemic toxicity, owing to the synergistic effect of O2 supplied-SDT and energy-depleting chemotherapy. This study demonstrates that biomimetic Exo-M(ICG/FX11) is a safe and efficient nanoplatform for the treatment of hypoxic tumors.