MnO2 Research Articles

A nano drug delivery system loading drugs and chlorin e6 separately to achieve photodynamic-chemo combination therapy.

To develop a new drug delivery system (DDS) that can load chemotherapy agents and photosensitizer chlorin e6 (Ce6) onto the pores and surfaces of mesoporous silica nanoparticle (MSN) separately. Doxorubicin (DOX) was loaded into the pores of MSNs. Then, polyethyleneimine (PEI) was used to coat the surface of MSN to protect DOX, and then manganese dioxide (MnO2) nanoparticles were loaded through adding potassium permanganate (KMnO4) to bind with Ce6. Finally, polydopamine (PDA) was coated and coupled with hyaluronic acid (HA). The synthesized versatile nanoparticle was pH-sensitive and exhibited positive photodynamic therapy (PDT) performance. Besides, it could be observed that the nanoparticles were efficiently taken up by tumor cells through confocal laser scanning microscopy (CLSM) and flow cytometry. Additionally, in vitro experiments suggested that the nanoparticles had pleasing toxicity to various tumor cells and equally positive therapeutic effect when curcumin replaced DOX. Our work suggests that the nanoparticles designed by our strategy have satisfactory combination therapy performance and can enable more chemotherapy drugs to be used in photodynamic-chemo combination therapy.

One-step depositing method of PAni/MnO2 composites for enhanced supercapacitor performance.

Manganese dioxide (MnO2) is extensively used in supercapacitors, but its poor conductivity and low power density limit its applications. This study employed a one-step electrochemical deposition method to fabricate a polyaniline (PAni)/MnO2/carbon cloth (CC) composite electrode, which was assembled into flexible supercapacitors. Optimal process parameters were determined through exploring the effect of deposition durations on the electrochemical performance. With optimized synergistic effects between the components, the PAni/MnO2@CC composite electrode exhibits high specific capacitance of 1,694.25 mF cm-2 at 1 mA cm-2, which is remarkably better than that of PAni@CC, MnO2@CC, and other reported PAni-based electrodes. The assembled supercapacitor displays high energy density, superior bending performance, and good cycle stability. This easy-to-prepare composite electrode, with excellent energy storage capability, offers significant potential for flexible energy storage devices.

3D-printed manganese dioxide incorporated scaffold promotes osteogenic-angiogenic coupling for refractory bone defect by remodeling osteo-regenerative microenvironment

The treatment of refractory bone defects is a major clinical challenge, especially in steroid-associated osteonecrosis (SAON), which is characterized by insufficient osteogenesis and angiogenesis. Herin, a microenvironment responsiveness scaffold composed of poly-L-lactide (PLLA), and manganese dioxide (MnO2) nanoparticles is designed to enhance bone regeneration by scavenging endogenous reactive oxygen species (ROS) and modulating immune microenvironment in situ. A catalase-like catalytic reaction between MnO2 and endogenous hydrogen peroxide (H2O2) generated at the bone defect area, which typically becomes acidic and ROS-rich, triggers on-demand release of oxygen and Mn2+, significantly ameliorating inflammatory response by promoting M2-type polarization of macrophages, reprograming osteoimmune microenvironment conducive to angiogenesis and osteogenesis. Furthermore, the fundamental mechanisms were explored through transcriptome sequencing analysis, revealing that PLLA/MnO2 scaffolds (PMns) promote osteogenic differentiation by upregulating the TGF-β/Smad signaling pathway in human bone marrow mesenchymal stem cells (hBMSCs). Overall, the PMns exhibit superior immunomodulatory, excellent osteogenic-angiogenic properties and promising candidates as bone graft substitutes for therapy clinical refractory bone defects.

A Dual-Pipeline Lactate Removal Strategy to Reverse Vascular Hyperpermeability for the Management of Lipopolysaccharide-Induced Sepsis.

Sepsis is an underappreciated yet severe threat to human life, marked by organ dysfunction and high mortality resulting from disordered inflammatory responses to blood infection. Unfortunately, no specific drugs are available for effective sepsis treatment. As a pivotal biomarker for sepsis, lactate levels are closely related to vascular permeability and sepsis-associated mortality. Herein, a dual-pipeline lactate removal strategy is reported from circulating blood to ameliorate vascular permeability and lipopolysaccharide (LPS)-induced sepsis. This is achieved by formulating lactate oxidase (LOX)-encapsulated hollow manganese dioxide (HMnO2) nanohybrids (LOX@HMnO2-P[5]A) bearing pillar[5]arene (P[5]A) macrocycle with excellent host-guest properties. The highly biocompatible nanohybrids enable direct lactate consumption through LOX catalytic degradation and block lactate production by P[5]A-mediated LPS trapping, allowing for dual-pipeline lactate removal to maximize the reversal of lactate-mediated vascular hyperpermeability. Besides, HMnO2 cores decompose hydrogen peroxide produced from lactate oxidation into oxygen, further contributing to lactate consumption and mitigating the hypoxic inflammatory environment. In vivo investigations demonstrate that intravenous administration of LOX@HMnO2-P[5]A nanohybrids with extended blood circulation can effectively ameliorate endothelial barrier dysfunction, inflammatory responses, and multiple organ injury, ultimately improving survival outcomes in LPS-induced sepsis. Taken together, this dual-pipeline lactate removal strategy offers a promising approach for efficient sepsis treatment.

Rapid synthesis of manganese dioxide nanoparticles for enhanced biocompatibility and theranostic applications.

Manganese dioxide (MnO2), lauded for its biocompatibility and distinctive optical and physical characteristics, has become an indispensable material in the biomedical field, showing immense potential in disease detection, treatment, and prevention. Particularly, the ability of MnO2 nanoparticles to oxidize glutathione (GSH) to its oxidized form has positioned them as pivotal players in GSH sensing. However, conventional preparation methods, whether top-down or bottom-up, often result in nanoparticles that require multi-step processing and modification to achieve good dispersion in physiological conditions, which is both time-consuming and complex. To address this, a rapid and efficient method was developed for producing well-dispersed and stable MnO2 nanoparticles using tannic acid to reduce potassium permanganate. The polyphenolic structure of tannic acid not only facilitates the reduction process but also enhances the dispersibility of the nanoparticles in biological environments. In addition, PEG could improve the stability of MnO2 nanoparticles and also reduce their size. Moreover, we demonstrate the application of these nanoparticles in a colorimetric assay for GSH detection, leveraging their ability to react with GSH to produce Mn2+. Furthermore, these nanoparticles were utilized in a colorimetric assay for GSH detection, harnessing their reactivity with GSH to generate Mn2+. Beyond this, the MnO2 nanoparticles exhibit potential for the loading of a spectrum of molecules, including small molecules, peptides, DNA, RNA, and proteins, through electrostatic interactions, π-π stacking, and the inherent reactivity of polyphenols. This groundbreaking strategy heralds a new era for MnO2 in the realm of theranostic agent delivery, offering a promising avenue for enhancing diagnostic accuracy and therapeutic efficacy in biomedical applications.

Green quantification of amino(poly)phosphonates using ion chromatography coupled to integrated pulsed amperometric detection.

Aminopolyphosphonates (APPs) are widely used as chelating agents, and their increasing release into the environment has raised concerns due to their transformation into aminomethylphosphonic acid (AMPA) and glyphosate, compounds of controversial environmental impact. This transformation highlights the urgent need for detailed studies under controlled conditions. Despite the availability of various methods for quantifying individual aminopolyphosphonates and aminomonophosphonates, a green, low-cost approach for the simultaneous quantification of APPs and their transformation products in laboratory experiments has been lacking. In this study, we present a novel analytical method utilizing ion chromatography (IC) coupled to integrated pulsed amperometric detection (IPAD) to simultaneously quantify the six aminophosphonates: AMPA, glyphosate, iminodi(methylene phosphonate) (IDMP), aminotrismethylene(phosphonates) (ATMP), ethylenediamine tetra(methylene phosphonate) (EDTMP), and diethylenetriamine penta(methylene phosphonate) (DTPMP). This method achieves separation within a 35-min run time and method detection limits (MDLs) ranging from 0.014μM for AMPA to 0.14μM for DTPMP. The method's applicability was successfully shown by monitoring DTPMP, IDMP, and AMPA during DTPMP transformation on manganese dioxide. A key advantage of this method is its environmental friendliness compared to existing aminophosphonate quantification techniques. Next to the simultaneous analysis, it avoids the use of derivatization agents and organic solvents and employs an energy-efficient detector. While the method's limitations lie in the detector's inherent non-specific nature, it offers a low-cost and sustainable alternative to existing methods.

The Fluorescent Detection of Alkaline Phosphatase Based on Iron Nanoclusters and a Manganese Dioxide Nanosheet.

Fluorescent iron nanoclusters are emerging fluorescent nanomaterials. Herein, we synthesized hemoglobin-coated iron nanoclusters (Hb-Fe NCs) with a significant fluorescence emission peak at 615 nm and investigated the inner-filter effect of fluorescence induced by a manganese dioxide nanosheet (MnO2 NS). The fluorescence quenching of Hb-Fe NCs by a MnO2 NS can be significantly reversed by the addition of ascorbic acid. On the basis of fluorescent recovery by ascorbic acid, we proposed a system that consisted of Hb-Fe NCs, a MnO2 NS and ascorbate phosphate, and the proposed system was successfully used for alkaline phosphatase (ALP) detection in the range of 0-20 μg/mL based on the significant fluorescence recovery achieved.

The clean analysis process of Mn2+ for industries: a comparative study on direct determination of high-concentration Mn2+ in solution using spectrophotometry

Mn2+ is an essential cation extensively utilized in various industrial processes, including electrolytic manganese production, manganese dioxide manufacturing, and zinc processing. It also poses significant environmental challenges as a primary pollutant in Mn-containing wastewater and hazardous materials. Effective monitoring and control of Mn2+ in these processes are vital for improving resource conversion efficiency and minimizing pollutant production. However, the direct determination of high concentrations of Mn2+ remains challenging due to rapid reactions, which impede improvements in cleaner industrial production. Traditional detection method like potassium periodate spectrophotometry (PPS) method is limited to low concentrations and involve complex processes that contribute to secondary pollution. In this study, we evaluated the performance of four alternative methods—External Standard Calibration (EC), Area Under the Curve (AUC), Standard Addition (SA), and Multi-Energy Calibration (MEC)—for determining high-concentration Mn²⁺. The study found that the weak absorption characteristic of aqueous Mn²⁺ due to spin-forbidden transitions is advantageous for direct determination at high concentrations in its original valence state. By optimizing the optical path and wavelength, concentrations up to 50 g/L were detected, surpassing the PPS upper limit by 5000 times. Among the methods, EC demonstrated superior accuracy and precision, with a performance rate of 98.07% and a relative standard deviation of less than 1%. The EC method’s minimal time consumption and cost-effectiveness make it suitable for automation and integration into industrial systems for continuous, real-time monitoring. This research offers valuable insights into high-concentration Mn2+ determination using spectrophotometry, highlighting the EC method’s potential for real-time monitoring and its adaptability for large-scale industrial operations. The findings provide a substantial reference for the direct detection of other industrial components, promoting more efficient and environmentally friendly industrial practice.

A comparative study on the structural, chemical, morphological and electrochemical properties of α-MnO2, β-MnO2 and δ-MnO2 as cathode materials in aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are considered to be highly promising electrochemical energy storage device due to their affordability, inherent safety, large zinc resources, and optimal specific capacity. Among various cathode materials, manganese dioxide (MnO2) stands out for its high voltage, environmental benignity, and theoretical specific capacity. This study systematically investigates the phase formation and structural parameters of α-MnO2, β-MnO2, and δ-MnO2 synthesized via hydrothermal method, employing Rietveld refinement. FTIR and Raman spectroscopy confirms Mn-O and O-H bond formation. BET analysis reveals surface areas, and pore size distribution is calculated with BJH method. High-resolution XPS spectra exhibit a spin energy split of ~ 11.9 eV for Mn 2p confirming the presence of MnO2. Electrochemical studies shows an initial discharge capacities of 230.5, 188.74 and 263.30 mAh g− 1 at 0.1 A g− 1 for α-MnO2, β-MnO2 and δ-MnO2. The EIS spectra revealed the capacitive behaviour and electrode reaction kinetics where a RcT value of 484.14, 327.6, 162.5 Ω for α-MnO2, β-MnO2 and δ-MnO2. These study give insights into relation of various properties of MnO2 with electrochemical performance and its viability in grid storage applications.Graphical

Influence of Synthesis Conditions on the Capacitance Performance of Hydrothermally Prepared MnO2 for Carbon Xerogel-Based Solid-State Supercapacitors.

In this study, the potential to modify the phase structure and morphology of manganese dioxide synthesized via the hydrothermal route was explored. A series of samples were prepared at different synthesis temperatures (100, 120, 140, and 160 °C) using KMnO4 and MnSO4·H2O as precursors. The phase composition and morphology of the materials were analyzed using various physicochemical methods. The results showed that, at the lowest synthesis temperature (100 °C), an intercalation compound with composition K1.39Mn3O6 and a very small amount of α-MnO2 was formed. At higher temperatures (120-160 °C), the amount of α-MnO2 increased, indicating the formation of two clearly distinguished crystal structures. The sample obtained at 160 °C exhibited the highest specific surface area (approximately 157 m2/g). These two-phase (α-MnO2/K1.39Mn3O6) materials, synthesized at the lowest and highest temperatures, respectively, and containing an appropriate amount of carbon xerogel, were tested as active mass for positive electrodes in a solid-state supercapacitor, using a Na+-form Aquivion® membrane as the polymer electrolyte. The electrochemical evaluation showed that the composite with the higher specific surface area, containing 75% manganese dioxide, demonstrated improved characteristics, including 96% capacitance retention after 5000 charge/discharge cycles and high energy efficiency (approximately 99%). These properties highlight its potential for application in solid-state supercapacitors.

Direct laser writing of planar and stretchable supercapacitors based on a graphene oxide and manganese dioxide nanoparticle composite on a paper substrate

Paper-based supercapacitors (P-SCs) exhibit superior electrochemical performance owing to the flexibility and unique surface properties of paper substrates. Currently, most P-SCs adopt a sandwich structure that is limited by electrode fabrication methods. However, the development of planar paper-based devices is crucial to satisfy the tremendous demand for wearable electronics. Herein, based on the mechanism of interaction between the laser and material, we used direct laser writing (DLW) techniques to fabricate in-plane P-SCs based on graphene oxide (GO) and manganese dioxide (MnO2) composite-covered paper substrates. Owing to the in-plane device structure and pseudocapacitive MnO2, the acquired rGO-MnO2-based planar P-SCs possessed a much higher specific capacitance value (17.7 mF/cm2) than that based on sandwich-structured reduced GO (rGO) (1.71 mF/cm2). In addition, three in-series integrated devices can be easily achieved via the DLW fabrication method, which shows potential for practical applications such as powering a light emitting diode. In addition, by carefully designing the paper substrate structure, the paper-based device exhibited excellent stretching stability. A specific capacitance retention of 86.8% remained after 5000 stretch cycles. Therefore, this study provides valuable insights into the design and fabrication of wearable paper-based electronics.

Manganese Dioxides Induce the Transformation and Protection of Dissolved Organic Matter Simultaneously: A Significance of Crystallinity.

Interactions between manganese dioxides (MnO2) and dissolved organic matter (DOM) have long been the subject of scientific inquiry. However, the effect of MnO2 crystallinity on the DOM fate remains unclear. Herein, we comprehensively investigate the adsorption, protection, and mineralization of DOM by MnO2 with various crystallinities (order of crystallinity: γ-30 < γ-90 < γ-120). The results show that DOM adsorption is positively correlated with the specific surface area (SSA) of MnO2; γ-30 with the largest SSA adsorbs the highest amount of DOM, resulting in DOM protection. However, γ-90 and γ-120 with a smaller SSA could induce the Maillard reaction and thereby promote the formation of geopolymerized organic matter, leading to reduced bioavailability of DOM. Furthermore, the capability of MnO2 to mineralize DOM decreases in the order γ-120 > γ-90 > γ-30, and it is determined by both Mn4+ and hydroxyl radical (·OH) content. In particular, the contribution of radical-based oxidation of ·OH to DOM mineralization is 64.8, 47.4, and 23.7% for γ-30, γ-90, and γ-120, respectively. We propose that crystallinity of MnO2 may have a significant but hitherto unexplored influence on the global carbon cycle over geological time.

Boosting peroxymonosulfate activation for complete removal of gatifloxacin by a bead-chain zeolitic imidazolate framework composite.

A bead-chain metal-organic framework composite was designed and synthesized by assembling a zeolitic imidazolate framework (ZIF) onto manganese dioxide (MnO2) nanowires. The prepared catalyst MnO2@ZIF-X (X = 1, 2 and 3) was used to facilitate gatifloxacin (GAT) degradation by using potassium peroxymonopulfate (PMS) as an activator. MnO2@ZIF-2 exhibited excellent catalytic performance, achieving 100% degradation of GAT (10mg/L) in the presence of PMS (1mM) in 15min, and the toxicity of the majority of degradation intermediates decreased. Furthermore, the removal efficiency was maintained above 90% throughout a wide pH range (3-11) and in the coexistence of anions ( [Formula: see text] , Cl-, SO42-). The main mechanism of the MnO2@ZIF-2/PMS system involves the synergistic effect of radicals and non-radicals (single linear oxygen and electron-mediated transfer), making the system highly resistant to interference from environmental matrices. Moreover, the GAT degradation pathway was elucidated through intermediate analysis and theoretical calculations. In particular, MnO2@ZIF-2 was well dispersed on a microporous filter membrane to create an immobilized membrane reactor that displayed excellent catalytic performance for the continuous degradation of GAT for 300min. This work offers an avenue for the design of catalysts with good catalytic activity, particularly for PMS activation in antibiotic wastewater remediation.

Rate capability and electrolyte concentration: Tuning MnO2 supercapacitor electrodes through electrodeposition parameters.

Manganese dioxide (MnO2) is a well-known pseudocapacitive material that has been extensively studied and highly regarded, especially in supercapacitors, due to its remarkable surface redox behavior, leading to a high specific capacitance. However, its full potential is impeded by inherent characteristics such as its low electrical conductivity, dense morphology, and hindered ionic diffusion, resulting in limited rate capability in supercapacitors. Addressing this issue often requires complicated strategies and procedures, such as designing sophisticated composite architectures. This study introduces a straightforward and cost-effective approach to tune and enhance the rate capability of MnO2 pseudocapacitor electrodes fabricated via the electrodeposition method. Among the electrodeposition parameters, the deposition time and electrolyte concentration, which influence the mass loading, electrode thickness, microstructure, and electrochemical properties, were the primary focus. Various electrodes were prepared potentiostatically in a two-electrode cathodic electrodeposition setup on a Ni foam substrate in a KMnO4 aqueous electrolyte, with bath concentrations (in terms of Mn ion) of 0.01 and 0.1M, and electrodeposition times ranging from 1 to 15min. Optimal rate capabilities were achieved at low bath concentrations and deposition times, primarily due to the structural properties of electrodes prepared under such circumstances. While electrodeposition at a 0.1M electrolyte concentration resulted in the formation of electrolytic MnO2 with high supercapacitive rate sensitivity, reducing the bath concentration to 0.01M primarily led to the formation of birnessite δ-MnO2, capable of maintaining a reasonable specific capacitance in the range of approximately 90-100 Fg-1 with almost no sensitivity to the charging/discharging rate, as confirmed by galvanostatic charge-discharge (1-10 Ag-1) and cyclic voltammetry (10-100mVs-1) examinations. Along with the positive structural impacts of the layered birnessite with large interlayer spacing, the porous morphology (vertically aligned two-dimensional interconnected columns) and low thickness (≈2μm) of the electrode prepared at the lowest bath concentration and electrodeposition time (0.01M in 1min electrode) contributed to its fast ionic diffusion kinetics for pseudocapacitive charge storage and the consequent high rate capability.

NiFe-based arrays with manganese dioxide enhance chloride blocking for durable alkaline seawater oxidation.

Seawater splitting is increasingly recognized as a promising technique for hydrogen production, while the lack of good electrocatalysts and detrimental chlorine chemistry may hinder further development of this technology. Here, the interfacial engineering of manganese dioxide nanoparticles decorated on NiFe layered double hydroxide supported on nickel foam (MnO2@NiFe LDH/NF) is reported, which works as a robust catalyst for alkaline seawater oxidation. Density functional theory calculations and experiment findings reveal that MnO2@NiFe LDH/NF can selectively enrich OH- and repel Cl- in oxygen evolution reaction (OER). MnO2@NiFe LDH/NF attains a current density of 1000mAcm-2 in alkaline seawater with an ultralow overpotential of only 313mV. Furthermore, it can maintain stability at 1500mAcm-2 over 600h. Further phosphidation of MnO2@NiFe LDH/NF can create MnOx@NiFeP/NF used in efficient hydrogen evolution reaction. Moreover, an anion exchange membrane electrolyzer with MnO2@NiFe LDH/NF as the anode and MnOx@NiFeP/NF as the cathode was also capable of seawater splitting at 500mAcm-2 for 100h. This work offers light to develop effective and long-lasting electrocatalysts for seawater splitting.

Copper ions-intercalated manganese dioxide self-supporting mesoporous carbon electrode for aqueous zinc-ion batteries

The insertion of copper ions expands the layer spacing of MnO2, stabilizes the structure of MnO2, enhances the diffusion ability of H+, and thus exhibits excellent electrochemical properties.

Lightweight core-shell multilayer nanocomposites of Yttrium oxide @ Silicon dioxide @ Polypyrrole @ Manganese dioxide for broadband microwave absorption

Lightweight core-shell multilayer nanocomposites of Yttrium oxide @ Silicon dioxide @ Polypyrrole @ Manganese dioxide for broadband microwave absorption

In situ formed colloidal manganese dioxide enhances permanganate oxidation for sulfide control in sewers

In situ formed colloidal manganese dioxide enhances permanganate oxidation for sulfide control in sewers

The smartphone-assisted sensing platform based on manganese dioxide nanozymes for the specific detection and degradation of hydroquinone.

Hydroquinone (HQ) is a prevalent pollutant in aquatic environments, posing significant risks to ecosystems and human health. Practical methods for the simultaneous detection and degradation of HQ are essential. To address this requirement, a dual-mode detection and degradation strategy has been developed utilizing designed nanozymes (DM) consisting of a porous SiO2 core and MnO2 shell. Due to the catalytic activity of DM nanozymes, the three types of reactive oxygen species (ROS), singlet oxygen (1O2), superoxide anion (O2•-), and hydroxyl radical (•OH), were generated to induce the color transferring of 3,3',5,5'-tetramethylbenzidine (TMB) from colorless to blue form (oxTMB). During the reductive HQ-mediated oxTMB fading, the DM has significant selectivity towards HQ from isomers (catechol and resorcinol) due to the differing reductive reaction rates, with an excellent linear range of 0.2-45 μM with a detection limit as low as 0.11 μM. In addition, according to the color parameter changes in the sensing process, colorimeters and smartphones are utilized to achieve on-site and convenient HQ detection. Besides, the DM nanozyme can oxidatively decompose HQ without auxiliary equipment. We believe this research provides a powerful tool for detecting and removing HQ precisely.

Raman spectroscopy study of K-birnessite single crystals

The alterations in the crystal structure and Raman spectra of K-birnessite single crystals when water molecules intercalate into or deintercalate from the interlayer space were subjected to an in-depth examination.