Manganese Oxide Nanoparticles Research Articles

Investigation on corrosion behaviour of metal oxide nanoparticles reinforced magnesium composites by salt spray and immersion corrosion test methods

ABSTRACT This study explores the increasing utilisation of lightweight materials, particularly magnesium (Mg) alloy, in sectors such as automobile, aerospace, and marine due to its notable advantages such as high strength-to-weight ratio, good castability, and excellent damping capacity. Despite these merits, Mg alloy faces challenges, notably in wear and corrosion resistance. The research focuses on enhancing the corrosion resistance of Mg alloy by incorporating Zinc Oxide (ZnO), Manganese Oxide (MnO), and Titanium Oxide (TiO2) nanoparticles. The alloy AZ91D and three nanocomposites, namely AZ91D + 1% ZnO, AZ91D + 1% MnO, and AZ91D + 1% TiO2, were manufactured using a stir squeeze casting technique combined with an ultrasonication process. To confirm the even distribution of reinforcement particles, Optical Microscope (OM), Scanning Electron Microscope (SEM) and High-Resolution Scanning Electron Microscope (HR-SEM) were employed. X-ray Diffraction (XRD) analysis revealed the presence of matrix and reinforcement material with intermetallic precipitates around the grain boundaries. Corrosion properties were assessed following ASTM standards and utilising a 3.5% NaCl concentration. The study found that AZ91D + 1% TiO2 nanocomposites exhibited superior corrosion resistance compared to the AZ91D alloy, showing a remarkable 77.78% and 69.89% improvement in corrosion behaviour under salt spray and immersion environments, respectively, after 48 hours.

Synthesis of Trimanganese Tetraoxide (Mn3O4) as a promising electrode and Photocatalyst for the degradation of Rhodamine B dye

The article involves the facile bio-synthesis of Manganese (III) Oxide (Mn3O4) nanoparticles (NPs) using Curry leaf (Murraya Koenigii) extract as an efficacious chelating agent. The prepared NPs were subjected to various characterization methods such as Powder X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) with Energy Dispersive X-Ray (EDX) Analysis, Transmission Electron Microscopy (TEM), Fourier Transform Infrared analysis (FTIR), Ultra Violet spectroscopy study (UV–Vis), Cyclic Voltammetry (CV) and Vibrating Sample Magnetometer (VSM) to study the crystalline structure, morphology, optical properties, electrochemical activity and magnetic property of the sample. The XRD result proved the crystallinity of the sample having crystallite size around 15 nm with tetragonal structure. The absorption band observed at 612 cm−1 indicates the Mn-O stretching modes of tetrahedral sites in FTIR analysis of the prepared sample which confirmed the formation of Mn3O4 NPs. Using SEM and TEM techniques, the surface morphology and NPs size were examined. The composition and distribution of the NPs was verified using EDX spectrum and elemental mapping. Using the UV–Visible spectroscopy, the energy band gap (Eg) for the NPs was computed and calculated as 2.34 eV. The Mn3O4 NPs evinced a specific capacitance of 276 Fg-1 at 10 mV/s scan rate. This result proposes that the obtained Mn3O4 NPs can be used as a suitable electrode mainly for supercapacitor applications. VSM study revealed the paramagnetic behavior of the synthesized Mn3O4 NPs. The synthesized Mn3O4 NPs exhibited moderate antibacterial activity with gram positive bacteria such as Staphylococcus aureus, Streptococcus pneumoniae, and gram negative bacteria such as Klebsiella pneumoniae, with the inhibition zones of 12, 10, and 9 mm respectively. Photo catalytic degradation study was carried out for Rhodamine B (RhB) dye, which showed a strong characteristic absorption peak nearly at 554 nm with 94 % of degradation efficiency.

Green synthesised Mn3O4 and poly (o-phenylenediamine) for antimicrobial textile-based supercapacitor applications

The advancement of wearable supercapacitors (SCs) has recently garnered a lot of attention owing to their ease of fabrication into textiles, low cost, long cycle life, fast charging and discharging, high efficiency, and ability to bridge the energy and power gap between conventional capacitors and batteries. The present study focuses on the development of wearable textile-based SC electrodes using green-synthesised manganese oxide nanoparticles functionalised on poly(o-phenylenediamine) reinforced to a polymer nanocomposite. The prepared nanocomposite was characterized using spectroscopic techniques such as UV-visible spectroscopy, Fourier transform infrared spectroscopy, x-ray diffraction studies, and scanning electron microscopy to validate the incorporation of metal oxide nanoparticles into the polymer matrix. The thermal properties were studied using thermogravimetric analysis and differential scanning calorimetry. The electrochemical performance of the bare polymer and the nanocomposite was evaluated using cyclic voltammetry, galvanostatic charge-discharge, and impedance spectroscopy techniques. An impressive specific capacitance of 213 Fg-1was achieved at a current density of 1 Ag-1for the polymer nanocomposite and even after 1000 cycles a capacitance retention of 89% was observed. Enhanced antimicrobial activity was also observed for the nanocomposite against both gram-negative and gram-positive bacteria. Based on these attributes, the fabricated device can be used as an efficient antimicrobial wearable SC.

Synthesis of PPy-MnO2 Nanocomposite for Utilization in Supercapacitor Applications

Polypyrrole (PPy) nanocomposites were prepared using chemical oxidation and were combined with manganese oxide (MnO2) nanoparticles. The PPY-MnO2 nanocomposite was synthesized by integrating PPy nanofibers with varying volume ratio percentages of MnO2 dopant (10, 30, and 50% vol. ratio). The structural features of the PPy and PPy-MnO2 nanocomposite were investigated using X-ray diffraction (XRD). Fourier transfor infrared (FTIR) spectroscopy was used to demonstrate the molecular structures of primary materials and the final product of PPy, MnO2, and PPy- MnO2 nanocomposites. Field Emission Scanning Electron Microscopy (FESEM) showed that the morphology of PPy consisted of a network of nanofibers. Increasing the volume ratios of manganese oxide added to the PPY nanofiber led to the increase of manganese oxide nanoparticles on the surface of the PPY nanofiber network. This resulted in a noticeable alteration in the structure of the nanocomposite. It has been observed that the nanocomposites demonstrate a significant level of pseudocapacitive activity. The highest capacitance of 236 F/g was observed when pure PPy was doped with 30% MnO2 compared to 125 F/g of the pure PPy.

Optimizing Energy Storage Performance: In situ Synthesized Manganese Oxide (Mn3O4) Nanoparticle‐Based Symmetric Supercapacitor on a Paper Substrate

AbstractIn this study, a redox reaction is employed to synthesize manganese oxide (Mn3O4) nanoparticles using potassium permanganate as a precursor in the presence of diethyl amine. The structural characterization reveals the formation of the tetragonal phase of Mn3O4 nanoparticles with a space group of I41/amd. A free‐standing Mn3O4‐based paper electrode is fabricated and its electrochemical performances are investigated. The electrode exhibits a maximum specific capacitance value of ~353 F g−1 and an areal capacitance of ~530 mF cm−2 at a current density of 0.2 A g−1. A symmetric supercapacitor‐based device is also designed using Mn3O4 nanoparticles as an active material in a gel electrolyte configuration. The Mn3O4 device achieves specific and areal capacity values of ~208 mAh g−1 and 260 mA cm−2, respectively, at a current density of 0.3 A g−1. The device delivers maximum energy and power density values of ~104 Wh kg−1 and ~220 W kg−1, respectively, with ~92 % specific capacity retention at 0.3 A g−1 after 5000 cycles. The above results suggest that the Mn3O4‐based device has the potential for energy storage applications.

Tetragonal crystalline MnO nanoparticles alleviate Pb stress in wheat by modulating antioxidant enzymes in leaves.

Agriculture ecosystems are seriously threatened by lead (Pb) contamination, which impacts plant growth and productivity. In this study, green synthesized manganese oxide nanoparticles (MnO NPs) using citrus peel were used for priming of wheat seeds. For the synthesis of MnO nanoparticles, peel extract of Citrus paradisi and 1mM solution of manganese acetate were stirred and calcinated at 500°C. Successful synthesis of MnO NPs was determined using advanced techniques. In Fourier-transform infrared spectroscopy (FTIR), the presence of amines, alkanes, aldehydes, and alcohol molecules, on the surface of MnO NPs, confirmed their stability. X-ray diffraction analysis described their average size (22nm), while scanning electron microscopy showed tetragonal crystalline shape and nano-flowers structure of MnO NPs. Sharp peaks of energy dispersive x-ray analysis described the presence of oxygen (28.81%) and manganese (71.19%) on MnO NPs. Priming of wheat seeds with synthesized MnO NPs significantly improved the growth attributes of wheat seedlings including the size of leaf, root length, size of shoots, chlorophyll and carotenoid contents, relative water content, decreased relative electrolyte leakage, high proline accumulation and decreased concentration of malondialdehyde. Application of MnO NPs also helped plants to accumulate antioxidant enzymes in their leaves. These results proved that the priming of MnO NPs can greatly reduce lead-induced stress in wheat seedlings and these NPs can alsobe used for the priming of other crops.

MnO2 decoration onto the guava leaves: A sustainable and cost-effective material for methylene blue dye removal

Excessive number of dyes in water is becoming the main cause of water pollution, which is very important to remove because it is harmful. Dye contaminated water is being treated by various methods. Adsorption method can be considered best for the study of dye removal due to several technological reasons. The adsorption method has also been emphasized in this study. In the present work, a nano-bio-composite was fabricated by growing manganese oxide nanoparticles on abundant cellulosic guava leaf powder. This allows nanocomposite to be prepared in large quantities at nominal cost. The characterization technique confirmed the irregular growth of manganese oxide nanoparticles onto the guava leaf powder. The electrostatic and non-electrostatic interactions was confirmed in between manganese oxide nanoparticles and the carbon structure of guava leaf powder. The massive functional groups were found to be in the prepared nano-bio-composite. The grain size of prepared material was in nano range. The developed nano-bio-composite was used to remove methylene blue from water. This showed a very good adsorptive capacity for methylene blue. The analyzed adsorption data was modelled through isotherms, kinetics and thermodynamics models. The nature of the adsorption process was determined to be spontaneous and exothermic. The reusability test was carried out for five adsorption-desorption cycles. The reusability results suggested the better removal efficiency (%) in the first two cycles with only 20 % reduction in removal efficiency (%). The leaching test result revealed the good stability of MnO2/GL at neutral pH. It was a unique and cheap adsorbent of its kind, which had not been noticed anywhere before.

The Inhibitory Effect of Manganese Oxide Nanoparticles Synthesized by Prodigiosinagainst Pathogenic P. aeruginosa

The Inhibitory Effect of Manganese Oxide Nanoparticles Synthesized by Prodigiosinagainst Pathogenic P. aeruginosa

Exploring the performance of biodiesel-hydrogen blends with diverse nanoparticles in diesel engine: A hybrid machine learning K-means clustering approach with weighted performance metrics

Biodiesel, an eco-friendly fuel with lower greenhouse gas emissions, is a crucial alternative to traditional fossil fuels. Adding hydrogen and nanoparticles to biodiesel enhances diesel engine performance, reduces emissions, and improves fuel efficiency through better combustion and fuel atomization. In this study, various nanoparticles were experimented, and their performance, emission, and acoustic outcomes were systematically evaluated, resulting in a comprehensive ranking and clustering. The k-means clustering-Entropy-TOPSIS method is applied to weigh performance outcomes, rank the nanoparticles, and create clusters among them among best and worst, considering multiple criteria's in this study. This study further divides diverse nanoparticles into clusters, employing a hybrid machine learning k-means clustering method. The CO parameter carries the highest weight (57%), followed by UBHC (22%), owing to their significant variation induced by the addition of nanoparticles, surpassing the variability observed in other parameters. Manganese oxide nanoparticles exhibited superior performance across various critical parameters among all nanoparticles with a minimum centroidal distance of 25.97. Moreover, enrichment with hydrogen gas, combined with nanoparticles, significantly enhanced diesel engine performance, manifesting in an approximate 8 % increase in Brake Thermal Efficiency (BTE) and 23 % reduction in CO emissions. Identifying the optimal nanoparticles is crucial for enhancing biodiesel properties, and the paramount importance of hydrogen mixing lies in its potential to significantly improve combustion efficiency, emissions, and overall diesel engine performance.

Green, environmentally friendly synthesis of MnO Nanoparticles for corrosion inhibition in mild steel

<p>This study uses green, environmentally friendly methods to synthesize manganese oxide nanoparticles (MnO-NPs) that can be applied on mild steel as a safe and eco-friendly material with corrosion inhibition attributes. Mukia madaraspatana leaf extract is effective in the green synthesis of Mno-NPs. Several critical parameters can influence the corrosion rate and inhibition efficiency of the MnO-NPs, including the dose of nanoparticles in parts per million (PPM), acid concentration, temperature, and exposure time. Response Surface Methodology-Box Behnken Design (RSM-BBD) was employed to optimize these parameters. An optimal dosage of 550 parts per million (ppm) of nanoparticles, an acid concentration of 0.9 M, a temperature of 37°C, and an exposure time of 3.2 hours resulted in an inhibition efficiency of 92.5%. It reduced the corrosion rate to 0.652 (mm/Y) in an independent validation run. These findings demonstrate that the environmentally friendly synthesized MnO-NPs have great potential as an anti-corrosive agent for mild steel.</p>

Facile preparation of CoFe-MnO2@titania nanotube array bifunctional electrodes for high-current-density water splitting at industrial temperatures

The development of bifunctional electrocatalysts for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) at high current density under industrial temperatures is crucial for large-scale industrial hydrogen production from water splitting. In this work, M-MnO2@TNTA composite electrodes were prepared by depositing various metal ion-doped manganese oxide nanoparticles on the titania nanotube array (TNTA) by successive ionic layer adsorption reaction (SILAR) method, and their HER and OER electrocatalytic performances were investigated in 1 M KOH. Results show that the CoFe-MnO2@TNTA composite electrode prepared by simultaneous doping of Co3+ and Fe3+ in MnO2 exhibits optimal catalytic performance. Compared with MnO2@TNTA without ion doping, the overpotentials of CoFe-MnO2@TNTA at 10 mA cm−2 (η10) for HER and OER are reduced by 571 and 665 mV. In addition, the electrode performance can be significantly enhanced by increasing the test temperature, and the porous array structure enables CoFe-MnO2@TNTA to exhibit better performance at high current densities. At 50 °C, which is the common industrial electrolytic water temperature, the η10 of CoFe-MnO2@TNTA for HER is almost equal to that of the Pt/C electrode. The η100 of CoFe-MnO2@TNTA for HER is reduced by 35 mV compared with the Pt/C electrode. Moreover, η200 of CoFe-MnO2@TNTA for OER is significantly lowered by 111 and 184 mV compared with IrO2 and RuO2 electrodes. Utilizing CoFe-MnO2@TNTA as both the cathode and anode for overall water splitting, the electrolysis voltage is merely 2.33 V under the current density of 200 mA cm−2, much lower than that of IrO2 (+)||Pt/C (–) (2.68 V). The present work may provide a valuable reference for the development of self-supporting bifunctional electrodes suitable for high-current-density water splitting at industrial temperatures.

Cytotoxic Effect of Biosynthesized Manganese Oxide Nanoparticles on Human Skin Squamous Carcinoma Cell Line (HSSCC) in vitro

The current study intended to biosynthesis of manganese oxide nanoparticles (MnO -NPs) depending on prodigiosin pigment as stabilizing and reducing agent. which produced from environmental isolate of Serratia marcescens . The study of the biosynthesis of MnO NPs was characterized by different techniques, such as ( UV-VIS, XRD, AFM, FE-SEM and FTIR). The results refer, the wavelength of biosynthesis of MnO NPs by using UV-VIS was (284 nm), the average volume was (45) nm). and image FE-SEM shows that the MnO- NPs mainly consists of nanosheets assembled in flower-like shape with different diameters. The cytotoxic effects of (MnO -NPs) on Human Skin Squamous Carcinoma Cell Line (HSSCC) was significant (p≤0.05) comparative with control viability 100%. Maximum effective concentration were 4000 μg/ml for 72hr exposure time which gave the highest inhibition rate 95% comparative with viability control 100%, but the minimum concentration was 3.9 μg/ml which induced proliferation of (HSSCC)cells. So when the exposure time and the concentration was increased, the inhibition rate was increased. Keywords:Serratia marcescens, Human skin squamous carcinoma cell line, cytotoxic effect, prodigiosin, MnO –NP.

A facile green synthesis of manganese oxide nanoparticles using gum karaya polymer as a bioreductant for efficient photocatalytic degradation of organic dyes and antibacterial activity

The release of organic dyes into water systems, mainly textile industries, poses a significant threat to human and animal health. This approach shows great potential for effectively removing harmful dyes and microorganisms from wastewater treatment for environmental remediation. This study utilized gum karaya polymer bio-reductant to synthesize manganese oxide (MnO2) nanoparticles through a green approach. The synthesized MnO2 nanoparticles were characterized and confirmed by various analytical techniques. These results revealed their nanoscale dimensions, morphology, chemical purity, crystal nature, decolorized intermediate, and band gap. The photocatalytic degradation of hazardous Congo red and methyl orange dyes using KRG-MnO2 nanoparticles under visible light irradiation. Furthermore, the results demonstrated that Congo red dye degradation efficiency of 93.34 % was achieved. The dye concentration (8 to 16 mg/L), pH concentration, and radical trapping were studied. This suggests that holes and hydroxyl radicals play a crucial role in degrading the Congo red dye and demonstrate superior recyclability after three successive cycles and good stability. The possible intermediates from the Congo red dye degradation were identified through LC-MS analysis. The polymer composite MnO2 NPs have displayed notable antibacterial activity against pathogenic bacteria such as Staphylococcus aureus and Escherichia coli. The research indicates that MnO2 nanoparticles functionalized with polymers can efficiently remove pathogens and organic dyes from diverse industrial water treatment processes.

Phyto-mediated fabrication of Mn2O3 nanoparticles using Hyphaene thebaica fruit extract as a promising photocatalyst for MB dye degradation

Manganese oxide nanoparticles (Mn2O3 NPs) synthesized through a green approach using Hyphaene thebaica fruit extract demonstrate promising photocatalytic activity. Characterized extensively through various techniques, including SEM, TEM, XRD, FTIR, and UV–vis spectroscopy, the Mn2O3 NPs exhibit crystalline morphology with a size of 20.3 ± 5 nm. Notably, the photocatalytic degradation of methylene blue reveals a high efficiency of around 98 %, underscoring the potential of the green synthesized Mn2O3 NPs for environmental remediation. This study contributes to the field by introducing a cost-effective, eco-friendly synthesis method for Mn2O3 NPs and highlighting their viability as efficient photocatalysts for pollutant degradation.

Assessment of skin sensitization potential of zinc oxide, aluminum oxide, manganese oxide, and copper oxide nanoparticles through the local lymph node assay: 5-bromo-deoxyuridine flow cytometry method

ABSTRACT The advent of nanotechnology has significantly spurred the utilization of nanoparticles (NPs) across diverse sectors encompassing industry, agriculture, engineering, cosmetics, and medicine. Metallic oxides including zinc oxide (ZnO), copper oxide (CuO), manganese oxide (Mn2O3), and aluminum oxide (Al2O3), in their NP forms, have become prevalent in cosmetics and various dermal products. Despite the expanding consideration of these compounds for dermal applications, their potential for initiating skin sensitization (SS) has not been comprehensively examined. An in vivo assay, local lymph node assay: 5-bromo-2-deoxyuridine-flow cytometry method (LLNA: BrdU-FCM) recognized as an alternative testing method for screening SS potential was used to address these issues. Following the OECD TG 442B guidelines, NPs suspensions smaller than 50 nm size were prepared for ZnO and Al2O3 at concentrations of 10, 25, and 50%, and Mn2O3 and CuO at concentrations of 5, 10, and 25%, and applied to the dorsum of each ear of female BALB/c mice on a daily basis for 3 consecutive days. Regarding the prediction of test substance to skin sensitizer if sensitization index (SI)≥2.7, all 4 NPs were classified as non-sensitizing. The SI values were below 2.06, 1.33, 1.42, and 0.99 for ZnO, Al2O3, Mn2O3, and CuO, respectively, at all test concentrations. Although data presented were negative with respect to adverse SS potential for these 4 NPs, further confirmatory tests addressing other key events associated with SS adverse outcome pathway need to be carried out to arrive at an acceptable conclusion on the skin safety for both cosmetic and dermal applications.

Chitosan-modified manganese oxide-conjugated methotrexate nanoparticles delivering 5-aminolevulinic acid as a dual-modal T1-T2* MRI contrast agent in U87MG cell detection.

Glioblastoma multiforme is a highly aggressive form of brain cancer, and early diagnosis plays a pivotal role in improving patient survival rates. In this regard, molecular magnetic resonance imaging has emerged as a promising imaging modality due to its exceptional sensitivity to minute tissue changes and the ability to penetrate deep into the brain. This study aimed to assess the efficacy of a novel contrast agent in detecting gliomas during MRI scans. The contrast agent utilized modified chitosan coating on manganese oxide nanoparticles. The modification included adding methotrexate and 5-aminolevulinic acid (MnO2/CS@5-ALA-MTX) to target cells with overexpressed folate receptors and breaking down excess hydrogen peroxide in tumor tissue, resulting in enhanced signal intensity in T1-weighted MR images but diminished signal intensity in T2*-weighted MR images. The nanosystem was characterized and evaluated in MR imaging, safety, and ability to target cells both in vivo and in vitro. MTX-free nanoparticles (MnO2/CS@5-ALA NPs) had no obvious cytotoxicity on cell lines U87MG and NIH3T3 after 24/48 h at a concentration of up to 160 µgr/mL (cell viability more than 80%). In this system, methotrexate enables tumor targeting and the MnO2/5-ALA improves T1-T2*-weighted MRI. In addition, MRI scans of mice with M109 carcinoma indicated significant tumor uptake and NP capacity to improve the positive contrast effect. This developed MnO2/CS@5-ALA-MTX nanoparticle system may exhibit great potential in the accurate diagnosis of folate receptor over-expressing cancers such as glioblastoma.

Preparation and Effects of Manganese Oxide Nanoparticles Against Quinolone-Resistant Bacteria Isolated from Hospital Wastewater

Background: The widespread administration of quinolones may have led to an increase in bacterial resistance development. Objective: To synthesize and characterize manganese oxide nanoparticles (MnO2NPs) and evaluate their effects on the viability and biofilm formation of quinolone-resistant gram-positive and negative pathogenic bacteria. Methods: We prepared MnO2NPs using the photo-irradiation method and recorded their characteristics using XRD, TEM, and SEM. Staphylococcus aureus, Streptococcus pneumonia, Escherichia coli, Klebsiella pneumonia, and Pseudomonas aeruginosa were collected from the wastewater of Baghdad hospitals during the period from July 3rd to July 14th, 2023. We used the VITEK2 system to confirm and identify all of the isolates. We conducted biofilm formation and antibiotic susceptibility tests using nalidixic acid, ciprofloxacin, norfloxacin, aztreonam, levofloxacin, and ofloxacin, and also detected the qnrA and qnrB genes. Finally, we evaluated the effects of the prepared nanoparticles on the viability and biofilm formation of bacterial isolates. Results: MnO2NPs characterizations showed a diffraction peak at 2θ values with 21 nm average sizes; qnrA and qnrB genes were found in three and four isolates, respectively; and significant effects of MnO2NPs against viability and biofilm formation were recorded. Conclusions: The synthesized nanoparticles have antibacterial and anti-biofilm activities against a variety of bacteria possessing qnr genes. Even multi-resistant bacterial isolates have the potential to be strong antimicrobial agents against these pathogens.

Microstructural Characterization, Mechanical Performance, and Anti-Corrosive Response of Zinc Multifaceted Coating on Mild Steel

Zinc has attracted significant attention in research due to its cost-effective use as an electrodeposited material, effectively protecting various types of steel from corrosion and wear. However, despite its advantages, zinc has limitations in fully guarding steel against corrosion. Recent studies propose that blending zinc with other metals during the coating process can proficiently shield mild steel from deterioration. The motivation for this study stems from recognizing the restrictions of zinc electrodeposition and the limited exploration of zinc multi-facet composite coatings for mild steel. In this study, the electrodeposition technique was employed to apply a coating to mild steel using zinc and nanoparticles of calcium oxide (CaO) and manganese oxide (MnO2). The coating bath's chemical composition included mass variations of 0-12 g/L for CaO and MnO2, along with 10 g/L each of boric acid, thiourea, and Na2SO4, and 15 g/L of K2SO4 and ZnSO4. The coating process occurred over a twenty-minute period, with a pH of 4.8, voltage set at 3.2V, current density at 1 A/cm2, temperature at 47°C, and stirring rate at 200 rpm. Results obtained from the coated mild steel demonstrated that Zn-6CaO-6MnO2 exhibited the greatest coating thickness at 0.2308 mm, and it showcased impressive corrosion resistance at 2.0618 mm/year. The Zn-CaO-MnO2 coating displayed a substantial deposit of crystallites in its microstructure, assisted by the presence of manganese, contributing to a smoother surface texture.

Rutin-coated ultrasmall manganese oxide nanoparticles for targeted magnetic resonance imaging and photothermal therapy of malignant tumors

Manganese oxide nanoparticles (MONs)-based contrast agents have attracted increasing attention for magnetic resonance imaging (MRI), attributed to their good biocompatibility and advantageous paramagnetism. However, conventional MONs have poor imaging performance due to low T1 relaxivity. Additionally, their lack of tumor-targeting theranostics capabilities and complex synthesis pathways have impeded clinical applications. Rutin (Ru) is an ideal tumor-targeted ligand that targets glucose transporters (GLUTs) overexpressed in various malignant tumors, and exhibits photothermal effects upon chelation with metal ions. Herein, a series of Ru-coated MONs (Ru/MnO2) were synthesized using a straightforward, rapid one-step process. Specifically, Ru/MnO2-5, with the smallest crystal size of approximately 4 nm, exhibits the highest T1 relaxivity (33.3 mM-1s−1 at 1.5 T, surpassing prior MONs) along with notable stability, photothermal efficacy, and tumor-targeting ability. Furthermore, Ru/MnO2-5 shows promise in MRI and photothermal therapy of H22 tumors owing to its superior GLUTs-mediated tumor-targeting capability.

A novel potentiometric screen-printed electrode based on crown ethers/nano manganese oxide/Nafion composite for trace level determination of copper ion in biological fluids.

Copper levels in biological fluids are associated with Wilson's, Alzheimer's, Menke's, and Parkinson's diseases, making them good biochemical markers for these diseases. This study introduces a miniaturized screen-printed electrode (SPE) for the potentiometric determination of copper(II) in some biological fluids. Manganese(III) oxide nanoparticles (Mn2O3-NPs), dispersed in Nafion, are drop-casted onto a graphite/PET substrate, serving as the ion-to-electron transducer material. The solid-contact material is then covered by a selective polyvinyl chloride (PVC) membrane incorporated with 18-crown-6 as a neutral ion carrier for the selective determination of copper(II) ions. The proposed electrode exhibits a Nernstian response with a slope of 30.2 ± 0.3mV/decade (R2 = 0.999) over the linear concentration range 5.2 × 10-9 - 6.2 × 10-3mol/l and a detection limit of 1.1 × 10-9mol/l (69.9ng/l). Short-term potential stability is evaluated using constant current chronopotentiometry (CP) and electrochemical impedance spectroscopy (EIS). A significant improvement in the electrode capacitance (91.5 μF) is displayed due to the use of Mn2O3-NPs as a solid contact. The presence of Nafion, with its high hydrophobicity properties, eliminates the formation of the thin water layer, facilitating the ion-to-electron transduction between the sensing membrane and the conducting substrate. Additionally, it enhances the adhesion of the polymeric sensing membrane to the solid-contact material, preventing membrane delamination and increasingthe electrode's lifespan. The high selectivity, sensitivity, and potential stability of the proposed miniaturized electrode suggests its use for the determination of copper(II) ions in human blood serum and milk samples. The results obtained agree fairly well with data obtained by flameless atomic absorption spectrometry.