A benzimidazole-appended double-armed salamo type fluorescence and colorimetric bifunctional sensor for identification of MnO4- and its applications in actual water samples

The symmetrically double-armed salamo type fluorescent sensor BMS, incorporating benzimidazole units, was designed and synthesized. Showcasing remarkable specificity and responsiveness to MnO4- within a DMSO:H2O (V/V = 9:1, pH = 7.2) Tris-HCl buffer medium, it enabled dual-channel detection of MnO4- through fluorescent and colorimetric changes. Critical experimental parameters, including detection and quantification thresholds (LOD and LOQ) along with binding affinity constants (Ka), were calculated using the Origin software. A rational interaction mechanism between BMS and MnO4- was deduced, based on fluorescence titration, Electrospray Ionization Mass Spectrometry (ESI-MS), Ultraviolet-Visible Spectroscopy (UV-Vis), Infrared Spectroscopy (IR), Stern-Volmer plots, and Density Functional Theory (DFT) computations. Additionally, the sensor BMS was applied to monitor MnO4- in real water samples. Advancing its practical utility, BMS was fabricated into test strips for the selective detecting of MnO4-.

Conquering Challenges: A Case Series of Yellow Phosphorus Poisoning at a Tertiary Care Hospital in Pune, Western India

Rodenticides are easily available in the market and suicidal attempts by ingesting such poisonous products are commonly reported in rural India. We aimed to analyze predictive factors, biological markers, and treatment outcomes among patients who ingested rodenticides (yellow phosphorus) with the brand name, Rattol. Here, we present three such cases who were admitted to a tertiary care hospital. We recorded socio-demographic characteristics, probable predictive factors, and serial charting biological markers. Conventional treatment was given to these cases. All cases were young women (age range: 17-30 years) from rural areas, two were married and one was unmarried. The approximate quantity of ingestion was 20, 10, and 5 grams, respectively. The time lag between the ingestion and sought first health care was 6 hours, 18 hours, and 1 hour, respectively. Major symptoms were vomiting, abdominal pain, and headache. Biological markers, including total bilirubin, alanine aminotransferase, aspartate aminotransferase, creatinine, prothrombin time, international normalized ratio, and model for end-stage liver disease (MELD) score were statistically significant. Two women had toxic hepatitis and acute liver failure and one did not have any organ damage. All of them were recovered within 17 days of mean hospital stay. A lethal dosage of rodenticides and delayed presentation to the hospital can prompt acute liver failure and severe ailment. Creating awareness, promoting mental health and suicide prevention, and framing proper guidelines for treatment will reduce morbidity and mortality.

Peracetic acid pretreatment improves biogas production from anaerobic digestion of sewage sludge by promoting organic matter release, conversion and affecting microbial community

Peracetic acid (PAA) pretreatment is considered as a novel and effective chemical pretreatment method for sludge. However, there is little information available on potential mechanisms of how PAA pretreatment affects sludge anaerobic digestion (AD). To fill the knowledge gap, this study investigated the effects and potential mechanisms of PAA pretreatment on sludge AD systems from physicochemical and microbiological perspectives. Batch experiments resulted that biogas production was enhanced by PAA pretreatment and the highest cumulative biogas yield (297.94 mL/g VS (volatile solid)) was obtained with 2 mM/g VS of PAA pretreatment. Kinetic model analysis illustrated that the PAA pretreatment improved the biogas potential (Pt) of sludge AD, but prolonged the lag phase (λ) of AD. Mechanistic studies revealed that reactive oxygen species (ROS) (HO•, O2-•, 1O2 and CH3C(O)OO•) were the major intermediate products of PAA decomposition. These ROS effectively promoted the decomposition and solubilization of sludge, and provided more biodegradable organic matter for the following AD reactions. 16S rRNA amplicon sequencing showed that some functional microorganisms associated with hydrolysis, acidogenesis, acetogenesis as well as methanogenesis, such as Hydrogenispora, Romboutsia, Longivirga, Methanosarcina and Methanosaet, were significantly enriched in reactors pretreated with PAA. Redundancy analysis and variation partitioning analysis indicated that functional microorganisms were significantly correlated with intermediate metabolites (soluble carbohydrate, soluble protein, soluble chemical oxygen demand and volatile fatty acids) and cumulative biogas production. This study provides a fresh understanding of the effects and mechanisms of PAA pretreatment on sludge AD, updates the insights into the response of functional microorganisms to PAA pretreatment, and the findings obtained might provide a fundamental basis for chemical pretreatment of sludge AD using oxidants.

Epoxide of Diosgenin Acetate Synthesis: DoE for Diastereoselective Yield Optimization, Antimicroibial, antioxidant and antiproliferative effects

Diosgenin and its derivatives have proved a huge importance in diverse biological activities. The optimized production of the diastereoisomers of the epoxide of diosgenin acetate by means of mCPBA is reported herein. This transformation had a previous design of experiments using the application of a statistical factorial DoE of 4 parameters (n^k), where one variable is varied at a time, while others stay constant. The temperature showed the greatest effect on the reaction yield; so, at 298 K the diastereomeric ratio 3:1 of α and β-epoxides, normally found, was raised to 1:1. Time was the second significant variable, but due to its high correlation with temperature, 30 minutes were required for a global 90% conversion at least. These diastereoisomers were characterized both isolated and in the mixtures obtained, to determine their antioxidant, antimicrobial and antiproliferative activity, finding a low antioxidant capacity by DPPH, but antimicrobial activity at the level of penicillin in gram negative bacteria by 1β better to 1α. The antiproliferative capacity was higher for diastereoisomer β, agreeing with the proportion of the mixture obtained by different conditions, increasing this in relation to the amount of this diastereoisomer present in hormone-dependent cancer cell lines such as Hela, PC-3 and MCF-7, with 10.0 µM obtained values of viability at 21.8 %, 35.8 % and 12.3 % respectively. DoE optimization allows to manipulate the ratio between diastereoisomers with the minimum number of experiments, extending the analysis of the effect of the ratio between diastereoisomers and the in silico potential as well as the biological activity.

Development of an azo functionalized oligomeric chitosan sensor for rapid visual, spectrophotometric and spectrofluorometric detection of KMnO4 up to micromolar concentrations

A water-soluble azo functionalized oligomeric chitosan reagent (β-NAC) has been developed for the visual detection and quantification of KMnO₄ at micromolar concentrations. The β-NAC sensor was also explored as a detection probe for the spectrophotometric and spectrofluorometric detection of several metal ions and anions. The synthesized reagent was characterized by TGA-DTA-DTG analysis, DLS studies, BET analysis, and spectral analysis. The β-NAC reagent produces conspicuous colours with different concentrations and different pH values of KMnO₄ solution. This provides evidence for high selectivity in the visual detection of KMnO₄ up to the micromolar level because of its interactions in the case of KMnO₄ only. The colour of the β-NAC reagent after interacting with KMnO₄ (10^-3 M) changes from brown to blood red. Furthermore, the β-NAC sensor was employed for the spectrophotometric detection of KMnO₄. The absorption spectrum of β-NAC shows a peak at 327 nm and on interacting with KMnO₄, it shows a bathochromic shift to 331 nm. The intensity of the peak at 331 nm increases as the concentration of KMnO₄ was increased from 1 μM to 0.01 M. The detection and quantification limits in the spectrophotometric detection of KMnO₄ were found to be 4.55 μM and 15.17 μM, respectively. The results of pH studies show that there is a pH effect of the KMnO₄ solution on KMnO₄ detection. The stability of the complex was determined by investigating the effect of time on the absorption intensity. In the spectrofluorometric detection, the fluorescence intensity of β-NAC at the 427 nm emission maxima was decreased on adding KMnO₄ solution. The fluorescence quenching increased on increasing the KMnO₄ concentration from 1 μM to 0.008 M. The optimum pH for fluorescence quenching was found to be 8. The detection and quantification limits in the spectrofluorometric detection of KMnO₄ were found to be 0.967 μM and 3.223 μM, respectively. The Stern-Volmer constant value was found to be 41 366.2 L mol^-1, confirming the significant complexation between KMnO₄ and the β-NAC reagent. Interference studies were conducted to analyse the effect of various metal ions and anions on KMnO₄ detection. Electrochemical studies were also performed to analyse the mechanism of complex formation.

Biomass-Derived Carbon Dots and Their Sensing Applications

Carbon dots (CDs) can be widely used in the field of sensing because of its good water solubility, low toxicity, high fluorescence stability and excellent biocompatibility. It has become a popular trend to prepare high-value, inexpensive, renewable and environmentally friendly CDs sensors from biomass resources. This article reviewed the research progress of biomass-derived CDs as chemical, physical and biological sensors in recent years and studied their preparation processes and sensing abilities. Furthermore, the prospects and challenges of biomass-CDs sensors were discussed. This article is expected to provide inspirations for the design, preparation and application of biomass-CDs sensors in the future.

The Influence of Graded Amount of Potassium Permanganate on Corrosion of Hot-Dip Galvanized Steel in Simulated Concrete Pore Solutions

This paper evaluates the amount of KMnO₄ in simulated concrete pore solution (pH 12.8) on the corrosion behaviour of hot-dip galvanized steel (HDG). In the range of used MnO₄^- (10^-4, 10^-3, 10^-2 mol·L^-1), corrosion behaviour is examined with regard to hydrogen evolution and composition (protective barrier properties) of forming corrosion products. The corrosion behaviour of HDG samples is evaluated using R_p/E_corr and EIS. The composition of corrosion products is evaluated using SEM, XRD, XPS and AAS. The effective MnO₄^- ion concentration to prevent the corrosion of coating with hydrogen evolution is 10^-3 mol·L^-1; lower concentrations only prolong the time to passivation (corrosion with hydrogen evolution). The highest used MnO₄^- concentration ensures corrosion behaviour without hydrogen evolution but also leads to the formation of less-protective amorphous corrosion products rich in Mn^II/Mn^III phases.

Complete Inhibition of the Rotation in a Barrierless TICT Probe for Fluorescence-On Qualitative Analysis

Inhibition of twisting intramolecular charge transfer (TICT) is one of the most attractive methods for fluorescence-on analysis, whereas it remains enigmatic whether the fluorescence in a TICT-based probe could be thoroughly lightened. Here, for maximizing the fluorescence-on signal of the TICT-based probe, we develop a model by employing chemical reaction to directly cleave the linkage between the rotational electron donor and acceptor with a predisposed fluorescent signal close to zero. To validate this assumption, a nonfluorescent probe with barrierless rotation is successfully achieved by grafting acryloyl with -C═C- recognition sites onto coumarin, and 7-hydroxycoumarin with bright blue fluorescence could be released within 3 s upon probing KMnO₄ with an amount as low as 0.95 nM and 6.6 pg. We believe that the present strategy could not only deepen the insights of photochemistry but also facilitate the development of a theranostic drug delivery system, energy conversion, pollution control, and health risk reduction.

Analytical quantification of aqueous permanganate: Direct and indirect spectrophotometric determination for water treatment processes

Three spectrophotometric methods have been developed and compared for the quantification of low concentrations (0.03-63 μM) of aqueous permanganate in neutral pH conditions. Although permanganate is a widely used oxidant in drinking water and wastewater treatment, no widely accepted method of quantification has been reported to date. While one method presented does not require the need for any reagent chemicals (direct spectrophotometric analysis), it yielded a relatively low molar absorption coefficient of 3340 M^-1 cm^-1 at 525 nm and a level of detection (LOD) and quantification (LOQ) of 0.45 and 1.51 μM, respectively. Some instability of permanganate species during direct quantification was found to occur over 60 min, with a total decrease of 0.002 (arbitrary units) of absorbance, equivalent to a decrease in concentration of 0.6 μM. Beyond 60 min, no further degradation was observed. Indirect spectrophotometric analyses using 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) and sodium iodide (NaI) provided a significantly more sensitive method for permanganate quantification, yielding molar absorption coefficients of 140,030 and 61,130 M^-1 cm^-1, respectively. The LOD and LOQ were determined to be 0.01 and 0.03 μM for the ABTS method and 0.02 and 0.08 μM for the NaI method, respectively. Although conservative and accurate limits of quantification for both the ABTS and NaI methods are presented, which should be sufficient of most practical applications, lower limits may be possible with further refinement of the methods.

Water-stable LnIII-based coordination polymers displaying slow magnetic relaxation and luminescence sensing properties

Six Ln-CPs were synthesized: Dy-CP shows slow magnetic relaxation, and Eu-CP and Tb-CP exhibit recyclable and multi-responsive sensing for Fe³⁺, MnO₄⁻, Cr^VI-anions (CrO₄²⁻, Cr₂O₇²⁻) and TNP in an aqueous system.

A white-light-emitting lanthanide metal–organic framework for luminescence turn-off sensing of MnO4− and turn-on sensing of folic acid and construction of a “turn-on plus” system

A white-light-emitting lanthanide MOF shows recyclable and dual-responsive sensing for MnO₄⁻ and folic acid in an aqueous system with high selectivity and sensitivity.

Fluorescent N/Al Co-Doped Carbon Dots from Cellulose Biomass for Sensitive Detection of Manganese (VII)

Development of metallic and nonmetallic heteroatom doped carbon dots have gained attention due to their enhanced physicochemical and photoluminescence properties. In this study, a facile one pot hydrothermal carbonisation approach was taken to synthesise nitrogen, aluminum co-doped carbon dots (N/Al-CDs) with a photoluminescence quantum yield of 28.7%. Durian shell, a cellulose biomass waste, was used as the primary carbon source and compared to previously reported cellulose based carbon dots, this study presents one of the highest quantum yields. The structural and fluorescent properties of the synthesised N/Al-CDs were characterized through X-ray photoelectron spectroscopy (XPS), fluorescence spectra, and Fourier transform infrared spectroscopy (FTIR). The maximum emission was at 415 nm upon excitation at 345 nm. The synthesised N/Al-CDs were resistant to photobleaching and highly photostable within the pH, ionic strength and temperature variations investigated. The transmission electron microscopy (TEM) images showed particles were quasi-spherical and well dispersed with an average diameter of 10.0 nm. Further, the N/Al-CDs was developed as a fluorescence sensor for highly selective and sensitive detection of Mn (VII) ions. A linear relationship was developed over a concentration range of 0-100 μM while the limit of detection was 46.8 nM. Application of the sensor for detection of Manganese (VII) to two real water samples showed relative standard deviation was less than 3.9% and 1.3%, respectively.

Series of Water-Stable Lanthanide Metal-Organic Frameworks Based on Carboxylic Acid Imidazolium Chloride: Tunable Luminescent Emission and Sensing

A series of isomorphic lanthanide metal-organic frameworks (Ln-MOFs), {[Ln(L)(H₂O)₂]·5H₂O}_n (1-Ln, where Ln = Eu, Tb, Gd, and Eu_xTb_1-x), have been synthesized by a rigid 1,3-bis(3,5-dicarboxyphenyl)imidazolium chloride (H₄L⁺Cl^-) ligand and Ln³⁺ ions via a solvothermal method. Single-crystal X-ray diffraction indicated that 1-Ln exhibited similar three-dimensional porous frameworks with one-dimensional channels decorated by the uncoordinated carboxylate oxygen atoms. The luminescent sensing studies indicated that 1-Eu is an outstanding reusable luminescent probe suitable for the simultaneous detection of Cr₂O₇^2-, CrO₄^2-, and MnO₄^- ions in an aqueous solution. Remarkably, the different proportions of Eu³⁺ and Tb³⁺ can be combined into the same Ln-MOF to yield a new series of differently doped 1-Eu_xTb_1-x MOFs. At the same excitation wavelength, they generated dual-emission peaks of Eu³⁺ and Tb³⁺ to show a gradual change in luminous color between yellow-green, yellow, orange, orange-red, and red. On the basis of the excellent optical properties of 1-Ln complexes, they can be employed as promising luminescent probe and multicolor tunable photoluminescence materials.

Label-Free, Single-Particle, Colorimetric Detection of Permanganate by GNPs@Ag Core-Shell Nanoparticles with Dark-Field Optical Microscopy

Rapid quantification of permanganate (MnO₄^-) in aqueous solution with a convenient and sensitive single-particle-detection (SPD) method is demonstrated by dark-field optical microscopy. The design is based on the selective etching of the Ag shell of a glucose-protected GNPs@Ag nanoparticle by MnO₄^-. In the presence of MnO₄^-, a noticeable red-shift of localized surface-plasmon resonance (LSPR, from blue to green) together with a tremendous decrease in the extinction coefficient from individual GNPs@Ag nanoparticles is observed. MnO₄^- can then be quantified by calculating the ratio between the number of green and blue particles on the cover glass surface after the etching process. A linear dynamic range of 0-6 μM and a limit of detection (LOD) as low as 46 nM were readily achieved, which are much lower than those of spectroscopic measurements in bulk solution. In tap water, a comparable LOD (50 nM) and satisfactory recovery efficiency are demonstrated. As a consequence of these merits, the method demonstrated herein will find promising applications for the ultrasensitive detection of MnO₄^- under complex milieu in the future.

Absorption of Ethylene on Membranes Containing Potassium Permanganate Loaded into Alumina-Nanoparticle-Incorporated Alumina/Carbon Nanofibers

Ethylene is a natural aging hormone in plants, and controlling its concentration has long been a subject of research aimed at reducing wastage during packaging, transport, and storage. We report on packaging membranes, produced by electrospinning, that act as efficient carriers for potassium permanganate (PPM), a widely used ethylene oxidant. PPM salt loaded on membranes composed of alumina nanofibers incorporating alumina nanoparticles outperform other absorber systems and oxidize up to 73% of ethylene within 25 min. Membrane absorption of ethylene generated by avocados was totally quenched in 21 h, and a nearly zero ethylene concentration was observed for more than 5 days. By comparison, the control experiments exhibited a concentration of 53% of the initial value after 21 h and 31% on day 5. A high surface area of the alumina nanofiber membranes provides high capacity for ethylene absorption over a long period of time. In combination with other properties, such as planar form, flexibility, ease of handling, and lightweight, these membranes are a highly desirable component of packaging materials engineered to enhance product lifetime.