Propanesulfonic Acid Research Articles

RuSiNPs@N,S-GQDs as self-enhanced anodic electrochemiluminescent immunobeacons for the highly sensitive quantitation of okadaic acid in shellfish.

Acompetitive electrochemiluminescence (ECL) immunosensor isproposed to accurately and rapidly assess okadaic acid (OA) levels in shellfish using a novel self-reinforced solid-state ECL marker, which is essential for ensuring seafood safety. Graphene quantum dots doped with nitrogen and sulfur (N,S-GQDs) were synthesized, for the first time, through the electrolysis of graphite in 3-(N-morpholine) propane sulfonic acid solution. Intriguingly, these N,S-GQDs exhibited exceptional co-reactant properties, significantly enhancing the anodic ECL performance of Ru(bpy)32+ in a phosphate-buffered saline solution. Following the functionalization of Ru(bpy)32+-doped silica nanoparticles (RuSiNPs) with poly(diallyldimethylammonium) chloride, we achieved a well-dispersed assembly of N,S-GQDs on the exterior of the RuSiNPs through electrostatic interactions. Importantly, the core-shell structure of RuSiNPs@N,S-GQDs efficiently encapsulated both the luminophore and co-reactant, thus improving the transfer rates of electrons, shorting interaction distances, and reducing energy loss during light emission. Leveraging this "bright" ECL beacon, theECL immunosensor demonstrated remarkable analytical performance, yielding a low half maximal inhibitory concentration (IC50) of 0.14ngmL-1, an extensive linear range spanning 0.003-40ngmL-1, and impressively low limit of detection of 0.001ngmL-1 for OA determination.

MoS2 nanosheet assisted poly vinyl alcohol cross-linked with carboxylated acryl-amido-2-methyl-1-propanesulfonic acid in medium temperature proton exchange membrane fuel cell application

ABSTRACT Initially, the carboxylated-acryl amido propane sulfonic acid (C-AMPSA) was synthesized through the thiol-ene reaction using 2-acrylamido-2-methylpropane sulfonic acid and 3-mercapto propane sulfonic acid monomers. The C-AMPSA was cross-linked with polyvinyl alcohol to create a non-perfluorinated membranes were of these acid group-containing monomers. Using a cross-linking technique, a poly vinyl alcohol cross-linked C-AMPSA (PVA-C-AMPSA) polymer was prepared. Following that, the MoS2 nanosheets (NSs) were synthesized through the one-pot hydrothermal method, and their phase purity, functionality, and morphology were evaluated by p-XRD, FT-IR, and FE-SEM analyses. These nanosheets were then incorporated into PVA-C-AMPSA polymer nanocomposite membranes at various concentrations (0%, 1%, 2%, 3%, and 5% by weight). In addition, the physicochemical properties of bare and MoS2 nanosheets incorporated PVA-C-AMPSA polymer nanocomposite membranes were assessed, including water uptake, swelling ratio, and ion-exchange capacity. Remarkably, the membrane with 5% of MoS2 NSs in PVA-C-AMPSA displayed an ion-exchange capacity of 1.13 mmol g−1 and a proton conduction of 1.8 × 10−3 S cm−1 at 110°C. The Arrhenius plot indicated that the proton transport was involved in both Grotthuss and vehicular mechanisms. In the fuel cell testing, the PVA-C-AMPSA polymer nanocomposite membrane containing MoS2 NSs demonstrated superior performance, achieving a peak power density (PD) exceeding 0.7 W cm−2 and an open-circuit voltage (OCV) surpassing 0.93 V at 110°C. In contrast, the pure PVA-C-AMPSA membrane exhibited a peak PD of over 0.4 W cm−2 and an OCV of around 0.6 V at the same temperature. Additionally, the 5% of MoS2 NSs incorporated PVA-C-AMPSA polymer nanocomposite membrane exhibited outstanding oxidative stability with 87.7% of degradation when exhibited to a Fenton reagent at 80°C for 8 h.

Facile Determination of Aluminum Content in Industrial Brine by Investigating the Effects of Buffer Systems.

The aluminum content of concentrated (27 wt%) sodium chloride solutions could be crucial for large-scale chlor-alkali-based industries applying membrane cell electrolysis. Thus, a facile method which enables a fast and reliable protocol to determine the Al content of these solutions on ppb scale in industrial environments is fundamentally important. It was demonstrated that the increased sensitivity of colorful Al-ECR (eriochrome cyanine R) complex by the use of a cationic surfactant and specific biological buffers could effectively indicate the Al content in an extended pH interval of a concentrated saline medium under industrial conditions. The dependence of the analytical protocol on pH, temperature, time, wavelength, and the salinity of the medium was investigated. It was shown that the absorbance-based measurements of the solution should be performed at least 2-4 h after its preparation. By applying the selected two Good's buffers (HEPES: 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid, MOPS: 3-(N-morpholino)-propanesulfonic acid) and Tris (tris(hydroxymethyl)aminomethane), 32.8-38.1 % increase in the sensitivity was achieved for saturated NaCl solutions. Moreover, the limits of detection and quantification (LOD, LOQ) were also lowered by 19.0-29.8 %, and the salinity dependence of the calibration was also reduced.

Electrochemical Studies of Gold in Mops Buffer System

Recent work in this laboratory has investigated interactions of L-cysteine with metal ions.1 For this purpose the MOPS [(3-N-morpholino)propanesulfonic acid] aqueous buffer system has been employed in order to minimize interactions between the metal ions and buffer anions.2 Gold electrodes are expected to be useful in the investigation of L-cysteine and related substances,3 so it is useful to ascertain the background behavior of gold in the aqueous MOPS buffer system. It is the purpose of the present work to determine the voltammetric features in this situation for use in amino acid/metal ion studies.As shown in the accompanying figure, an initial positive-going sweep has a very small oxidation process at +0.45 V vs Ag/AgCl, presumably for the initial oxidation of the gold surface in pH 7.4 MOPS buffer. As this sweep continues, a much larger cathodic process corresponding to bulk gold oxidation is observed. On the return negative-going sweep, there is only a reduction process corresponding to the initial surface oxidation process. It is interesting to note that this reduction process is not observed upon reversing the sweep at only +0.50 V. On the second scan, the initial oxidation process has increased, possibly due to surface roughening in the first scan. Another investigation has involved addition of EDTA to the MOPS solution, resulting in an increase of the second (or bulk) gold oxidation process. This increase is apparently due to the ability of the EDTA to complex the gold cations formed in the oxidation process. This overall behavior is somewhat different compared to that found in other buffer systems such as phosphate,3 and contrasts to such behavior are planned for presentation in this talk. T. Cheek and D. Peña, J. Electrochem. Soc., 167, 155522 (2020).M. H. Ferreira, I. S. S. Pinto, E. V. Soares, and H. M. V. M Soares, RSC Advances, 5(39), 30989 (2015). G.T. Cheek and M.A. Worosz, ECS Trans., 72(27), 1 (2016). doi:10.1149/07227.0001ecst Figure 1

Electrochemical and Spectroscopic Investigations of Bismuth(III) Pharmaceuticals with L-Glutathione

Due to the importance of L-cysteine in the human system, the interaction of metals with this amino acid are worthy of investigation by various methods. In this laboratory1, we have investigated the interaction of bismuth(III) compounds with L-cysteine by both cyclic voltammetry and UV-VIS spectroscopy in an attempt to understand the role of bismuth in treating gastrointestinal maladies.2 The addition of bismuth(III) compounds to solutions of L-cysteine causes a negative potential shift for bismuth(III) reduction as an indication of complex formation between bismuth(III) and L-cysteine. This interaction is also evident by the appearance of a UV-VIS spectroscopic band at 340 nm (Bi-sulfur bond). Even at low pH values (pH 1.0), electrochemical studies show evidence of some kind of interaction even when there is no 340 nm band. These investigations have been conducted at pH 1.00 and 3.00 to simulate conditions in the human stomach and at pH 7.40 MOPS [(3-N-morpholino)propanesulfonic acid] to simulate general physiological conditions, in particular the intestinal tract. Recent work has involved extension of this work to L-glutathione, a tripeptide incorporating L-cysteine, under similar conditions. As might be expected, these interactions are considerably more complicated than those involving L-cysteine. As an example, there is a considerable positive potential shift for the reduction of bismuth(III) citrate in the presence of L-glutathione on the first and second voltammetric sweeps at gold and glassy carbon electrodes. This behavior evidently reflects the rather long (several seconds) time required for the re-formation of the bismuth complex with L-glutathione after its reductive ligand (L-glutathione) loss during bismuth(III) reduction on the first sweep. In addition, there is evidence of a film buildup on the electrode surface as observed by peak current increases during multiple potential sweeps. These observations are planned for inclusion in this symposium presentation.References T. Cheek and D. Peña, J. Electrochem. Soc., 167, 155522 (2020)Li, R. Wang, and H. Sun, Acc. Chem. Res., 52, 216 (2019).

Concentration-induced spontaneous polymerization of protic ionic liquids for efficient in situ adhesion

The advancement of contemporary adhesives is often limited by the balancing act between cohesion and interfacial adhesion strength. This study explores an approach to overcome this trade-off by utilizing the spontaneous polymerization of a protic ionic liquid-based monomer obtained through the neutralization of 2-acrylamide-2-methyl propane sulfonic acid and hydroxylamine. The initiator-free polymerization process is carried out through a gradual increase in monomer concentration in aqueous solutions caused by solvent evaporation upon heating, which results in the in-situ formation of a tough and thin adhesive layer with a highly entangled polymeric network and an intimate interface contact between the adhesive and substrate. The abundance of internal and external non-covalent interactions also contributes to both cohesion and interfacial adhesion. Consequently, the produced protic poly(ionic liquid)s exhibit considerable adhesion strength on a variety of substrates. This method also allows for the creation of advanced adhesive composites with electrical conductivity or visualized sensing functionality by incorporating commercially available fillers into the ionic liquid adhesive. This study provides a strategy for creating high-performance ionic liquid-based adhesives and highlights the importance of in-situ polymerization for constructing adhesive composites.

MoS2/graphene dispersed 2‐acrylamide‐2‐methyl propane sulfonic acid grafted polyarylene ether of di‐phenylenedi‐acetal high temperature‐proton exchange membrane fuel cell application

AbstractA polyaryleneether has been synthesized from bis‐(4‐cholorophenyl)di‐acetal (DPDA) monomer with bisphenol A and allyl bisphenol‐A. The copolymer was then functionalized with 2‐acrylamide‐2‐methyl propane sulfonic acid through radical grafting (SPAE/DPDA). The successfully synthesized SPAE/DPDA polymer was validated by using FTIR and NMR. Secondly, a composite nanostructure of MoS2/GNS nanosheet has been prepared and characterized using PXRD, FE‐SEM, and HR‐TEM. The composite membrane casted with SPAE/DPDA and varying weight percentage of 1%, 2%, 3%, 5%, 7%, and 10% MoS2/GNS nanosheet, has been characterized for ion exchange capacity (IEC), water stability (WU), swelling properties (SR), oxidative stability, and proton conductivity (PC).The MoS2/GNS dispersed SPAE/DPDA polymer nanocomposites membrane showed a chemical degradation of 22.56% and proton conductivity (PC) of 2.5 × 10−2 S/cm at 110°C. The results show that these membranes have high proton conductivity and can be used in proton exchange membrane fuel cells (HT‐PEMFCs).

A Simple Fluorescence Sensor Based on Merocyanine 540-MnO2 System to Detect Hypochlorite

Merocyanine 540 (MC540)- Manganese oxide (MnO2) system-based fluorescence sensor is reported as an anion sensor in aqueous solution. MnO2 was synthesized in the presence of Potassium permanganate (KMnO4) and Cetyltrimethylammonium bromide (CTAB) using 3-(N-morpholino) propane sulfonic acid (MOPS) buffer. The formation of MnO2 was first confirmed by a color change and characterized using X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and Ultraviolet–Visible (UV–Vis). absorption spectroscopy techniques. Next, the interaction of MC540 with MnO2 in aqueous solution was investigated at various conditions by UV–Vis. absorption and fluorescence spectroscopy. The sensing ability of the MC540-MnO2 was tested to detect hypochlorite (ClO-) ion as a “Turn-off” fluorescent sensor. The MC540-MnO2 revealed to be high selectivity and sensitivity to detect hypochlorite (ClO-) ion without being affected by the other thirteen anions. The detection limits for ClO- were evaluated in two different concentration ranges and calculated to be 0.14 μM at 0.33-4.46 μM and 0.38 μM at 5.06-14.30 μM, respectively.

Buffer-Dependent Photophysics of 2-Aminopurine: Insights into Fluorescence Quenching and Excited-State Interactions.

2-Aminopurine (2AP) is the most widely used fluorescent nucleobase analogue in DNA and RNA research. Its unique photophysical properties and sensitivity to environmental changes make it a useful tool for understanding nucleic acid dynamics and DNA-protein interactions. We studied the effect of ions present in commonly used buffer solutions on the excited-state photophysical properties of 2AP. Fluorescence quenching was negligible for tris(hydroxymethyl)aminomethane (TRIS), but significant for phosphate, carbonate, 3-(N-morpholino) propanesulfonic acid (MOPS), and 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffers. Results indicate that the two tautomers of 2AP (7H, 9H) are quenched by phosphate ions to different extents. Quenching by the H2PO4- ion is more pronounced for the 7H tautomer, while the opposite is true for the HPO42- ion. For phosphate ions, the results of the time-resolved fluorescence study cannot be explained using a simple collisional quenching mechanism. Instead, results are consistent with transient interactions between 2AP and the phosphate ions. We postulate that excited-state interactions between the 2AP tautomers and an H-bond acceptor (phosphate and carbonate) result in significant quenching of the singlet-excited state of 2AP. Such interactions manifest in biexponential fluorescence intensity decays with pre-exponential factors that vary with quencher concentration, and downward curvatures of the Stern-Volmer plots.

Fabrication and characterization of tamarind seed gum based novel hydrogel for the targeted delivery of omeprazole magnesium

The tamarind seed gum based novel hydrogel was fabricated by varying concentration of polymer, monomer and crosslinker for the targeted delivery of omeprazole magnesium at stomach pH of 1.5. The free radical graft copolymerization of 2-acrylamido-2-methyl propane sulfonic acid with tamarind seed gum backbone resulted in hydrogel. The formation of sulfonic acid pendant groups in hydrogel was observed by the existence of an infrared absorption band at 1152 cm−1 for SO group. The conversion to semicrystalline nature on incorporation of drug evidenced by powder X-ray diffraction studies with peaks at 2θ = 20.4° 31.5° and 52.2°. The scanning electron microscopy images showed bigger voids which narrowed down for drug loaded matrix, supported by the presence of a peak for magnesium in the energy dispersive X-ray spectroscopy. The greatest swelling was observed at pH 7 with second-order rate constant 1.5371 (g/g)/min and drug release was found to be 97.85 ± 1 % over 1200 min at pH 1.5. The drug release transport was found combination of diffusion and erosion of polymer chain to be super case II diffusion and Hill equation model was good fit. The hydrogel drug conjugate found to be non-toxic at tested concentrations (17 mg/50 mg) on in-vivo testing in Drosophila model.

Preparation of the modified chitosan flocculant introduced acryloyloxyethyl trimethyl ammonium chloride and 2-acrylamido-2-methyl propane sulfonic acid for the treatment of papermaking wastewater

To solve the shortcomings of poor solubility, low cationic strength, and small molecular weight of chitosan (CTS), acryloyloxyethyl trimethyl ammonium chloride (DAC) and 2-acrylamido-2-methylpropanesulfonic acid (AMPS) were introduced into the amino group of chitosan by graft copolymerization, and the modified chitosan flocculant CTS-DAC-AMPS was successfully prepared. The performance of CTS-DAC-AMPS in the treatment of papermaking wastewater was investigated, and the mechanism of the flocculation process was analyzed. The results showed that the crystal habit of CTS-DAC-AMPS was reduced, and the solubility range was broadened compared with CTS due to the introduction of DAC and AMPS. In addition, CTS-DAC-AMPS with quaternary ammonium and sulfonic groups prompted its cationic strength stronger than CTS. In addition to high thermal stability, CTS-DAC-AMPS, composed of two CTS molecules, one DAC molecule, and one AMPS molecule, had a long molecular chain. The results of flocculation experiments showed that the performance of CTS-DAC-AMPS in treating papermaking wastewater was better than that of unmodified CTS and commercially available flocculants. Based on the experimental results, the mechanism of CTS-DAC-AMPS treatment of papermaking wastewater was mainly charge neutralization.

The Good pH probe: non-invasive pH in-line monitoring using Good buffers and Raman spectroscopy

In bioprocesses, the pH value is a critical process parameter that requires monitoring and control. For pH monitoring, potentiometric methods such as pH electrodes are state of the art. However, they are invasive and show measurement value drift. Spectroscopic pH monitoring is a non-invasive alternative to potentiometric methods avoiding this measurement value drift. In this study, we developed the Good pH probe, which is an approach for spectroscopic pH monitoring in bioprocesses with an effective working range between pH 6 and pH 8 that does not require the estimation of activity coefficients. The Good pH probe combines for the first time the Good buffer 3-(N-morpholino)propanesulfonic acid (MOPS) as pH indicator with Raman spectroscopy as spectroscopic technique, and Indirect Hard Modeling (IHM) for the spectral evaluation. During a detailed characterization, we proved that the Good pH probe is reversible, exhibits no temperature dependence between 15 and 40 °C, has low sensitivity to the ionic strength up to 1100 mM, and is applicable in more complex systems, in which other components significantly superimpose the spectral features of MOPS. Finally, the Good pH probe was successfully used for non-invasive pH in-line monitoring during an industrially relevant enzyme-catalyzed reaction with a root mean square error of prediction (RMSEP) of 0.04 pH levels. Thus, the Good pH probe extends the list of critical process parameters monitorable using Raman spectroscopy and IHM by the pH value.Graphical abstract

γ-Glutamyl transpeptidase activatable probe for fluorescence-assisted guiding surgery and imaging of human tumors via spraying

γ-Glutamyltranspeptidase (GGT) is an ectoenzyme anchored on the surface of the cell membrane, and it is closely associated with many diseases. Abnormal expression (>36 U/L) of GGT is involved in the progression of tumors and can act as a biomarker for tumor diagnosis. Here, we presented a series of GGT-activatable fluorescent probes, the P1, the P2 and the P3. By investigating the in vitro properties of the probes, P3 demonstrated the most sensitivity and better water solubility, which benefited from the introduction of the self-elimination moiety of p-aminobenzyl alcohol and the propanesulfonic acid moiety. Importantly, P3 was able to clearly delineate tumor boundaries in live tumor-bearing mice and clinical human liver tissue specimens by spraying in situ, which facilitated accurate resection of tumors under fluorescence guidance. The proposed enzyme-activated fluorescent probe has potential as a surgical resection tool in image-guided surgery.

Electrochemical and Spectroscopic Investigations of L-Glutathione with Bismuth Pharmaceuticals

Introduction The electrochemical and spectroscopic investigation of bismuth(III) compounds with L-cysteine has been carried out in this laboratory since our initial publication.1 Cyclic voltammetry has shown that the interaction of L-cysteine with bismuth nitrate, bismuth salicylate, and bismuth citrate increases the solubility of these compounds by complexation with L-cysteine, thereby increasing the reduction current for the bismuth complexes formed. The appearance of a UV-VIS spectroscopic band at 340 nm indicates the formation of a Bi-S bond, the sulfur being supplied by the L-cysteine. These investigations have been conducted at pH 1.00 and 3.00 to simulate conditions in the human stomach and at pH 7.40 MOPS [(3-N-morpholino)propanesulfonic acid] to simulate general physiological conditions, in particular the intestinal tract. In this presentation, continuing studies of L-glutathione, a tripeptide incorporating L-cysteine, under these conditions shall be discussed. This work is applicable to the important field of bismuth pharmaceuticals as a means of understanding the interaction of these compounds under various conditions in the human digestion system.2 Results and Discussion Initial studies of L-glutathione with bismuth nitrate, bismuth salicylate, and bismuth citrate have been carried out under conditions similar to those of our initial work.1 It has been found that the general characteristics of the cyclic voltammograms for L-glutathione (GSH) are similar to those for L-cysteine; however, the slower rate of complexation of GSH with these bismuth compounds is evident in the changes in voltammetric features in successive sweeps. In the case of GSH addition to bismuth citrate in pH 7.4 MOPS buffer, for instance, the first sweep shows reduction of the bismuth:GSH complex at -0.71 V vs Ag/AgCl at a gold electrode, whereas a reduction process at -0.60 V is observed on the second sweep. Similar results are obtained at glassy carbon. The bismuth:GHS complex is destroyed during the reduction process as a bismuth film forms on the electrode surface. The following sweep, then, is indicative of the complexation environment in solution at that point. The bismuth ion, restored in the stripping step, apparently does not have time in the few seconds after the stripping process to fully form a complex with GSH. The observed reduction potential around -0.60 V is due to the reduction of another bismuth complex, perhaps with citrate. Further investigations are in progress to more fully describe this situation.References G. T. Cheek and D. Peña, J. Electrochem. Soc., 167, 155522 (2020)H. Li, R. Wang, and H. Sun, Acc. Chem. Res., 52, 216 (2019).

A quick, easy and efficient protocol for extracting high-quality RNA from Mycobacterium tuberculosis using a spin column commercial kit

RNA extraction from Mycobacterium tuberculosis has been a historically challenging task for researchers due to the thick lipids associated with the cell wall of this “notorious” pathogen that is responsible for Tuberculosis (TB) outbreaks. Several studies have successfully extracted RNA from M. tuberculosis using a Trizol reagent combined with organic solvents. Recently, our laboratory has successfully extracted high quality total RNA using a commercial kit from clinical strains belonging to F15/LAM4/KZN, Beijing and F11 strain families and H37Rv laboratory strain by exploiting high speed homogenizer for cell lysis and spin columns for RNA purification. The quality and integrity of the extracted RNA was analyzed and confirmed through the Nanodrop, Bioanalyzer and RNA 3-(N-morpholino) propanesulfonic acid (MOPS) gel electrophoresis. Furthermore, to confirm the integrity of small RNA (sRNA) molecules due to their vulnerability to degradation, the RNA samples were converted to cDNA and sRNAs were amplified and confirmed through PCR. This detailed RNA extraction protocol proposes to carve a new path into TB transcriptome research without the use of organic solvent for downstream purification steps while yielding high quality RNA that can be used to understand M. tuberculosis transcriptome regulation.

Liquid–Liquid Equilibria of Butyric Acid, Water, and Methyl Isobutyl Ketone with the Aid of Biological Buffer as a Green Auxiliary Agent

Biological buffer has a significant impact on aqueous organic phase equilibria in extraction processes. This study investigated the effect of biological buffer on the efficacy of butyric acid extraction from aqueous solution utilizing methyl isobutyl ketone (MIBK) as the extraction solvent. The liquid–liquid equilibria (LLE) of quaternary systems of methyl isobutyl ketone (MIBK) + butyric acid + water + biological buffer MOPS [3-(N)-morpholino propane sulfonic acid], HEPES (2-(4-(2-hydroxyethyl)-1-piperazinyl)ethanesulfonic acid), or EPPS (4-(2-hydroxyethyl)-1-piperazine propanesulfonic acid) were determined at temperature T = 303.15 K (30 °C) and P = 0.1 MPa (atmospheric pressure). The addition of EPPS to the butyric acid aqueous solution resulted in superior extraction efficacy compared to the other biological buffers, as determined by experimental data. Generally, the extraction performance was in the order EPPS > MOPS > HEPES, which represented the buffering-out strength as well. The non-random two-liquid (NRTL) and UNIversal QUAsi Chemical (UNIQUAC) models fit well with the actual LLE data of the quaternary systems. The σ-profile analysis was also evaluated in this study. Additionally, a potential process flow sheet using biological buffer and MIBK solvent was suggested for removing butyric acid from its aqueous solution.

Mechanistic Insights into Superoxide Dismutation Driven by Dinuclear Manganese Complexes: The Role of the Mn2-Core

The dinuclear Mn2(II,II)L2-core (HL = 2-{[[di(2-pyridyl)methyl](methyl)amino]-methyl}phenol) has been recently reported to be the most active dual superoxide dismutase (SOD) and catalase (CAT) functional analogue, enabling cascade detoxification of the superoxide radical anion. Here, we investigated the mechanism of catalytic O2•– decomposition by two stereoisomers with the Mn2(II,II)L2-core, Mn2L2Ac and Mn2L2, in order to (i) precisely determine the catalytic SOD activity of the complexes, (ii) characterize the key intermediates involved in the dismutation process, and (iii) discriminate between single- and di-Mn center catalysis in relation to the configuration of the Mn2-core. The conclusions drawn from low-temperature mass spectrometry, stopped-flow kinetics, cyclic voltammetry, water exchange 17O nuclear magnetic resonance (NMR), and electron paramagnetic resonance (EPR) analyses were supported by the structural characterization and quantum chemical analysis of the proposed reaction intermediates. This study allows us to determine kcat for Mn2L2Ac and Mn2L2 (4.6 × 107 and 2.2 × 107 M–1 s–1, respectively, in 3-(N-morpholino)propanesulfonic acid (MOPS) at pH = 7.4) and detect the key intermediates involved in the catalytic cycle driven by these Mn2-SOD mimics, highlighting the formation of a side-on η2–Mn2(III,II)–peroxo, as an initial intermediate. The effects of the Mn2(II,II)-core configuration on the SOD activity were discussed.

A porcine bladder model of pre-clinical urodynamics demonstrates increased afferent nerve activity during filling.

Urodynamics are the accepted gold standard for the evaluation of multiple forms of voiding dysfunction. However, the tests are expensive, invasive, poorly reproducible, and often prone to artifacts. Therefore, there is a pressing need to develop next-generation urodynamics. The purpose of this study was to develop a novel ex vivo porcine bladder urodynamics model with afferent pelvic nerve signaling that can be used as a preclinical surrogate for bladder sensation. Porcine bladders including the ureters and vascular supply were harvested from local abattoirs using an established protocol in both male and female animals. Ex vivo bladder perfusion was performed using physiologic MOPS (3-(N-morpholino) propanesulfonic acid) buffer solution. The pelvic nerve adjacent to the bladder was grasped with micro-hook electrodes and electroneurogram (ENG) signals recorded at 20 kHz. Bladders were filled with saline at a nonphysiologic rate (100 mL/min) to a volume of 1 L using standard urodynamics equipment to simultaneously record intravesical pressure. ENG amplitude was calculated as the area under the curve for each minute, and ENG firing rate was calculated as number of spikes (above baseline threshold) per minute. At the conclusion of the experiment, representative nerve samples were removed and processed for nerve histology by a pathologist (hematoxylin and eosin and S100 stains). A total of 10 pig bladders were used, and nerve histology confirmed the presence of nerve in all adequately processed samples. Vesical pressure, ENG firing rate, and ENG amplitude all increased as a function of filling. During filling tertiles (low fill: min 1-3, med fill: min 4-6, and high fill: min 7-10), normalized pressures were 0.22 ± 0.04, 0.38 ± 0.05, and 0.72 ± 0.07 (cmH2O). Similarly, normalized ENG firing rates were 0.08 ± 0.03, 0.31 ± 0.06, and 0.43 ± 0.04 spikes/minute, respectively, and normalized nerve amplitudes were 0.11 ± 0.06, 0.39 ± 0.06, and 0.56 ± 0.14) μV, respectively. Strong relationships between average normalized pressure values and averaged normalized ENG firing rate (r2 = 0.66) and average normalized ENG amplitude (r2 = 0.8) were identified. The ex vivo perfused porcine bladder can be used as a preclinical model for the development of next-generation urodynamics technologies. Importantly, the model includes a reproducible method to measure afferent nerve activity that directly correlates with intravesical pressure during filling and could potentially be used as a surrogate measure of bladder sensation.

L-DOPA Assay of Polyphenol Oxidase (PPO) for Varietal Identification in Rice (Oryza sativa L.)

A phenol colour response test on the grain is used to identify varieties of wheat and rice. It is a harmful, damaging procedure due to the carcinogenic properties of phenol. The activity of polyphenol oxidase (PPO) provides the basis for the phenol colour reaction. The goal of this research was to assess a method similar to the phenol colour reaction, by determining where the polyphenol oxidase activity threshold lies for classifying rice types into different groups. The new PPO assay was applied to commercially available rice varieties with the intention of classifying those that ranged from extremely high to extremely low PPO levels into manageable categories. Substrates such as phenol, L-tyrosine, catechol and 3,4-dihydroxyphenylalanine (L-DOPA) were tested. Twenty cultivars cultivated under identical conditions were put through a screening using a standard assay [1.5 mL of 10 mM L-DOPA in 50 mM 3-(N-morpholino) propane sulphonic acid (MOPS) buffer, pH 6.5, with 3 to 5 seeds constantly rotated in a 2-mL microcentrifuge tube for 0.5 or 1 hour at room temperature]. At 30 minutes, PPO levels were assessed. Based on the PPO values, the varieties belonging to phenol colour groups such as black, dark brown, brown, light brown or no colour matched perfectly. Considering easiness in estimation and other advantages of PPO activity, L-DOPA is proposed as a means of identifying rice varieties instead of the phenol colour reaction test.

Employment and performance of modified chitosan for the removal of copper ions and methylene blue in wastewater

AbstractExploring new and efficient adsorbents for the purification of water from heavy metals and organic waste to provide clean drinking water is highly demanded. Herein, the synthesis of polymeric materials based on grafting chitosan (Cs) by various acrylic monomers as acrylic acid (AA), 2‐acrylamide‐2‐methyl propane sulfonic acid (AMPS), and acrylamide (Am) namely S1, S2, or S3, respectively, using methylene bisacrylamide (NMBAm) as crosslinker was performed. The formed polymeric compound was characterized by utilizing Fourier transform infrared spectroscopy, scanning electron microscopy, energy dispersive X‐ray, and Brunauer–Emmett–Teller. It was determined that S2 possessed a higher specific surface area of 109.133 m2/g, which is higher than S1 (71.2553 m2/g) and S3 (62.8847 m2/g). The as‐prepared polymeric compounds were utilized for the removal of copper ions (Cu2+) and methylene blue (MB) from wastewater in the absence and presence of UV light irradiation. The kinetic study and the adsorption isotherms for the removal of Cu2+ and MB as organic pollutants using the as‐prepared polymeric compound were studied.