Kinetic Plots Research Articles

Designing pH-Responsive alizarin hybrids with easily tunable physicochemical properties via polymer grafting

This study focuses on the synthesis and characterization of novel pH-sensitive color materials based on alizarin, (1,2-dihydroxyanthraquinone), a natural pigment with versatile properties. The polymer-based indicators were prepared by grafting poly(methyl methacrylate) (PMMA) and poly(2-hydroxyethyl methacrylate) (PHEMA) from alizarin through an ester pH-liable bond, allowing for easy tunability of their physicochemical properties. The synthesis process involved the esterification of alizarin using 2-bromo-2-methylpropionyl bromide, facilitated by triethylamine as an acid scavenger. The resulting alizarin served as a difunctional initiator for atom transfer radical polymerization (ATRP) of methyl methacrylate and 2-hydroxyethyl methacrylate. The molecular structures of the synthesized hybrids were confirmed using 1H NMR and GPC analyses. The color characteristic, surface energy, thermal stability, and pH sensing activity of the alizarin-based hybrids were studied according to the type of grafted polymer nature as well as their degree of polymerization. PHEMA-grafted alizarin showed more rapid and more visible color changes under the influence of NH3 vapours compared to PMMA hybrids, due to their less hydrophobic nature. Furthermore, kinetic plots demonstrated various hydrolysis rates, with PMMA hydrolysis being slower than that of PHEMA due to its stronger hydrophobic character. UV–Vis spectra and GPC traces confirmed the occurrence of hydrolysis and successful cleavage of the ester bond links between the grafted polymers and alizarin with a decrease of the molar mass by a factor of two as expected. Such behavior offers opportunities for tailoring degradation profiles and achieving specific release profiles upon application of a wide range of polymers with varied character. The designed polymer-based pigments exhibited a high ability to monitor calorimetrically the pH changes, especially in alkaline conditions. Overall, this study contributes to the broadening of the application of alizarin-based materials, paving the way for further exploration and development in the field of functional materials.

Enhanced photocatalytic degradation of organic pollutants by green-synthesized gold nanoparticles using polysaccharide for environmental remediation

The recent rise in textile dye wastewater discharge into the environment has detrimental effects on living organisms and human health. The present study reports a facile approach to green-synthesized AuNPs employing sesbania gum for catalytic and photocatalytic degradation of organic pollutants. The obtained AuNPs were characterized by various techniques such as UV–vis, FT-IR, SEM, TEM, AFM, zeta potential, LC-MS, and XPS. The XRD patterns revealed a highly crystalline and face-centered cubic structure. XPS and EDX analysis defined the chemical composition and product purity of SBG-AuNPs. Photocatalytic degradation of hazardous dyes congo red and safranin-O using SBG-AuNPs showed a rapid decomposition rate with 94.69 % under visible light irradiation. The effect of pH, dye concentration, and catalyst dose on photodegradation and recyclability was also studied. The kinetic plots were used to calculate the rate constant, showing a pseudo-first-order reaction. Scavenger trap experiments confirmed the role of h+ and superoxide(.O2−) as active species, and LCMS analysis was used to identify the degradation intermediates. The catalytic reduction of SBG–AuNPs was studied for brilliant green (BG) and methylene blue (MB) in the presence of NaBH4, resulting the degradation efficiency of 90.37 % and 84.52 %, respectively. This study presents an innovative approach for designing highly efficient photocatalysts for environmental remediation and wastewater treatment from textile dyes.

Abstract 4722: Enhanced phenotypic screening: A kinetic, multiplexed approach to analyzing drug effects using Incucyte® Live-Cell Analysis System

Abstract Phenotypic screening is a valuable tool for analysis of the complex mix of effects that drug treatment has on cells. Traditionally image-based screening uses fixed cells stained with reagents at a pre-chosen end point, however our technique combines kinetic, label-free readouts with non-perturbing fluorescence reporters to enable information-rich quantification of compound effects. A549 lung cancer cells were treated with a library of over 800 FDA-approved drugs while images were acquired in the Incucyte® Live-Cell Analysis System every two hours for four days. Cell growth and viability were measured using label-free readouts of confluence and dead cell count while cell cycle, cell death and Akt pathways were investigated using multiplexed fluorescent readouts. Cytotoxicity was measured using label-free Incucyte® AI Cell Health Analysis Software Module which uses two neural networks to segment individual cells and classify them as live or dead. Assay robustness was quantified using the time course of positive and negative controls (camptothecin and vehicle, respectively). Z’ reached a maximal value >0.9 between 48h and 72h; at 72h 4.4% of the compounds within the library induced >50% cell death. Correlation between % Live cells and % Confluence indicated 3 types of effect: cytotoxic (low viability, low confluence), cytostatic (high viability, low confluence), and none (high viability, high confluence). Morphological changes were observed in a multitude of wells with 29 compounds inducing cell enlargement >1800 µm2, suggesting induction of senescence. Hits from fluorescent readouts were identified as the compounds which perturbed the quantified readout more than 3 standard deviations away from the mean value of the vehicle. Mechanisms of cell death were examined by correlative analysis of the total dead cell population (label-free cell death identification), caspase-active (caspase 3/7-reagent positive) and Annexin V positive cells. This enabled rapid identification of compounds which induced apoptosis by caspase-independent pathways, including the serotonin-selective reuptake inhibitor Sertraline. Kinetic plots of cell cycle stage (% S|G2|M or G1) revealed contrasting mechanisms. Mycophenolic acid induced cell cycle arrest, observed as a consistent increase in the percentage of cells in G1 over time. However flumazenil displayed repeated, transient peaks in the percentage of cells in S|G2|M over the same 72h period, indicating synchronisation behavior. Incucyte® Live-Cell Analysis System as a phenotypic screening platform provides valuable kinetic data from cells within the physiologically relevant environment of a standard incubator. Label-free readouts yield direct cellular information and can be combined with fluorescent data to provide vastly more information than a single endpoint readout. Citation Format: Kirsty McBain, Gillian Lovell, Jasmine Trigg, Nicola Bevan, Daniel Appledorn. Enhanced phenotypic screening: A kinetic, multiplexed approach to analyzing drug effects using Incucyte® Live-Cell Analysis System [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4722.

Facile green synthesis of SnO2:Zn@g-C3N4 heterojunction nanocomposite using Murraya paniculata leaves extract for effective photocatalytic degradation of organic dye malachite green by sunlight illumination

In this work nanocomposite heterojunction of SnO2:Zn conjugated with g-C3N4 was successfully synthesized by a green synthesis method using Murraya paniculata leaves extract. Materials were characterized by XPS, FTIR, XRD, BET, HRTEM, FESEM, EDAX, and UV–visible spectrophotometer. XRD and HRTEM results revealed the formation of highly crystalline and small sized particles having mean grain size of 4.4 and 4.9 nm for SnO2:Zn and SnO2:Zn@g-C3N4, respectively and interplanar spacing of 0.333 nm. The 2-D sheeted structure of g-C3N4 acts as a translucent layer that captures and provide a considerable extent of self-agglomeration on the underlying sphere shaped SnO2:Zn NPs which results in excellent charge flow which eventually results in enhanced photocatalytic degradation performance of the synthesized heterojunction. The XPS analysis verifies the presence of Sn, Zn, O, C, and N in the synthesized heterojunction SnO2:Zn@g-C3N4. The UV–Visible and photoluminescence spectra helped to demonstrate the effective inhibition of excitons annihilation within the heterojunction nanocomposite. The heterojunction shows an excellent photodegradation efficiency of 93.84 % in the process of photodegradation of dye Malachite green (MG). Effect of pH, catalyst dose on photodegradation and the recyclability were also investigated. The kinetic plots were used to calculate the rate constant which shows the nature of a pseudo first order reaction with a rate constant of 0.299 min−1. Trap experiments were conducted to confirm the role of h+ and O2.− as active species.

Facile synthesis of Zn/Co LDH for the removal of oxytetracycline from wastewater: Experimental and DFT-Based analysis

Zn/Co layer double hydroxide (LDH) was first time synthesized for the removal of oxytetracycline (OTC) from aqueous solution. It was characterization by XRD, FTIR, BET, and SEM. The adsorption capacity of Zn/Co LDH for OTC was investigated by batch experimental method at different parameters and adsorption capacity was significantly enhanced to 387.59 mg.g−1 at pH = 8 and T = 15 °C. The kinetic and isothermal studies were performed at the best-selected pH and temperature with the help of different models. The adsorption kinetics plots were consistent with the pseudo-second-order model (R2 = 0.9935), indicating chemical adsorption through electrostatic interactions. The adsorption isotherm curves were more accorded with the Langmuir model as compared to the Freundlich model (R2 = 0.9986) indicating the monolayer mechanism of adsorption. The adsorption mechanism was well explained by DFT studies. The study suggests Zn/Co LDH has great potential for the removal of OTC at a large scale for wastewater treatment.

Criteria analysis for kinetics curves of initiated blood serum chemiluminescence.

The chemiluminescence (CL) methods unlike the other methods of determining free radicals (FR) allow investigating the kinetics of the derivation and recombination of radicals/antioxidants, and thus the development and attenuation of the process/processes after excitation in time. However, these methods are of limited application because the knowledge of the explored parameters is insufficient (maximum intensity and integrated area under the kinetics plot). The kinetics is studied by the CL methods and a new parameter (IR-criterion) of analysis of damping of the initiated CL dynamics has been introduced. The IR-criterion parameter: identifies the relationship between the rates of initiation and recombination of peroxide radicals in blood-serum samples; allows the full straightening of the CL curves; provides new information in the considered pathological processes; can serve as an additional universal characteristic of FR activity of blood serum in pathological processes.

Functionalization, protonation and ligand extension on MIL-53 (Al) MOFs to boost water adsorption and thermal energy storage for heat transformations

Understanding the relationship between the geometry of metal–organic frameworks (MOFs) and the shape of H2O adsorption isotherms is of utmost importance to control the hydrophilic and hydrophobic behaviors of water in MOFs with adsorption/desorption kinetics to realize their applications in thermal energy storage (TES). The MOFs are potential candidates for TES through water adsorption process. The TES can be used as a pivot for heat transformations related to cooling, heat pump, desalination, power generation, water harvesting and dehumidification. The TES performances are mainly determined by water adsorption characteristics such as water uptake/offtake loadings, kinetics and adsorbents-water interaction energy. Therefore, this paper presents a comprehensive analysis on the restructuring of MIL-53 (Al) MOFs for heat transformation applications. In this work, the original MOF is first functionalized with amino or hydroxyl functional groups. Next, the functionalized MOF is protonated with hydrochloric acid. In addition, ligand extension is applied on the original MOF by replacing the original organic linker with the progressively longer linkers. The surface properties of these restructured MOFs are measured by XRD, FTIR, TGA and N2 adsorption analysis. The water uptakes under equilibrium and dynamic conditions are presented in the form of isotherms and kinetic plots. The structural, thermal and cyclic water transfer stabilities of these MOFs are also presented. It is found that the tailored MIL-53 (Al) MOFs modify both the hydrophilicity and hydrophobicity of the original MOFs and improve the water loadings up to 0.9 g/g. The functionalized and protonated MIL-53 (Al) MOFs show higher water transfer with faster kinetics as compared to the parent MIL-53(Al) MOFs. The ligand extended MIL-53 (Al) MOFs provide higher water transfer between humid (relative humidity RH of 80% to 90%) and regenerated (RH of 30%) conditions with promising thermal energy storage density (TESD, up to 1.54 MJ/L).

Studies on Chitosan modified ZrO2–CeO2 metal oxide and their Photo catalytic activity under solar light irradiation for water remediation

Chitosan modified CeO2/ZrO2 were prepared by co-precipitation method and its photocatalytic activity was studied while exposed to solar light. Various doping concentrations was evaluated and 30 mol % CeO2/ZrO2 doping concentration enhanced higher activity when it was modified into Chitosan employing Orange G dye as a model pollutant while exposed to sun light. The synthesized catalyst was highly crystalline, and its average crystalline size was found to be 30 nm using X-ray diffraction analysis. Structural morphology, functional groups, thermal decomposition temperature and particle size were confirmed by Scanning Electron Microscope (SEM), Fourier Transform-Infra Red, Thermal Gravimetric Analysis and Transmission Electron Microscope analysis. XPS confirms the band alignment and oxidation states of the synthesized photo catalyst. In accordance with the UV-Diffused Reflectance Spectrum, the band gap energy is 2.9 eV. The enhanced photo catalytic activities of the prepared photocatalyst were confirmed by effect of catalyst, effect of dye concentration, effect of electrolytes, kinetics and COD. The reaction follows first order kinetics, and the pseudo first order rate constant was evaluated from the kinetics plot.

Facile access to redox responsive self-healing coating materials via living cationic block copolymerization of styrene and 2-chloroethyl vinyl ether

Poly(alkyl vinyl ether)-based functional copolymers have wide applications in many high-tech areas. However, their synthesis is still challenging which limits their applications. This article describes the synthesis of an unprecedented redox-responsive polystyrene-block-poly(2-thioethyl vinyl ether) (PSt-b-PTEVE) diblock copolymers via sequential “water tolerant” cationic polymerization of St and CEVE, followed by post-polymerization transformation of the pendant -CH2CH2Cl functionalities of PCEVE segment to -CH2CH2SH functionalities. The initiating system enabled controlled cationic polymerization of styrene (St), yielding well-defined PSt (at least up to 22500 g/mol) with relatively low dispersity (Đ ≤ 1.36) and polystyrene-block-poly(2-chloroethyl vinyl ether) (PSt-b-PCEVE) diblock copolymers with acceptable dispersity values (Đ ≤ 1.38) thereof, demonstrating high chain-end fidelity. The controlled character of the cationic polymerization reaction was confirmed by linear kinetic plots, linear increase of Mns (with low Đs) and synthesis of PSts of changing Mns simply by varying initial [St]0/[Initiator]0 feed ratio. The synthesized PSt-b-PTEVE diblock copolymers exhibited redox responsivity and self-healing behaviour. The self-healing property of the PSt-b-PTEVE diblock copolymer was studied by optical microscopy. For this, first, a mechanical cut was introduced in the cross-linked PSt-b-PTEVE thin films and then images were taken at regular intervals to investigate the healing. These promising PSt-b-PTEVE diblock copolymers might have potential applications in many emerging areas, including functional coating.

Dl-Methionine-Mediated Reversible Deactivation Radical Polymerization of Styrene and Methyl Methacrylate.

Reversible deactivation radical polymerization (RDRP) is a facile and highly efficient technique for the synthesis of well-defined polymer with precise structure. dl-Methionine (Met) as a RDRP control agent is described and assessed for RDRP of styrene (St) and methyl methacrylate (MMA) with AIBN as radical initiator at 75°C, which enables excellent control of this polymerization. The addition of dl-Methionine significantly decreased the dispersity (Đ) of the polymers for both monomers and first-order linear kinetic plots of polymethyl methacrylate (PMMA) are observed in DMSO. Considering the heat resistance of dl-Methionine, kinetic studies indicate that polymerization develops at a faster rate at higher reaction temperature (100°C) with the same dl-Methionine content. Well-defined polymethyl methacrylate-block-polystyrene (PMMA-block-PSt) is successfully achieved by the chain extension reaction that demonstrates the high end fidelities of this polymerization approach. The system allows the use of dl-Methionine, a rich source and easily synthesized agent, to mediate RDRP strategy.

Column selection considerations in compact capillary liquid chromatography

Recent years have seen significant advances in compact, portable capillary LC instrumentation. This study explores the performances of several commercially available columns within the pressure and flow limits of both the columns and one of these compact LC instruments. The commercially available compact capillary LC system with UV-absorbance detector used in this study is typically operated using columns in the 0.15–0.3 mm internal diameter (i.d.) range. Efficiency measurements (i.e., theoretical plates, N) for six columns with i.d.s in this range and of varying lengths and pressure limits, packed with stationary phases of different particle diameters and morphologies, were made using a mixture of standard alkylphenones. Kinetic plot comparisons between columns that vary by one (or more) of these parameters are described, along with calculated kinetic performance and Knox-Saleem limits. These theoretical performance descriptions provide insight into optimal operating conditions when using capillary LC systems. Based on kinetic plot evaluation of available capillary columns in the 0.2–0.3 mm i.d. range with a conservative upper pressure limit of 330 bar packed with superficially porous particles, a 25 cm column could generate ∼47,000 plates in 7.85 min when operated at 2.4 µL/min. For comparison, more robust 0.3 mm i.d. columns (packed with fully porous particles) that can be operated at higher pressures than can be provided by the pumping system (conservative pump upper pressure limit of 570 bar), a ∼20 cm column could generate nearly 40,000 plates in 5.9 min if operated at 6 µL/min. Across all capillary LC columns measured, higher pressure limits and shorter columns can provide the best throughput when considering both speed and efficiency.

Evaluation of Kinetic Performance of Reversed-Phase Columns for Protein Separations by Gradient Kinetic Plots

The increasing importance of protein biopharmaceuticals has triggered the development of new, highly efficient stationary phases for reversed-phase liquid chromatography (LC) of proteins. They typically have C4 ligands or phenyl surfaces for weak hydrophobic interactions and are based on various morphologies, such as silica monolith, sub-2-µm fully porous particles (FPPs), or superficially porous particles (SPPs). Selection of the best column based on physical parameters provided by vendors may sometimes be unequivocal. Simple performance evaluation tools, such as the gradient kinetic plot methodology reported by Desmet and co-workers, can help to shed light on this issue and allow for a more differentiated view on column performance. This article compares the performance of wide-pore silica monolithic, sub-2-µm FPP, and SPP columns. It also addresses the question of whether 1000 Å or 400 Å SPP columns are more suitable for reversed-phase LC-type protein separations and presents a kinetic performance comparison of a number of wide-pore core–shell particle columns.

In-Depth Performance Analysis and Comparison of Monolithic and Particulate Zwitterionic Hydrophilic Interaction Liquid Chromatography Polymer Columns.

The kinetic performance of different zwitterionic hydrophilic interaction liquid chromatography polymer columns is evaluated and compared in-depth. For this purpose, two lab-made monolithic columns, synthesized with different crosslinkers, and a commercial particle packed column are considered. It is found that performance evaluation techniques, such as comparing plate height curves or fitted A-, B- and C-terms, obtained by fitting experimental plate height data to a plate height model, are complicated by the determination of a reliable characteristic length. This is due to the very different morphology of these column types, and the heterogeneity of the monolithic columns. The occurrence of a convective flow through the packed particle column further complicates the interpretation of the obtained fitting parameters, as part of the C-term is wrongfully attributed to the A-term. Therefore, the use of the kinetic plot method is suggested for the comparative evaluation of these columns, as kinetic plots do not require the determination of a characteristic length, nor rely on any fitting parameters. With the kinetic plot method, it is demonstrated that the lab-made monolithic columns outperform the packed particle column for plate counts between 10,000 and 800,000. This is attributed to the higher column efficiency of these columns, due to their small domain and skeleton sizes, and their high permeability, resulting from their high external porosity and the occasional occurrence of preferential flow paths.

Photocatalytic degradation of malachite green using TiO2 and ZnO impregnated on fecal sludge derived biochar

The present study focused on the degradation of malachite green (MG) dye which is extensively used in the aqua-culture and later disposed in water bodies. In order to treat the wastewater streams a sustainable and novel low cost material was synthesized using a waste i.e. fecal sludge. Later, the biochar obtained from the fecal sludge were impregnated with TiO2 and ZnOnano-particles to enhance its functional properties. The study reports the degradation of malachite green (MG) dye from aqueous solution under a parametric optimized condition by combined effect of adsorption and photocatalysis using TiO2 and ZnO impregnated on biochar (BC-TiO2-ZnO) synthesized from fecal sludge. The main contributing factors towards the dye degradation, namely catalyst dose (25–75 mg), dye concentration (50–150 mg/L), temperature (25–55 °C), pH (4–12) and stirring speed (50–250 rpm) were used as operation parameters for the experiments. The conditions thus obtained (catalyst dose of 50 mg, dye concentration of 100 mg/L, stirring speed of 150 rpm, temperature of 35 °C and at pH 8 for 30 min) were the optimal conditions for MG dye degradation (nearly 98% removal) using BC-TiO2-ZnO photocatalyst. Investigation revealed that adsorption-photocatalysis process is in good agreement with Langmuir-Hinshelwood kinetics. The kinetic data plots revealed the rate constant to be (k) = 0.087 min−1 having a 3% deviation from the experimental results (=0.09 min−1). Furthermore, the half-life of the reaction was calculated to be t1/2=7.7min while the value of R2 was 0.98. The photocatalyst showed no significant changes in its degradation efficiency even after 6th cycle indicating the appreciable reusability. MG has been used extensively in aquaculture as antimicrobial agent which leads to release of the residual molecules to the aquatic environment leading to multiplication of antibiotic resistant microbes. Therefore, the treated water obtained from the present process was investigated for its possible activity against E. coli and no remarkable antibacterial activity was noticed.

Effect of addition of surfactant on physicochemical properties of cobalt oxide nanoparticles synthesised using a domestic microwave: Applications as photocatalyst and supercapacitor

The present work highlights the comparison of the physicochemical properties of the metal oxide nanoparticles of cobalt synthesised using a domestic microwave in the presence and absence of surfactant. XRD analysis revealed that the addition of the surfactant was responsible for the reduction in the crystallite size of the metal oxide nanoparticles. SEM images showed more agglomeration in the case of surfactant-capped nanoparticles than the bare ones. The elemental composition obtained using EDAX of both nanoparticles showed a higher percentage of oxygen in the bare nanoparticles and better elemental stoichiometry in the surfactant-capped nanomaterials. The energy band gap calculated from the optical studies was higher in the case of surfactant-loaded nanoparticles than the bare ones. The photocatalytic studies of nanoparticles without and with surfactant showed 48 % and 40 % degradation of Methylene blue, respectively, in the presence of UV light with 1 g L−1 catalyst dose and 50 mg L−1 dye concentration at 300 min of irradiation time. Langmuir-Hinshelwood kinetic plots showed a marginally higher apparent rate constant value (2.22 × 10−3 min−1) for nanoparticles without surfactant than for nanoparticles with surfactant (2.11 × 10−3 min−1). The cyclic voltammograms of both the nanoparticles at a scan rate of 5 mV s−1 were faradic in nature and showed pseudo capacitance. The capacitance of nanoparticles with surfactant (166 F g−1) was found to be higher than that obtained for bare nanoparticles (111 F g−1). A comparison of the properties indicated that the addition of surfactant plays a vital role in tuning the properties of cobalt oxide nanoparticles for their specific application.

Exploring kinetic and thermodynamic mechanisms of switchgrass pyrolysis using iterative linear integral isoconversional method and master plots approach

This study aimed to explore the kinetic mechanism of switchgrass pyrolysis through isoconversional kinetic analysis and master plots approach. The pyrolysis kinetics of switchgrass was experimentally studied by thermogravimetric analysis at 5, 10, 20, and 40 K min−1. The experimental kinetic data of switchgrass pyrolysis was processed by the iterative linear integral isoconversional method and the obtained effective activation energies varied significantly with conversion: from 190.3 to 216.7, 217.3 ± 0.9 and 219.4 to 301.4 kJ·mol−1 in the conversion range of 0.05 – 0.45, 0.45 – 0.75 and 0.75 – 0.95, respectively. The significant conversion dependence of activation energies indicated switchgrass pyrolysis was a kinetically complex process, which was caused by the overlapping decomposition reactions of lignocellulosic components contained in switchgrass. Based on the master plots approach and the general empirical reaction model, the pyrolysis kinetic process of switchgrass pyrolysis followed the reaction model: f(α) = α-0.307·(1–1.020α)2.276. The frequency factor of switchgrass pyrolysis varied from 4.2 × 1012 to 3.9 × 1018 s−1 in the conversion range of 0.05 – 0.95, and a kinetic compensation effect between the frequency factor and activation energy was discovered. Based on the kinetic results, the changes in Gibbs free energy, enthalpy and entropy for switchgrass pyrolysis were calculated. It is expected that this study can provide a methodological guideline for the kinetics and thermodynamics of lignocellulosic biomass pyrolysis.

Geobacillus stearothermophilusandBacillus atrophaeusspores exhibit linear inactivation kinetic performance when treated with an industrial scale vaporized hydrogen peroxide (VH2O2) sterilization process

This study aims to determine the inactivation kinetics of Geobacillus stearothermophilus and Bacillus atrophaeus biological indicators, treated with vaporized hydrogen peroxide (VH2O2) at an industrial scale. There is an assumption that sterilization processes generate linear kinetic plots of treated biological indicators that are used for informing probability-based decision-making by the MedTech industry for effective sterilization treatments; however, this has not been reported for sterilization using VH2O2. Survivor curves were generated, and sterilization performances were separately determined using G. stearothermophilus and B. atrophaeus biological indicators following the development of appropriate process challenge devices (PCDs). Regression analysis revealed that the inactivation kinetics for VH2O2-treated microorganisms exhibited log linear profiles. The use of scanning electron microscope (SEM) revealed no significant topographical changes in the outer surface of these VH2O2-treated spores. Both biological indicators exhibited log linear inactivation kinetics when treated with an industrial scale vaporized hydrogen peroxide (VH2O2) sterilization process. Therefore, this novel finding corroborates and proves the appropriateness of using VH2O2 as a sterilization method in accordance with applicable ISO standards.

Synchronized Reverse Scan Collision Induced Dissociation in Digital Ion Trap Mass Spectrometer for Improving Fragment Ion Detection

Development of fragment ion detection methods is of great importance for mass spectrometer advancement or substance identification. To date, collision induced dissociation (CID) remains the most commonly used ion activation method in MS/MS experiments, and the effectiveness of CID in an ion trap mass spectrometer is limited by low mass cutoff and weak fragmentation yields. Theoretically, controlling the q value is the key to maintain the fragment efficiency and trapping efficiency of MS/MS, thus improving the detection of fragment ion, while currently reported techniques usually require complex circuitry and often produce different CID patterns. In this paper, with the developed synchronized reversed scanning-collision induced dissociation (SRS-CID) technique, we demonstrate its effective improvement in fragment ion detection. The SRS-CID is implemented on a digital ion trap mass spectrometer (DITMS) by reverse scanning the q values during CID process, or specifically, the frequency is increased during the CID process. With the SRS-CID technique, the fragmentation efficiency of precursor ions can be slightly improved. For reserpine analyte, the trapping efficiency for low-mass fragment ions is improved at least 3 times, and for YGGFL, the trapping efficiency for low-mass fragment ions is improved at least 9 times. These experimental results can also be validated by simulations, and the kinetic energy variation plot suggests consecutive fragmentation occurs. In any case, the SRS-CID provides a solution to the low efficiency of fragment ion detection during tandem MS analysis, which will certainly be useful in the future.

Development, Evaluation and in vitro Release Kinetics Study of Immediate Release Tablets of Quercetin Isolated from Bauhinia acuminata Leaves Extract

Objective: To isolate quercetin, a flavonoid, from leaves extract of Bauhinia acuminata and to formulate and evaluate immediate release tablets of this quercetin employing direct compression method. Methods: Quercetin was isolated by column chromatography and characterized by FTIR, 1H and 13C NMR. Next different formulation blends were prepared using the isolated quercetin with microcrystalline cellulose, magnesium stearate and sodium starch glycolate. Pre-compression studies were performed and tablets were prepared by direct compression method. Tablets were evaluated for various post formulation parameters including disintegration and in vitro dissolution. Release kinetics and release mechanism were also studied from different kinetics plots. Finding : The pre-compression parameters were within the range of hardness (3.37  0.058 to 3.78  0.058 kg/cm2), weight variation (251.25  5.38 to 251.45  5.66 mg), friability (<1%), Drug content (98.17  0.86 to 98.20  0.99 %), disintegration (187.17  2.48 to 126.5  2.26 sec) and in vitro dissolution study (85.33  0.95 % and 86.47  0.70 %) within 30 minutes and 96.84 % and 98.19 % ) within 1 hr respectively for F2 and F3. Novelty: Only few scientific reports are present for Bauhinia acuminata and majority of them are related to pharmacological properties of the extract from the plant only. Here in this study quercetin was isolated for the very first time from Bauhinia acuminata to the best of our knowledge and not only this, the isolated quercetin was formulated to immediate release tablet which is again being reported from this plant for the first time. Keywords: Bauhinia acuminata; Immediate Release Tablet; Quercetin; Super Disintegrating Agents; Release Kinetics

Deciphering the species differences in CES1A-mediated hydrolytic metabolism by using a bioluminescence substrate

Carboxylesterases 1A (CES1A) is a key enzyme responsible for the hydrolytic metabolism of a great deal of endogenous and exogenous substrates bearing ester- or amide-bond(s). This study aimed to decipher the species difference in CES1A-mediated hydrolytic metabolism by using a newly developed bioluminescence CES1A sensor (termed NLMe) as the probe substrate, while the liver microsomes from six different mammalian species (human, cynomolgus monkey, dog, minipig, rat and mouse) were used as the enzyme sources. Metabolite profiling demonstrated that all tested liver microsomes from various species could catalyze NLMe hydrolysis, but significant difference in hydrolytic rate was observed. Kinetic plots of NLMe hydrolysis in liver microsomes from different species showed that the inherent clearance rates (Clint) of NLMe in human liver microsomes (HLM), cynomolgus monkey liver microsomes (CyLM), and pig liver microsome (PLM) were comparable, while the Clint values of NLMe in dog liver microsomes (DLM), mouse liver microsomes (MLM), and rat liver microsomes (RLM) were relatively small. Moreover, chemical inhibition assays showed that NLMe hydrolysis in all tested liver microsomes could be competently inhibited by BNPP (a potent broad-spectrum inhibitor of CES), but CUA (a selective inhibitor of human CES1A) only inhibited NLMe hydrolysis in human liver microsomes and dog liver microsomes. In summary, the species differences in CES1A-catalyzed NLMe hydrolysis were carefully investigated from the views of the similarities in metabolite profile, hydrolytic kinetics and inhibitor response. All these findings provide new insights into the species differences in CES1A-mediated hydrolytic metabolism and suggest that it is necessary for the pharmacologists to choose appropriate animal models to replace humans for evaluating the in vivo effects of CES1A inhibitors.