Development of an Indirect Competitive ELISA Based on Polyclonal Antibody for the Detection of Diethylstilbestrol in Water Samples

An indirect competitive enzyme-linked immunosorbent assay （icELISA） based on polyclonal antibody for the estrogen diethylstilbestrol （DES） was developed. With this aim, two different haptens mono-O-3-carboxypropyldiethylstilbestrol （DES-CP） and mono-O-carboxymethyldiethylstilbestrol （DES-CM） with carboxylic group that preserve the molecular structure character of diethylstilbestrol were synthesized. The haptens were conjugated with the carder proteins bovine serum albumin （BSA） by mixed-anhydride method for immunogen and conjugated with ovalbumin （OVA） by active ester method for coating antigen. Polyclonal antibodies for diethylstilbestrol were raised by immunizing mice with immune antigen DES-CP-BSA. Under optimized system, the lowest limit of detection （LLD） of diethylstilbestrol was 0.01 ng/mL, and IC50= 1.02 ng/mL. Its analogs were tested and no obvious cross-reactivity was found to anti-diethylstilbestrol antibody. DES-fortified water samples were determined by simple dilution to diminish the matrix effect. The comparison between the amount of DES estimated by ELISA and the amount added indicates good agreement for all water samples tested, with mean recovery values ranging from 86% to 120.2%.     

Amperometric Immunoassay of Azinphos‐Methyl in Water and Honeybees Based on Indirect Competitive ELISA

Abstract

An electrochemical immunosensor based on indirect competitive ELISA technique has been developed and tested for the detection of azinphos‐methyl in aqueous solutions and spiked honeybee extracts. The detection of the pesticide was based on competition for binding to monoclonal antibodies with an ovalbumin (OVA) conjugate, followed by the incubation with anti‐mouse IgG labeled with horseradish peroxidase, whose activity was measured amperometrically with hydroquinone as the substrate. The sensitivity of the azinphos‐methyl assay, estimated as the IC₅₀ value, was found to be 1.2 nmol L^?1 (60 min incubation), with a linear range of 0.6–500 nmol L^?1 in optimal conditions. The matrix effect on the detection of azinphos‐methyl in honeybee extract was found negligible, with the recovery values in the range 92–105%.     

Immunochromatographic Test Systems using Anti-Species Antibodies–Colloidal Gold Conjugate: Their Features and Benefits on the Example of Ochratoxin A Detection

The traditional immunochromatographic assay using a conjugate of gold nanoparticles with specific ochratoxin A (OTA) antibodies and a new type of assay with indirect labeling using a combination of free antibodies and a conjugate of gold nanoparticles with anti-species antibodies were compared using the example of OTA detection. In the proposed assay, specific antibodies are included in the sample dilution buffer, which increases the duration of their interaction with the antigen, while a conjugate of anti-species antibodies with the marker is applied to the test strip. The assay was approbated for OTA detection in maize extracts. Transition to indirect labeling was shown to reduce the OTA detection limit by two orders of magnitude up to 0.12 ng/mL. The causes of this improvement are discussed. The high sensitivity of immunochromatography with indirect labeling makes it a promising approach for detection of various antigens with low molecular weight.     

Direct quantification of intact FIM in monkey plasma using a selective chromatography–tandem mass spectrometry method: Application in a pharmacokinetic study

FIM protein, which consists of 155 amino acids, was developed as a novel GLP-1 analog to reduce blood glucose, and pharmacodynamic results showed that it had a certain effect when used in treating Alzheimer's disease. The molecular weight of FIM is 16,304 Da. In theory, the concentration of FIM in biological samples should be determined by the ligand binding assay method or indirectly quantified using LC–MS/MS instrumentation. However, the above methods are complex and time-consuming. In this study, we successfully developed a simpler LC–MS/MS method for directly quantifying the intact FIM protein in monkey plasma for the first time. The chromatographic separation of FIM was achieved using an InertSustain Bio C₁₈ column with a mobile phase of acetonitrile containing 0.1% formic acid (A)–water containing 0.1% formic acid (B) at a flow rate of 0.3 ml/min. Good linearity was observed in the concentration range of 5–500 ng/ml (r² > 0.99). The intra- and inter-day precisions (expressed as relative standard deviation, RSD) of FIM were 2.30–12.8 and 7.30–13.2%, respectively. The intra- and inter-day accuracies (expressed as a relative error, RE) were −12.7–6.55 and − 10.1–0.892%, respectively. This method was successfully applied for a pharmacokinetic study of the FIM protein in four monkeys after subcutaneous administration.     

A Novel Glucose Biosensor Based on Palladium Nanoparticles and Its Application in Detection of Glucose Level in Urine

IntroductionThelevelofglucoseinbloodorurineindicateshyper andhypoglycaemia ,bothofwhichcanresultfromavarietyofendocrinedisorders .1 4 Therapidandreliabledetermi nationofglucoselevelisaroutineprojectinclinicchem istry.Urinesamplesaresaferandmoreconvenientthanbloodones .Meanwhile ,theconcentrationofglucoseinserumiscloselyassociatedwiththatinurine .2 4 Eventhoughglucoseelectrodeshavebeensuccessfullyusedinseruminclinicalapplication ,thequestionstillremainedofhowtodetecttheglucoselevelinurine ,wh…     

Smart Materials Based on Synthetic Host Molecules: The Role of Host–Guest Chemistry in the Fabrication and Application

Stimuli-responsive or smart materials have recently shown a significant impact on the frontier of material science and engineering. The exponential development of synthetic host molecules (SHMs) over the last decades and their corresponding host–guest chemistry, have empowered researchers with new opportunities to design and construct tailored or guest-specific smart materials. In this Minireview, we present the recent advancements in synthetic host based smart materials, ranging from the fabrication strategies to the state-of-art applications including adsorption, separation, luminescence, self-healing and actuation. The role that the host–guest chemistry plays in these systems is highlighted throughout to give a better prospective of the available possibilities for emerging materials of future economies.     

Production of a Novel Material Based on a Collagen–Chitosan Composite and Ibuprofen in a Supercritical Medium

A novel material for biomedical applications was obtained from a collagen–chitosan composite and ibuprofen by a fluid process using supercritical carbon dioxide. The material was characterized by IR and X-ray photoelectron spectroscopy. The applicability of XPS analysis of biomaterials for quantification of loaded therapeutic agents is demonstrated.     

Determination of Pseudoephedrine Hydrochloride in Some Pharmaceutical Drugs by Potentiometric Membrane Sensor Based on Pseudoephedrine–Phosphotungstate Ion Pair

Abstract

An ion-selective electrode (ISE) was developed for the rapid determination of pseudoephedrine hydrochloride (PSEHCl) in pharmaceutical preparations. The electrode incorporates a PVC membrane with a pseudoephedrine–phosphotungstate ion pair complex. The influences of membrane composition, temperature, pH of the test solution, and the interfering ions on the electrode performance were investigated. The sensor exhibits a Nernstian response for pseudoephedrine hydrochloride ions over a relatively wide concentration range (1.0 × 10^?1 to 1.0 × 10^?5 mol L^?1) with a slope of 56.2 ± 0.5 mV per decade at 25°C. It can be used in the pH range 4.0–10.5. The isothermal temperature coefficient of this electrode amounted to 0.0009 V/°C. The membrane sensor was successfully applied to determination of PSEHCl in its tablets and syrup.     

Ultrathin Two-Dimensional Metal–Organic Framework Nanosheets Based on a Halogen-Substituted Porphyrin Ligand: Synthesis and Catalytic Application in CO2 Reductive Amination

Ultrathin two-dimensional metal–organic framework nanosheets have emerged as a promising kind of heterogeneous catalysts. Herein, we report a series of 2D porphyrinic metal–organic framework nanosheets (X-PMOF, X=F, Cl, Br), which was prepared from the self-assembly of a halogen-based porphyrin ligand X-TCPP (X-TCPP=5-(4-halogenatedphenyl)-10,15,20-tris(4-carboxyphenyl)-porphyrin) and ZrCl₄ in the presence of trifluoroacetic acid as the modulating reagent. The framework of X-PMOF possessed the ftw topology as in MOF-525. The lamellar X-PMOF nanosheets with the thickness of down to 4.5 nm were assembled and aggregated into a flower-like morphology. With the introduction of iridium(III) atoms into the porphyrin rings, the resultant X-PMOF(Ir) nanosheets were prepared by a similar method. Catalytic results show that Br-PMOF(Ir) nanosheets were efficient for CO₂ reduction and aminolysis, giving rise to formamides in high yields under room temperature and atmospheric pressure, and can be recycled and reused for 3 runs. The total turnover number of Br-PMOF(Ir) after 3 runs was 1644 based on Ir. Mechanistic studies disclose that the high efficiency of Br-PMOF(Ir) nanosheets was ascribed to three factors, including the superior activation capability of iridium(III) porphyrin for Si−H bonds, more active sites on the external surfaces of Br-PMOF(Ir) nanosheets, and the defects caused by unsymmetrical porphyrin ligand that increased the framework's affinity towards CO₂.     

Direct determination of total sulfur in wine using a continuum-source atomic-absorption spectrometer and an air–acetylene flame

Determination of sulfur in wine is an important analytical task, particularly with regard to food safety legislation, wine trade, and oenology. Hitherto existing methods for sulfur determination all have specific drawbacks, for example high cost and time consumption, poor precision or selectivity, or matrix effects. In this paper a new method, with low running costs, is introduced for direct, reliable, rapid, and accurate determination of the total sulfur content of wine samples. The method is based on measurement of the molecular absorption of carbon monosulfide (CS) in an ordinary air–acetylene flame by using a high-resolution continuum-source atomic-absorption spectrometer including a novel high-intensity short-arc xenon lamp. First results for total sulfur concentrations in different wine samples were compared with data from comparative ICP–MS measurements. Very good agreement within a few percent was obtained.Dedicated to the memory of Wilhelm Fresenius     

The Synthesis of a Multiple D–A Conjugated Macrocycle and Its Application in Organic Photovoltaic

As a novel class of materials, D–A conjugated macrocycles hold significant promise for chemical science. However, their potential in photovoltaic remains largely untapped due to the complexity of introducing multiple donor and acceptor moieties into the design and synthesis of cyclic π-conjugated molecules. Here, we report a multiple D–A ring-like conjugated molecule ( RCM ) via the coupling of dimer molecule DBTP-C3 as a template and thiophenes in high yields. RCM exhibits a narrow optical gap (1.33 eV) and excellent thermal stability, and shows a remarkable photoluminescence yield (Φ_PL) of 11.1 % in solution, much higher than non-cyclic analogues. Organic solar cell (OSC) constructed with RCM as electron acceptor shows efficient charge separation at donor-acceptor band offsets and achieves a power conversion efficiency (PCE) of 14.2 %-approximately fourfold higher than macrocycle-based OSCs reported so far. This is partly due to low non-radiative voltage loss down to 0.20 eV and a high electroluminescence yield (Φ_EL) of 4×10⁻⁴. Our findings emphasize the potential of D–A cyclic conjugated molecules in advancing organic photovoltaic technology.     

UPLC–MS–MS Analysis of Baicalin in the Cerebrospinal Fluid of Rabbits: Application to a Pharmacokinetic Study

A sensitive and selective ultra-performance liquid chromatographic–tandem mass spectrometric method has been developed for analysis of baicalin in the cerebrospinal fluid of rabbits. Samples were separated on a C₁₈ column with a gradient prepared from acetonitrile and 0.3% aqueous formic acid solution as mobile phase. The target compounds were quantified by multiple reaction monitoring (MRM) using electrospray ionization (ESI). Intra-and inter-day accuracy, precision, and linear range were investigated in detail. The lower limit quantification (LOQ) was 0.108 ng mL^?1. The method has been successfully used for evaluation of the pharmacokinetics of baicalin in 12 rabbits.     

Determination of Memantine in Human Plasma by LC–MS–MS: Application to a Pharmacokinetic Study

A sensitive and selective liquid chromatography–tandem mass spectrometry method for the determination of memantine was developed and validated over the linearity range 0.1–25 ng mL^?1 with 0.5 mL of plasma using procainamide as the internal standard. This analysis was carried out on a Cosmosil 5C₁₈-MS column and the mobile phase was composed of methanol: 0.5% formic acid (50:50, v/v). Detection was performed on a triple–quadrupole tandem mass spectrometer using positive ion mode electrospray ionization and quantification was performed by multiple reaction monitoring mode. The MS–MS ion transitions monitored were m/z 180 → 107 and 236 → 163 for memantine and procainamide, respectively. The between- and within-day precision was less than 10.9% and accuracy was less than 2.5%. The lower limit of quantification (LLOQ) was 0.1 ng mL^?1. The method proved to be accurate and specific, and was applied to the pharmacokinetic study of memantine in healthy Chinese volunteers.     

Synthetic Studies on Spirolides A and B: Formation of the Upper Carbon Framework Based on a Lewis Acid Template-Catalyzed Diels–Alder Reaction

The upper fragment of spirolides A and B, which are marine phycotoxins that exhibit strong antagonistic activities on nicotinic acetylcholine receptors, was constructed. The functionalized cyclohexene in spirolides was stereoselectively synthesized from the bicyclic lactone, which could be readily accessed by the Lewis acid template-catalyzed asymmetric Diels–Alder reaction of the pentadienol and methyl acrylate.     

Determination of Alkylphenols in Water by Dispersive Liquid–Liquid Microextraction Based on Solid Formation without a Disperser

Dispersive liquid–liquid microextraction based on solid formation without a disperser combined with high-performance liquid chromatography has been developed for the determination of 4-tert-butylphenol, 4-n-nonylphenol, and 4-tert-octylphenol. This method is rapid, easy, and uses only 10 µL of a low toxicity organic solvent (1-hexadecanethiol) for the extraction solvent and no disperser solvent. The extraction time and centrifugation time require less than 10 min. The linear range was 1–500 ng mL^?1 for 4-tert-butylphenol, 2–1000 ng mL^?1 for 4-tert-octylphenol, and 5–500 ng mL^?1 for 4-n-nonylphenol with r² ≥ 0.9986. The detection limits were between 0.2 and 1.5 ng mL^?1. The recoveries of lake and river water samples were in the range of 79% to 108%, and the relative standard deviations were 5% to 10%.     

A size-modified poisson–boltzmann ion channel model in a solvent of multiple ionic species: Application to voltage-dependent anion channel

We present a new size-modified Poisson–Boltzmann ion channel (SMPBIC) model and use it to calculate the electrostatic potential, ionic concentrations, and electrostatic solvation free energy for a voltage-dependent anion channel (VDAC) on a biological membrane in a solution mixture of multiple ionic species. In particular, the new SMPBIC model adopts a membrane surface charge density and a natural Neumann boundary condition to reflect the charge effect of the membrane on the electrostatics of VDAC. To avoid the singularity difficulties caused by the atomic charges of VDAC, the new SMPBIC model is split into three submodels such that the solution of one of the submodels is obtained analytically and contains all the singularity points of the SMPBIC model. The other two submodels are then solved numerically much more efficiently than the original SMPBIC model. As an application of this SMPBIC submodel partitioning scheme, we derive a new formula for computing the electrostatic solvation free energy. Numerical results for a human VDAC isoform 1 (hVDAC1) in three different salt solutions, each with up to five different ionic species, confirm the significant effects of membrane surface charges on both the electrostatics and ionic concentrations. The results also show that the new SMPBIC model can describe well the anion selectivity property of hVDAC1, and that the new electrostatic solvation free energy formula can significantly improve the accuracy of the currently used formula. © 2019 Wiley Periodicals, Inc.     

A New Electrochemical Sensor Based on Carbon Black Modified With Palladium Nanoparticles for Direct Determination of 17α-Ethinylestradiol in Real Samples

Electrochemical sensors to quantify concentrations of emerging pollutants have attracted great attention from the industry and scientific community. Nanomaterials such as carbon black have been applied in sensors to identify substances that are toxic to the environment and human health due to their excellent electroanalytical properties. The aim of the study was to develop a novel electrochemical sensor for the endocrine disruptor hormone determination. To our knowledge, for the first time the synthesis of material based on carbon black containing immobilized palladium nanoparticles, with the application for the hormone ethinylestradiol, is reported in the literature. The material was synthesized, characterized, and applied to the determination in tap water and human urine of the synthetic hormone 17α-ethinylestradiol (EE2), which is currently considered an emerging pollutant. The morphology, structure and electrochemical performance of the sensors were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV). Differential pulse voltammetry (DPV) in sodium phosphate buffer solution at pH 5.0 allowed the generation of a method to quantify the concentration of 17α-ethinylestradiol in a linear range of 0.5–119.0 μmol L⁻¹, obtaining 81.0 nmol L⁻¹ of calculated limit of detection (LOD). The system was efficient in detecting 17α-ethinylestradiol in real urine samples and showed no interferences for ascorbic acid, uric acid, progesterone, and dopamine. It is noteworthy that the results obtained showed good recovery values, considering that the urine samples were not previously treated or pre-concentrated, which suggests the development of an electrochemical sensor that works in situ and in real time to monitor relevant substances in the control clinical and environmental, with the possibility of point-of-care analyses.     

Influence of monomer concentration on polycarbazole–polyindole (PCz–PIn) copolymer properties: Application in Schottky diode

Copolymerization of carbazole (Cz) and indole (In) is successfully performed through potentiostatic polymerization; and the influence of the monomer concentrations ratio on copolymer formation, is investigated. It is found that 1:2 ratio of Cz to In monomer is optimum for the synthesis of a copolymer with high electroactivity. The structural, optical, thermal and morphological analysis of the copolymers are carried out with UV–vis, FT–IR spectroscopy, differential scanning coulometry (DSC) and scanning electron microscopic (SEM) technique. Electrochemical and thermal studies, further support better redox activity and thermal stability of the copolymer, respectively. We also report fabrication and characterizations of the electrochemically synthesized copolymer in organic Schottky diode with configuration metal Al/copolymer/indium tin oxide coated glass (ITO). The current density–voltage (J–V) characteristic of the Schottky diode is consequential in extracting the electronic parameters and the charge transport mechanism of the devices.     

From Distillation to Standardization: A French Perspective on the Shaping of Turpentine Spirit (1909–1976)

Turpentine is a complex substance of pine resin origin, widely used as a solvent in multiple industries. Attempts to define it, even when elaborated by scientists, have been marked by a whole range of extra-scientific market considerations. While the Pine Institute, a resin chemistry research centre in Bordeaux, succeeded in stabilizing the meaning of the word “turpentine” on the national level in France, its expertise was contested abroad. When the International Organization for Standardization (ISO) Committee 35 tried to establish a new international standard for turpentine, France was accused of protecting its industry by twisting scientific definitions for its own needs. The ISO members clashed over the relationship between trade standards and scientific definitions, at the same time highlighting the epistemological difficulties in constructing both categories.