Synthesis of boronic acid‐functionalized poly(glycerol‐oligoγ‐butyrolactone): Nano‐networks for efficient electrochemical sensing of biosystems

Despite the outstanding properties of hyperbranched polyglycerols such as biocompatibility and multifunctionality, enough attention has not been paid to the synthesis of their functional copolymers. This problem has limited the structural diversity of hyperbranched polyglycerols and hampers further developments and their practical usage. In this work, butyrolactone segments were incorporated into the backbone of polyglycerols by one‐pot ring‐opening copolymerization of a mixture of glycidol and γ‐butyrolactone in the presence of tin(II) 2‐ethylhexanoate. Poly(glycerol‐oligoγ‐butyrolactone)s were then crosslinked by 2,5‐thiophenediylbisboronic acid to obtain polymeric nanonetworks with 140 nm average size. Afterwards, the gold electrode was modified by the polymeric nano‐networks, and it was used for the determination of glucose, glycated hemoglobin, and Escherichia coli in phosphate buffer solution (pH = 9.0) through cyclic voltammetry and impedance spectroscopic. Taking advantage of the straightforward synthesis, cheap precursors and multifunctionality of poly(glycerol‐oligoγ‐butyrolactone)s, they could be used for real‐time sensing of a wide range of biosystems. © 2019 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2019, 57, 1430–1439     

Synthesis of glycerol-thiophene nanoparticles,a suitable sensing platform for voltammetric determination of guaifenesin

Boronic acid functionalized materials have gained much attention in both chemistry and biology fields due to their multivalent covalent interactions with cis-diol containing (macro) molecules. The remarkable progress in this field has resulted in the development of their biomedical applications, such as, biosensors and nanocarriers. In this study, the spherical nanoparticles consisting of glycerol and 2,5-thiophenediylbisboronic acid were synthesized by one-pot ring opening copolymerization of a mixture of glycidol and 2,5-thiophenediylbisboronic acid. The synthesized nanoparticles were used for the modification of the glassy carbon electrode and the determination of Guaifenesin. The synthesized polymeric nanoparticles were characterized by different spectroscopic and microscopic methods including UV–vis, IR, NMR, DLS, and SEM. Additionally, the electrochemical behavior of the fabricated electrode toward Guaifenesin was investigated with cyclic voltammetry and electrochemical impedance spectroscopy.     

Sensitive determination of ethosuximide in human fluids by electromembrane extraction coupled with high performance liquid chromatography ultraviolet spectroscopy

Ethosuximide (ETX) is a common antiepileptic drug in the first line of absence epilepsy. In this study, for the first time, an economical and efficient electro-membrane (EME) method for determination of ETX in a complex biological matrix using HPLC-UV has been developed. Factors affecting conventional EME were evaluated. 1-Octanol was immobilized in a polypropylene membrane and a voltage of 35 V was applied between two platinum electrodes for 15 min. The pH of acceptor and donor phases for ionization of ETX was adjusted to 13 and 11, respectively. Under optimal microextraction conditions, the enrichment factor was 21.02 and the linear range of ETX was 0.25 to 8.00 μg/mL with an acceptable R² ≥ 0.9986. Inter-day and intra-day precision and accuracy of the suggested method were calculated with RSD < 9.5% and relative error <7.0%, respectively. The mean relative recovery of ETX in the human saliva and plasma samples was 81.68% and 74.47, respectively; while limit of detection and quantification concentrations were 0.08 and 0.25 μg/mL, respectively. Furthermore, to evaluate the application of the method, plasma and saliva samples of volunteers administering a single dose of ETX were analyzed successfully by EME-HPLC-UV method.     

Simultaneous Spectrophotometric Determination of Zinc and Nickel in Water Samples by Mean Centering of Ratio Kinetic Profiles

The mean centering of ratio kinetic profiles method was used for the simultaneous determination of binary mixtures of Ni(II) and Zn(II) in water samples, without prior separation steps. The method is based on the difference in the rate of the reaction of Ni(II) and Zn(II) with xylenol orange at pH 5.3. The method allows rapid and accurate determination of Ni(II) and Zn(II). The analytical characteristics of the methods for the simultaneous determination of binary mixtures of Ni(II) and Zn(II) were calculated. The linear range was 0.025‐2.400 μg mL^?1 and 0.025‐2.20 μg mL^?1 for Zn(II) and Ni(II), respectively. Interference effects of common anions and cations were studied, and the method was successfully applied to the simultaneous determination of Zn(II) and Ni(II) in water samples.     

Mass spectrometry‐based proteomics of oxidative stress: Identification of 4‐hydroxy‐2‐nonenal (HNE) adducts of amino acids using lysozyme and bovine serum albumin as model proteins

Modification of proteins by 4‐hydroxy‐2‐nonenal (HNE), a reactive by‐product of ω6 polyunsaturated fatty acid oxidation, on specific amino acid residues is considered a biomarker for oxidative stress, as occurs in many metabolic, hereditary, and age‐related diseases. HNE modification of amino acids can occur either via Michael addition or by formation of Schiff‐base adducts. These modifications typically occur on cysteine (Cys), histidine (His), and/or lysine (Lys) residues, resulting in an increase of 156 Da (Michael addition) or 138 Da (Schiff‐base adducts), respectively, in the mass of the residue. Here, we employed biochemical and mass spectrometry (MS) approaches to determine the MS “signatures” of HNE‐modified amino acids, using lysozyme and BSA as model proteins. Using direct infusion of unmodified and HNE‐modified lysozyme into an electrospray quadrupole time‐of‐flight mass spectrometer, we were able to detect up to seven HNE modifications per molecule of lysozyme. Using nanoLC‐MS/MS, we found that, in addition to N‐terminal amino acids, Cys, His, and Lys residues, HNE modification of arginine (Arg), threonine (Thr), tryptophan (Trp), and histidine (His) residues can also occur. These sensitive and specific methods can be applied to the study of oxidative stress to evaluate HNE modification of proteins in complex mixtures from cells and tissues under diseased versus normal conditions.     

Preparation of forcespun γ-irradiated chitin from shrimp shell wastes and its evaluation as uranyl ion adsorbent

Journal of Radioanalytical and Nuclear Chemistry - Chitosan (CS) was synthesized by gamma irradiation of chitin extracted from shrimp shell wastes. CS nanofibers (CS-NFs) with a diameter of...     

Design,synthesis, in vivo and in vitro studies of 1,2,3,4-tetrahydro-9H-carbazole derivatives,highly selective and potent butyrylcholinesterase inhibitors

Molecular Diversity - Inhibition of butyrylcholinesterase (BChE) might be a useful therapeutic target for Alzheimer’s disease (AD). A new series of 1,2,3,4-tetrahydro-9H-carbazole derivatives...     

Using hyperbolic secant pulses to assist characterization of chemical shift tensors for half‐integer spin quadrupolar nuclei in MAS powder samples

Determination of the NMR anisotropic magnetic shielding parameters from magic angle spinning, MAS, powder samples containing half‐integer spin quadrupolar nuclei is achieved by analysis of the difference spectrum obtained with and without application of a hyperbolic secant pulse. Application of a hyperbolic secant pulse to any spinning sideband associated with the central transition, m_I = 1/2 to m_I = ? 1/2, results in ‘saturation’ of the entire central transition manifold. Similarly, if one spinning sideband associated with the m_I = 3/2 to m_I = 1/2 and m_I = ? 1/2 to m_I = ? 3/2 satellite transitions is perturbed, the entire satellite manifold associated with these transitions is ‘saturated’ while the central transition is enhanced by population transfer. Three ‘difference spectrum’ techniques are employed to selectively yield the spinning sidebands associated predominantly from the central transition. The success of these difference techniques is first demonstrated by examining ⁵¹V NMR spectra of three metavanadate salts and ⁵⁹Co NMR spectra of Co(acac)₃. The vanadium and cobalt chemical shift tensors in these compounds have spans between 400 and 1400 ppm. Because the hyperbolic secant techniques proposed here yielded results that are in good agreement with earlier reports, they have been applied to characterize the ⁵¹V chemical shift tensor of the dimer of bis(N, N‐dimethylhydroxamido)‐hydroxooxovanadate, {V(O)(ONMe₂)₂}₂O, whose chemical shift tensor has not been previously reported. Copyright © 2009 John Wiley & Sons, Ltd.