A Comparative Study of Fluorescein Isothiocyanate-Encapsulated Silica Nanoparticles Prepared in Seven Different Routes for Developing Fingerprints on Non-Porous Surfaces

Preparation of fluorescein isothiocyanate (FITC)-encapsulated silica nanoparticles (F-SiNPs) via seven different approaches to be used as developing agents for fingerprints detection is presented in this report. In this study, the suitability of each synthesis route toward incorporation of the selected fluorophore into silica matrix and its efficiency in fingerprints detection were systematically studied. The composition of the particles was designed to examine the hydrophobic and dipole-dipole interactions between the silicate backbone and both of the fluorescent reporter molecules and the fingerprint residues. F-SiNPs were prepared with two conventional sol-gel approaches; the Stöber method and the water in oil reverse microemulsion (WORM) method. The alkoxysilane precursor, tetraethoxyorthosilicate (TEOS) and its binary mixtures with phenyltriethoxysilane (PTEOS) or 3-aminopropyl triethoxysilane (APTES) have been used in preparing the F-SiNPs to study the effect of nanoparticles composition on fingerprints development. In addition, FITC was conjugated with APTES so it can be covalently bonded to the silica matrix and to be compared with non-covalently FITC-doped SiNPs. Moreover, the enhancement effect of introducing polyvinylpyrrolidone (PVP) onto the surface of the less hydrophobic F-SiNP on fingerprints detection on different non-porous surfaces was also investigated. The mean diameters of the F-SiNPs were between 4.1?±?0.6 and 110.4?±?31.1 nm as obtained from the TEM size measurement for the nanoparticles prepared by the WORM and Stöber methods, respectively. The obtained results clearly highlight the advantages of using a mixture of TEOS and PTEOS alkoxysilane precursors in preparing F-SiNPs with remarkable encapsulation efficiency and clear detection of fingerprints due to efficient embedding of the fluorophore inside the silica network even without conjugation. It was also observed that both the Stöber and WORM methods can be used in preparing the F-SiNPs developing agents and that PVP coated particles did not show any significant enhancement in fingerprints visualization.     

Optical properties,structural, and DFT studies of Pd(II) complexes with 1-phenyl-1H-tetrazol-5-thiol,X-ray crystal structure of [Pd(κ1-S-ptt)2(κ2-dppe)] complex

Seven tetrazole-thione complexes, [Pd₂(κ²-ptt)₄]( 1 ), trans-[Pd(k¹-S-ptt)₂(PPh₃)₂] ( 2 ), trans-[Pd(k¹-S-ptt)₂(SPPh₃)₂] ( 3 ), trans-[Pd(k¹-S-ptt)₂(OPPh₃)₂] ( 4 ), [Pd(k¹-N-ptt)₂(k²-dppe)] ( 5a ), [Pd(k¹-S-ptt)₂(k²-dppe)] ( 5b ), [Pd(k¹-S-ptt)₂(k²-dppeS₂)] ( 6 ), and [Pd(k¹-S-ptt)₂(k²-dppeO₂)] ( 7 ), were prepared from 1-phenyl-1H-tetrazole-5-thiol (Hptt), with substituted phosphines. These complexes were investigated by CHNS analysis; infrared (IR), nuclear magnetic resonance (NMR) (¹H and ³¹P), and ultraviolet–visible (UV–Vis) spectroscopy; and single-crystal X-ray data for 5b . In Complex 1 , the ptt⁻ ligand adopted μ²- k-N, k-S bridging mode to afford a dimeric complex, whereas in Complexes 2–4 , 6 , and 7 , the ptt⁻ was covalently coordinated via sulfur atom of the thiol group as a solo product. In contrast, in Complex 5 , the ptt⁻ ligand was bonded in a monodentate fashion through a deprotonated tetrazole ring nitrogen atom in isomer 5a or via a thiolato sulfur atom in isomer 5b . These linkage isomers were clearly shown in the ³¹P-{¹H} NMR. To explain the adoption of the ligand binding modes in Complexes 5a and 5b , geometry optimization calculations were carried out on two isomers. Very small differences of all molecular parameters were found between 5a and 5b isomers. This confirms the reason for obtaining two isomers. Also, theoretical studies are made for all compounds, and excellent agreement is obtained with experimental data. The direct band gap (Eg) values are equal to 2.88, 2.85, and 2.45 eV for Complexes 1 , 2 , and 4 , respectively, revealing a semiconductor nature. The inhibition activity of Complexes 1–3 , 5 , and 8 were evaluated versus the growth of four types of bacteria in vitro. The complexes showed a good activity compared with free ligand and a standard antibiotic.     

Structural characterization,thermal investigation and biological activity of metal complexes containing Schiff Base ligand (Z)‐3‐(1‐((4,6‐dimethyl‐1H‐pyrazolo[3,4‐b] pyridin‐3‐yl)imino)ethyl)‐4‐hydroxy‐6‐methyl‐2H‐pyran‐2‐one

A new series of metal complexes containing Co(II), Pd(II), Fe(III) chloride and Cu(II) salts (chloride, bromide, sulphate and perchlorate) have been prepared with Schiff base ligand ( HL ). The synthesized compounds were elucidated using elemental analyses, spectral techniques, molar conductance, magnetic measurements and thermogravimetric studies. The analytical data established (1 M:1 L) stoichiometry for complexes ( 1 ), ( 2 ), ( 4 ), ( 6 ) and ( 7 ) as well as (1 M:2 L) and (2 M:3 L) stoichiometry for complexes ( 5 ) and ( 3 ), respectively. As a result, the ligand HL coordinates in complexes ( 1 ), ( 2 ), ( 4 ), ( 6 ) as a monobasic tridentate ONN moiety via the oxygen atom of the deprotonated phenolic OH, the nitrogen atoms of the azomethine and the imine group in pyrazolopyridine ring. While, it behaves as a neutral bidentate in complexes ( 3 , 7 ), chelates via oxygen and nitrogen atoms of enolic OH and azomethine groups. Also, in complex ( 5 ) Cu²⁺ ion binds via NO sits of two ligand molecules in its monobasic and neutral forms. The magnetic moment and electronic spectral data proposed octahedral structure for complexes ( 2 , 3 and 7 ) as well as triagonal bipyramidal and square pyramidal geometry for complexes ( 1 and 4 ), while, chelates ( 5 ) and ( 6 ) possess square planar geometry. TG/DTG studies confirmed the chemical formula for these complexes and established the thermal decomposition processes ended with the formation of metal or metal oxides contaminated with carbon residue. An axial electron spin resonance spectra were suggested for Cu(II) complexes pointing to ²B_1g as a ground state with hyperfine structure for complex ( 4 ). In vitro antibacterial and antioxidant activities were performed for HL ligand and its metal complexes. The biological studies indicate that complex ( 3 ) has better antibacterial activity compared to the ligand and the other complexes.     

5-Aryl-1-Arylideneamino-1H-Imidazole-2(3H)-Thiones: Synthesis and In Vitro Anticancer Evaluation

A novel series of N-1 arylidene amino imidazole-2-thiones were synthesized, identified using IR, ¹H-NMR, and ¹³C-NMR spectral data. Cytotoxic effect of the prepared compounds was carried out utilizing three cancer cell lines; MCF-7 breast cancer, HepG2 liver cancer, and HCT-116 colon cancer cell lines. Imidazole derivative 5 was the most potent of all against three cell lines. DNA flow cytometric analysis showed that, imidazoles 4d and 5 exhibit pre-G1 apoptosis and cell cycle arrest at G2/M phase. The results of the VEGFR-2 and B-Raf kinase inhibition assay revealed that compounds 4d and 5 displayed good inhibitory activity compared with reference drug erlotinib.     

An overview on the synthesis and chemical properties ofp-aminoacetanilide and its derivatives

Chemical reactivity of amino group that connected with the para position of acetanilide moiety (p-aminoacetanilide) attained more attention in chemistry. In this review article, we report the chemistry of p-aminoacetanilide and its utilization in the synthesis of azo compounds, pyrrole, imidazole, thiazole and various heterocycles of biological importance.     

Discovery of New S‐Glycosides and N‐Glycosides of Pyridine‐biphenyl System with Antiviral Activity and Induction of Apoptosis in MCF7 Cells

Glycosylation of small molecule‐based drugs can dramatically improve the biological activities of the parent scaffold. In the current study, S‐glycosides and N‐glycosides of polyfunctionalized pyridine‐biphenyl system tethered with benzotriazole moiety were designed and synthesized. S‐Glycosides of pyridine‐2‐thione derivatives 5a – h and N‐glycosides of pyridine‐2‐one derivatives 9a , b were synthesized by a facile, convenient, and high‐yielding procedure. The epimers glucose and galactose, acetylated or deacetylated, were used to form the glycone part. The structures of these compounds were confirmed by microanalysis and spectroscopic data (IR, ¹ H–NMR, and ¹³C‐NMR). The anticancer activities of the target compounds, in comparison with standard cisplatin, were assessed by MTT assay against MCF7 cell line. Compounds 4f , 4g , 5f , and 5h exhibited the highest cytotoxic effect on MCF7. The anticancer effect of these four compounds induced the apoptosis as evident by the up‐regulated expression of the apoptotic genes Bax and p53 and down‐regulated expression of the anti‐apoptotic gene BCl₂. S‐Glycoside derivatives are more active than N‐glycosides. Moreover, the nontoxic doses of the tested compounds were evaluated in MA104, FRHK4, BGM, Hep2, and Vero cells. Compounds 4a – d and 5a – d were also evaluated for their antiviral effect against HSV‐1, HAV, and rotavirus Wa strain. The compounds' results showed less, moderated, and high antiviral activities. The docking study for these compounds with MDM2 revealed that deacetylated galactose is important for binding with the receptor as it facilitates the formation of hydrogen bond in the receptor. Rapid overlay of chemical structures analysis was employed to understand the compounds' similarity on the basis of their shape structure using the Tanimoto scores.     

Utilization of oxidation reactions for the spectrophotometric determination of captopril using brominating agents

Three simple, accurate and sensitive methods (A–C) for the spectrophotometric assay of captopril (CPL) in bulk drug, in dosage forms and in the presence of its oxidative degradates have been described. The methods are based on the bromination of captopril with a solution of excess brominating mixture in hydrochloric acid medium. After bromination, the excess brominating mixture is followed by the estimation of surplus bromine by three different reaction schemes. In the first method (A), the determination of the residual bromine is based on its ability to bleach the indigo carmine dye and measuring the absorbance at 610 nm. Method B, involves treating the unreacted bromine with a measured excess of iron(II) and the remaining iron(II) is complexed with 1,10-phenanthroline and the increase in absorbance is measured at 510 nm. In method (C), the surplus bromine is treated with excess of iron(II) and the resulting iron(III) is complexed with thiocyanate and the absorbance is measured at 478 nm. In all the methods, the amount of bromine reacted corresponds to the drug content. The different experimental parameters affecting the development and stability of the color are carefully studied and optimized. Beer's law is valid within a concentration range of 0.4–6.0, 0.4–2.8 and 1.2–4.8 μg mL^?1 for methods A, B and C, respectively. The calculated apparent molar absorptivity was found to be 5.16 × 10⁴, 9.95 × 10⁴ and 1.74 × 10⁵ L mol^?1 cm^?1, for methods A, B and C, respectively. Sandell's sensitivity, correlation coefficients, detection and quantification limits are also reported. No interference was observed from common additives found in pharmaceutical preparations. The proposed methods are successfully applied to the determination of CPL in the tablet formulations with mean recoveries of 99.94–100.11% and the results were statistically compared with those of a reference method by applying Student's t- and F-test.     

Protein expression dynamics during replicative senescence of endothelial cells studied by 2-D difference in-gel electrophoresis

Endothelial senescence contributes to endothelium dysfunctionality and is thereby linked to vascular aging. A dynamic proteomic study on human umbilical vein endothelial cells, isolated from three umbilical cords, was performed. The cells were cultured towards replicative senescence and whole cell lysates were subjected to 2-D difference gel electrophoresis (DIGE). Despite the biological variability of the three independent isolations, a set of proteins was found that showed senescence-dependent expression patterns in all isolations. We focused on those proteins that showed significant changes, with a paired analysis of variance (RM-ANOVA) p-value of < or =0.05. Thirty-five proteins were identified with LC-Fourier transform MS, and functional annotation revealed that endothelial replicative senescence is accompanied by increased cellular stress, protein biosynthesis and reduction in DNA repair and maintenance. Nuclear integrity becomes affected and cytoskeletal structure is also changed. Such important changes in the cell infrastructure might accelerate endothelium dysfunctionality. This study provides biological information that will initiate studies to further unravel endothelial senescence and gain more knowledge about the consequences of this process in the in vivo situation.     

Predicting substrates by docking high-energy intermediates to enzyme structures

With the emergence of sequences and even structures for proteins of unknown function, structure-based prediction of enzyme activity has become a pragmatic as well as an interesting question. Here we investigate a method to predict substrates for enzymes of known structure by docking high-energy intermediate forms of the potential substrates. A database of such high-energy transition-state analogues was created from the KEGG metabolites. To reduce the number of possible reactions to consider, we restricted ourselves to enzymes of the amidohydrolase superfamily. We docked each metabolite into seven different amidohydrolases in both the ground-state and the high-energy intermediate forms. Docking the high-energy intermediates improved the discrimination between decoys and substrates significantly over the corresponding standard ground-state database, both by enrichment of the true substrates and by geometric fidelity. To test this method prospectively, we attempted to predict the enantioselectivity of a set of chiral substrates for phosphotriesterase, for both wild-type and mutant forms of this enzyme. The stereoselectivity ratios of the six enzymes considered for those four substrate enantiomer pairs differed over a range of 10- to 10,000-fold and underwent 20 switches in stereoselectivities for favored enantiomers, compared to the wild type. The docking of the high-energy intermediates correctly predicted the stereoselectivities for 18 of the 20 substrate/enzyme combinations when compared to subsequent experimental synthesis and testing. The possible applications of this approach to other enzymes are considered.     

Localization for Random Unitary Operators

We consider unitary analogs of one-dimensional Anderson models on defined by the product U _ω=D _ω S where S is a deterministic unitary and D _ω is a diagonal matrix of i.i.d. random phases. The operator S is an absolutely continuous band matrix which depends on a parameter controlling the size of its off-diagonal elements. We prove that the spectrum of U _ω is pure point almost surely for all values of the parameter of S. We provide similar results for unitary operators defined on together with an application to orthogonal polynomials on the unit circle. We get almost sure localization for polynomials characterized by Verblunsky coefficients of constant modulus and correlated random phases Mathematics Subject Classification. 82B44, 42C05, 81Q05