Synthesis of hapten-phosphoramidites from 2′-deoxyuridine

A total of 11 novel phosphoramidites, 3a-d, 4a-d and 14a-c were prepared from 2′-deoxyuridine functionalized at 5 and 6-position of the pyrimidine ring with hapten reporter groups, e.g. adamantane, carbazole, dansyl and dabsyl, suitable for use in immunodetection nucleic acid testing assays.     

Surface modification of nanoporous alumina surfaces with poly(ethylene glycol)

Nanoporous alumina surfaces have a variety of applications in biosensors, biofiltration, and targeted drug delivery. However, the fabrication route to create these nanopores in alumina results in surface defects in the crystal lattice. This results in inherent charge on the porous surface causing biofouling, that is, nonspecific adsorption of biomolecules. Poly(ethylene glycol) (PEG) is known to form biocompatible nonfouling films on silicon surfaces. However, its application to alumina surfaces is very limited and has not been well investigated. In this study, we have covalently attached PEG to nanoporous alumina surfaces to improve their nonfouling properties. A PEG-silane coupling technique was used to modify the surface. Different concentrations of PEG for different immobilization times were used to form PEG films of various grafting densities. X-ray photoelectron spectroscopy (XPS) was used to verify the presence of PEG moieties on the alumina surface. High-resolution C1s spectra show that with an increase in concentration and immobilization time, the grafting density of PEG also increases. Further, a standard overlayer model was used to calculate the thickness of PEG films formed using the XPS intensities of the Al2p peaks. The films formed by this technique are less than 2.5 nm thick, suggesting that such films will not clog the pores which are in the range of 70-80 nm.     

Syntheses and characterization of poly(benzimidazolyl) thiaxanthones

Novel polybenzimidazoles containing thiaxanthone heterocyclic units were synthesised from 2,7-thiaxanthonedicarboxylic acid-5,5′-dioxide and 2,8-thiaxanthonedicarboxylic acid-5,5′-dioxide and two aromatic tetramine hydrochlorides by PPA solution polycondensation in 60–70% yield. Two model compounds, 2,7-bis(2-benzimidazolyl)thiaxanthone-5,5′-dioxide and 2,8-bis(2-benzimidazolyl)thiaxanthone-5,5′-dioxide, were prepared and characterized by spectral methods. The polybenzimidazoles have inherent viscosities in the range 1.13–1.50 dL/g and decomposition temperatures of 495–560°C. The effect of thiaxanthone units on polymer properties are discussed.     

Synthesis and studies on metal coordination with a novel carboxyamide ligand

Novel complexes of Co(II), Ni(II), Cu(II) and Pd(II) with the new ligand [N,N'-bis(2-carboxy-1-oxo-phenelenyl)ethylenediamine] (H2L) have been synthesized and characterized on the basis of elemental analyses, magnetic susceptibility, thermal, infrared, electronic, 1H NMR and EPR spectral studies. Infrared and 1H NMR spectra show that H2L acts as a binegative tetradentate ligand. Coordination occurs through deprotonated carboxylate oxygens and nondeprotonated amido nitrogens in all the complexes. Electronic spectral studies and magnetic moment values suggest N2O2 coordination around each metal centre with strong field square planar chromophores. The probable structures of the complexes have been assigned on the basis of spectral studies. The complex formation between M(II) [M(II) = Mn(II), Co(II), Ni(II), Cu(II) and Zn(II)] and (L2-) has also been studied potentiometrically in 75% aqueous DMF at 25 degrees C in 0.1 M NaClO4. The stability constants were found to follow the order: Mn(II) < Co(II) < Ni(II) < Cu(II) > Zn(II).     

(Vapor + liquid) equilibria of the binary mixtures of m-cresol with C1-C4 aliphatic alcohols at 95.5 kPa

Bubble point temperatures at 95.5 kPa, over the entire composition range, are measured for the binary mixtures formed by m-cresol with: methanol, ethanol, 1-propanol, 2-propanol, and n-, iso-, sec-, and tert-butanols - using a Swietoslawski-type ebulliometer. The liquid phase composition - bubble point temperature measurements are well represented by the Wilson model. (Vapor + liquid) equilibria predicted from the model are presented.     

A note on a result of Zolotarev and Bernstein

In this note we obtain error bounds to x²ⁿ⁺¹–x²ⁿ on [–1, 1] by polynomials of degree at most (2n–1). The result proved here improves and extends some of the known results of Zolotarev and Bernstein. The proof presented here is different (and simple) from the one adopted by Zolotarev and Bernstein.     

A simple stereocontrolled synthesis of salinosporamide A

A simple and effective stereocontrolled synthesis of salinosporamide A has been developed. This process, the first synthesis of salinosporamide A, is capable of providing the compound in substantial quantities for further biological studies. Salinosporamide A was of special interest as a synthetic target because of its potent in vitro cytotoxic activity against many tumor cell lines (IC(50) values of 10 nM or less).     

Ciprofloxacin-protected gold nanoparticles

The antibacterial drug ciprofloxacin (cfH) has been used to protect gold nanoparticles of two different mean diameters, 4 and 20 nm. The protection is complete with about 65 and 585 cfH molecules covering 4 and 15 nm particles, respectively. The nature of binding has been investigated by several analytical techniques. The nitrogen atom of the NH moiety of piperazine group binds on the gold surface, as revealed by voltammetric and spectroscopic studies. The cfH-adsorbed particles are stable in the dry state as well as at room temperature, and as a result, redispersion is possible. The rate of release of the drug molecule from the nanoparticles is more in the basic medium than in pure water, and the kinetics depend on the size of the particle; faster desorption is seen in smaller particles. The bound cfH is fluorescent, and this property could be used in biological investigations. This study shows that metal nanoparticles could be useful carriers for cfH and fluoroquinolone molecules. Most of the bound molecules could be released over an extended period of time.     

Phase equilibria for binary systems of octane boosters with 2,2,4-trimethylpentane

Isobaric vapor–liquid equilibrium data at 95.96 kPa for the three binary systems of 2,2,4-trimethylpentane with methyl tert-butyl ether, di-isopropyl ether and dimethoxymethane are determined. A Swietoslawski type ebulliometer is used for the measurements. The experimental T–x data are used to estimate Wilson parameters and the parameters, in turn, are used to calculate vapor phase compositions and activity coefficients. All the systems studied here do not exhibit azeotropes and behave like non-ideal solutions.