Interaction Studies of Anticancer Drug Lomustine with Calf Thymus DNA using Surface Enhanced Raman Spectroscopy

Drug–DNA interaction study plays a significant role in understanding the drug action at molecular level and hence rationale drug designing. Lomustine (1-[2-chloroethyl]-3-cyclohexyl-1-nitroso-urea) is an alkylating antineoplastic nitrosourea derivative, used to treat various types of cancer. In the present investigation, conformational and structural effects of lomustine on DNA structure are analyzed using surface enhanced Raman spectroscopy. Different drug/DNA molar ratios are studied to determine the binding sites and binding mode of lomustine with DNA. Results suggest binding of lomustine with nitrogenous bases guanine and cytosine alongwith weak interaction to the sugar–phosphate backbone of DNA. The present study may support rational drug designing efforts to develop nitrosourea based novel therapeutics.     

Characterization of gas sensing behavior of multi walled carbon nanotube polyaniline composite films

In this paper, we report multiwall carbon nanotube (MWNT) doped polyaniline (PANI) composite thin films for hydrogen gas sensing applications. PANI was synthesized by in- situ chemical oxidative polymerization of aniline using ammonium persulfate in acidic medium.This emeraldine salt form of PANI was converted into emeraldine PANI base and doped with MWNT (4 wt%) in presence of champhor sulfonic acid (CSA) by solution mixing method. The MWNT/PANI composite films were deposited onto ITO coated glass substrate using spin cast technique. The gas sensitivity of these composite films was evaluated by measuring the change in electrical resistance of composite films in presence of hydrogen gas for different pressures at room tempeature. It is observed that the MWNT/PANI composite film shows a higher sensitivity in comparison to pure PANI and it decreases on increasing hydrogen gas pressure. The composite films have also been characterized by X-ray diffraction (XRD) analysis and Atomic force microscopy (AFM).     

Performance analysis of cooperative spectrum monitoring in cognitive radio network

Wireless Networks - The imperfect spectrum monitoring (SM) is a major obstacle to detect the emergence of primary user (PU) quickly during the cognitive users’ (CUs’) data transmission...     

Density functional study of adsorption and desorption dynamics of hydrogen in zirconium doped aluminium clusters

To reduce the greenhouse effect and as a fuel alternatives hydrogen is used as a secure and clean energy. But there are some challenges in the storage of hydrogen energy, the present accurate dynamics of adsorption and release of hydrogen. We report the adsorption and desorption of hydrogen atoms (up to eight) on the ZrAl_m (m = 3 to 7) clusters using density functional theory within B3PW91/LANL2DZ basis sets in the GAUSSIAN 09 package. Adsorption energy for per hydrogen atom in all clusters is found in the range of ?2.5 eV to ?3.3 eV, which shows the chemisorption of hydrogen on the ZrAl_m clusters. Change in the DOS with number of hydrogen is attributed to the charge transfer between the ZrAl_m clusters and hydrogen atoms. Highest HOMO-LUMO gap of 3.055 eV is found for the ZrAl₃H₇ cluster which indicates that the ZrAl₃H₇ cluster is chemically more stable. Work function values for hydrogen doped clusters are in the range of 3.5 eV–4.4 eV which suggests the low optical absorption in considered clusters. The calculated enthalpy difference further confirms the chemisorption of hydrogen on ZrAl_m clusters ZrAl₃H_n and ZrAl₇H_n(for n = 1 to 5 and 7) are more exothermic than other considered clusters. Desorption energies per hydrogen for these clusters are found lower than the some of the best catalytic clusters Pd₁₃ and Pt₁₃ indicating more catalytic active nature.     

Biosorption of Ni(Ⅱ) ions from aqueous solution using modified Aloe barbadensis Miller leaf powder

This study aimed to investigate the biosorption potential of Na_2 CO_3-modified Aloe barbadensis Miller(Aloe vera) leaf(MABL) powder for removal of Ni(II) ions from a synthetic aqueous solution. Effects of various process parameters(pH, equilibrium time, and temperature) were investigated in order to optimize the biosorptive removal. The maximum biosorption capacity of MABL was observed to be 28.986 mg/g at a temperature of 303 K, a biosorbent dose of 0.6 g, a contact time of 90 min, and a pH value of 7. Different kinetic models(the pseudo-first-order,pseudo-second-order, Elovich, and intraparticle diffusion models) were evaluated. The pseudo-second-order kinetic model was found to be the best fitted model in this study, with a coefficient of determination of R~2 = 0.974. Five different isotherm models(the Langmuir, Freundlich,Temkin, Dubinin-Radushkevich, and Brunauer-Emmett-Teller(BET) models) were investigated to identify the best-suited isotherm model for the present system. Based on the minimum chi-square value(x~2 = 0 027) and the maximum coefficient of determination(R~2 = 0.996), the Langmuir isotherm model was found to represent the system well, indicating the possibility of monolayer biosorption. The sticking probability(S*) was found to be 0.41, suggesting a physisorption mechanism for biosorption of Ni(II) on MABL. The biosorbent was characterized using Fourier-transform infrared spectroscopy(FTIR), scanning electron microscopy(SEM), zeta potential, and BET surface area, in order to understand its morphological and functional characteristics.     

Redox behavior and optical response of nanostructured poly(3,4-ethylenedioxythiophene) films grown in a camphorsulfonic acid based micellar solution

Poly(3,4-ethylenedioxythiophene) (PEDOT) films have been electropolymerized from an aqueous micellar solution comprising camphorsulfonic acid (CSA), lithium trifluoromethanesulfonate (LiCF₃SO₃) and EDOT. The inclusion of the dopants CS⁻ and CF₃SO₃⁻ in the polymer structure and an unusually high doping level of 0.54 have been ascertained by the X-ray photoelectron spectroscopy. Transmission electron microscopy and atomic force microscopy studies show that the micellar effect of CSA leads to a morphology wherein polymer particles link together to form elongated shapes and also endows the film with a surface roughness of 25-30 nm. These nanostructures permit a facile intercalation-deintercalation of anions in the film during redox cycling. Electrochemical impedance spectroscopy show that the charge transfer phenomenon at the PEDOT-electrolyte interface is dominant in the high frequency region and diffusion controlled ionic movement prevails in the low frequency regime. The use of these films as potential cathodes in electrochromic windows is rationalized not only on the basis of their high scalability and ease of processing but also due to their large coloration efficiency (123 cm² C⁻¹) and transmission modulation (50%) at a photopic wavelength of 550 nm. But further improvement in color-bleach kinetics and reproducibility of redox behavior is desirable to broaden their spectrum of utility.     

Synthesis,structural studies,and antimicrobial activity of polymeric copper(II) tetrathiocyanato diargentate(I) complexes with some acylhydrazones

Copper(II) complexes of the type Cu[Ag(SCN)₂]₂·L (where L is acetophenone benzoyl hydrazone, acetophenone isonicotinoyl hydrazone, acetophenone salicyloyl hydrazone, acetophenone anthraniloyl hydrazone, p‐hydroxyl acetophenone benzoylhydrazone, p‐hydroxyl acetophenone isonicotinoyl hydrazone, p‐hydroxyl acetophenone salicyloyl hydrazone, or p‐hydroxyl acetophenone anthraniloyl hydrazone) were synthesized and characterized. All the complexes were polymeric and insoluble in common organic solvent and were nonelectrolytes. The ligands were coordinated through >C?O and >C?N? groups. All the SCN groups present in the complexes acted as bridges between two metal centers, resulting in a polymeric structure of the Lewis acid Cu[Ag(SCN)₂]₂ as well as its complexes. Electronic and electron spin resonance spectra suggested a square planar geometry for the Lewis acid and an elongated tetragonally distorted octahedral geometry for all the complexes. The powder X‐ray diffraction parameters for acetophenone salicyloyl hydrazone and p‐hydroxyl acetophenone anthraniloyl hydrazone complexes corresponded to orthorhombic and tetragonal crystal lattices, respectively. The complexes showed a fair degree of antifungal activity against Rizoctonia sp., Aspergillus sp., and Stemphylium sp. and moderate antibacterial activity against Clostridium sp. (Gram‐positive) and Pseudomonas sp. (Gram‐negative). The complexes were more active than the parent ligands. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Lipase immobilized on poly (vinyl alcohol) modified polysulfone membrane: application in hydrolytic activities for olive oil

The advancement of membrane research closely relates to the activities of ‘immobilization of enzymes’. The modification of polymeric membrane surfaces according to tailor-made specifications is considered an art and useful in this arena. In this study, lipase is immobilized on Polyvinyl alcohol photomodified Polysulfone (PS–PVA) membranes. The maximum immobilization (1.48 mg/cm²) for PS–PVA membranes is achieved. The amount of immobilized lipase directly relates on the PVA content on the membrane. Scanning Electron Microscope and X-ray diffraction patterns show the evidences of lipase immobilization on membranes. The hydrolytic performances of lipase immobilized PS and PS–PVA–glu membranes for olive oil are studied. The free fatty acid (FFA %) and acid value (AV) parameters are determined by titrimetic analysis (1.53 and 3.04 for PS–PVA–glu) and compared with esterification GC-mass analysis data. The K _m and V _max values are 105 mM and 0.9 mM/min for lipase immobilized on PS–PVA–glu and 153.8 mM and 0.51 mM/min for lipase on PS. The reusability feature shows the lipase immobilized on PS–PVA–glu matrix have better stability (10.7% decrease) compared to lipase immobilized on PS matrix (33.3% decrease) after five cycles.     

Impact of omega-3 fatty acids and/or plant sterol supplementation on non-HDL cholesterol levels of dyslipidemic Indian adults

Independent and combined effects of 2 g/d long chain omega-3 fatty acids (omega-3) from fish oil (capsules) and 2 g/d plant sterol (yogurt drink) on LDL-C and non-HDL-C levels in Indian subjects were compared. Following a 2-week run-in period, 200 mildly hypercholesterolemic (total cholesterol 5.0–8.0 mmol/l) adults (35–55 years) were randomized into one of four groups [(1) both placebo (2) active omega-3 (3) active plant sterol (4) both active] of a 2 × 2 factorial, double-blind, placebo-controlled trial. Blood samples were obtained before and after the 4-week intervention (n = 178). Lipid levels were analyzed using ANCOVA models with relevant baseline measurements as covariates; adjusted means were compared across groups. While plant sterols significantly lowered LDL-C (?4.5%; P = 0.017) and non-HDL-C (?7.9%; P = 0.0019) levels, omega-3 did not demonstrate any such impact. The combination resulted in 4.2% and 3.9% reduction (non-significant), respectively. Thus, the beneficial effects of the omega-3-PS combination on lipid levels demonstrated earlier (lowered triacylglycerols by 15%, increased HDL-C by 5.4%) in addition to the present findings could make this combination a useful alternative for lowering coronary heart disease risk in Indian adults.