Carbonization of solvent and capping agent based enhancement in the stabilization of cobalt nanoparticles and their magnetic study

We describe a hybrid synthetic protocol, the solvated metal atom dispersion (SMAD) method, for the synthesis and stabilization of monodisperse amorphous cobalt nanoparticles. By employing an optimized ratio of a weakly coordinating solvent and a capping agent monodisperse colloidal cobalt nanoparticles (2 +/- 0.5 nm) have been prepared by the SMAD method. However, the as-prepared samples were found to be oxidatively unstable which was elucidated by their magnetic studies. Oxidative stability in our case was achieved via a pyrolysis process that led to the decomposition of the organic solvent and the capping agent resulting in the formation of carbon encapsulated cobalt nanoparticles which was confirmed by Raman spectroscopy. Controlled annealing at different temperatures led to the phase transformation of metallic cobalt from the hcp to fcc phase. The magnetic behaviour varies with the phase and the particle size; especially, the coercivity of nanoparticles exhibited strong dependence on the phase transformation of cobalt. The high saturation magnetization close to that of the bulk value was achieved in the case of the annealed samples. In addition to detailed structural and morphological characterization, the results of thermal and magnetic studies are also presented.

LbL-coated microcapsules as systems for encapsulation of optical brightening agent

We report the encapsulation of optical brightening agent (OBA) into hollow microcapsules prepared by the controlled Layer- by-Layer (LbL) self-assembly process, achieved by the sequential adsorption of oppositely charged polyelectrolytes using negatively charged silica template. Loading takes place by spontaneous deposition method which was proved by confocal laser scanning microscopy (CLSM) using rhodamine 6G (Rd6G) as a fluorescent probe. The loading of the OBA into the microcapsules was found to be dependent on the feeding concentration, pH of the medium, and loading temperature. The encapsulation efficiency of OBA decreased on increasing feeding concentration. Maximum loading was observed at pH 4 and amount of OBA loaded decreased with increase in pH. The loaded OBA was released in a sustained manner for 8 h. No degradation of the OBA was observed during the process of encapsulation and release. Polyelectrolyte capsules potentially offer an innovative way of encapsulating large amounts of active materials for a variety of applications. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 127: 1609-1614, 2013

Oxidative DNA cleavage, cytotoxicity and antimicrobial studies of L-ornithine copper (II) complexes

New ternary copper (II) complexes, Cu(L-orn)(B)(Cl)](Cl center dot 2H(2)O) (1-2) where L-orn is L-ornithine, B is an N,N-donor heterocyclic base, viz. 2,2'-bipyridine (bpy, 1) and 1,10-phenanthroline (phen, 2), were synthesized and characterized by various spectroscopic techniques. Complex 2 is characterized by the X-ray single crystallographic method. The complex shows a distorted square-pyramidal (4 + 1) CuN3OCl coordination sphere. Binding interactions of the complexes with calf thymus DNA (CT-DNA) were investigated by UV-Vis absorption titration, ethidium bromide displacement assay, viscometric titration experiment and DNA melting studies. Complex 2 shows appreciable chemical nuclease activity in the presence of 3-mercaptopropionic acid (MPA). The complexes were subjected to in vitro cytotoxicity studies against carcinomic human alveolar basal epithelial cells (A-549) and human epithelial (HEp-2) cells. The IC50 values of 1 and 2 are less than that of cisplatin against HEp-2 cell lines. MIC values for 1 against the bacterial strains Streptococcus mutans and Pseudomonas aeruginosa are 0.5 mM. (C) 2012 Elsevier Ltd. All rights reserved.

Curcumin reduces the antimicrobial activity of ciprofloxacin against Salmonella Typhimurium and Salmonella Typhi

Typhoidal and non-typhoidal infection by Salmonella is a serious threat to human health. Ciprofloxacin is the last drug of choice to clear the infection. Ciprofloxacin, a gyrase inhibitor, kills bacteria by inducing chromosome fragmentation, SOS response and reactive oxygen species (ROS) in the bacterial cell. Curcumin, an active ingredient from turmeric, is a major dietary molecule among Asians and possesses medicinal properties. Our research aimed at investigating whether curcumin modulates the action of ciprofloxacin. We investigated the role of curcumin in interfering with the antibacterial action of ciprofloxacin in vitro and in vivo. RTPCR, DNA fragmentation and confocal microscopy were used to investigate the modulation of ciprofloxacin-induced SOS response, DNA damage and subsequent filamentation by curcumin. Chemiluminescence and nitroblue tetrazolium reduction assays were performed to assess the interference of curcumin with ciprofloxacin-induced ROS. DNA binding and cleavage assays were done to understand the rescue of ciprofloxacin-mediated gyrase inhibition by curcumin. Curcumin interferes with the action of ciprofloxacin thereby increasing the proliferation of Salmonella Typhi and Salmonella Typhimurium in macrophages. In a murine model of typhoid fever, mice fed with curcumin had an increased bacterial burden in the reticuloendothelial system and succumbed to death faster. This was brought about by the inhibition of ciprofloxacin-mediated downstream signalling by curcumin. The antioxidant property of curcumin is crucial in protecting Salmonella against the oxidative burst induced by ciprofloxacin or interferon (IFN), a pro-inflammatory cytokine. However, curcumin is unable to rescue ciprofloxacin-induced gyrase inhibition. Curcumins ability to hinder the bactericidal action of ciprofloxacin and IFN might significantly augment Salmonella pathogenesis.

Mobile agent based TCP attacker identification in MANET using the traffic history (MAITH)

TCP attacks are the major problem faced by Mobile Ad hoc Networks (MANETs) due to its limited network and host resources. Attacker traceback is a promising solution which allows a victim to identify the exact location of the attacker and hence enables the victim to take proper countermeasure near attack origins, for forensics and to discourage attackers from launching the attacks. However, attacker traceback in MANET is a challenging problem due to dynamic network topology, limited network and host resources such as memory, bandwidth and battery life. We introduce a novel method of TCP attacker Identification in MANET using the Traffic History - MAITH. Based on the comprehensive evaluation based on simulations, we showed that MAITH can successfully track down the attacker under diverse mobile multi-hop network environment with low communication, computation, and memory overhead.

Discrimination of alpha-Amino Acids Using Green Tea Flavonoid (-)-Epigallocatechin Gallate as a Chiral Solvating Agent

We report a special, hitherto-unexplored property of (-)-epigallocatechin gallate (EGCG) as a chiral solvating agent for enantiodiscrimination of alpha-amino acids in the polar solvent DMSO. This phenomenon has been investigated by H-1 NMR spectroscopy. The mechanism of the interaction property of EGCG with alpha-amino acids has been understood as arising out of hydrogen-bonded noncovalent interactions, where the -OH groups of two phenyl rings of EGCG play dominant roles. The conversion of the enantiomeric mixture into diastereomers yielded well-resolved peaks for D and L amino acids permitting the precise measurement of enantiomeric composition. Often one encounters complex situations when the spectra are severely overlapped or partially resolved hampering the testing of enantiopurity and the precise measurement of enantiomeric excess (ee). Though higher concentration of EGCG yielded better discrimination, the use of lower concentration being economical, we have exploited an appropriate 2D NMR experiment in overcoming such problems. Thus, in the present study we have successfully demonstrated the utility of the bioflavonoid (-)-EGCG, a natural product as a chiral solvating agent for the discrimination of large number of alpha-amino acids in a polar solvent DMSO. Another significant advantage of this new chiral sensing agent is that it is a natural product and does not require tedious multistep synthesis unlike many other chiral auxiliaries.

Bimetallic core-shell nanocomposites using weak reducing agent and their transformation to alloy nanostructures

An in situ seeding growth methodology towards the preparation of core-shell nanoparticles composed of noble metals has been developed by employing trimethylamine borane (TMAB) as the reducing agent. Being a weak reducing agent, TMAB is able to distinguish the smallest reduction potential window of any two metals which renders selective reduction of metal ions thus affording a core-shell architecture of the nanoparticles. A dramatic effect of solvent was noted during the reduction of Ag+ ions: an immediate reduction took place at room temperature when dry THF was used as solvent however, usage of wet THF (THF used directly from the bottle) brings out the reduction only at reflux conditions. In the case of Au and Pd nanoparticles, preparation was found to be independent of the quality of solvent used. Au nanoparticles are realized at room temperature whereas reflux conditions are required in the case of Pd nanoparticles. This difference in behavior of the monometallic nanoparticles was successfully exploited to construct different noble metal nanoparticles with core-shell architectures such as Au@Ag, Ag@Au, and Ag@Pd. Transformation of these core-shell nanoparticles to their thermodynamically stable alloy counterparts is also demonstrated under very mild conditions reported to date.

Mobile agent based node monitoring protocol for MANETs

Mobile ad-hoc network is a wireless ad-hoc network with dynamic network topology. The Dynamicity, due to the random node movement, and scarcity of resources lead to a challenge in monitoring the nodes in a MANET. Monitoring the lack of resources (bandwidth, buffer, and energy), misbehavior, and mobility at node level remains, a challenge. In a MANET the proposed protocol uses both static as well as mobile agents, where the mobile agents migrate to different clusters of the zones respectively, collect the node status information periodically, and provide a high level information to the static agent (which resides at the central node) by analyzing the raw information at the nodes. This, in turn, reduces the network traffic and conserves the workload of the central node, where a static agent is available with high level information and in coordination with other modules. The protocol has been tested in different size MANETs with variable number of nodes and applications. The results shown in the simulation indicates the effectiveness of the protocol.

Synthesis, Antimicrobial and Cytotoxic Activities of Sulfonamidomethane Linked Heterocycles

A new class of sulfonamidomethane pyrrolyl-oxadiazoles/thiadiazoles and pyrazolyl-oxadiazoles/thiadiazoles was prepared from arylsulfonylaminoacetic acid hydrazides and E-cinnamic acid. The lead compounds were tested for antimicrobial and cytotoxic activities. The thiadiazole compounds having chloro substituent on the aromatic ring 4c, 8c and 10c exhibited comparable antibacterial activity against Pseudomonas aeruginosa and also antifungal activity against Penieillium ehrysogenunz. The styryl oxadiazole compound 3c showed appreciable cytotoxic activity on A549 lung carcinoma cells which can be used as a lead compound in the future studies.

A Novel Anticancer Agent, 8-Methoxypyrimido4 `,5 `: 4,5]thieno(2,3-b) Quinoline-4(3H)-One Induces Neuro 2a Neuroblastoma Cell Death through p53-Dependent, Caspase-Dependent and Independent Apoptotic Pathways

Neuroblastoma is the most common cancer in infants and fourth most common cancer in children. Despite recent advances in cancer treatments, the prognosis of stage-IV neuroblastoma patients continues to be dismal which warrant new pharmacotherapy. A novel tetracyclic condensed quinoline compound, 8-methoxypyrimido 4 `,5 `: 4,5] thieno(2,3-b) quinoline-4(3H)-one (MPTQ) is a structural analogue of an anticancer drug ellipticine and has been reported to posses anticancer property. Study on MPTQ on neuroblastoma cells is very limited and mechanisms related to its cytotoxicity on neuroblastoma cells are completely unknown. Here, we evaluated the anticancer property of MPTQ on mouse neuro 2a and human SH-SY5Y neuroblastoma cells and investigated the mechanisms underlying MPTQ-mediated neuro 2a cell death. MPTQ-mediated neuro 2a and SH-SY5Y cell deaths were found to be dose and time dependent. Moreover, MPTQ induced cell death reached approximately 99.8% and 90% in neuro 2a and SH-SY5Y cells respectively. Nuclear oligonucleosomal DNA fragmentation and Terminal dUTP Nick End Labelling assays indicated MPTQ-mediated neuro 2a cell death involved apoptosis. MPTQ-mediated apoptosis is associated with increased phosphorylation of p53 at Ser15 and Ser20 which correlates with the hyperphosphorylation of Ataxia-Telangiectasia mutated protein (ATM). Immunocytochemical analysis demonstrated the increased level of Bax protein in MPTQ treated neuro 2a cells. MPTQ-mediated apoptosis is also associated with increased activation of caspase-9, -3 and -7 but not caspase-2 and -8. Furthermore, increased level of caspase-3 and cleaved Poly ( ADP Ribose) polymerase were observed in the nucleus of MPTQ treated neuro 2a cells, suggesting the involvement of caspase-dependent intrinsic but not extrinsic apoptotic pathway. Increased nuclear translocation of apoptosis inducing factor suggests additional involvement of caspase-independent apoptosis pathway in MPTQ treated neuro 2a cells. Collectively, MPTQ-induced neuro 2a cell death is mediated by ATM and p53 activation, and Bax-mediated activation of caspase-dependent and caspase-independent mitochondrial apoptosis pathways.

Design and synthesis of positional isomers of 5 and 6-bromo-1-(phenyl)sulfonyl]-2-(4-nitrophenoxy)methyl]-1H-benzimida zoles as possible antimicrobial and antitubercular agents

In this Letter, we report the structure activity relationship (SAR) studies on series of positional isomers of 5(6)-bromo-1-(phenyl)sulfonyl]-2-(4-nitrophenoxy)methyl]-1H-benzim idazoles derivatives 7(a-j) and 8(a j) synthesized in good yields and characterized by H-1 NMR, C-13 NMR and mass spectral analyses. The crystal structure of 7a was evidenced by X-ray diffraction study. The newly synthesized compounds were evaluated for their in vitro antibacterial activity against Staphylococcus aureus, (Gram-positive), Escherichia coil and Klebsiella pneumoniae (Gram-negative), antifungal activity against Candida albicans, Aspergillus flavus and Rhizopus sp. and antitubercular activity against Mycobacterium tuberculosis H37Rv, Mycobacterium smegmatis, Mycobacterium fortuitum and MDR-TB strains. The synthesized compounds displayed interesting antimicrobial activity. The compounds 7b, 7e and 7h displayed significant activity against Mycobacterium tuberculosis H37Rv strain.

Laser receptive polyelectrolyte thin films doped with biosynthesized silver nanoparticles for antibacterial coatings and drug delivery applications

We report a simple method to fabricate multifunctional polyelectrolyte thin films to load and deliver the therapeutic drugs. The multilayer thin films were assembled by the electrostatic adsorption of poly (allylamine hydrochloride) (PAH) and dextran sulfate (DS). The silver nanoparticles (Ag NPs) biosynthesized from novel Hybanthus enneaspermus leaf extract as the reducing agent were successfully incorporated into the film. The biosynthesized Ag NPs showed excellent antimicrobial activity against the range of enteropathogens, which could be significantly enhanced when used with commercial antibiotics. The assembled silver nano composite multilayer films showed rupture and deformation when they are exposed to laser. The Ag NPs act as an energy absorption center, locally heat up the film and rupture it under laser treatment. The antibacterial drug, moxifloxacin hydrochloride (MH) was successfully loaded into the multilayer films. The total amount of MH release observed was about 63% which increased to 85% when subjected to laser light exposure. Thus, the polyelectrolyte thin film reported in our study has significant potential in the field of remote activated drug delivery, antibacterial coatings and wound dressings. (C) 2013 Elsevier B.V. All rights reserved.

Mitochondria-Targeting Oxidovanadium(IV) Complex as a Near-IR Light Photocytotoxic Agent

Oxidovanadium(IV) complexes VO(L-1)(phen)]Cl (1) and VO(L-2)(L-3)]Cl (2), in which HL1 is 2-{(benzimidazol-2-yl)methylimino]-methyl}phenol (sal-ambmz), HL2 is 2-({1-(anthracen-9-yl)methyl]-benzimidazol-2-yl}methylimino)-met hyl]phenol (sal-an-ambmz), phen is 1,10-phenanthroline and L-3 is dipyrido3,2-a:2,3-c]phenazine (dppz) conjugated to a Gly-Gly-OMe dipeptide moiety, were prepared, characterized, and their DNA binding, photoinduced DNA-cleavage, and photocytotoxic properties were studied. Fluorescence microscopy studies were performed by using complex 2 in HeLa and HaCaT cells. Complex 1, structurally characterized by X-ray crystallography, has a vanadyl group in VO2N4 core with the VO2+ moiety bonded to N,N-donor phen and a N,N,O-donor Schiff base. Complex 2, having an anthracenyl fluorophore, showed fluorescence emission bands at 397, 419, and 443nm. The complexes are redox-active exhibiting the V(IV)/V(III) redox couple near -0.85V versus SCE in DMF 0.1M tetrabutylammonium perchlorate (TBAP). Complex 2, having a dipeptide moiety, showed specific binding towards poly(dAdT)(2) sequence. The dppz-Gly-Gly-OMe complex showed significant DNA photocleavage activity in red light of 705nm through a hydroxyl radical ((OH)-O-.) pathway. Complex 2 showed photocytotoxicity in HaCaT and HeLa cells in visible light (400-700nm) and red light (620-700nm), however, the complex was less toxic in the dark. Fluorescence microscopy revealed the localization of complex 2 primarily in mitochondria. Apoptosis was found to occur inside mitochondria (intrinsic pathway) caused by ROS generation.

A method of developing an agent based ubiquitous node monitoring protocol

A ubiquitous network plays a critical role to provide rendered services to ubiquitous application running nodes. To provide appropriate resources the nodes are needed to be monitored continuously. Monitoring a node in ubiquitous network is challenging because of dynamicity and heterogeneity of the ubiquitous network. The network monitor has to monitor resource parameters, like data rate, delay and throughput, as well as events such as node failure, network failure and fault in the system to curb the system failure. In this paper, we propose a method to develop a ubiquitous system monitoring protocol using agents. Earlier works on network monitoring using agents consider that the agents are designed for particular network. While in our work the heterogeneity property of the network has been considered. We have shown that the nodes' behaviour can be easily monitored by using agents (both static and mobile agent). The past behavior of the application and network, and past history of the Unode and the predecessor are taken into consideration to help SA to take appropriate decision during the time of emergency situation like unavailability of resources at the local administration, and to predict the migration of the Unode based on the previous node history. The results obtained in the simulation reflects the effectiveness of the technique.

In vitro and in silico biological studies of novel thiazolo3,2-a]pyrimidine-6-carboxylate derivatives

In the present study, we report the synthesis, characterization of new series of thiazolo3,2-a]pyrimidine-6-carboxylate derivatives 3a-f and 4a-f. The newly synthesized compounds were screened for in vitro antimicrobial and antiviral activities. The probable mode of action of these active compounds was determined through in silico docking study by docking the receptor methionyl-tRNA synthetase and human inosine-5'-monophosphate dehydrogenase (IMPDH) for antibacterial and antiviral activities, respectively. Among the compounds, 4c exhibited excellent in vitro antimicrobial activity against all tested strains with binding and docking energies -35.6 and -12.4 kcal/mol, respectively. The antiviral studies were carried out for the selected compounds in which 4a exhibited 73.69 and 54.42 % of inhibition of buffalopox and camelpox viruses, respectively. Furthermore, compound 4a showed minimum docking and binding energy along with the maximum hydrogen/hydrophobic interaction with IMPDH. The study contributes towards identification and screening of potential antimicrobial and antiviral agent's against the pathogens.