Synthesis and optical properties of small Au nanorods using a seedless growth technique

Gold nanoparticles have shown potential in photothermal cancer therapy and optoelectronic technology. In both applications, a call for small size nanorods is warranted. In the present work, a one-pot seedless synthetic technique has been developed to prepare relatively small monodisperse gold nanorods with average dimensions (length × width) of 18 × 4.5 nm, 25 × 5 nm, 15 × 4.5 nm, and 10 × 2.5 nm. In this method, the pH was found to play a crucial role in the monodispersity of the nanorods when the NaBH(4) concentration of the growth solution was adjusted to control the reduction rate of the gold ions. At the optimized pH and NaBH(4) concentrations, smaller gold nanorods were produced by adjusting the CTAB concentration in the growth solution. In addition, the concentration of silver ions in the growth solution was found to be pivotal in controlling the aspect ratio of the nanorods. The extinction coefficient values for the small gold nanorods synthesized with three different aspect ratios were estimated using the absorption spectra, size distributions, and the atomic spectroscopic analysis data. The previously accepted relationships between the extinction coefficient or the longitudinal band wavelength values and the nanorods' aspect ratios found for the large nanorods do not extend to the small size domain reported in the present work. The failure of extending these relationships over larger sizes is a result of the interaction of light with the large rods giving an extinction band which results mostly from scattering processes while the extinction of the small nanorods results from absorption processes.     

Stereoselective α-quaternization of 3-methoxycycloalk-2-enones via 1,4-diastereoinduction of alkoxy dienolates

The alkylation of dienolates generated from 3-methoxycycloalk-2-enones having a 3'-hydroxyl alkenyl chain provides the corresponding quaternized cycloalkenones in a highly diastereoselective manner. The high degree of stereocontrol in the α-quaternization possibly implies intervention of a rigid chelating transition state that allows an efficient 1,4-asymmetric induction to take place.     

Synthesis and study of some new <Emphasis Type="Italic">N</Emphasis>-substituted imide derivatives as potential antibacterial agents

Dibenzobarrelene (I) was used as a starting compound for the synthesis of some new 3a,4,9,9a-tetrahydro-4,9-[1,2]benzeno-1H-benzo[f]isoindole-1,3(2H)-diones, N-substituted with: 4-toluenesulfonyloxy, III; butoxy, IV; 3-bromopropoxy, V; 3-(4-phenylpiperazin-1-yl)propoxy, VI; 3-chloro-3-oxopropyl, VIII; 3-(4-phenylpiperazin-1-yl)-3-oxopropyl, IXa; 3-(4-methylpiperazin-1-yl)-3-oxopropyl, IXb; 3-oxo-3-(piperidin-1-yl)propyl, X; 3-morpholino-3-oxopropyl, XI; 3-phenylamino-3-oxopropyl, XII; 2-acetylaminoethyl, XIV; 2-aminoethyl, XV, and 2-acetoxyethyl, XVI. Newly synthesized compounds were characterized by IR, ¹H and ¹³C NMR, and mass spectral data. Selected products were tested for antimicrobial activity.     

Synthesis and Antimicrobial Activity of Some 3-Substituted-5,6-dimethoxy-2,3-dihydrobenzo[d]thiazol-2-one

Sixteen new compounds derived from the 2,3-dihydrobenzo[d]thiazol-2-one template with various side-chains in position-3 were synthesized and evaluated for their antimicrobial activity. Antibacterial and antifungal screening of the compounds prepared showed that 5,6-dimethoxy-3-(2-oxo-propyl)-2,3-dihydrobenzo[d]thiazol-2-one (3g) exhibited the highest activity.     

Synthesis,Characterization, In Vitro Anticancer Potentiality,and Antimicrobial Activities of Novel Peptide–Glycyrrhetinic-Acid-Based Derivatives

Glycyrrhetinic acid (GA) is one of many interesting pentacyclic triterpenoids showing significant anticancer activity by triggering apoptosis in tumor cell lines. This study deals with the design and synthesis of new glycyrrhetinic acid (GA)–amino acid peptides and peptide ester derivatives. The structures of the new derivatives were established through various spectral and microanalytical data. The novel compounds were screened for their in vitro cytotoxic activity. The evaluation results showed that the new peptides produced promising cytotoxic activity against the human breast MCF-7 cancer cell line while comparing to doxorubicin. On the other hand, only compounds 3, 5, and 7 produced potent activity against human colon HCT-116 cancer cell line. The human liver cancer (HepG-2) cell line represented a higher sensitivity to peptide 7 (IC₅₀; 3.30 μg/mL), while it appeared insensitive to the rest of the tested peptides. Furthermore, compounds 1, 3, and 5 exhibited a promising safety profile against human normal skin fibroblasts cell line BJ-1. In order to investigate the mode of action, compound 5 was selected as a representative example to study its in vitro effect against the apoptotic parameters and Bax/BCL-2/p53/caspase-7/caspase-3/tubulin, and DNA fragmentation to investigate beta (TUBb). Additionally, all the new analogues were subjected to antimicrobial assay against a panel of Gram-positive and Gram-negative bacteria and the yeast candida Albicans. All the tested GA analogues 1–8 exhibited more antibacterial effect against Micrococcus Luteus than gentamicin, but they exhibited moderate antimicrobial activity against the tested bacterial and yeast strains. Molecular docking studies were also simulated for compound 5 to give better rationalization and put insight to the features of its structure.     

Inhibition of NF-kB/IL-6/JAK2/STAT3 Pathway and Epithelial-Mesenchymal Transition in Breast Cancer Cells by Azilsartan

Metastatic breast cancer is an incurable form of breast cancer that exhibits high levels of epithelial-mesenchymal transition (EMT) markers. Angiotensin II has been linked to various signaling pathways involved in tumor cell growth and metastasis. The aim of this study is to investigate, for the first time, the anti-proliferative activity of azilsartan, an angiotensin II receptor blocker, against breast cancer cell lines MCF-7 and MDA-MB-231 at the molecular level. Cell viability, cell cycle, apoptosis, colony formation, and cell migration assays were performed. RT-PCR and western blotting analysis were used to explain the molecular mechanism. Azilsartan significantly decreased the cancer cells survival, induced apoptosis and cell cycle arrest, and inhibited colony formation and cell migration abilities. Furthermore, azilsartan reduced the mRNA levels of NF-kB, TWIST, SNAIL, SLUG and bcl2, and increased the mRNA level of bax. Additionally, azilsartan inhibited the expression of IL-6, JAK2, STAT3, MMP9 and bcl2 proteins, and increased the expression of bax, c-PARP and cleaved caspase 3 protein. Interestingly, it reduced the in vivo metastatic capacity of MDA-MBA-231 breast cancer cells. In conclusion, the present study revealed, for the first time, the anti-proliferative, apoptotic, anti-migration and EMT inhibition activities of azilsartan against breast cancer cells through modulating NF-kB/IL-6/JAK2/STAT3/MMP9, TWIST/SNAIL/SLUG and apoptosis signaling pathways.     

Hydrodynamic Behaviour of Very Large Floating Structures (VLFS) in Waves

An effective way to solve multiphysics scenarios in general and fluid-structure interaction problems in particular is to rely on a partitioned solution approach, which allows for the use of different discretisation schemes and specialised solvers for each of the individual subdomains. A coupling interface, which manages the transfer of the field quantities between the solvers, has been developed and successfully applied to a great variety of coupled problems. Different predictor and relaxation techniques have been implemented to stabilize the solution algorithm and accelerate its convergence. (© 2014 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim)