Current Nanoscience - Volume 9, Issue 1, 2013

Metal oxide nanotubes were produced on Ti, Nb, and TiTa and TiNb alloy surfaces by anodic oxidation in fluoride containing electrolytes. Tube diameters from 7 to 110 nm and tube lengths from 50 nm to 1.6 μm were achieved, depending on the substrate material, the anodization parameters, and the composition of the electrolyte. With the application of a voltage of 20 V for 1 h to Nb substrates tubes with 124.3±8.3 nm length were formed, while the same anodization conditions resulted in a tube length of only 66.7±14.2 nm, when applied in a glycol based electrolyte. While there was a linear connection between tube diameter and voltage for Ti anodization, Nb showed limits in the achievable tube dimensions. Furthermore, significant influences on the ion transport mechanisms were found for variations of electrolyte viscosity and stirring frequency, which highly affected the morphology and the size distribution of the obtained nanotubes. Very different anodization behaviour was found for alloys of Ti with Nb resp. Ta, leading to the conclusion that the Pilling- Bedworth ratio must be kept at an average value below 2.44, if fabrication of isolated nanotubes on an alloy surfaces should be successful.

To enantioseparate ofloxacin, we demonstrated a new method of using multi-walled carbon nanotubes (MWCNTs) impregnated thin-lay chromatography (TLC). A general discussion that focuses on the possibility of CNTs in the field of chromatographic enantioseparation is presented. We hope it will be useful for the chromatographer and pharmaceutical industries.

Cyanobacteria produce oligopeptides that are predominantly synthesized by the non-ribosomal pathway. Among these are the aeruginosin and cyanopeptolin protease inhibitors, which act against enzymes known to cause several human health problems. Atomic force microscopy (AFM) was used to study the effect of cyanopeptides produced by Microcystis aeruginosa NPCD-1 on pathogenic bacterial cell surfaces. The selected strain was characterized based on the 16S rRNA gene sequence and the intergenic spacer region of the phycocyanin operon. PCR amplification was employed to investigate the presence of genes encoding for aeruginosin and cyanopeptolin. Purified extract from M. aeruginosa NPCD-1 cells was screened for bioactive compounds. The effect of purified extract containing protease inhibitors produced by the NPCD-1 strain on bacterial cells was observed using AFM. Aeruginosin and cyanopeptolin genes were confirmed by both PCR amplification and gene sequencing. Mass spectrometry analysis confirmed the production of aeruginosin. The interaction of Bacillus cereus, Escherichia coli and Staphylococcus aureus with cyanopeptides was characterized by examining the loss of surface stiffness and the formation of micelles, most likely originating from the membrane disruption. The AFM results demonstrate the ability of cyanobacterial extract to alter the cellular membrane of bacterial pathogens.

Tin antimony sulphide thin films have been deposited on glass substrate by thermal evaporation technique at a chamber pressure of 10-4 torr. For the characterization purpose, thin films were deposited and annealed in argon gas at 100 °C, 150 °C and 250 °C. The physical properties of the films have been inspected relating annealing temperature. XRD studies revealed that both the as deposited and annealed films exist in Sn2Sb2S5 phase. The absorption coefficient of the annealed films was found to be ~105 cm-1. Photoconductivity response of these films was also fine and enhanced with the increasing temperature. However, the transmittance of the films investigated was quite low. No transmittance was found below 750 nm which decreased with annealing temperature. The band gap calculated by ellipsometry technique was in the range 2.5-1.6 eV. Thickness of the film was observed as 1450 nm and the films possess n-type conductivity.

In current work, we perform molecular dynamics simulations to investigate the effect of machining velocity on the nanoscratching of amorphous polystyrene. In particular, the deformation mechanisms of the material are analyzed and are related to its frictional response. Simulation results reveal that inter-chain sliding and intra-chain change are two competing deformation mechanisms governing the permanent deformation of polystyrene specimen. Furthermore, quantitative characterization of dihedral angle evolution indicates that intra-chain change is more energetically stable than inter-chain sliding. It is found that the deformation behavior of polystyrene specimen under nanoscratching strongly depends on machining velocity, which subsequently affects scratching results.

The chronic hyperproliferative diseases (CHD) include cancer, precancerous lesions and diseases of unknown etiology such as psoriasis. Various drugs have been used in the treatment of CHD, such as antiproliferative and corticosteroids in general. However, some drugs have properties that limit their effectiveness, such as low solubility in water and low penetration of the skin. Thus, the control of drug release in the skin may improve efficacy and reduce side effects of many drugs used in hyperproliferative diseases. The purpose of this study was to make a systematic review of nanotechnology-based drug delivery systems used against hyperproliferative skin diseases.

One focus in nanotechnology is the development and use of nonviral vectors for safe and efficient gene delivery. Inorganic and organically modified silica nanoparticles are chemical and biologically inert, optically transparent and can be doped with imaging agents and/or functionalized to promote its conjugation with different therapeutic molecules. Silica/ORMOSIL nanoparticles can be engineered to improve diagnosis, treatment and follow-up of diseases. A combination of diagnosis devices and therapeutics (theranostics) would be beneficial for patients. In this work, ORMOSIL nanoparticles as non-viral vectors for gene delivery were prepared via a modified Stober sol-gel process directly with 3-aminopropyltriethoxysilane (APTES), methyltriethoxysilane (MTES), vinyltrimethoxysilane (VTES), N1- [3-(trimethoxysilyl)-propyl]diethylenetriamine (DETA), and tetraethylorthosilicate (TEOS) as precursors. Dynamic light scattering, transmission electron microscopy and Fourier transformed infrared spectroscopy were used to characterize the ORMOSIL nanospheres. Synthesis has been optimized and monodisperse spherical nanoparticles with desired size have been obtained. Nanoparticle-DNA complexes were successfully obtained at different ratios (nanoparticle/pDNA) and confirmed by agarose gel electrophoresis and ethidium bromide exclusion test.