Current Nanoscience (v.9, #1)

Preface by Atta-ur-Rahman (i-i).

Development of a Sustained-release System for Nitric Oxide Delivery using Alginate/Chitosan Nanoparticles by Priscyla D. Marcato, Leonardo F. Adami, Raquel de Melo Barbosa, Patricia S. Melo, Iasmin R. Ferreira, Larissa de Paula, Nelson Duran, Amedea B. Seabra (1-7).
Free radical nitric oxide (NO) has been known to interact with various physiological processes, such as wound repair processes and control of vascular tone. However, NO is an unstable molecule and the development of NO delivery systems that enhance its stability has also been studied. In this work, alginate/chitosan nanoparticles have been studied as a drug delivery system of the Snitrosoglutathione (GSNO) as NO donor. For this, glutathione, GSH, the GSNO precursor, was encapsulated in alginate/chitosan nanoparticles. The presence of GSNO was confirmed by UV spectra at 336 nm. Alginate/chitosan nanoparticles with negative and positive surface charges were obtained by increasing the chitosan amount. The encapsulation efficiency (EE) relied on the nanoparticle zeta potential, obtaining 80% of EE for positive particles. The NO release from GSNO showed that polymeric nanoparticles lead to the stabilization of GSNO decomposition, at physiological temperature. Moreover, this system did not exhibit cytotoxicity for fibroblast V79 cells up to the maximum concentration tested (18 μmolL-1). These results showed that alginate/chitosan nanoparticles are interesting particles to encapsulate NO donors for biomedical applications where NO might have a therapeutic effect.

Cytotoxicity and Antibacterial Activity of Chitosan-organic Rectorite Intercalated Nanofibrous Mats by Jing Du, Xueyong Li, Chen Yang, Wei Li, Weijuan Huang, Rong Huang, Xue Zhou, Hongbing Deng (8-13).
The chitosan (CS)-organic rectorite (OREC) composites are prepared with the method of solution intercalation. Electrospun nanofibrous mats are made from intercalated CS-OREC composites at different mass ratios. The properties and structure of intercalated CS-OREC can be verified by small angle X-ray diffraction (SAXRD) and transmission electron microscopy (TEM) micrographs. Energy dispersive X-ray (EDX) spectroscopy and fourier transform infrared (FT-IR) spectra reveal that OREC presents in the composite nanofibrous mats. The MTT assay indicates that the cytotoxicity of the intercalated CS-OREC nanofibrous mats is low. Besides, the content of OREC in nanofibrous mats has a significant influence on the viability of cells. Antibacterial test confirms that OREC can increase the inhibition rate of the nanofibrous mats against Escherichia coli.

Investigation of Polymeric Composite Films Using Modified TiO2 Nanoparticles for Organic Light Emitting Diodes by Do Ngoc Chung, Nguyen Nang Dinh, David Hui, Nguyen Dinh Duc, Tran Quang Trung, Mircea Chipara (14-20).
Nanocomposite films for hole transport and emitting layer were prepared from poly(3,4-ethylenedioxythiophene), poly(styrenesulfonate), and poly[2-methoxy-5-(2&'-ethylhexyloxy)-1,4-phenylene vinylene] - as MEH-PPV - incorporated with anatase (TiO2) nanoparticles dispersed in oleic acid. The precursor for the sol was a solution of tetraiso-propyl orthotitanate [Ti(iso-OC3H7)4]. The research showed that both the electrical and spectral properties of the conjugated polymers were enhanced due to the incorporation of anatase. The best volume ratio between the oleic acid precursor and tetraiso-propyl orthotitanate was found to be of 10. Current-voltage characteristics of organic light emitting diodes made from these nanocomposite films were considerably enhanced in comparison with those made from pure polymers. The luminous efficiency is reported. Mechanical properties of the nanocomposite materials, (in particular for MEH-PPV-TiO2) were found to be dependent on constituent organic and inorganic materials and on the geometric position of constituents. It was concluded that such composite organic light emitting diodes can exhibit larger performance efficiency and longer lifetimes than classical light emitting diodes.

A controlled drug delivery system which provides stable plasma concentration could be the most appropriate dosage form for the successful delivery of selegiline. The objective of this study was to develop nanospheres of selegiline using gelatin and evaluate in vitro for the feasibility of oral delivery. Nanospheres of selegiline were prepared by spray drying method and evaluated for compatibility, particle size, surface morphology and in vitro drug release. Compatibility studies indicate no interaction between selegiline and gelatin. Moderate production recovery (89.52 ± 3.71%) and high drug content (98.41± 1.22%) were observed for the prepared formulation. Scanning electron microscopy images indicate that the prepared nanospheres possess round external smooth surface with a continuous wall, although they were shriveled. In vitro drug release profile suggests two phase drug release, an initial burst release followed by a slow release over an extended period of time (~10 h). The release kinetics indicates higher regression coefficient values (R2= 0.9641) with Korsmeyer-Peppas fit, suggesting that the release of the drug primarily governed by Fick's law of diffusion. The in vitro data provided above indicate that the newly developed gelatin nanospheres have the desired characteristics for the controlled delivery of selegiline by oral route, which necessitate further in vivo studies.

Olanzapine Loaded Cationic Solid Lipid Nanoparticles for Improved Oral Bioavailability by Sumeet Sood, Natarajan Jawahar, Kunal Jain, Kuppusamy Gowthamarajan, Subramania Nainar Meyyanathan (26-34).
Olanzapine, a lipophilic antipsychotic drug, has poor oral bioavailability due to hepatic first-pass metabolism. Solid Lipid Nanoparticles (SLNs) of Olanzapine were developed using lipids (Stearic acid and Glyceryl monostearate), soy lecithin, poloxamer 188 and charge modifier stearyl amine by microemulsion technique. The aim of this research was to find out whether the bioavailability of olanzapine can be improved by administering olanzapine SLN orally to Wistar rats. Area under curve was increased (up to 4-fold) and clearance was decreased when olanzapine entrapped in SLNs with stearylamine were administered orally compared with that of olanzapine suspension. The enhanced relative bioavailability by the SLNs formulation might be attributed to avoidance of first-pass hepatic metabolism by intestinal lymphatic transport, direct uptake of nanoparticles through the GI tract, increased permeability by surfactants, and decreased degradation and clearance. These results indicate that olanzapine can be loaded into solid lipid nanoparticles for improvement of its oral bioavailability.

Electrooxidized ZnO Nanoparticles by Iraj Kazeminezhad, Azar Sadollahkhani (35-38).
In this research, ZnO nanoparticles were synthesized using electrooxidation method for the first time. This method is based on electrooxidation of zinc in the presence of an amine which acts as a supporting electrolyte and electrostatic stabilizer. The amine was used in order to control the particle size and also to avoid the aggregation of particles during the synthesis of the particles. An electrochemical cell containing a zinc cathode, a sacrificial zinc anode, and aqueous solution of (CH3)4NCl salt was used for all experiments. In order to investigate the effect of cell voltage on structural and optical properties of the products, the experiments were performed under various voltages between 3V to 15V. Structural investigation of products by X-ray diffraction confirmed the hexagonal phase for all products. Fourier transform infrared spectroscopy showed that the products have covered by the surfactant. Finally the results obtained by scanning and transmission electron microscopy and UV-visible absorption spectroscopy showed that the average size and also the size distribution of as-prepared samples decrease with increasing the cell voltage.

In the present study, using sol-gel method titanium dioxide (TiO2) nanoparticles with a new doping material have been synthesized, and a Dodecyl Benzene Sulfonic Acid (DBSA)-doped TiO2/p-Si Metal-Oxide-Semiconductor (MOS) structure has been fabricated. The characterizations of the structural and morphological properties of the DBSA-doped TiO2 nanoparticles have been carried out by means of X-Ray Diffraction (XRD) and Atomic Force Microscopy (AFM), respectively. The XRD results show that DBSA-doped TiO2 have a crystalline rutile phase along the (110) growth direction. It was confirmed from AFM images that the nanostructure of DBSAdoped TiO2 is grown as rock-like. The electrical characteristics of the device have also been performed, including current–voltage (I–V) and capacitance–voltage (C–V) at room temperature.

The present study was aimed to determine the therapeutic potential of novel carriers to deliver insulin into brain, by passing the BBB. PLGA nanoparticles and PEGylated PLGA nanoparticles were prepared by double emulsification method. PEG-PLGA copolymer was synthesized and characterized by FTIR, NMR and Mass spectroscopies. The release profiles of drug in various formulations were studied in PBS (pH 7.4). Results showed more sustained release of drug with Tween-80 based formulation in comparison with Tween-20 and PVA based formulations. A more sustained and extended release was observed upon chitosan coating of PEG-PLGA nanoparticles. Blood glucose level monitoring suggested that glucose level was not decreased significally in the peripheral region (p > 0.05), when chitosan coated insulin loaded PEGylated nanoparticle was administered by intranasal route. This outcome in particular along with expected mucoadhesive and targeted benefit associated with chitosan based formulation drove us to conclude this formulation to be working best for the undertaken brain delivery issue.

Pool-Boiling Heat Transfer Characteristics of Al2O3-Water Nanofluids on a Horizontal Cylindrical Heating Surface by Weerapun Duangthongsuk, Taklaew Yiamsawasd, Ahmet Selim Dalkilic, Somchai Wongwises (56-60).
This research involved conducting an experiment on pool boiling characteristics of Al2O3–water nanofluid. The experimental concentration ranged between 0.00005 and 0.03 %vol. The pressure used was at 1 and 2 atm. The boiling surface was a horizontal copper cylinder with a diameter of 28.5 mm, a length of 90 mm, and surface roughness of 3.14 μm. The main purpose of this research was to study the effect of the nanofluid's concentration and pressure on the heat transfer coefficient and on heat flux, by comparing with water. Calibration of the experimental apparatus with water revealed that the experimental results corresponded to the prediction by Rohsenow's equation. Results from the experiment on pool boiling of nanofluids indicated that the heat transfer coefficient of Al2O3–water nanofluid was lower than that of water and tended to decrease when the concentration was higher.

A numerical study including a validation process with experimental data was performed on the forced convection flows of nanofluids; the object of study was water containing TiO2 nanoparticles in smooth and micro-fin tubes at a constant wall temperature. Constant heat flux and temperature-dependent properties were used to determine the hydrodynamics and thermal behaviors of the nanofluid flow;a single-phase numerical model was used to solve two-dimensional equations by means of a CFD program for the water flow, contained in a smooth tube and in various micro-fin tubes having various helix angles (0°, 18°). An extensive literature review on the determination of the physical properties (k, μ, ρ, Cp) of nanofluids is given in this paper. Multilayer Perceptron (MLP), one of theartificial neural network (ANN) methods, was used to determine the most agreeable physical propertiesof TiO2 nanofluids among correlations. The inputs ofthe ANN analyses were the correlations of physical properties, the average temperature and velocity of water in the test tubes, and the nanoparticle concentrations, while the outputs were shear stress, friction factor, heat flux, convective heat transfer coefficient, and pressure drop. After obtaining the best combination of physical properties of TiO2 nanofluids from the ANN analyses, the numerical model was validated by means of a CFD program,with the experimental smooth tube data as a case study; it was also validatedas a simulation studyfor several micro-fin tubes through a CFD program. This paper shows temperature, pressure, and velocity distributions in the investigated tubes; in addition, average and local experimental, theoretical, and numerical values in the smooth and micro-fin tubes are compared with oneanother in terms of friction factors, shear stresses, convective heat transfer coefficients, and pressure drops, according to various nanoparticle concentrations.

γ-Al2O3 nanoparticles were dispersed in 20 % wt. aqueous solution to prepare four types of non-Newtonian nanofluids. Rheological characteristics of the base fluid and nanofluids with various nanoparticle volume concentrations were measured. Results show that all nanofluids as well as the base fluid exhibit pseudoplastic (shear thinning) behavior. The rheological characteristics of nanofluids and those of the base fluid are functions of particle concentrations. Electrical conductivity show polynomial behavior at a temperature of 25°C for different concentration fluids. The flow characteristics show rheopectic behavior according to concentration of Al2O3 with highly non-Newtonian characteristics at lower shear stresses. Rheological characteristics suggest that at room temperature viscosity is higher for higher concentration nanofluids.

Preparation and Characterization of Diiodocarbene Functionalized Multi-walled Carbon Nanotubes by Jin-Gang Yu, Xin-Yu Jiang, Dong-Ming Zeng, Xiao-Qing Chen, Fei-Peng Jiao, Zhi-Guang Peng (89-92).
The addition of diiodocarbene to Multi-walled carbon nanotubes was investigated. Using iodoform as precursor and benzyltriethylammonium chloride (BZTMAC) as the phase transfer catalyst, the degree of diiodocarbene functionalization was around 29.4 wt%. High-resolution transmission electron microscopy (HR-TEM) images showed that the morphology of the nanotubes was found to be largely intact after functionalization. The functionalized carbon nanotubes were fully characterized using X-ray photoelectron spectroscopy (XPS), Raman spectroscopy, Fourier transform infrared (FT-IR) spectroscopy. The band gap energy values for pristine multiwalled carbon nanotubes and the functionalized multi-walled carbon nanotubes were measured and calculated.

The Functionalization of Beta-Cyclodextrins on Multi Walled Carbon Nanotubes: Effects of the Dispersant and Non Aqueous Media by Abdul Latif Ahmad, Zeinab Abbas Jawad, Siew Chun Low, Sharif Hussein Sharif Zein (93-102).
Sidewall functionalization by chemical agents can improve the dispersion of carbon nanotubes (CNTs), but the improvement is at the expense of their properties and structure. An environmentally friendly dispersant, cyclodextrins (CD), was revealed as a preferable alternative to functionalize CNTs without changing their pristine structure and properties. In this study, multi-walled carbon nanotubes (MWCNTs) were functionalized using beta-CD (β-CD). Different concentrations of β-CD served as the dispersants, and different non aqueous media (ethanol, acetic acid, and water) were studied to achieve required degree of functionalization for MWCNTs. The functionalized MWCNTs were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, field emission scanning electron microscopy, transmission electron microscopy, dynamic light scattering, thermo gravimetric analysis, and X-ray diffraction. The analytical results indicated the degree of functionalization increases with increasing β-CD ratios. However, a lower degree of functionalization was shown by using a higher solvent polarity of non aqueous media. The functionalized MWCNTs were shown to have open-ended and defect free walls.

The crystal size of nano-crystalline germanium dependence depends on the gate current in memory devices has been theoretically investigated when the mean diameter is uniquely controlled by the nominal thickness of the deposition of Ge layer. Because the band gap and dielectric constant of nano-crystalline germanium will be largely affected by crystal size in the regime of nano-scale, the calculated gate currents in nano-crystalline germanium strongly depends on the crystal size, especially on a few nanometers, when the equivalent oxide thickness memoirs the same. The numerical calculations demonstrate that dielectric constant of nano-crystalline germanium impacts on the Fowler-Nordheim tunneling current can be neglected when the oxide field is higher than 3 MV/cm. The results also demonstrate that the leakage current can be reduced by fabricating thinner nc-Ge layer in memory devices.

An important challenge of considerable topical significance in nanotechnology is the development of eco-friendly experimental processes for the synthesis of nanomaterials in large quantities with variable sizes, shapes and chemical compositions. Green synthesis routes for the production of inorganic metal nanoparticles using whole cell of microorganisms and plant extracts are gaining tremendous popularity as these are non-toxic, cheap and occur at ambient conditions. The present work emphasizes on gold nanoparticles synthesis protocol using live plant callus cells. Peanut callus cells when incubated with HAuCl4 solution in ambient conditions reduced the precursor and lead to formation of well dispersed, water soluble extracellular and intracellular gold nanoparticles within 24 hours. The biosynthesis of gold nanoparticles was monitored by UV-visible spectroscopy (UV-Vis) and further characterized by X-ray diffraction analysis (XRD), Energy Dispersive Spectroscopy (EDS) and Selected Area Electron Diffraction (SAED). The particle size distribution shows that the average particle size is 50 nm for extra- and 31 nm for intracellular gold nanoparticles. The nanoparticles may be stabilized by proteins secreted by callus cells. The reduction process is believed to occur enzymatically, thus creating the possibility of a rational, plant cell-based method for the synthesis of nanoparticles over a wide range of chemical compositions.

Mn-Sn-Dy-substituted and pure strontium ferrite, were prepared from metal nitrates and citric acid through citrate sol–gel method. The phase composition, microstructure, coercivity, and microwave absorption properties of the particles were investigated by means of X-ray diffraction, transmission electron microscopy (TEM), vibrating sample magnetometry and a vector network analyzer. The ferrite–polymer composites with different ferrite ratios of, 60%, 70% and 80% in acrylic resin matrix were prepared. The microwave absorption properties of these composites were investigated in the frequency range of 12–20 GHz. The results showed that the composite with 70% ferrite content has shown a minimum reflection loss of -28 dB at 15.7 GHz with the -15 dB bandwidth over the extended frequency range of 14.3–20 GHz for an absorber thickness of 1.6 mm. A minimum reflection loss of -38 dB was obsevred at 18.2 GHz for composite with 80% ferrite. Based on this study it can be argued that such powders are very useful in military applications such as RCS (Radar Cross Section ) reduction, camouflaging of the target and prevention of EMI (Electromagnetic Interference), etc.

One-step Synthesis of Water-dispersible ZnSe(S)-alloy Quantum Dots in the Presence of Thiol Species by Sonia Bailon-Ruiz, Oscar Perales-Perez, Yi-feng Su, Yan Xin (117-121).
Semiconductors quantum dots (QD) exhibit unique size-dependent optical properties which enable them to be considered for biomedical applications, including diagnosis and cancer treatment. Furthermore, the synthesis of less toxic and Cd-free QDs directly in aqueous phase assures their biocompatibility as required for nanomedicine applications. Accordingly, the present work was focused on the direct synthesis of alloyed ZnSe(S) QDs capped with thioglycolic acid (TGA) or 3-mercaptopropionic acid (MPA) in aqueous medium under microwave irradiation conditions. X-ray diffraction measurements suggested that as-synthesized QDs exhibited a solidsolution like structure with an average crystallite size of 3.8 ± 0.1 nm and 2.1 ± 0.2 nm for TGA- and MPA-capped Zn-based QDs, respectively. HRTEM measurements confirmed the small size and monodispersity of the synthesized QDs. The chemisorption of carboxylate groups in TGA (vas COO at 1577 cm-1 and vs COO at 1388 cm-1) and MPA (vas COO at 1560 cm-1 and vs COO at 1401 cm-1) onto the QDs was confirmed by FT-IR spectroscopy analyses. The band gap energy values were estimated at 3.1eV or 3.3eV, respectively, when the QDs were synthesized in the presence of TGA or MPA species. QDs suspended in biocompatible Phosphate Buffer Saline (PBS) exhibited a remarkable photo-stability; the corresponding photo-luminescence spectra recorded under 302nm excitation evidenced strong emission peaks centered on 390nm and 395nm for TGA- and MPA-capped QDs, respectively. As-synthesized thiol-capped alloyed ZnSe(S) QDs can be considered very promising biocompatible candidates for nanomedicine applications.

In order to investigate the effect of the substitution groups on the intercalation, nine quaternized carboxymethyl chitosans (QCMCs) with different degree of substitution (DS) of carboxymethyl and quaternary ammonium groups were intercalated into the interlayer of organic montmorillonite (OMMT). Small-angle XRD, TEM and FT-IR techniques were used to characterize the structure and morphology of QCMC/OMMT nanocomposites, the thermogravity analysis (TGA) was performed to evaluate the thermal stability. The results revealed that positively charged quaternary ammonium groups contributed to the intercalation of QCMC, certain amount of negatively charged carboxymethyl groups could also induce better intercalation, but too much carboxymethyl groups prevented the entrance of QCMC into the interlayer of OMMT. In addition, as carboxymethyl and quaternary ammonium groups increased, the interaction between QCMC and OMMT was stronger, but the thermal stability was lower. When DS of carboxymethyl groups and quaternary ammonium groups in QCMC were respectively 53 % and 41 %, the exfoliated nanocomposite was obtained, in this case, its thermal stability was the highest.

Catalytic Degradation of Phenol by Co3O4 Nanocubes by Xu Chun Song, Zhi Ai Yang, Yi Fan Zheng, Hao Yong Yin (128-131).
The Co3O4 nanocubes have been synthesized by a hydrothermal route. The products are characterized in detail by multiform techniques: X-ray diffraction(XRD), energy-dispersive X-ray analysis(EDS), scanning electron microscopy(SEM), and transmission electron microscopy(TEM). The results show that the obtained products are Co3O4 nanocubes with size ranging between 20 and 50 nm. The catalytic activity towards the degradation of phenol over Co3O4 nanocubes was further studied under continuous bubbling of air through the liquid phase. The results showed that sample has the highest catlytic activity. The degradation of phenol catalyzed by the Co3O4 nanocubes fits the first-order kinetics. According to the estimated reaction rate of Co3O4 nanocubes at different temperature, the activation energy of 28.41 kJ/mol were calculated.

Nanostructuring of Refractory Metal Surfaces by Electrochemical Oxidation: Nb and the Binary Systems Ti-Ta and Nb-Ta by Claus Moseke, Christian Lehmann, Tobias Schmitz, Friedrich Reinert, Jurgen Groll, Uwe Gbureck (132-138).
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.

Multi-Walled Carbon Nanotubes Mediated Thin-Layer Chromatographic Enantioseparation of Ofloxacin by Dushu Huang, Jingang Yu, Wei Liu, Zijing Li, Zhongzhou Yi, Jie Wu (139-140).
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.

Antimicrobial Cyanopeptide Action on Bacterial Cells Observed with Atomic Force Microscopy by Maria Estela Silva-Stenico, Adriana Sturion Lorenzi, Omar Teschke, Caroline Souza Pamplona Silva, Augusto Etchegaray, Marli Fatima Fiore (141-148).
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.

Physical Properties of the Absorber Layer Sn2Sb2S5 thin Films for Photovoltaics by N. Ali, A. Hussain, S.T. Hussain, M.A. Iqbal, M. Shah, I. Rahim, N. Ahmad, Z. Ali, K. Hutching, D. Lane, W.A.A. Syed (149-152).
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.

Velocity-dependent Nanoscratching of Amorphous Polystyrene by Kai Du, Yongjian Tang, Junjie Zhang, Fangda Xu, Yongda Yan, Tao Sun (153-158).
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.

Nanotechnology-Based Drug Delivery Systems for Treatment of Hyperproliferative Skin Diseases - A Review by Fernanda Kolenyak dos Santos, Marcia Helena Oyafuso, Charlene Priscila Kiill, Maria Palmira Daflon- Gremiao, Marlus Chorilli (159-167).
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.

Preparation and Chemical Characterization of Eco-friendly ORMOSIL Nanoparticles of Potential Application in DNA Gene Therapy by Rui Colaco, M. Clara Goncalves, L.M. Fortes, Lidia M.D.Goncalves, Antonio J. Almeida, Barbara F. Martins (168-172).
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.