Journal of Nanotechnology The latest articles from Hindawi Publishing Corporation © 2014 , Hindawi Publishing Corporation . All rights reserved. Synthesis and Characterization of Cobalt Nanoparticles Using Hydrazine and Citric Acid Thu, 13 Mar 2014 11:36:48 +0000 Cobalt nanoparticles were produced by employing the liquid-phase reduction method and hydrazine. The effect of citric acid additives on the formation and growth mechanism of cobalt nanoparticles was investigated using polarization methods. The cobalt nanoparticles produced in 0.2 M cobalt sulfate and 5 M hydrazine at 298 K had a spherical shape with a diameter of 400 nm. The dendritic nanoparticles formed with the decreasing of hydrazine concentration at 298 K. On the other hand, dendritic large particles are confirmed at 353 K. It was confirmed that the reduction reaction progressed with the addition of citric acid, and a hexagonal close-packed (εCo) phase was formed. S. A. Salman, T. Usami, K. Kuroda, and M. Okido Copyright © 2014 S. A. Salman et al. All rights reserved. Magnetic Nanoparticles of Chitosan for Targeted Delivery System of Plasmids to the Lungs Wed, 12 Mar 2014 15:40:43 +0000 One of the major problems of gene therapy is the efficient, specific, and targeted delivery as well as the safety of the materials used in such systems. The specific targeted delivery of genes to the lung offers the possibility to treat a variety of specific diseases. We developed chitosan nanoparticles with the plasmid pCEM-Luc, which contains a promoter activated by magnetic field. Nanoparticles of 200–250 nm obtained by ionic gelation with a 99% retention rate were transfected in B16F10 cells and in vivo in the lungs of Balb/c mice by intratracheal administration. We observed that an external magnetic field increased the expression of the luciferase reporter gene in B16F10 cells transfected with magnetic nanoparticles and in homogenized lungs of mice which determined differences in levels of expression between different regions of the lungs (apical or distal and left or right). The highest levels of luciferase activity were observed in the apical left region. The magnetic nanoparticles prove an efficient delivery system to in vitro transfection of cells and lung tissue. Cynthia Aracely Alvizo Báez, Itza Eloisa Luna Cruz, Maria Cristina Rodríguez Padilla, and Juan Manuel Alcocer González Copyright © 2014 Cynthia Aracely Alvizo Báez et al. All rights reserved. Reviewing the Tannic Acid Mediated Synthesis of Metal Nanoparticles Tue, 11 Mar 2014 12:52:37 +0000 Metal nanoparticles harbour numerous exceptional physiochemical properties absolutely different from those of bulk metal as a function of their extremely small size and large superficial area to volume. Naked metal nanoparticles are synthesized by various physical and chemical methods. Chemical methods involving metal salt reduction in solution enjoy an extra edge over other protocols owing to their relative facileness and capability of controlling particle size along with the attribute of surface tailoring. Although chemical methods are the easiest, they are marred by the use of hazardous chemicals such as borohydrides. This has led to inclination of scientific community towards eco-friendly agents for the reduction of metal salts to form nanoparticles. Tannic acid, a plant derived polyphenolic compound, is one such agent which embodies characteristics of being harmless and environmentally friendly combined with being a good reducing and stabilizing agent. In this review, first various methods used to prepare metal nanoparticles are highlighted and further tannic acid mediated synthesis of metal nanoparticles is emphasized. This review brings forth the most recent findings on this issue. Tufail Ahmad Copyright © 2014 Tufail Ahmad. All rights reserved. Noncovalent Attachment of PbS Quantum Dots to Single- and Multiwalled Carbon Nanotubes Mon, 10 Mar 2014 15:59:40 +0000 Attachment of PbS quantum dots (QD) to single-walled carbon nanotubes (SWNT) and multiwalled carbon nanotubes (MWCNT) is described; wherein commercially obtained PbS-QD of size 2.7 nm, stabilized by oleic acid, are added to a suspension of single- or multiwalled carbon nanotubes (CNT) prefunctionalized noncovalently with 1,2-benzenedimethanethiol (1,2-BDMT) in ethanol. The aromatic part of 1,2-BDMT attaches to the CNT by π-π stacking interactions, noncovalently functionalizing the CNT. The thiol part of the 1,2-BDMT on the functionalized CNT replaces oleic acid on the surface of the QD facilitating the noncovalent attachment of the QD to the CNT. The composites were characterized by TEM and FTIR spectroscopy. Quenching of NIR fluorescence of the PbS-QD on attachment to the carbon nanotubes (CNT) was observed, indicating FRET from the QD to the CNT. Anirban Das, Eric Hall, and Chien M. Wai Copyright © 2014 Anirban Das et al. All rights reserved. Peeling of Long, Straight Carbon Nanotubes from Surfaces Sun, 23 Feb 2014 13:20:16 +0000 The adhesion of long, straight, single-walled carbon nanotubes to surfaces is examined using multidimensional force spectroscopy. We observed characteristic signatures in the deflection and frequency response of the cantilever indicative of nanotube buckling and slip-stick motion as a result of compression and subsequent adhesion and peeling of the nanotube from the surface. The spring constant and the elastic modulus of the SWNT were estimated from the frequency shifts under tension. Using elastica modeling for postbuckled columns, we have determined the static coefficient of friction for the SWNT on alkanethiol-modified gold surfaces and showed that it varies with the identity of the monolayer terminal group. Kane M. Barker, Mark A. Poggi, Leonardo Lizarraga, Peter T. Lillehei, Aldo A. Ferri, and Lawrence A. Bottomley Copyright © 2014 Kane M. Barker et al. All rights reserved. Pharmacokinetic and Tissue Distribution Study of Solid Lipid Nanoparticles of Zidovudine in Rats Wed, 19 Feb 2014 10:14:23 +0000 Zidovudine-loaded solid lipid nanoparticles (AZT-SLNs) and zidovudine in solution were prepared and administered in rats. The aim of this research was to study whether the bioavailability of zidovudine can be improved by AZT-SLNs perorally to rats as compared to oral administration of zidovudine. Zidovudine was determined in plasma and tissues by reverse phase high performance liquid chromatography. The pharmacokinetic parameters of zidovudine were determined after peroral administration: area under curve of concentration versus time (AUC) for AZT-SLNs was 31.25% greater than AZT solution; meanwhile mean resident time (MRT) was found to be 1.83 times higher for AZT-SLNs than AZT solution. Elimination half life of zidovudine was also increased for SLN formulation. Tissue distribution pattern of zidovudine was changed in case of AZT-SLNs. AUC of zidovudine in brain and liver was found to be approximately 2.73 and 1.77 times higher in AZT-SLNs than AZT solution, respectively, indicating that AZT-SLNs could cross blood brain barrier. Distribution of zidovudine was approximately 0.95 and 0.86 times lesser in heart and kidney, respectively. It can be concluded from the study that oral administration of AZT-SLNs modifies the plasma pharmacokinetic parameters and biodistribution of zidovudine. Shah Purvin, Parameswara Rao Vuddanda, Sanjay Kumar Singh, Achint Jain, and Sanjay Singh Copyright © 2014 Shah Purvin et al. All rights reserved. Application of Iron Oxide Nanomaterials for the Removal of Heavy Metals Wed, 19 Feb 2014 08:14:29 +0000 In the 21st century water polluted by heavy metal is one of the environment problems. Various methods for removal of the heavy metal ions from the water have extensively been studied. Application of iron oxide nanaparticles based nanomaterials for removal of heavy metals is well-known adsorbents for remediation of water. Due to its important physiochemical property, inexpensive method and easy regeneration in the presence of external magnetic field make them more attractive toward water purification. Surface modification strategy of iron oxide nanoparticles is also used for the remediation of water increases the efficiency of iron oxide for the removal of the heavy metal ions from the aqueous system. Pragnesh N. Dave and Lakhan V. Chopda Copyright © 2014 Pragnesh N. Dave and Lakhan V. Chopda. All rights reserved. Intestinal Lymphatic Delivery of Praziquantel by Solid Lipid Nanoparticles: Formulation Design, In Vitro and In Vivo Studies Wed, 19 Feb 2014 06:38:56 +0000 The aim of the present work was to design and develop Praziquantal (PZQ) loaded solid lipid nanoparticles (PZQ-SLN) to improve the oral bioavailability by targeting intestinal lymphatic system. PZQ is practically insoluble in water and exhibits extensive hepatic first-pass metabolism. PZQ SLN were composed of triglycerides, lecithin and various aqueous surfactants; were optimized using hot homogenization followed by ultrasonication method. The optimized SLN had particle size of  nm, EE of %. The drug release of PZQ-SLN showed initial burst release followed by the sustained release. Inspite of zeta potential being around −10 mV, the optimized SLN were stable at storage conditions (°C and °C/% RH) for six months. TEM study confirmed the almost spherical shape similar to the control formulations. Solid state characterization using differential scanning calorimeter (DSC) and powder X-ray diffraction (PXRD) analysis confirmed the homogeneous distribution of PZQ within the lipid matrix. The 5.81-fold increase in , after intraduodenal administration of PZQ-SLN in rats treated with saline in comparison to rats treated with cycloheximide (a blocker of intestinal lymphatic pathway), confirmed its intestinal lymphatic delivery. The experimental results indicate that SLN may offer a promising strategy for improving the therapeutic efficacy and reducing the dose. Amit Mishra, Parameswara Rao Vuddanda, and Sanjay Singh Copyright © 2014 Amit Mishra et al. All rights reserved. Nanocatalysis: Academic Discipline and Industrial Realities Mon, 17 Feb 2014 13:14:01 +0000 Nanotechnology plays a central role in both academic research and industrial applications. Nanoenabled products are not only found in consumer markets, but also importantly in business to business markets (B2B). One of the oldest application areas of nanotechnology is nanocatalysis—an excellent example for such a B2B market. Several existing reviews illustrate the scientific developments in the field of nanocatalysis. The goal of the present review is to provide an up-to-date picture of academic research and to extend this picture by an industrial and economic perspective. We therefore conducted an extensive search on several scientific databases and we further analyzed more than 1,500 nanocatalysis-related patents and numerous market studies. We found that scientists today are able to prepare nanocatalysts with superior characteristics regarding activity, selectivity, durability, and recoverability, which will contribute to solve current environmental, social, and industrial problems. In industry, the potential of nanocatalysis is recognized, clearly reflected by the increasing number of nanocatalysis-related patents and products on the market. The current nanocatalysis research in academic and industrial laboratories will therefore enable a wealth of future applications in the industry. Sandro Olveira, Simon P. Forster, and Stefan Seeger Copyright © 2014 Sandro Olveira et al. All rights reserved. Fabrication of Electrospun Polyamide-6/Chitosan Nanofibrous Membrane toward Anionic Dyes Removal Sun, 16 Feb 2014 12:01:29 +0000 Nanofibrous filter media of polyamide-6/chitosan were fabricated by electrospinning onto a satin fabric substrate and characterized by scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and water contact angle (WCA). Anionic dye removal capability of the filter was investigated for Solophenyl Red 3BL and Polar Yellow GN, respectively, as acidic and direct dyes were investigated with respect to solution parameters (pH and initial dye concentration) and membrane parameters (electrospinning time and chitosan ratio) through filtration system. Experiments were designed using response surface methodology (RSM) based on five-level central composite design (CCD) with four parameters to maximize removal efficiency of the filter media. Moreover, the effect of parameters and their likely interactions on dye removal were investigated by mathematically developed models. The optimum values for solution pH, initial dye concentration, electrospinning time, and chitosan ratio were predicted to be 5, 50 mg/L, 4 hr, 30% and 5, 100 mg/L, 4 hr, 10%, respectively, for achieving 96% and 95% removal of Solophenyl Red 3BL and Polar Yellow GN. Evaluation of the estimation capability of applied models revealed that the models have a good agreement with experimental values. This study demonstrated that polyamide-6/chitosan nanofibrous membrane has an enormous applicable potential in dye removal from aqueous solutions. Mozhdeh Ghani, Ali Akbar Gharehaghaji, Mokhtar Arami, Negar Takhtkuse, and Babak Rezaei Copyright © 2014 Mozhdeh Ghani et al. All rights reserved. Studies on Characterization, Optical Absorption, and Photoluminescence of Yttrium Doped ZnS Nanoparticles Thu, 13 Feb 2014 13:38:03 +0000 Pure ZnS and ZnS:Y nanoparticles were synthesized by a chemical coprecipitation route using EDTA-ethylenediamine as a stabilizing agent. X-ray diffraction (XRD), high resolution transmission electron microscopy (HRTEM), field emission scanning electron microscopy (FE-SEM), Fourier transform infrared spectrometry (FTIR), thermogravimetric-differential scanning calorimetry (TG-DSC), and UV-visible and photoluminescence (PL) spectroscopy were employed to characterize the as-synthesized ZnS and ZnS:Y nanoparticles, respectively. XRD and TEM studies show the formation of cubic ZnS:Y particles with an average size of ~4.5 nm. The doping did not alter the phase of the zinc sulphide, as a result the sample showed cubic zincblende structure. The UV-visible spectra of ZnS and ZnS:Y nanoparticles showed a band gap energy value, 3.85 eV and 3.73 eV, which corresponds to a semiconductor material. A luminescence characteristics such as strong and stable visible-light emissions in the orange region alone with the blue emission peaks were observed for doped ZnS nanoparticles at room temperature. The PL intensity of orange emission peak was found to be increased with an increase in yttrium ions concentration by suppressing blue emission peaks. These results strongly propose that yttrium doped zinc sulphide nanoparticles form a new class of luminescent material. Ranganaik Viswanath, Halehatty Seethya Bhojya Naik, Yashavanth Kumar Gubbihally Somalanaik, Prashanth Kumar Parlesed Neelanjeneallu, Khandugadahalli Nagarajappa Harish, and Mustur Channabasappa Prabhakara Copyright © 2014 Ranganaik Viswanath et al. All rights reserved. Green Synthesis of Novel Jasmine Bud-Shaped Copper Nanoparticles Thu, 13 Feb 2014 13:01:34 +0000 Novel jasmine bud-shaped copper nanoparticles were synthesized by a green chemical reduction method using polyvinylpyrrolidone (PVP) as a capping agent, L-ascorbic acid (AA) as a reducing agent as well as antioxidant agent, isonicotinic acid hydrazide (INH) as a reducing agent, and water as a solvent at 60–70°C (pH-7) in the presence of air. The UV-Vis absorption maximum obtained is 573 nm. The crystal lattice (fcc) structure of Cu Nps was confirmed by X-ray diffraction (XRD). The novel jasmine bud shape was visualized in a transmission electron microscope (TEM). The height of single copper nanobud was 6.41 nm as measured by atomic force microscope (AFM). The average particle size 6.95 nm is obtained by XRD results. Antibacterial activity of the Cu nanobuds was evaluated by testing against Gram-negative (Escherichia coli) and Gram-positive (Staphylococcus aureus) bacteria. Malathi Sampath, Ramya Vijayan, Ezhilarasu Tamilarasu, Abiraman Tamilselvan, and Balasubramanian Sengottuvelan Copyright © 2014 Malathi Sampath et al. All rights reserved. Cyclosporine A Loaded PLGA Nanoparticles for Dry Eye Disease: In Vitro Characterization Studies Wed, 12 Feb 2014 00:00:00 +0000 Dry eye disease is a common disease of the tear film caused by decreased tear production or increased evaporation. The objective of this study was to develop and evaluate poly (dl-lactide-co-glycolide) (PLGA) nanoparticles for CsA (CsA) ophthalmic delivery, for the treatment of dry eye disease. Topical CsA is currently the only and safe pharmacologic treatment of severe dry eye symptoms. Nanoparticles (NPs) were prepared by W/O solvent evaporation technique followed by probe sonicator and characterized for various properties such as particle size, entrapment efficiency, zeta potential, in vitro drug release, in vitro permeation studies by Franz diffusion cells, XRD, DSC, SEM, and stability studies. The developed nanosuspension showed a mean particle size in the range from 128 to 253.50 nm before freeze drying and after freeze drying 145.60 to 260.0 nm. The drug entrapment efficiency was from 58.35 to 95.69% and production yield was found between and % in all preparations. The zeta potential of the Eudragit RL containing nanoparticles was positive, that is, 20.3 mV to 34.5 mV. The NPs formulations exhibited a biphasic drug release with initial burst followed by a very slow drug release and total cumulative release up to 24 h ranged from 69.83 to 91.92%. Kinetically, the release profiles of CsA from NPs appeared to fit best with the Higuchi model. The change of surface characteristics of NPs represents a useful approach for improvement of ocular retention and drug availability. Vijay D. Wagh and Dipak U. Apar Copyright © 2014 Vijay D. Wagh and Dipak U. Apar. All rights reserved. Direct-Write Ion Beam Lithography Mon, 10 Feb 2014 11:51:21 +0000 Patterning with a focused ion beam (FIB) is an extremely versatile fabrication process that can be used to create microscale and nanoscale designs on the surface of practically any solid sample material. Based on the type of ion-sample interaction utilized, FIB-based manufacturing can be both subtractive and additive, even in the same processing step. Indeed, the capability of easily creating three-dimensional patterns and shaping objects by milling and deposition is probably the most recognized feature of ion beam lithography (IBL) and micromachining. However, there exist several other techniques, such as ion implantation- and ion damage-based patterning and surface functionalization types of processes that have emerged as valuable additions to the nanofabrication toolkit and that are less widely known. While fabrication throughput, in general, is arguably low due to the serial nature of the direct-writing process, speed is not necessarily a problem in these IBL applications that work with small ion doses. Here we provide a comprehensive review of ion beam lithography in general and a practical guide to the individual IBL techniques developed to date. Special attention is given to applications in nanofabrication. Alexandra Joshi-Imre and Sven Bauerdick Copyright © 2014 Alexandra Joshi-Imre and Sven Bauerdick. All rights reserved. Nanosensor Data Processor in Quantum-Dot Cellular Automata Sun, 09 Feb 2014 08:19:37 +0000 Quantum-dot cellular automata (QCA) is an attractive nanotechnology with the potential alterative to CMOS technology. QCA provides an interesting paradigm for faster speed, smaller size, and lower power consumption in comparison to transistor-based technology, in both communication and computation. This paper describes the design of a 4-bit multifunction nanosensor data processor (NSDP). The functions of NSDP contain (i) sending the preprocessed raw data to high-level processor, (ii) counting the number of the active majority gates, and (iii) generating the approximate sigmoid function. The whole system is designed and simulated with several different input data. Fenghui Yao, Mohamed Saleh Zein-Sabatto, Guifeng Shao, Mohammad Bodruzzaman, and Mohan Malkani Copyright © 2014 Fenghui Yao et al. All rights reserved. Synthesis of Nickel and Nickel Hydroxide Nanopowders by Simplified Chemical Reduction Wed, 05 Feb 2014 09:25:21 +0000 Nickel nanopowders were synthesized by a chemical reduction of nickel ions with hydrazine hydrate at pH ~12.5. Sonication of the solutions created a temperature of 54–65°C to activate the reduction reaction of nickel nanoparticles. The solution pH affected the composition of the resulting nanoparticles. Nickel hydroxide nanoparticles were formed from an alkaline solution (pH~10) of nickel-hydrazine complexed by dropwise titration. X-ray diffraction of the powder and the analysis of the resulting Williamson-Hall plots revealed that the particle size of the powders ranged from 12 to 14 nm. Addition of polyvinylpyrrolidone into the synthesis decreased the nickel nanoparticle size to approximately 7 nm. Dynamic light scattering and scanning electron microscopy confirmed that the particles were in the nanometer range. The structure of the synthesized nickel and nickel hydroxide nanoparticles was identified by X-ray diffraction and Fourier transform infrared spectroscopy. Jeerapan Tientong, Stephanie Garcia, Casey R. Thurber, and Teresa D. Golden Copyright © 2014 Jeerapan Tientong et al. All rights reserved. Graphene/Gold Nanocomposites-Based Thin Films as an Enhanced Sensing Platform for Voltammetric Detection of Cr(VI) Ions Wed, 05 Feb 2014 00:00:00 +0000 A highly sensitive and selective Cr(VI) sensor with graphene-based nanocomposites film as an enhanced sensing platform is reported. The detection of chromium species is a challenging task because of the different possible oxidation states in which the element can occur. The sensing film was developed by homogenously distributing Au nanoparticles (AuNPs) onto the two-dimensional (2D) graphene nanosheet matrix by electrochemical method. Such nanostructured composite film platforms combine the advantages of AuNPs and graphene nanosheets because of the synergistic effect between them. This effect greatly facilitates the electron-transfer processes and the sensing behavior for Cr(VI) detection, leading to a remarkably improved sensitivity and selectivity. The interference from other heavy metal ions is studied in detail. Such sensing elements are very promising for practical environmental monitoring applications. Chella Santhosh, Murugan Saranya, Rajendran Ramachandran, Sathiyanathan Felix, Venugopal Velmurugan, and Andrews Nirmala Grace Copyright © 2014 Chella Santhosh et al. All rights reserved. Empirical Correlation of the Morphology of Coiled Carbon Nanotubes with Their Response to Axial Compression Sun, 02 Feb 2014 11:04:51 +0000 The mechanical response of thirteen different helical multi-walled carbon nanocoils to axial compression is reported. Each nanocoil was attached to the apex of a cantilever probe tip; its dimensions and orientation relative to the tip apex were determined with scanning electron microscopy. The atomic force microscope was employed to apply a cyclic axial load on the nanocoil. Its mechanical response was determined by simultaneous collection of the thermal resonance frequency, displacement, and oscillation amplitude of the cantilever-nanotube system in real time. Depending upon compression parameters, each coil underwent buckling, bending, and slip-stick motion. Characteristic features in the thermal resonance spectrum and in the force and oscillation amplitude curves for each of these responses to induced stress are presented. Following compression studies, the structure and morphology of each nanocoil were determined by transmission electron microscopy. The compression stiffness of each nanocoil was estimated from the resonant frequency of the cantilever at the point of contact with the substrate surface. From this value, the elastic modulus of the nanocoil was computed and correlated with the coiled carbon nanotube’s morphology. Jabulani R. Barber, Jeffrey S. Boyles, Aldo A. Ferri, and Lawrence A. Bottomley Copyright © 2014 Jabulani R. Barber et al. All rights reserved. Growth of CuS Nanostructures by Hydrothermal Route and Its Optical Properties Thu, 30 Jan 2014 12:58:35 +0000 CuS nanostructures have been successfully synthesized by hydrothermal route using copper nitrate and sodium thiosulphate as copper and sulfur precursors. Investigations were done to probe the effect of cationic surfactant, namely, Cetyltrimethylammonium bromide (CTAB) on the morphology of the products. A further study has been done to know the effect of reaction time on the morphology of CuS nanostructures. The FE-SEM results showed that the CuS products synthesized in CTAB were hexagonal plates and the samples prepared without CTAB were nanoplate like morphology of sizes about 40–80 nm. Presence of nanoplate-like structure of size about 40–80 nm was observed for the sample without CTAB. The synthesized CuS nanostructures were characterized by X-ray diffraction (XRD), FE-SEM, DRS-UV-Vis spectroscopy, and FT-IR spectroscopy. A possible growth mechanism has been elucidated for the growth of CuS nanostructures. Murugan Saranya, Chella Santhosh, Rajendran Ramachandran, and Andrews Nirmala Grace Copyright © 2014 Murugan Saranya et al. All rights reserved. Synthesis, Characterization, and Magnetic Studies of - Nanoparticles Wed, 29 Jan 2014 00:00:00 +0000 Very fine nanosized metal oxide, namely, iron oxide (α-Fe2O3) has been synthesized by precipitation method using ammonia as precipitating agent and characterized by using XRD (X-ray diffraction), TGA/DTA, surface area measurement, transmission electron microscopy (TEM), and magnetic measurements techniques. XRD studies show that iron oxide was formed as α-Fe2O3 instead of the commonly formed magnetite nanoparticles (Fe3O4) or a mixture of magnetite (Fe3O4) and maghemite (γ-Fe2O3, cubic), and it has rhombohedral structure. Magnetic measurements showed that iron oxide has five unpaired electrons and is ferromagnetic in nature, Ms value being 1.7 emu/g. The particle size of the synthesized iron oxide was determined by TEM. TEM images show that the size of particles of Fe2O3 varied from 15 nm to 49 nm with average crystallite size 35 nm. Avnish Kumar Arora, Mohan Sharma, Ritu Kumari, Vivek Sheel Jaswal, and Pankaj Kumar Copyright © 2014 Avnish Kumar Arora et al. All rights reserved. Sensitivity Improvement of Ammonia Gas Sensor Based on Poly(3,4-ethylenedioxythiophene):Poly(styrenesulfonate) by Employing Doping of Bromocresol Green Wed, 22 Jan 2014 14:16:19 +0000 The aim of this research is to improve the sensitivity of ammonia gas sensor (hereafter referred to as sensor) based on poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) by employing the doping dye of bromocresol green (BCG). The doping process was carried out by mixing the BCG and the PEDOT:PSS in a solution with an optimum ratio of 1 : 1 in volume. The sensor was fabricated by using spin-coating technique followed by annealing process. For comparison, the BCG thin film and the PEDOT:PSS thin film were also deposited with the same method on glass substrates. For optical characterization, a red-light laser diode with a 650 nm wavelength was used as light source. Under illumination with the laser diode, the bare glass substrate and BCG film showed no absorption. The sensor exhibited linear response to ammonia gas for the range of 200 ppm to 800 ppm. It increased the sensitivity of sensor based on PEDOT:PSS with BCG doping being about twofold higher compared to that of without BCG doping. Furthermore, the response time and the recovery time of the sensor were found very fast. It suggests that the optical sensor based on BCG-doped PEDOT:PSS is promising for application as ammonia gas sensor. La Aba, Yusril Yusuf, Mitrayana, Dwi Siswanta, Junaidi, and Kuwat Triyana Copyright © 2014 La Aba et al. All rights reserved. Evaluation of Cytotoxic Effects of Different Concentrations of Porous Hollow Au Nanoparticles (PHAuNPs) on Cells Sun, 19 Jan 2014 11:58:18 +0000 Nanoparticles (NPs) have been introduced as a suitable alternative in many in vivo bioapplications. The risks of utilizing nanoparticles continue to be an ongoing research. Furthermore, the various chemicals used in their synthesis influence the cytotoxic effects of nanoparticles. We have investigated the cytotoxicity of Porous Hollow Au Nanoparticles (PHAuNPs) on cancer cell lines PC-3, PC-3ML, and MDA-MB-231 and the normal cell line PNT1A. Cell proliferation for the different cells in the presence of different concentrations of the PHAuNPs was assessed after 24 hours and 72 hours of incubation using MTT assay. The study also included the cytotoxic evaluation of pegylated PHAuNPs. Identical cell seeding densities, particle concentrations, and incubation times were employed for these two types of Au nanoparticles. Our results indicated that (1) impact on cell proliferation was concentration dependent and was different for the different cell types without cellular necrosis and (b) cellular proliferation might be impacted more based on the cell line. Smitha Rao, Chienwen Huang, Uday Tata, Peter Wu, Nikhil Arora, Jinsung Ahn, Victor K. Lin, Yaowu Hao, and J.-C. Chiao Copyright © 2014 Smitha Rao et al. All rights reserved. Biosynthesis of Silver Nanoparticles Using Kedrostis foetidissima (Jacq.) Cogn. Sun, 19 Jan 2014 08:00:12 +0000 Nanosilver was synthesized using the aqueous solution of solvent extracts of leaf and stem of Kedrostis foetidissima. Three different methods of formation of silver nanoparticles such as reaction at (i) room temperature, (ii) higher temperature, and (iii) sonication were employed in the present study. The synthesized silver nanoparticles were characterized by UV-visible spectroscopy, X-ray diffractometer, Scherrer’s formula, scanning electron microscopy, and FTIR analysis. M. Amutha, P. Lalitha, and M. Jannathul Firdhouse Copyright © 2014 M. Amutha et al. All rights reserved. Enhancing Hydrogen Diffusion in Silica Matrix by Using Metal Ion Implantation to Improve the Emission Properties of Silicon Nanocrystals Mon, 06 Jan 2014 11:17:10 +0000 Efficient silicon-based light emitters continue to be a challenge. A great effort has been made in photonics to modify silicon in order to enhance its light emission properties. In this aspect silicon nanocrystals (Si-NCs) have become the main building block of silicon photonic (modulators, waveguide, source, and detectors). In this work, we present an approach based on implantation of Ag (or Au) ions and a proper thermal annealing in order to improve the photoluminescence (PL) emission of Si-NCs embedded in SiO2. The Si-NCs are obtained by ion implantation at MeV energy and nucleated at high depth into the silica matrix (1-2 μm under surface). Once Si-NCs are formed inside the SiO2 we implant metal ions at energies that do not damage the Si-NCs. We have observed by, PL and time-resolved PL, that ion metal implantation and a subsequent thermal annealing in a hydrogen-containing atmosphere could significantly increase the emission properties of Si-NCs. Elastic Recoil Detection measurements show that the samples with an enhanced luminescence emission present a higher hydrogen concentration. This suggests that ion metal implantation enhances the hydrogen diffusion into silica matrix allowing a better passivation of surface defects on Si NCs. J. Bornacelli, J. A. Reyes-Esqueda, L. Rodríguez-Fernández, J. L. Ruvalcaba-Sil, F. J. Jaimes, and A. Oliver Copyright © 2014 J. Bornacelli et al. All rights reserved. Immobilization of α-Chymotrypsin on the Surface of Magnetic/Gold Core/Shell Nanoparticles Sun, 29 Dec 2013 12:21:24 +0000 Over the last decade, nanoparticles used as protein carriers have opened new avenues for a variety of biomedical applications. The main concern for these applications is changes in biological activity of immobilized proteins due to conformational changes on the surface of the carrier. To evaluate this concern, the preparation and biocatalyst activity of α-chymotrypsin-Fe3O4 @ Au core/shell nanoparticles were investigated. First, Fe3O4 @ Au core/shell nanoparticles were synthesized by coprecipitation method and citrate reduction of HAuCl4. TEM imaging revealed a core size of 13 ± 3 nm and a shell thickness of 4 ± 1 nm for synthesized nanoparticles. X-ray diffraction (XRD) was used to study the crystalline structure of the nanoparticles. Next, the enzyme was immobilized on the surface of synthesized nanoparticles by covalent bonding of Au shell with thiol and amine groups present in the protein structure (e.g., cysteine and histidine residues). FTIR and fluorescence spectroscopy were utilized to study secondary and tertiary structures of the immobilized enzyme. Results show that the secondary and tertiary structures of the enzyme remain virtually unchanged after immobilization on the nanoparticles surface. However, the biocatalyst activity of the enzyme was reduced by thirty percent, indicating possible conformational changes or active site occlusion. Mahmoud Kamal Ahmadi and Manouchehr Vossoughi Copyright © 2013 Mahmoud Kamal Ahmadi and Manouchehr Vossoughi. All rights reserved. Fluorescent Silica Nanoparticles in the Detection and Control of the Growth of Pathogen Thu, 26 Dec 2013 11:13:16 +0000 In this present study the bioconjugated fluorescent silica nanoparticles give an efficient fluorescent-based immunoassay for the detection of pathogen. The synthesized silica nanoparticles were polydispersed and the size of the silica nanoparticles was in the range of 114–164 nm. The energy dispersive X-ray spectrophotometer showed the presence of silica at 1.8 kev and the selected area diffractometer showed amorphous nature of silica nanoparticles. The FTIR spectrum confirmed the attachment of dye and carboxyl group onto the silica nanoparticles surface. The fluorescent silica nanoparticles showed highly efficient fluorescence and the fluorescent emission of silica nanoparticles occurred at 536 nm. The SEM image showed the aggregation of nanoparticles and bacteria. The growth of the pathogenic E. coli was controlled using silica nanoparticles; therefore silica nanoparticles could be used in food packaging material, biomedical material, and so forth. This work provides a rapid, simple, and accurate method for the detection of pathogen using fluorescent-based immunoassay. Kethirabalan Chitra and Gurusamy Annadurai Copyright © 2013 Kethirabalan Chitra and Gurusamy Annadurai. All rights reserved. PVP-Stabilized Palladium Nanoparticles in Silica as Effective Catalysts for Hydrogenation Reactions Tue, 17 Dec 2013 14:33:09 +0000 Palladium nanoparticles stabilized by poly (N-vinyl-2-pyrrolidone) (PVP) can be synthesized by corresponding Pd(acac)2 (acac = acetylacetonate) as precursor in methanol at 80°C for 2 h followed by reduction with NaBH4 and immobilized onto SiO2 prepared by sol-gel process under acidic conditions (HF or HCl). The PVP/Pd molar ratio is set to 6. The effect of the sol-gel catalyst on the silica morphology and texture and on Pd(0) content was investigated. The catalysts prepared (ca. 2% Pd(0)/SiO2/HF and ca. 0,3% Pd(0)/SiO2/HCl) were characterized by TEM, FAAS, and SEM-EDS. Palladium nanoparticles supported in silica with a size 6.6 ± 1.4 nm were obtained. The catalytic activity was tested in hydrogenation of alkenes. Caroline Pires Ruas, Daiane Kessler Fischer, and Marcos Alexandre Gelesky Copyright © 2013 Caroline Pires Ruas et al. All rights reserved. Nanocomposites 2013 Thu, 05 Dec 2013 09:02:31 +0000 Hongmei Luo, John Zhanhu Guo, Menka Jain, Ping Xu, and Guifu Zou Copyright © 2013 Hongmei Luo et al. All rights reserved. Some Fundamental Aspects of Mechanics of Nanocomposite Materials and Structural Members Sun, 10 Nov 2013 09:29:34 +0000 This paper is devoted to formulation and analysis of fundamental aspects of mechanics of nanocomposite materials and structural members. These aspects most likely do not exhaust all of the possible fundamental characteristics of mechanics of nanocomposite materials and structural members, but, nevertheless, they permit to form the skeleton of direction of mechanics in hand. The proposed nine aspects are described and commented briefly. Alexander N. Guz and Jeremiah J. Rushchitsky Copyright © 2013 Alexander N. Guz and Jeremiah J. Rushchitsky. All rights reserved. Synthesis by Microwaves of Bimetallic Nano-Rhodium-Palladium Mon, 04 Nov 2013 14:49:02 +0000 An improved acrylamide sol-gel technique using a microwave oven in order to synthesize bimetallic Rh-Pd particles is reported and discussed. The synthesis of Pd and Rh nanoparticles was carried out separately. The polymerization to form the gel of both Rh and Pd was carried out at 80°C under constant agitations. The method chosen to prepare the Rh and Pd xerogels involved the decomposition of both gels. The process begins by steadily increasing the temperature of the gel inside a microwave oven (from 80°C to 170°C). In order to eliminate the by-products generated during the sol-gel reaction, a heat treatment at a temperature of 1000°C for 2 h in inert atmosphere was carried out. After the heat treatment, the particle size increased from 50 nm to 200 nm, producing the bimetallic Rh-Pd clusters. It can be concluded that the reported microwave-assisted, sol-gel method was able to obtain nano-bimetallic Rh-Pd particles with an average size of 75 nm. M. Ugalde, E. Chavira, M. T. Ochoa-Lara, I. A. Figueroa, C. Quintanar, and A. Tejeda Copyright © 2013 M. Ugalde et al. All rights reserved.