Volume 4, Issue 12, December 2013

Indian Materials Congress® (IMC)

Ashutosh Tiwari

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 875-875
DOI: 10.5185/amlett.2013.12001

We are pleased to announce Indian Materials Congress® (IMC). It will be an annual event organised by Vinoba Bhave Research Institute, India during 08-11 December each year from 2014. The goal of congress is to provide a global platform for Indian researchers and engineers coming from academia and industry to present their research results and activities in the field of fundamental and interdisciplinary research of materials science.

ZnO Quantum Dots For Biomedical Applications

Sunita Gulia;Rita Kakkar

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 876-887
DOI: 10.5185/amlett.2013.3440

Quantum dots (QDs), highly luminescent semiconductor nanocrystals, have found extensive applications in different fields, ranging from optoelectronic to bio-imaging. Numerous applications are emerging daily. Among these, ZnO QDs have higher biological significance because of their relative non-toxicity. The primary aim of this review is to overview the literature based on the biological applications of ZnO QDs, including gene therapy, drug delivery, optical imaging, allergen and antigen detection, cancer cell sensing, antibacterial agents and DNA detection. The luminescent properties of ZnO nanoparticles have attracted considerable attention for numerous applications like ultraviolet light emitting devices, flat panel displays, as low voltage phosphors and biosensing devices. The review throws light on the developments in fabrication techniques of nanometer-sized, water-dispersible, bio-compatible and stable ZnO QDs in aqueous medium for biological applications, including employing organic ligands, coating nanoparticles with inorganic shells, doping with a suitable element and capping nanoparticles surfaces with polymers. The low toxicity of ZnO and its high natural abundance make it a good alternative to cadmium based II-VI semiconductors, which cause toxicity via photoinduced reactive oxygen species (ROS) generation.

Study Of In Vitro Toxicity Of Glucose Capped Gold nanoparticles In Malignant And Normal Cell Lines

Harminder Kaur; Geetanjali Pujari; Asitikantha Sarma; Yogendra Kumar Mishra; Mi Kyung Jin; Bikesh K. Nirala; Nivedita K Gohil; Rainer Adelung; Devesh Kumar Avasthi

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 888-894
DOI: 10.5185/amlett.2013.5484

Gold nanoparticles (AuNPs) are potential candidates for targeted drug delivery, imaging and early detection of cancer cells due to their ability to bind with cancer cells. To ensure their safe use in various possible biomedical applications, it is essential to examine the cytotoxicity and biocompatibility of AuNPs before use. The present work aims to study the cytotoxicity of glucose capped gold nanoparticles (Glu-AuNPs) in several cell lines (HeLa, A549, Jurkat, L929 and HUVEC). The synthesized Glu-AuNPs, using β-D glucose as reducing as well as capping agent, were characterized by SPR and TEM/EDAX analysis. Internalization of Glu-AuNPs in cells was studied by cross sectional TEM imaging. The cytotoxicity of Glu-AuNPs was evaluated by means of colony formation and MTT assays. The present study reveals that Glu-AuNPs (7±2 nm diameter) are non-toxic to the above-mentioned five cell lines, which are cancerous cell lines except HUVEC. Therefore Glu-AuNPs (around 7nm) can be explored for various bio-medical applications and can be of importance for therapeutic applications as evident from enhancement in radiosensitization from our previous work.

TiO2 Modified ZnO Thick Film Resistors As Ammonia Gas Sensors

V. S. Kalyamwar; F. C. Raghuwanshi

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 895-898
DOI: 10.5185/amlett.2013.4456

Zinc oxide nanostructures were synthesized by chemical route method. The XRD spectrum indicates that the sample is wurtezite (hexagonal) structured ZnO with lattice constants of a = 3.249A 0 , c = 5.206 A0. Thick films of synthesized ZnO were prepared by screen printing technique. The TiO2 modified ZnO were obtained by dipping them into an aqueous solution of titanium tetrachloride for different interval of time. Gas sensing properties of pure and modified ZnO thick films were investigated. The TiO2 modified ZnO thick film dipped for 5 min were observed to be more sensitive as compared to other modified thick films at 125 0 C. The effect of surface microstructure and TiO2 concentrations on the sensitivity, selectivity, response and recovery of the sensor in the presence of NH3 and other gases ware studied and discussed.

Using Gibbs Standard State Free Energy And A Power Regulating Device To Predict And Control The Fabrication Of Nanoporous Alumina

Alaba O. Araoyinbo; Azmi Rahmat; Mohd Nazree Derman; Khairel Rafezi Ahmad

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 899-904
DOI: 10.5185/amlett.2013.4468

The basic concept of Gibbs standard state free energy predicts a favorable condition for both room and high temperature fabrication of nanoporous alumina in phosphoric acid electrolyte. The anodization of aluminum foil in acidic electrolytes is made possible by the well known process parameters that have been studied over the years. These parameters i.e. voltage, current density, type of electrolyte etc have been very effective when anodizing aluminum at freezing temperatures. When the operating temperature is raised above the freezing temperature, additional process parameters would be required to make the pore formation possible. The fabrication of the aluminum foil was carried out using phosphoric acid as the electrolyte source. The electrolyte pH was adjusted to 1, 3 and 5 in order to simulate different anodizing conditions. A potential of 50 V from a dc power supply was applied across the electrochemical cell, while a power regulating device with different power rating was attached to the electrochemical cell to provide the operating system with additional parameters that could influence the surface structure of the alumina. The micrographs obtained show that the propagation and growth of the pores at both room and high temperatures was made possible by the power regulating device attached to the cell.

Synthesis Of Porous Titania And Its Application To Dye-sensitized Solar Cells

Ammar Elsanousi; Kamal Khalifa Taha; Nazar Elamin

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 905-909
DOI: 10.5185/amlett.2013.5472

Nanocrystalline porous titania with rutile and anatase bi-phase structure has been fabricated by the sol-gel method without the introduction of any surfactant, using tetrabutile titanate as precursor. The porous material was integrated as an electrode in a dye-sensitized solar cell as an electrode and its photoelectrical parameters were measured. Experimental measurements showed that the cell exhibits higher values of short-circuit current density and overall conversion efficiency compared to P25 (typical commercial titania powder) cells. The overall conversion efficiency of both samples was calculated to be 2.81 and 1.57 for the prepared and commercial (P-25) sample respectively. This drastic increase in the conversion efficiency of the prepared sample was attributed to its high surface area and porous structure, allowing more sensitizer dye to be chemically anchored in the electrode and, as a consequence, improved the light harvesting drastically. These results indicate that it is possible to achieve commendable conversion efficiencies using porous bi-phase titania.

Characterization Of Nano-structured Magnesiumchromium ferrites Synthesized By Citrate-gel auto Combustion Method

M. Raghasudha; D. Ravinder; P. Veerasomaiah

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 910-916
DOI: 10.5185/amlett.2013.5479

Nano-ferrites of the composition Mg Crx Fe2-xO4 (where x=0.0, 0.1, 0.3, 0.5, 0.7, 0.9 and 1.0) were synthesized at a very low temperature (180°C) by Citrate-gel auto combustion method. The as synthesized powders were sintered at 500 0 C for four hours in an air and were characterized by X-ray diffraction (XRD) which confirmed the formation of cubic spinel structure of ferrites. The crystallite size was in the range of 7 to 23nm for different compositions with the significant decrease of ~16nm in response to the increase in Cr substitution. Such low nano sized ferrites are desirable for variety of applications like, in magnetic data storage and in targeted drug delivery, etc. Morphological studies by Scanning Electron Microscopy (SEM) revealed formation of largely agglomerated, well defined nano particles of the sample. Elemental composition characterizations of the prepared samples were performed by Energy Dispersive Spectroscopy (EDS) which shows the presence of Mg, Cr, Fe and O without precipitating cations. The FTIR spectral studies at room temperature in the range of 400 to 800cm-1 showed two strong absorption bands. The high frequency band (ν1) around 600 cm -1 is attributed to the intrinsic vibrations of tetrahedral complexes and the low frequency band (ν2) around 400 cm -1 is due to octahedral complexes. The spectra showed the characteristic peaks of ferrite sample. The observed results can be explained on the basis of composition and crystal size.

Energy Transport During Plasma Enhanced Surface Coating Mechanism: A Mathematical Approach

Satish Tailor; Swarniv Chandra; R. M. Mohanty; P. R. Soni

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 917-920
DOI: 10.5185/amlett.2013.5476

Heat transfer enhancement is still needed for the compactness and its smaller temperature difference of evaporator. This paper is introducing a mathematical model (Tailor-Chandra Model) for energy transport in plasma sprays process of a droplet. The model useful for calculate heat transfer through surfaces processed by thermal spraying. The model describes fluid flow of particle droplet during plasma spraying and its different energies: Thermal Energy (ETh), Surface Energy (ES), Kinetic Energy (EK) and the energy lost by way of radiation (ER) before deposition on substrate. A dynamic and thermal balance allows to calculate particle temperature and all energies of droplet during the spray process. As a result point of view, the model is able to show how molten droplets produced higher heat transfer as well as the effect of channel orientation in the low quality, low mass flux condition.

Thermoluminescence Glow Curve Analysis Of Eu3+ Activated CaWO4 Phosphor

K. V. Dabre;S. J. Dhoble

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 921-926
DOI: 10.5185/amlett.2013.3430

In this work we report the synthesis of CaWO4 pure and doped by various concentration of Eu 3+ by solid state method. Crystallinity and formation of as-synthesized phosphors were confirmed by XRD technique. PL emission of the Eu 3+ activated as-synthesized phosphors shows the strong red emission at 619 nm which corresponds to the characteristic transition 5 D0 → 7 F2 of Eu 3+ ion at excitation wavelength 273 nm. TL glow curve of Eu 3+ activated CaWO 4 shows the two glow peaks was observed at 400K and 500K whereas undoped CaWO4 shows only single peak observed at low temperature (354K). Doping effect on TL glow curve was discussed. Glow curve of Eu 3+ activated were fitted to five peaks which were analyzed and trap parameter were calculated by using Chens’ method, and the dose response curve shows the phosphor is fairly sensitivity to lower dose also. Thus reported phosphor can be applicable in LED and environmental dosimetry.

Thermally Reduced Graphene oxide/thermoplastic Polyurethane Nanocomposites As Photomechanical Actuators 

M. N. Muralidharan;Seema Ansari

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 927-932
DOI: 10.5185/amlett.2013.5474

Optically triggered actuators offer unique advantages like wireless actuation and remote control when comared to other type of actuators. They are extremely useful where stimulus other than electricity or heat is preferred. Thermally reduced graphene oxide (TRGO)/thermoplastic polyurethane (TPU) composite actuators were prepared by simple solution casting technique. The photomechanical actuation properties of the composites were studied under infrared illumination. It was found that the photomechanical response can be tuned by controlling the applied prestrain and the filler loading. Even with a low filler loading of 2 wt. % TRGO, the composite exhibited a very high photomechanical strain of 50.2% with an excellent stress of 1680 kPa at a prestrain of 220%. These high values were achieved at a very low light intensity of 16mWcm -2 . The high values of strain obtained with very good generative forces indicate that this is a promising material for light triggered actuators for many potential applications including robotics and biomedical devices.

Green Synthesis Of Gold Nanoparticles For controlled Delivery

S. Malathi; M. D. Balakumaran; P. T. Kalaichelvan; S. Balasubramanian

Advanced Materials Letters, 2013, Volume 4, Issue 12, Pages 933-940
DOI: 10.5185/amlett.2013.5477

Gold nanoparticles (AuNPs) have been synthesized by green method using chitosan as a reducing/capping agent. We designed a biocompatible carrier for controlled release of hydrophobic drugs. The designed carrier was prepared by using single oil-in-water (O/W) emulsion. The resulting AuNPs were characterized by UV–Vis spectroscopy (UV–Vis) and Fourier transform infrared spectroscopy (FTIR). The transmission electron microscopy (TEM) studies indicate the spherical nature of drug loaded nanoparticles with the size of 50nm while the average particle size of AuNPs is found to be 2-3nm. The chitosan capped AuNPs showed a surface plasmon resonance at 526nm. The FTIR spectra suggest that the amine group is mainly responsible for the reduction of tetrachloroauric acid and capping the AuNPs. The controlled release of rifampicin (RIF) was investigated by in vitro studies using phosphate buffer saline (PBS) at pH=7.4. The loading efficiency of drug molecule was found to be 71%. The encapsulated drugs were released at 37 °C temperature. The results have been fit into various mechanistic models and it is found that the Higuchi model fits in to the release behavior of RIF. Further, the antibacterial activity of RIF loaded nanoparticles was examined by Gram +ve (bacillus subtils) and Gram -ve (Pseudomonas aeruginosa) bacteria. The application of similar drug loaded nanocarrier for treating other diseases like cancer can also be investigated.