A.R. Phani

Nanomaterials for Hydrogen Storage Applications: A Review

Nanomaterials have attracted great interest in recent years because of the unusual mechanical, electrical, electronic, optical, magnetic and surface properties. The high surface/volume ratio of these materials has significant implications with respect to energy storage. Both the high surface area and the opportunity for nanomaterial consolidation are key attributes of this new class of materials for hydrogen storage devices. Nanostructured systems including carbon nanotubes, nano-magnesium based hydrides, complex hydride/carbon nanocomposites, boron nitride nanotubes, nanotubes, alanates, polymer nanocomposites, and metal organic frameworks are considered to be potential candidates for storing large quantities of hydrogen. Recent investigations have shown that nanoscale materials may offer advantages if certain physical and chemical effects related to the nanoscale can be used efficiently. The present review focuses the application of nanostructured materials for storing atomic or molecular hydrogen. The synergistic effects of nanocrystalinity and nanocatalyst doping on the metal or complex hydrides for improving the thermodynamics and hydrogen reaction kinetics are discussed. In addition, various carbonaceous nanomaterials and novel sorbent systems (e.g. carbon nanotubes, fullerenes, nanofibers, polyaniline nanospheres and metal organic frameworks etc.) and their hydrogen storage characteristics are outlined.

Structural characterization of iron titanium oxide synthesized by sol-gel spin-coating technique

Abstract For the first time, crack-free, dense and transparent polycrystalline orthorhombic Fe2TiO5 single-phase structure thin films have been prepared by a sol–gel method using titanium isopropoxide and iron oxalate. The formation of the Fe2TiO5 phase started from 400°C onwards. No cracks, formation of other phases or diffusion of Si was observed even after application of the annealing temperature of 800°C for 5 h. The structural, morphological and elemental evolution of these Fe2TiO5 thin films produced by the sol–gel synthesis were characterized by Grazing Incidence X-ray Diffraction (GIXRD), Tapping Mode Atomic Force Microscopy (TMAFM), and X-ray Photoelectron Spectroscopy (XPS), respectively.

Polyvinylpyrrolidone oral films of enrofloxacin: film characterization and drug release.

Enrofloxacin is a fluoroquinolone derivative used for treating urinary tract, respiratory and skin infections in animals. However, low solubility and low bioavailability prevented it from using on humans. Polyvinylpyrrolidone (PVP) is an inert, non toxic polymer with excellent hydrophilic properties, besides it can enhance bioavailability by forming drug polymer conjugates. With the aim of increasing solubility and bioavailability, enrofloxacin thin films were prepared using PVP as a polymer matrix. The obtained oral thin films exhibited excellent uniformity and mechanical properties. Swelling properties of the oral thin films revealed that the water uptake was enhanced by 21%. The surface pH has been found to be 6.8±0.1 indicating that these films will not cause any irritation to oral mucosa. FTIR data of the oral thin films indicated physical interaction between drug and polymer. SEM analysis revealed uniform distribution of drug in polymer matrix. In vitro drug release profiles showed enhanced release profiles (which are also pH dependant) for thin films compared to pure drug. Antibacterial activity was found to be dose dependent and maximum susceptibility was found on Klebsiella pneumonia making this preparation more suitable for respiratory infections.

Spectroscopic and electrical properties of SiO2 films prepared by simple and cost effective sol–gel process

Amorphous SiO2 thin films were prepared on glass and silicon substrates by cost effective sol-gel method. Tetra ethyl ortho silicate (TEOS) was used as the precursor material, ethanol as solvent and concentrated HCl as a catalyst. The films were characterized at different annealing temperatures. The optical transmittance was slightly increased with increase of annealing temperature. The refractive index was found to be 1.484 at 550 nm. The formation of SiO2 film was analyzed from FT-IR spectra. The MOS capacitors were designed using silicon (100) substrates. The current-voltage (I-V), capacitance-voltage (C-V) and dissipation-voltage (D-V) measurements were taken for all the annealed films deposited on Si (100). The variation of current density, resistivity and dielectric constant of SiO2 films with different annealing temperatures was investigated and discussed for its usage in applications like MOS capacitor. The results revealed the decrease of dielectric constant and increase of resistivity of SiO2 films with increasing annealing temperature.

Anti-cancerous efficacy and pharmacokinetics of 6-mercaptopurine loaded chitosan nanoparticles

6-Mercaptopurine is a cytotoxic and immunosuppressant drug. The use of this drug is limited due to its poor bioavailability and short plasma half-life. In order to nullify these drawbacks, 6-mercaptopurine-chitosan nanoparticles (6-MP-CNPs) were prepared and evaluated to study the influence of preparation conditions on the physicochemical properties by using DLS, SEM, XRD and FTIR. The in vitro drug release profile at pH 4.8 and 7.4 revealed sustained release patterns for a period of 2 days. The nanoformulations showed enhanced in vitro anti-cancer activities (MTT assay, apoptosis assay, cell cycle arrest and ROS indices) on HT-1080 and MCF-7 cells. In vivo pharmacokinetics profiles of 6-MP-CNPs showed improved bioavailability. Thus, the results of the present study revealed that, the prepared 6-MP-CNPs have a significant role in increasing anti-cancer efficacy, bioavailability and in vivo pharmacokinetics profiles.

Nanostructured TiO2 and TiO2-Ag Antimicrobial Thin Films

Infection is one of the common clinical problems that cause high rates of death in various surgical operations. Coating the surgical instruments or implants with antibacterial properties is a useful method to reduce such infections during the operation period. The high incidence of infections caused by the use of implanted biomedical devices and environment in the hospital has a severe impact on the health of patients. However no comprehensive studies have been reported on active species of fungal and bacteria. In this present investigation, we have systematically studied the antifungal (against Candida albicans (MTCC-1637), Candida tropicalis (MTCC-184), Candida parapsilosis (MTCC-2509), Candida glabrata (MTCC 3019) and antibacterial properties of 4 species namely (against Staphylococcus faecalis (NCIM-2604). Staphylococcus epidermidis (NCIM-2493), Staphylococcus aureus (NCIL-2122), Bacillus subtilis ( NCIM-2549) each using pure TiO2 and TiO2 with Ag as additive by using the simple and cost effective sol-gel process. The films have been deposited on glass and Si substrates and their structural, morphological properties have been investigated by employing standard spectroscopic techniques such as XRay Diffraction and Scanning Electron Microscopy, X-Ray Photoelectron spectroscopy, respectively. The test for antifungal and antibacterial has been carried out by using drop test method. It is evident from the results that with increasing Ag concentration the antimicrobial activity increases.

Enhancement of dissolution rate of piroxicam by electrospinning technique

The use of electrospun nanofibers to enhance dissolution of poorly soluble drugs could be a novel strategy in future for pharmaceutical applications. In the present work electrospun nanofibers were prepared as a novel system for enhancing the delivery of piroxicam, a non-steroidal anti-inflammatory drug (NSAID). These nanofibers were prepared from polyvinyl pyrrolidone (PVP) (pharmaceutical grade), a biodegradable polymer, to obtain a solution with drug:polymer ratio of 1:4. The release rate of the piroxicam nanofibers was studied in simulated gastric fluid. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) are used to evaluate the chemical and physical nature. The results showed that the release rates were twice increased in comparison with the pure drug. However, the blend of drug and polymer could be varied to optimize the release rates depending upon the need and formulation

Fabrication, Characterization andIn VitroOsteogenic Potential of Polyvinyl Pyrrolidone-Titania (PVP-TiO ) Nanofibers

Abstract: For bone tissue engineering applications Titanium is the material of choice owing to its biocompatible and osteoconductive nature. Biocompatibility TiO2 is due to its unique properties of attracting surface proteins of cell surface. Our present study was designed to evaluate optimum conditions to get homogenous nanofibers of titanium with minimum fiber diameter. All the formulations were subjected to SEM analysis. By using protocol 1 the minimum size of nanofibers we could get is around 320 nm (NF1C) and for protocol 2 we could get around 90 nm (NF2C). XRD analysis of formulations NF1C and NF2C proved that the titanium is in anatase phase. We also evaluated biocompatibility, cell proliferation and osteogenic potential of two formulations (NF1C and NF2C) using mouse preosteoblasts (MC3T3-E1). Osteogenic potential of NF1C and NF2C was evaluated by quantifying osteogenic markers of differentiation like ALP and calcium content. ALP activity was highly expressed in cells grown on NF1C and NF2C formulations but higher degree of expression was seen on NF2C. A similar trend was followed for calcium deposition when cells were cultured on NF1C and NF2C formulations for 7 days. Our experimental results indicated that nanofibrous TiO2 substrates not only supported cellular growth, adhesion, and proliferation but also can guide preosteoblasts to osteoblast lineage. These results may be useful in preparing osteoconductive scaffolding materials for bone tissue engineering applications.

Increasing the Photocatalytic Activity by Mechano-chemically Milling on Zn- Doped TiO 2

This paper pursed one new cost effective strategy to improve the photocatalytic activity of the sol-gel developed Zn doped TiO 2 by mechano-chemically milling in high energy planetary mill. The results showed that the photocatlytic activity was improved two times due to the increase of the surface area and the decrease in average crystallite size at the same time after using the high energy ball milling. Kubelka-Munk spectra of pristine and ball milled samples revealed a blue shift from 3.2 eV to 3.35 eV, which may be because of the presence of quantum size effects. SEM microstructural investigations revealed variations in the surface morphology with different Zn doping concentrations in the TiO 2 -Xwt.% Zn nanoparticulates. EDS spectra of these samples confirmed the stoichiometric concentration of Zn. Other characterization including X-ray diffraction (XRD), BET surface and the photocatalytic decomposition were also studied and the results were in agreement with each other.

Preparation and Characterization of Nanofibrous Solid Dosage Form Containing Enrofloxacin

Abstract For the first time, we have prepared electrospun polyvinyl pyrrolidine (PVP) nanofibers loaded with enrofloxacin (PVP-ENRNF) using electrospinning technique. The morphology and physico-chemical properties were characterized by employing Scanning Electron Microscopy (SEM) and Fourier Transform InfraRed (FTIR) spectroscopy, respectively. Morphology by SEM revealed fiber diameter ranging from 450-725 nm. FTIR spectroscopy indicated physical interaction between the polymer and drug. Release profiles of enrofloxacin (ENR) from PVP-ENRNFs were studied, which controlled/influenced by the pH of the release media. Cumulative drug release profiles of PVP-ENRNFs at pH 3.8 (71.96 %), 6.4 (62.34 %) and 7.4 (54.14 %) were comparatively better than release profiles of pure ENR. These nanofibers exhibited potent antibacterial activity on tested microbes. These PVP-ENRNFs can be efficiently used as potential materials for oral as well as local delivery of enrofloxacin for treating respiratory and wound infections.