Applied Nanoscience (v.6, #2)

Nano-doped weakly polar versus highly polar liquid crystal by Kamal Kumar Pandey; Abhishek Kumar Misra; Rajiv Manohar (141-148).
Nanoparticles doped liquid crystal show changed dielectric properties in comparison to pure liquid crystals. These changes are strongly dependent on the inherent properties of guest and host particles. In the present work we have done comparative dielectric study of highly polar nematic liquid crystals 5CB and weakly polar liquid crystal D6AOB and its 1 % wt/wt concentration with zinc oxide nanoparticles (1 % Cu) doped. The relaxation modes in pure and nano doped samples are explained properly. We have also analyzed the dielectric anisotropy and relaxation frequency for all the samples.
Keywords: Nematic liquid crystals; Nanoparticles; Dielectric anisotropy; Relaxation

Graphene–nanometre-sized cerium oxide-incorporated aluminium was prepared and its electrochemical and surface morphological characteristics were studied. The atomic force micrographs and scanning electron micrographs evaluation highlighted that the graphene and nanometre-sized cerium oxide in aluminium had decreased the surface roughness and improved the surface morphological characteristics. The graphene: nanometre-sized cerium oxide (ratios 1:2 or 2:1) with lesser amounts of particle in the matrix showed excellent corrosion resistance in the marine environment as evidenced by linear polarization, electrochemical impedance and weight loss studies. Introduction of graphene in the aluminium matrix showed a barrier separation between the outermost layer and inner layer, increased roughness and increased corrosion. The material is found to be a potential candidate for use in marine environment.
Keywords: Graphene; Metal matrix composite; Corrosion

The research focuses on the development and optimization of ifosfamide nanostructured lipid carriers for oral delivery with the application of response surface methodology. The objectives of the study were to develop a formulation for ifosfamide to be delivered orally, overcome the instability of the drug in acidic environment during oral administration, to sustain the release, drug leakage during storage and low loading capacity. A modified solvent diffusion method in aqueous system was applied to prepare nanostructured lipid nanoparticles. Hydrophilic polymers such as chitosan and sodium alginate were used as coating materials. Glycerol mono oleate and oleic acid were used as solid and liquid lipid, respectively. Poloxamer is used as stabilizers. The central composite rotatable design consisting of three-factored factorial design with three levels was used in this study. The physiochemical characterization included evaluation of surface morphology, particle size and surface charge of the drug in the delivery system. The in vitro drug release, entrapment and drug loading efficiency and as well as the storage stability were evaluated. The results showed that the optimal formulation was composed of drug/lipid ratio of 1:3, organic/aqueous phase ratio of 1:10 and concentration of surfactant of 1 % w/v. Ifosfamide nanostructured lipid carrier under the optimized conditions gave rise to the entrapment efficiency of 77 %, drug loading of 6.14 %, mean diameter of 223 nm and zeta potential value of −25 mV. Transmission electron microscopy analysis showed spherical particles. The in vitro experiment proved that ifosfamide from the delivery system released gradually over the period of 72 h. Sodium alginate cross-linked chitosan nanostructured lipid carrier demonstrated enhanced stability of ifosfamide, high entrapment efficiency and sustained release.
Keywords: Ifosfamide; Nanostructured lipid carriers; Oral delivery; Response surface methodology; Solvent diffusion technique; Sustained release

Dielectric relaxation of CdO nanoparticles by Ramna Tripathi; Alo Dutta; Sayantani Das; Akhilesh Kumar; T. P. Sinha (175-181).
Nanoparticles of cadmium oxide have been synthesized by soft chemical route using thioglycerol as the capping agent. The crystallite size is determined by X-ray diffraction technique and the particle size is obtained by transmission electron microscope. The band gap of the material is obtained using Tauc relation to UV–visible absorption spectrum. The photoluminescence emission spectra of the sample are measured at various excitation wavelengths. The molecular components in the material have been analyzed by FT-IR spectroscopy. The dielectric dispersion of the material is investigated in the temperature range from 313 to 393 K and in the frequency range from 100 Hz to 1 MHz by impedance spectroscopy. The Cole–Cole model is used to describe the dielectric relaxation of the system. The scaling behavior of imaginary part of impedance shows that the relaxation describes the same mechanism at various temperatures. The frequency-dependent electrical data are also analyzed in the framework of conductivity and electrical modulus formalisms. The frequency-dependent conductivity spectra are found to obey the power law.
Keywords: Cadmium oxide; Chemical synthesis; Optical properties; Impedance spectroscopy

An analytical method using modified SiO2 nanoparticles as solid-phase extractant has been developed for the preconcentration of trace amounts of Hg(II) in different water samples. Conditions of the analysis such as preconcentration factor, effect of pH, sample volume, shaking time, elution conditions and effects of interfering ions for the recovery of analyte were investigated. The adsorption capacity of nanometer SiO2-APTMS was found to be 181.42 µmol g−1 at optimum pH and the detection limit (3σ) was 0.45 µg L−1. The extractant showed rapid kinetic sorption. The adsorption equilibrium of Hg(II) on nanometer SiO2-APTMS was achieved just in 15 min. Adsorbed Hg(II) was easily eluted with 4 mL of 2.0 M hydrochloric acid. The maximum preconcentration factor was 75. The method was applied for the determination of trace amounts of Hg(II) in various synthetic samples and water samples.
Keywords: SiO2-nanoparticles; Solid phase extraction; Preconcentration; Separation

Structural, opto-electronic and photoelectrochemical properties of tungsten diselenide thin films by D. J. Sathe; P. A. Chate; P. P. Hankare; A. H. Manikshete; U. B. Sankpal; V. M. Bhuse (191-196).
Nanocrystalline tungsten diselenide thin films have been deposited on non-conducting glass and stainless steel substrates by chemical methods. Various preparative conditions were optimized for the formation of thin films. The X-ray diffraction analysis shows that the film samples are in layer-hexagonal crystal structure. EDAX analysis shows that the films are nearly stoichiometries of W:Se. Optical properties show a direct band gap nature with band gap energy 1.5 eV. Specific electrical conductivity was found to be in the order of 10−3 to 10−2 (Ω cm)−1. The photoelectrochemical characterization of the films was carried out by studying current–voltage characteristics, capacitance–voltage and power output characteristics. The efficiency of photoelectrode was found to be 1.31 % using iodine–poly iodide electrolyte.
Keywords: Nanostructure; EDAX; Chemical synthesis; Electrical properties; Efficiency; Fill factor

Preparation and characterization of nanoparticles of carboxymethyl cellulose acetate butyrate containing acyclovir by Venkata Bharadwaz Vedula; Maulick Chopra; Emil Joseph; Sonal Mazumder (197-208).
Nanoparticles of carboxymethyl cellulose acetate butyrate complexed with the poorly soluble antiviral drug acyclovir (ACV) were produced by precipitation process and the formulation process and properties of nanoparticles were investigated. Two different particle synthesis methods were explored—a conventional precipitation method and a rapid precipitation in a multi-inlet vortex mixer. The particles were processed by rotavap followed by freeze-drying. Particle diameters as measured by dynamic light scattering were dependent on the synthesis method used. The conventional precipitation method did not show desired particle size distribution, whereas particles prepared by the mixer showed well-defined particle size ~125–450 nm before and after freeze-drying, respectively, with narrow polydispersity indices. Fourier transform infrared spectroscopy showed chemical stability and intactness of entrapped drug in the nanoparticles. Differential scanning calorimetry showed that the drug was in amorphous state in the polymer matrix. ACV drug loading was around 10 wt%. The release studies showed increase in solution concentration of drug from the nanoparticles compared to the as-received crystalline drug.
Keywords: Cellulose; Acyclovir; Nanoparticles; Drug release; Solubility; Reynolds number

Synthesis and characterization of oxytetracycline imprinted magnetic polymer for application in food by Sneha Aggarwal; Yudhishthir Singh Rajput; Gulab Singh; Rajan Sharma (209-214).
Magnetic imprinted polymer was prepared by polymerization of methacrylate and ethyleneglycoldimethacrylate in the presence of oxytetracycline on the surface of iron magnetite. Selectivity of prepared polymer was calculated from ratio of partition coefficient of oxytetracycline for imprinted and non- imprinted polymer in water, acetonitrile, methanol and at different pH in aqueous buffer. pH of solvent exhibited pronounced effect on selectivity. Selectivity at pH 7.0, 6.0 and 5.0 was 36.0, 2.25 and 1.61 fold higher than at pH 4.0. Imprinted polymer was not selective for oxytetracycline in methanol. However, selectivity in water and acetonitrile was 19.42 and 2.86, respectively. Oxytetracycline did bind to imprinted polymer in water or aqueous buffer (pH 7.0) and could be eluted with methanol. Prepared polymer extracted 75–80 % oxytetracycline from water, honey and egg white.
Keywords: Iron nanoparticle; Oxytetracycline imprinted polymer; Selectivity; Food

Surface roughness analysis of SiO2 for PECVD, PVD and IBD on different substrates by Muhammad Rizwan Amirzada; Andreas Tatzel; Volker Viereck; Hartmut Hillmer (215-222).
This study compares surface roughness of SiO2 thin layers which are deposited by three different processes (plasma-enhanced chemical vapor deposition, physical vapor deposition and ion beam deposition) on three different substrates (glass, Si and polyethylene naphthalate). Plasma-enhanced chemical vapor deposition (PECVD) processes using a wide range of deposition temperatures from 80 to 300 °C have been applied and compared. It was observed that the nature of the substrate does not influence the surface roughness of the grown layers very much. It is also perceived that the value of the surface roughness keeps on increasing as the deposition temperature of the PECVD process increases. This is due to the increase in the surface diffusion length with the rise in substrate temperature. The layers which have been deposited on Si wafer by ion beam deposition (IBD) process are found to be smoother as compared to the other two techniques. The layers which have been deposited on the glass substrates using PECVD reveal the highest surface roughness values in comparison with the other substrate materials and techniques. Different existing models describing the dynamics of clusters on surfaces are compared and discussed.
Keywords: Micro electro mechanical systems; Plasma-enhanced chemical vapor deposition; Physical vapor deposition; Ion beam deposition; Surface roughness; Stylus profilometry; Atomic force microscopy

In nanotechnology, the plant mediated synthesis of nanoparticles has terrific application in biomedicine due to its novel properties and its eco-friendly nature. The present study deals with the biosynthesis of stable silver nanoparticles (SNPs) from aqueous fruit extract of S. alternifolium an endemic medicinal plant to Eastern Ghats. The synthesized nanoparticles are characterized by UV–VIS spectroscopy, FTIR, XRD, AFM, SEM with EDAX and TEM. Colour change from brown to grey indicates the formation of nanoparticles and UV–VIS surface plasmon resonance spectroscopy observed at 442 nm further confirms the synthesized nanoparticles are SNPs. FTIR studies reveal that the phenols and primary amines of proteins are main responsible for reduction, stabilization and capping agents towards these SNPs. The XRD data show crystalline nature of nanoparticles and EDAX measurements reveal the (12.74 %) percentage presence of Ag metal. AFM, SEM and TEM microscopic analyses revealed that the size of synthesized SNPs ranging from 5 to 68 nm has spherical shape and they are in polydispersed condition. Further, the antimicrobial studies of synthesized SNPs show high toxicity towards different bacterial and fungal isolates. This is the first report on fruit mediated synthesis of silver nanoparticles from S. alternifolium.
Keywords: Syzygium alternifolium ; Endemic medicinal plant; Characterization of SNPs; Antimicrobial activity

Formation of Al-doped ZnO thin films on glass by sol–gel process and characterization by M. U. Shahid; K. M. Deen; A. Ahmad; M. A. Akram; M. Aslam; W. Akhtar (235-241).
In this study, pure ZnO and Al-doped ZnO thin films were developed on glass by sol–gel process followed by drying and annealing in air at 170 and 400 °C, respectively. The surface morphology and structural characteristics were determined through scanning electron microscopy, atomic force microscopy and X-ray diffraction. The Fourier transform infrared spectroscopy validated the formation of Al-doped ZnO film on glass substrate. It was evaluated that 1 at% aluminum (Al) doping in ZnO film showed low electrical resistivity and higher charge carrier concentration due to uniformly dispersed regular shape crystallites as compared to pure ZnO and 2 at% ‘Al’-doped thin films.
Keywords: Thin film; Resistivity; Carrier concentration; Glass; Sol–gel

Investigation on vibration of single-walled carbon nanotubes by variational iteration method by A. A. Ahmadi Asoor; P. Valipour; S. E. Ghasemi (243-249).
In this paper, the variational iteration method (VIM) has been used to investigate the non-linear vibration of single-walled carbon nanotubes (SWCNTs) based on the nonlocal Timoshenko beam theory. The accuracy of results is examined by the fourth-order Runge–Kutta numerical method. Comparison between VIM solutions with numerical results leads to highly accurate solutions. Also, the behavior of deflection and frequency in vibrations of SWCNTs are studied. The results show that frequency of single walled carbon nanotube versus amplitude increases by increasing the values of B.
Keywords: Carbon nanotubes; Variational iteration method (VIM); Non-linear vibration; Timoshenko beam theory; Frequency

Resistance of extremely halophilic archaea to zinc and zinc oxide nanoparticles by Bhakti B. Salgaonkar; Deepthi Das; Judith Maria Bragança (251-258).
Industrialization as well as other anthropogenic activities have resulted in addition of high loads of metal and/or metal nanoparticles to the environment. In this study, the effect of one of the widely used heavy metal, zinc (Zn) and zinc oxide nanoparticles (ZnO NPs) on extremely halophilic archaea was evaluated. One representative member from four genera namely Halococcus, Haloferax, Halorubrum and Haloarcula of the family Halobacteriaceae was taken as the model organism. All the haloarchaeal genera investigated were resistant to both ZnCl2 and ZnO NPs at varying concentrations. Halococcus strain BK6 and Haloferax strain BBK2 showed the highest resistance in complex/minimal medium of up to 2.0/1.0 mM ZnCl2 and 2.0/1.0–0.5 mM ZnO NP. Accumulation of ZnCl2/ZnO NPs was seen as Haloferax strain BBK2 (287.2/549.6 mg g−1) > Halococcus strain BK6 (165.9/388.5 mg g−1) > Haloarcula strain BS2 (93.2/28.5 mg g−1) > Halorubrum strain BS17 (29.9/16.2 mg g−1). Scanning electron microscopy and energy dispersive X-ray spectroscopy (SEM–EDX) analysis revealed that bulk ZnCl2 was sorbed at a higher concentration (21.77 %) on the cell surface of Haloferax strain BBK2 as compared to the ZnO NPs (14.89 %).
Keywords: Halophilic; Archaea; Halococcus strain BK6; Haloferax strain BBK2; Halorubrum strain BS17; Haloarcula strain BS2; ZnCl2 ; ZnO nanoparticles; Metal tolerance; Growth kinetics

Silver ions (Ag+) and its compounds are highly toxic to microorganisms, exhibiting strong biocidal effects on many species of bacteria but have a low toxicity toward animal cells. In the present study, silver nanoparticles (SNPs) were biosynthesized using aqueous extract of Chlorella vulgaris as reducing agent and size of SNPs synthesized ranged between 15 and 47 nm. SNPs were characterized by UV–visible spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray diffraction and Fourier infrared spectroscopy, and analyzed for its antibacterial property against human pathogens. This approach of SNPs synthesis involving green chemistry process can be considered for the large-scale production of SNPs and in the development of biomedicines.
Keywords: Silver ions; Green chemistry; Human pathogens; Biomedicines

The biosynthesis of nanoparticles has been proposed as a cost effective and environmentally benevolent alternative to chemical and physical methods. In the present study, microwave assisted synthesis of silver nanoparticles (AgNPs) has been demonstrated using leaf extract of Fraxinus excelsior reducing aqueous AgNO3 solution. The synthesized nanoparticles have been characterized on the basis of fourier transform infrared spectroscopy (FT-IR), UV–Vis spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis. The presence of a characteristic surface plasmon resonance (SPR) absorption band at 425 nm in UV–Vis reveals the reduction of silver metal ions into silver nanoparticles. FT-IR analysis was carried out to probe the possible functional group involved in the synthesis of AgNPs. Further leaf extracts and AgNPs were evaluated for antiradical scavenging activity by 1,1-diphenyl-2-picryl-hydrazyl (DPPH) assay.
Keywords: Microwave; Biosynthesis; Fraxinus excelsior ; Silver nanoparticles; Antioxidant activity

Fabrication of chitosan–magnetite nanocomposite strip for chromium removal by Vaishnavi Sureshkumar; S. C. G. Kiruba Daniel; K. Ruckmani; M. Sivakumar (277-285).
Environmental pollution caused by heavy metals is a serious threat. In the present work, removal of chromium was carried out using chitosan–magnetite nanocomposite strip. Magnetite nanoparticles (Fe3O4) were synthesized using chemical co-precipitation method at 80 °C. The nanoparticles were characterized using UV–visible spectroscopy, fourier transform infrared spectroscopy, X-ray diffraction spectrometer, atomic force microscope, dynamic light scattering and vibrating sample magnetometer, which confirm the size, shape, crystalline nature and magnetic behaviour of nanoparticles. Atomic force microscope revealed that the particle size was 15–30 nm and spherical in shape. The magnetite nanoparticles were mixed with chitosan solution to form hybrid nanocomposite. Chitosan strip was casted with and without nanoparticle. The affinity of hybrid nanocomposite for chromium was studied using K2Cr2O7 (potassium dichromate) solution as the heavy metal solution containing Cr(VI) ions. Adsorption tests were carried out using chitosan strip and hybrid nanocomposite strip at different time intervals. Amount of chromium adsorbed by chitosan strip and chitosan–magnetite nanocomposite strip from aqueous solution was evaluated using UV–visible spectroscopy. The results confirm that the heavy metal removal efficiency of chitosan–magnetite nanocomposite strip is 92.33 %, which is higher when compared to chitosan strip, which is 29.39 %.
Keywords: Magnetite nanoparticles; Chitosan; Chitosan–magnetite nanocomposite strip; Chromium

This article examines the influence of thermophoresis, Brownian motion of the nanoparticles with variable stream conditions in the presence of magnetic field on mixed convection heat and mass transfer in the boundary layer region of a semi-infinite porous vertical plate in a nanofluid under the convective boundary conditions. The transformed boundary layer ordinary differential equations are solved numerically using Maple 18 software with fourth-fifth order Runge–Kutta–Fehlberg method. Numerical results are presented both in tabular and graphical forms illustrating the effects of these parameters with magnetic field on momentum, thermal, nanoparticle volume fraction and solutal concentration boundary layers. The numerical results obtained for the velocity, temperature, volume fraction, and concentration profiles reveal interesting phenomenon, some of these qualitative results are presented through plots. It is interesting to note that the magnetic field plays a dominant role on nanofluid flow under the convective boundary conditions.
Keywords: Mixed convection; Nanofluid; Soret effect; Convective boundary condition; Magnetic field