Applied Nanoscience (v.3, #5)

Engineered multifunctional nanowires as novel biosensing tools for highly sensitive detection by Pooja Arora; Annu Sindhu; Neeraj Dilbaghi; Ashok Chaudhury (363-372).
Advances in semiconductive nanowires with novel electronic and optical properties contribute towards new detection methods and revolutionize the way of biosensing. Owing to the large amount of literature pertaining to nanowires (indium oxide, polymer, silicon, and gold), the consequent proposal highlights the research published to feature ultra-sensitive handy biosensors. The focus of this article is the effective evaluation of the outstanding scientific challenges in one-dimensional nanostructures (nanowires) towards innovative and exceptional prospects in designing and fabrication of excellent primary transducers/sensors.
Keywords: Biosensors; Electronics; Nanostructures; Nanowires; Semicoductor

Among the composite materials, ceramic/polymer possesses significant advantages of high mechanical reliability and excellent biocompatibility for applications in load-bearing areas. In this work, PVPCS(Poly (4-vinyl pyridine-co-styrene))/FHAp nanocomposites of varying weight percentages were synthesized and characterized physical-chemically by XRD, FTIR, 31P NMR, TGA, DTA, and FE-SEM and biologically by antimicrobial and anti-inflammatory assays for evaluating their potential use for biomedical applications. The results indicated that the size and crystallinity of FHAp nanoparticles decrease with increase in PVPCS concentration in the composite. SEM confirmed the presence of FHAp nano rod crystals in PVPCS matrix. The nano PVPCS20/FHAp demonstrated the highest antifungal and antibacterial activity and favorable inhibition of human cell hemolysis. The designed PVPCS/FHAp nanocomposites constitute promising candidates for biomedical applications.
Keywords: Fluorinated hydroxyapatite; Nanocrystalline; Nanocomposite; PVPCS[poly (4-vinylpyridine-co-styrene)]

Cobalt-doped ZnO nanoparticles have been synthesized using a simple citrate sol–gel auto-combustion method. The XRD confirms nano-single phase and Wurtzite structure. Increased cobalt solubility from 15 to 20 % was observed in ZnO matrix due to low temperature synthesis. Room temperature paramagnetic contribution is observed for all the samples, since cobalt is a neutral dopant and no free carriers are produced. Normally, ferromagnetism is observed in ZnO due to carrier mediated interaction between transition metal ions and free carriers. Hence no ferromagnetism was observed and only paramagnetism was observed due to non-availability of free carriers for long range ferromagnetic interaction in our system. At higher doping, peak broadening of the highly intense XRD peak (101) was observed indicating formation of cobalt cluster (metal–metal) which reduces paramagnetism due to antiferromagnetic interaction and the magnetization value decreases to 0.00456 from 0.0076 emu/g. Absence of photoluminescence peak at 520 nm due to oxygen related defects also supports, the presence of paramagnetism in our samples, since oxygen defects are the another source of ferromagnetism in ZnO. Indirect evidence for the presence of cobalt clustering is also obtained from the photoluminescence studies which lead to concentration quenching of peaks. Photoluminescence studies exhibit NBE peak at 412 nm and defect peaks at 471 and 672 nm. The intensity of red emission peak at 672 nm remains constant whereas the intensity of the peaks at 412 and 471 nm increases and then decreases due to doping induced disorder leading to concentration quenching.
Keywords: Citrate sol–gel low temperature synthesis; Solubility; Absence of free carriers; Paramagnetic study; Photoluminescence

The expansion of reliable and eco-friendly process for synthesis of semiconductor nanoparticle is an important step in the emerging field of biomedical nanotechnology. In this communication, the zinc sulfide nanoparticles were biologically synthesized by using Serratia nematodiphila which was isolated from chemical company effluent. The surface plasmon resonance centered at 390 nm on the UV spectrum indicates the presence of zinc sulfide nanoparticles in the reaction mixture (S. nematodiphila and zinc sulfate); EDAX analysis also confirmed the presence of zinc sulfide nanoparticles. Scanning electron microscope image showed that the synthesized zinc sulfide nanoparticles were spherical in nature and nanoparticles of about 80 nm in size were obtained from transmission electron microscope images. The peaks in the XRD spectrum corresponding to (111), (220) and (311) show that the zinc sulfide nanoparticles are crystalline in nature. Fourier transforms infrared spectroscopy shows the functional groups of the nanoparticle in the range of 4,000–400 cm−1. Further, the antibacterial activity of zinc sulfide nanoparticles was examined against Bacillus subtilis and Klebsiella planticola. The maximum zone of inhibition occurred at 200 μl of silver nanoparticles. Due to potent antimicrobial and intrinsic properties of zinc sulfide, it is actively used for biomedical and food packaging applications.
Keywords: Serratia nematodiphila ; Zinc sulfide nanoparticle; Biosynthesis; Antibacterial activity

The non-Fourier effect in heat conduction and the coupling effect between temperature and strain rate are the two significant effects in the nanoscale beam. In the present work, the solution of vibration of gold nanobeam resonator induced by thermal shock is developed in the context of generalized thermoelasticity with variable thermal conductivity. State-space and Laplace transform methods are used to determine the lateral vibration, the temperature, the displacement, the strain, the stress, and the strain–stress energy. The numerical results have been studied and represented graphically with some comparisons to stand on the effects of the variability of thermal conductivity.
Keywords: Thermoelasticity; Euler–Bernoulli equation; Gold nanobeam; State-space approach

A facile one-pot synthesis of polyaniline/magnetite nanocomposites by micelles-assisted method by K. Basavaiah; Y. Pavan Kumar; A. V. Prasada Rao (409-415).
Magnetic nanocomposites based on polyaniline (PANI) and magnetite nanoparticles (Fe3O4NPs) have been prepared by an in situ self-assembly method in presence of dodecylbenzene sulfonic acid (DBSA) as dopant as well as surfactant. Influence of the aniline to DBSA molar ratio on morphology, magnetic properties, and thermal stability of PANI/Fe3O4NPs composites has been investigated. Spectroscopic results indicated the interaction between PANI nanorods and Fe3O4NPs. Scanning electron microscopy and transmission electron microscopy images indicated that PANI rods were decorated with Fe3O4NPs. Morphologies of nanocomposites were found to be critically dependent on molar ratios of organic acid to monomer. PANI nanorod/Fe3O4NPs composites showed superparamagnetism and higher thermal stability with small mass fraction of Fe3O4NPs.
Keywords: Intrinsic conducting polymer; Polyaniline; Magnetite nanoparticle; Superparamagnetism

Production of highly pure iron disulfide nanoparticles using hydrothermal synthesis method by Asieh Akhoondi; Mahmoud Aghaziarati; Nahid Khandan (417-422).
Hydrothermal synthesis of nanopyrite was investigated in a stirred reactor. The product was characterized by X-ray diffraction (XRD). The result indicated that the synthesized powder was a mixture of pyrite and elemental sulfur. Purification of pyrite was studied via various methods including; solvent extraction, reaction with Na2SO3 and thermal treatment. Before and after purification the synthetic powder was characterized by XRD and scanning electron microscopy. Finally, it was concluded that thermal treatment at temperature 300 °C for 2.5 h was the most appropriate condition to purify pyrite.
Keywords: Hydrothermal synthesis; Nanopyrite; Sulfur; Solvent; Thermal treatment

Polypyrrole–ZnO nanohybrids: effect of CSA doping on structure, morphology and optoelectronic properties by M. A. Chougule; G. D. Khuspe; Shashwati Sen; V. B. Patil (423-429).
Polypyrrole–ZnO (PPy–ZnO) nanohybrid was prepared from PPy and ZnO nanoparticles (NPs). Nanohybrids of PPy–ZnO were doped with camphor sulfonic acid (CSA) with different weight ratios (10–50 %). The CSA-doped nanohybrids obtained were characterized by X-ray diffraction, FTIR, field emission SEM, UV–vis spectroscopy and electrical transport method. Structural investigations using X-ray diffraction shows new peaks appeared at 15.44° and 17.61° in the XRD pattern of CSA-doped PPy–ZnO nanohybrids belong to CSA. The FTIR spectra confirmed the strong interaction between the CSA and PPy–ZnO nanohybrids. The UV–visible spectrums revealed the enhancement of doping level for the 30 % CSA-doped PPy–ZnO nanohybrid film which is assigned to the existence of greater number of charges on the polymer backbone. The room temperature dc electrical conductivity of CSA-doped PPy–ZnO nanohybrids were observed to depend on the CSA doping and the morphology.
Keywords: PPy–ZnO nanohybrid; Structural properties; Optical properties; Electrical properties

The present investigation describes simple and effective method for synthesis of silver nanoparticles via green route. Solanum trilobatum Linn extract were prepared by both conventional and homogenization method. We optimized the production of silver nanoparticles under sunlight, microwave and room temperature. The best results were obtained with sunlight irradiation, exhibiting 15–20 nm silver nanoparticles having cubic and hexagonal shape. Biosynthesized nanoparticles were highly toxic to various bacterial strains tested. In this study we report antibacterial activity against various Gram negative (Klebsiella pneumoniae, Vibrio cholerae and Salmonella typhi) and Gram positive (Staphylococcus aureus, Bacillus cereus and Micrococcus luteus) bacterial strains. Screening was also performed for any antifungal properties of the nanoparticles against human pathogenic fungal strains (Candida albicans and Candida parapsilosis). We also demonstrated that these nanoparticles when mixed with shampoo enhance the anti-dandruff effect against dandruff causing fungal pathogens (Pityrosporum ovale and Pityrosporum folliculitis). The present study showed a simple, rapid and economical route to synthesize silver nanoparticles and their applications hence has a great potential in biomedical field.
Keywords: Antidandruff activity; Antimicrobial activity; Multidrug resistant pathogens (MDR); Ag nanoparticleSolanum trilobatum Linn

Influence of particle size of nano zinc oxide on the controlled delivery of Amoxicillin by L. Palanikumar; S. Ramasamy; G. Hariharan; C. Balachandran (441-451).
A great effort has been exerted to develop drug carriers aiming at satisfying the requirements, such as safety, greater efficiency, predictable therapeutic response, and prolonged release period. The present study aims at developing the use of zinc oxide nanoparticles as a carrier as a function of particle size for amoxicillin drug delivery system. The amoxicillin-loaded zinc oxide nanoparticles have a good antibacterial activity against infectious Gram-positive and Gram-negative bacteria. Zinc oxide nanoparticles have been prepared by wet chemical precipitation method varying the pH values. Particle size and morphology of the as-prepared ZnO powders are characterized by X-ray diffraction, Fourier transform infrared spectroscopy and transmission electron microscope. Drug loading, in vitro drug release and antibacterial activity have been analyzed. Maximum zone of inhibition is observed for Staphylococcus epidermis. The results show that inhibitory efficacy of drug-loaded ZnO nanoparticles is very much dependent on its chosen concentration, drug loading, and size.
Keywords: Amoxicillin; ZnO nanoparticles; Controlled release; Antibacterial activity

CdTe/CdSe heterostructure multilayer thin films and single layers of CdSe and CdTe thin films were prepared. Sequential thermal evaporation technique is made possible to adjust the layer thickness precisely. XRD studies were used to calculate average size of the crystallites and confirmed the (111) and (100) planes of CdTe and CdSe, respectively. Bulk CdTe has band gap energy of 1.54 eV that can be shifted to larger values by reducing the crystallite size to dimensions smaller than the Bohr radius of the exciton. Experimentally measured energy levels show the spin–orbit split of valance band of CdTe. Crystallite sizes (7–12 nm) were calculated with the predictions of effective mass approximation model (i.e., Brus model) which shows that the diameter of crystallites were much smaller than the Bohr exciton diameter (14 nm) of CdTe. It is found that the emission peaks of the prepared CdTe/CdSe ML samples were shifted from the peaks of CdSe and CdTe single layers toward red region as a characteristic of type II band alignment.
Keywords: CdSe; CdTe; Multilayer; Heterostructure; Quantum confinement