Study of synthesis, structural, optical and magnetic characterizations of iron/copper oxide nanocomposites: A promising novel inorganic antibiotic.

This paper reports the development of inorganic nanoparticles based novel antibiotic. Inorganic nanoparticles have the potential of being used as bactericidal agent due to their effective antimicrobial activity, colloidal aqueous stability and comparatively low toxic profile. Among them, iron oxide and copper oxide were chosen for this study because of the nascent bactericidal properties of both iron and copper. In this work, along with the pure samples of iron oxide and copper oxide nanoparticles, hybrid magnetic nanocomposites of iron oxide and copper oxide with varying molar concentrations of copper precursor were produced by wet-chemical approach. Structural, physical and chemical properties of the prepared samples were investigated using spectroscopic and microscopic techniques like XRD, SEM, TEM, EDAX, Raman, VSM and TGA-DTA. The antibacterial activity of the samples were established against pathogenic strains of bacteria E. coli, B. subtilis, S. aureus and S. typhi by using two different methods. The prepared nanomaterials were very adequate to combat the bacterial growth and their bactericidal efficiency was comparable to the commercial antibiotic gentamycin. Thus these non-toxic hybrid nanocomposites can be used as the potential antibiotic to counter the diseases caused by normal and multi drug resistant pathogenic bacterial strains.

Fabrication and a detailed study of antibacterial properties of α-Fe2O3/NiO nanocomposites along with their structural, optical, thermal, magnetic and cytotoxic features.

Nanomaterials have specific properties which are uncommon in their bulk counterparts. Because of these unique characteristics, nanotechnology has been explored for various applications by the scientific community and it can play a crucial role in providing solutions of current major healthcare problems. In the present work, we describe the fabrication of a novel inorganic alternative of traditional antibiotics, which can effectively counter the pathogenic bacteria including multi drug resistant bacterial strains. For this purpose, nanocomposites of Fe/Ni oxide with different molar concentrations of nickel have been prepared via wet-chemical approach along with the α-Fe2O3 and NiO nanoparticles. The bactericidal efficiency of the prepared samples were tested against pathogenic strains of B. subtilis, S. aureus, E. coli and S. typhi using two distinct methods. In addition to this, structural, physical and chemical properties of the nanomaterials were studied using XRD, TEM, EDAX, Raman, VSM and TGA-DTA. Also, the cytotoxicity of synthesized samples was assessed using MTT assay against human cell lines MCF-10A (normal) and MCF7 (cancer).

Chitosan conjugation: a facile approach to enhance the cell viability of LaF3:Yb,Er upconverting nanotransducers in human breast cancer cells.

In this study, chitosan functionalized LaF3:Yb,Er upconverting nanotransducers (UCNTs) with controlled size and shape have been successfully synthesized by a facile one pot precipitation method. The chitosan encapsulated UCNTs show bright upconversion fluorescence upon excitation with 974 nm NIR region. The average crystallite size of UCNTs about 7.6 nm was achieved using chitosan mediated synthesis. The FTIR result confirms the chitosan coating over the LaF3:Yb,Er nanoparticles. Due to the surface modification using natural biopolymer chitosan, the as-prepared nanocrystals show excellent biocompatibility even at high dose at 200 µg/ml. To the best of our knowledge the presented work is the first report on in vitro analysis of chitosan conjugated LaF3:Yb,Er upconverting nanocrystals in human breast (MCF-7) cancer cells. These nanotransducers can be used as luminescent probes for bioimaging and deep tissue cancer therapeutic applications.

Synthesis of YF3: Yb, Er upconverting nanofluorophores using chitosan and their cytotoxicity in MCF-7 cells.

In this work, we described one pot hydrothermal synthesis of surface modified water soluble YF3: Yb, Er upconverting nanofluorophores (UCNFs) using natural biopolymer chitosan. The obtained nanocrystals have undergone X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), high resolution transmission electron microscopy (HRTEM) and photoluminescence (PL) studies. The nanoparticles possess uniform particle size distribution with average size about 27 nm. The cytotoxicity results revealed that the chitosan capped nanoparticles exhibit excellent biocompatibility in human breast cancer cells. In conclusion, the water soluble chitosan capped YF3: Yb, Er nanoparticles could be used as a potential candidate in bio-imaging and therapeutic applications.

From clusters to semiconductor nanostructures.

In the last two decades there has been tremendous interest in various aspects of nanoscience and nanotechnology. Now the subject has matured into an important field in the general area of science and technology that has been identified as one of the thrust areas. Nanoscience and nanotechnology is really an interdisciplinary and/or multidisciplinary subject. This review describes work on transition metal molecular level clusters. The clusters were fabricated by making very dilute solutions and also by doping them in lattices of alkali halides and alkali cyanides. Size dependence of the bandgap was shown for the first time by using site-selective dye laser spectroscopy, time resolved spectroscopy, optical absorption and molecular orbital calculations. A number of semiconductor nanostructures such as quantum wires, quantum wells, and coupled quantum wells, and many-body effects in nanostructures such as self-assembled quantum dots, exciton-phonon interactions, four wave mixing, polymer composites, metallic nanoparticles and metal oxides are discussed.

GaN nanostructure-based light emitting diodes and semiconductor lasers.

GaN and related materials have received a lot of attention because of their applications in a number of semiconductor devices such as LEDs, laser diodes, field effect transistors, photodetectors etc. An introduction to optical phenomena in semiconductors, light emission in p-n junctions, evolution of LED technology, bandgaps of various semiconductors that are suitable for the development of LEDs are discussed first. The detailed discussion on photoluminescence of GaN nanostructures is made, since this is crucial to develop optical devices. Fabrication technology of many nanostructures of GaN such as nanowires, nanorods, nanodots, nanoparticles, nanofilms and their luminescence properties are given. Then the optical processes including ultrafast phenomena, radiative, non-radiative recombination, quantum efficiency, lifetimes of excitons in InGaN quantum well are described. The LED structures based on InGaN that give various important colors of red, blue, green, and their design considerations to optimize the output were highlighted. The recent efforts in GaN technology are updated. Finally the present challenges and future directions in this field are also pointed out.

Template free synthesis of mesoporous TiO2 with high wall thickness and nanocrystalline framework.

A simple procedure to prepare nanocrystalline mesoporous titania (meso-TiO2) is reported without any templating agent and it possesses a high BET surface area and a large pore wall thickness (11.3 nm) than that of meso-TiO2 prepared by other methods. Nanocrystalline meso-TiO, also has been synthesized with hexadecylamine template for comparison through known procedure. The meso-TiO2 materials were characterized by X-ray diffraction, FT-IR, UV-Vis absorbance spectra, thermal analysis, SEM, HRTEM and textural properties through N2 adsorption-desorption isotherms. Spherical shape particles in a range of few hundred nanometers are obtained in the template free method. Above systematic characterization provides direct indications toward the mechanism of formation of meso-TiO2 in the template free method. A comparison of the physical and textural properties indicates a possibility of coarse-tuning of the textural characteristics of mesoporous TiO2 by adopting different preparation methods.