Mansi Chitkara

Photo-catalytic activity of Zn1-xMnxS nanocrystals synthesized by wet chemical technique

Polyvinyl pyrrolidone capped Zn1-xMnxS (0 ≤ x ≤ 0.1) nanocrystals have been synthesized using wet chemical co-precipitation method. Crystallographic and morphological characterization of the synthesized materials have been done using X-ray diffraction and transmission electron microscope. Crystallographic studies show the zinc blende crystals having average crystallite size approx. 3 nm, which is almost similar to the average particle size calculated from electron micrographs. Atomic absorption spectrometer has been used for qualitative and quantitative analysis of synthesized nanomaterials. Photo-catalytic activity has been studied using methylene blue dye as a test contaminant. Energy resolved luminescence spectra have been recorded for the detailed description of radiative and non-radiative recombination mechanisms. Photo-catalytic activity dependence on dopant concentration and luminescence quantum yield has been studied in detail.

Synthesis, characterisation and antimicrobial activity of manganese- and iron-doped zinc oxide nanoparticles

The present work reports study on antimicrobial activity of pure and doped ZnO nanocomposites. Polyvinyl pyrrolidone capped Mn- and Fe-doped ZnO nanocomposites were synthesised using simple chemical co-precipitation technique. The synthesised materials were characterised using transmission electron microscope (TEM), X-ray powder diffraction (XRD), energy dispersive X-ray fluorescence (EDXRF), Fourier transform infrared (FTIR) spectroscopy and ultraviolet (UV) visible spectroscopy. The XRD and TEM studies reveal that the synthesised ZnO nanocrystals have a hexagonal wurtzite structure with average crystalline size ∼7–14 nm. EDXRF and FTIR study confirmed the doping and the incorporation of impurity in ZnO nanostructure. The antimicrobial activities of nanoparticles (NPs) were studied against fungi, gram-positive and gram-negative bacteria using the standard disc diffusion method. The photocatalytic activities of prepared NPs were evaluated by degradation of methylene blue dye in aqueous solution under UV light irradiation. Experimental results demonstrated that ZnO NPs doped with 10% of Mn and Fe ions showed maximum antimicrobial and photodegradation efficiency in contrast with that of the 1% loading. The enhancement in antimicrobial effect and photocatalytic degradation is attributed to the generation of reactive oxygen species due to the synergistic effects of Mn and Fe loading.

Nanobiomaterials: Applications in biomedicine and biotechnology

Recently, drug delivery research has dominated in biotechnology and biomedicine. As per the need of the patients controlled drug delivery systems and targeted drug delivery release only the amount of drug required to cure the disease. However, for evolution of medicine, personalized treatments are keys to the future and require a combination of nanoscale processes with genetics, gene sequencing, molecular biology, and computational design. Currently, nanotechnology is an efficient tool to address many of the current challenges in biomedicine and biotechnology. The literature concerning nanoscale biomaterials reveals that it is biocompatible, non-toxic, non-immunogenic, and biodegradable. These nanobiomaterials help synthesizing smart drug delivery systems involving peptides, drug molecules, and other biomolecules for personalized therapies. Nanoscale molecular tools in nanobiomedicine are used for diagnostic purposes and improvement of human health. This chapter reviews nanoscale biomaterials for biomedical and biotechnological applications.

Structural, magnetic and dielectric properties of pure and nickel-doped barium nanohexaferrites synthesized using chemical co-precipitation technique

Abstract Nickel-doped barium nanohexaferrites with the chemical formula BaNixFe(12-x)O19 are prepared using the chemical co-precipitation technique. The calcination of the samples is done at 800°C for 4 h. In order to carry out the structural analysis that includes the crystallographic and the morphological investigations, X-ray diffraction and TEM are carried out to govern the phase, structure and the size of the crystal. By the use of Debye–Scherrer equation, the size of the crystallite is calculated to be in the range of 38–100 nm. TEM results reveal the magnetoplumbite structure of the hexaferrites. The M–H curve obtained using the Vibrating Sample Magnetometer computes the magnetic parameters like saturation magnetization, coercivity, remanence and verifies the behaviour of hexaferrites as hard magnetic materials. Further, the effect of variation in calcination temperature is also investigated on the values of magnetic parameters of hexaferrites. In order to carry out the investigations on the electrical properties of hexaferrites, the two-probe method and parallel plate capacitor set-up are used. The values of relative permittivity, dielectric loss and loss tangent are computed as a function of frequency. The values of DC electrical resistance for pure and nickel-doped barium nanohexaferrites are evaluated from the slope of I–V graphs.