Ankita Sharma

Green synthesis of gold nanoparticles using extracts of Artocarpus Lakoocha fruit and its leaves, and Eriobotrya Japonica leaves

Gold nanoparticles (AuNPs) synthesis is demonstrated successfully using fresh young leaves of Artocarpus Lakoocha (A. Lakoocha), fruit pulp of A. Lakoocha and loquat (Eriobotrya Japonica) leaves. We have also compared green synthesis with chemical assisted tri-n-octyl-phosphine (TOP) stabilized gold nanoparticles. Samples were characterized with transmission electron microscopy (TEM), Fourier transform infrared spectroscopy and UV-Visible spectroscopy. TEM images have shown that the average size of the particles is 15.06, 36.8 and 25.08 nm for A. Lakoocha fruits, A. Lakoocha leaves and loquat leaves assisted gold nanoparticles, respectively. Hydrogen tetrachloroaurate is reduced and AuNPs are stabilized by phenols, hydroxyls and carboxyls groups such as terpenoids, flavonoids, tannins etc, present in young leaves and fruit extracts. It was observed that green synthesis using botanical extracts is a cost effective and non- toxic way for nanoparticle preparation.

Morphology and optical study of dye-doped TiO2-SiO2 thin films

In the present work, we have prepared functional dye doped TiO2-SiO2 thin films by vertical sedimentation technique. Thin film samples are annealed at different temperature from 50oC to 850oC. Morphology and chemical bonding information is analysed using atomic force microscopy (AFM), and Fourier transform infrared spectroscopy (FTIR) respectively. Optical properties are characterized by using UV-visible spectroscopy. Effect of annealing temperature on the photonic forbidden band gap is also presented. The experimental measured values are compared with theoretical estimated results.

Spectroscopic investigation of interaction between bovine gamma globulin and gold nanoparticles

The interaction of Citrate-capped gold nanoparticles (AuNPs) with Bovine gamma globulin (BGG) was studied using Fourier transform infrared (FTIR), UV-Visible and Fluorescence spectroscopy. FTIR has confirmed the conjugation of AuNPs and BGG. Fluorescence quenching of tryptophan has confirmed the strong interaction between BGG and AuNPs. UV-Visible and Fluorescence spectroscopy have investigated the extent of interaction by determining the binding constants. Binding constants evaluated from UV-Visible and Fluorescence data are in good agreement with each other. An independent class of binding site on BGG for AuNPs has been predicted, where AuNPs interact with a highly solvent accessible tryptophan residue.

Planar Alignment of Liquid Crystal in Silica-Based Photonic Structure

The planar orientation of Nematic Liquid crystal (NLC) molecules on the surface of (111) plane of silica photonic structure has been investigated. Nano voids of silica photonic crystal has been obtained by vertical deposition technique on indium tin oxide-coated substrate. NLC was infiltrated into the channels of voids in the photonic structures. Optical texture studies under with and without electric field were applied to investigate the NLC orientation. It is observed that NLC molecules in the nano voids of silica photonic structure exhibit an excellent planar alignment. This obtained hybrid composite structure on infiltration of NLC will be a promising candidate for electro optic applications.

Tuning the surface plasmon resonance of core-shell particles

Gold coated silica core-shell microspheres were synthesized using chemical reduction growth method. Coreshell microspheres were characterized using Scanning electron microscopy (SEM) and Ultraviolet-Visible (UV-Visible) spectroscopy. SEM images show that the surface of microspheres becomes rough which reflects the presence of gold nanoparticles (AuNPs) after coating. UV-Visible spectroscopy shows that the surface plasmon resonance peak undergoes red shift with the shell growth. Core-shell particles were also investigated for different gold concentrations.

Gold nanoparticles-globulin protein bio-conjugates: A spectroscopic study

Interaction between gold nanoparticles (AuNPs) of different sizes with Bovine gamma globulin (BGG) protein, in the form of bio-conjugates, was studied spectroscopically. Optical properties studied using UV-Visible spectra revealed a change in the environment of protein as well as AuNPs. Quenching of fluorescence of tryptophan residues was observed in case of bio-conjugates which confirmed a strong interaction between protein and AuNPs. Obtained values of binding constant inferred the effect of size and surface of nanoparticles on protein’s structure.