Showing papers by "Thalappil Pradeep published in 2006"

Investigations of the antibacterial properties of ciprofloxacin@SiO2

Abstract: The antibacterial activity of ciprofloxacin-encapsulated silica nanoshells synthesized from gold@silica core-shell nanoparticles has been investigated. The minimum inhibitory concentration of the material was found using the agar dilution method, and it showed better antibacterial activity compared to free ciprofloxacin in the case of Escherichia coli DH5, whereas the same activity was found for Lactococcus lactis MG 1363. Hydrophobicity measurements carried out in an octanol-water mixture suggested that ciprofloxacin@SiO2 is distributed almost equally in the aqueous and nonaqueous phases. The kinetics of the uptake of ciprofloxacin@SiO2 was compared with that of free ciprofloxacin. Fluorescence imaging studies carried out using fluorescein isothiocyanate@SiO2 showed that the nanoshells enter the bacterial cell. The uptake of silica shells has been probed by transmission electron microscopy also.

Societal implications of nanoscience and nanotechnology in developing countries

Abstract: The historically unprecedented developments of nanoscience and nanotechnology, in view of their phenomenal expansion and growth, in conjunction with their convergence with information science and molecular biology, confront our society and natural environment with new challenges. Technological revolutions have shown that discoveries at the frontiers of science have the potential to pave the way for radically innovative and integrated approaches, providing new solutions for some of the most pressing problems. In order to enable decision-makers to respond to what is best for people at large, the societal implications of the newly emerging fields need to be known and understood. Nanotechnology, unlike any other technology, can find applications in virtually all areas of human life. In spite of being an infant at its evolution, some of the known issues related to nanotechnology suggest a wide spectrum of potential societal impacts. The current public nano-discourse provides sociology with a unique opportunity to switch from a merely passive, observational role to an active participating one, especially where the key players involved meet to find joint and concerted solutions for development.

Polymerization of benzylthiocyanate on silver nanoparticles and the formation of polymer coated nanoparticles

Abstract: Polymerization of benzylthiocyanate on silver nanoparticles produces organic shell covered nanoparticles with controllable thickness in a one-pot process. Gram scale quantities of core–shell materials have been synthesized by this method. The methodology involves the addition of the precursor into Ag–citrate solution and the shell nucleates over a period of three weeks with complete precipitation of the core–shell material which can be dispersed subsequently in organic solvents. The material has been characterized using transmission electron microscopy, X-ray diffraction, FT-IR, laser desorption mass spectrometry, thermogravimetry, surface enhanced resonance Raman spectroscopy (SERRS) and Raman imaging. A typical composite material consists of a silver core of 40 nm diameter coated with a polymeric shell of 8 nm thickness. The polymer exhibits characteristic features in mass spectrometry and vibrational spectroscopy. The core–shell structure of nanoparticles is imaged for the first time using the Raman intensity of the shell. Proton assisted polymerization of benzylthiocyanate occurs on the silver surface, leading to a linear chain which subsequently deposits on the nanoparticle surface resulting in the core–shell structure.

Aniline incorporated silica nanobubbles

Abstract: We report the synthesis of stearate functionalized nanobubbles of SiO 2 with a few aniline molecules inside, represented as C 6 H 5 NH 2 @SiO 2 @stearate, exhibiting fluorescence with red-shifted emission. Stearic acid functionalization allows the materials to be handled just as free molecules, for dissolution, precipitation, storage etc. The methodology adopted involves adsorption of aniline on the surface of gold nanoparticles with subsequent growth of a silica shell through monolayers, followed by the selective removal of the metal core either using sodium cyanide or by a new reaction involving halocarbons. The material is stable and can be stored for extended periods without loss of fluorescence. Spectroscopic and voltammetric properties of the system were studied in order to understand the interaction of aniline with the shell as well as the monolayer, whilst transmission electron microscopy has been used to study the silica shell.