Biomedical subjects

Michael Rajamathi

Publications and source records attributed to Michael Rajamathi.

6 recordsLinked to original sources

PubMed2006

Layered double hydroxide-CdSe quantum dot composites through colloidal processing: effect of host matrix-nanoparticle interaction on optical behavior.

Layered double hydroxide (LDH)-monodispersed 4-nm CdSe nanoparticle composites were prepared through restacking of layers of colloidally dispersed delaminated LDH in the presence of CdSe nanoparticles in 1-butanol. The composites exhibit a blue shift for CdSe absorption, which increases with a decrease in nanoparticle content. The observed blue shift is due to the interaction of the quantum dots with the LDH layers, which leads to surface modification of the nanoparticles.

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PubMed2005

Surfactant intercalated alpha-hydroxides of cobalt and nickel and their delamination--restacking behavior in organic media.

Dodecyl sulfate and dodecylbenzene sulfonate intercalated alpha-hydroxides of nickel and cobalt were synthesized by ammonia precipitation. These solids delaminate to give a colloidal dispersion of layers in organic solvents such as 1-butanol. The dispersed layers could be reassembled either by evaporation of the colloid or by coagulation by the addition of a polar solvent.

Journal Article↗

PubMed2005

Effect of various factors influencing the delamination behavior of surfactant intercalated layered double hydroxides.

The delamination-restacking behavior of a number of layered double hydroxides (LDHs) differing in [M(II)]/[M(III)] ratio, constituent metal ions and intercalated surfactant anions in different organic solvents has been studied. Colloidal dispersion due to delamination and the stability of the colloid obtained have been found to be not affected much by the nature of the constituent metal ions but increase with increase in the size of the surfactant anion. LDHs with low [M(II)]/[M(III)] ratio delaminate better than the ones with high [M(II)]/[M(III)] ratio. Delamination is best in alcohols such as 1-butanol, 1-hexanol, 1-octanol and 1-decanol, while a little delamination occurs in nonpolar solvents such as hexane. In all the cases, the original layered solid could be obtained through restacking of layers from the colloidal dispersion.

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PubMed2005

Ferrimagnetic nanogranular Co3O4 through solvothermal decomposition of colloidally dispersed monolayers of alpha-cobalt hydroxide.

Co3O4 nanoparticles of 35 nm with a cauliflower-like morphology were obtained when a monolayer colloidal dispersion of dodecyl sulfate intercalated alpha-cobalt hydroxide in butanol was subjected to solvothermal hydrolytic decomposition. The nanogranular particles exhibit weakly ferromagnetic properties in contrast with both bulk and dispersed nanoparticulate Co3O4.

Journal Article↗

PubMed2005

Perpendicular magnetization in self-assembled films of citrate-capped gamma-Fe2O3 nanocrystals on Si(100) surfaces.

gamma-Fe2O3 nanocrystals capped with citrate and octylamine have been chemically prepared. The octylamine-capped nanocrystals exhibit a tendency to form ordered lattices. Films of nanocrystals of varying thickness (454, 720, and 1400 microg/cm2 in the case of citrate-capped nanocrystals and 300 microg/cm2 in the case of octylamine-capped nanocrystals) have been prepared on Si(100) substrates by drop casting and have been characterized by X-ray diffraction, scanning electron microscopy, and atomic force microscopy. Magnetic measurements have been carried out on the films as well as on nanocrystal powders. The films of citrate-capped gamma-Fe2O3 nanocrystals exhibit enhanced perpendicular magnetization, with the anisotropy depending on the film thickness.

Amines↗

PubMed2002

Hydrolysis and amine-capping in a glycol solvent as a route to soluble maghemite gamma-Fe2O3 nanoparticles.

The preparation of capped metal oxide nanoparticles through the hydrolysis of metal salts is made arduous by the difficulty of dissolving long organic chain capping agents in water; by performing the reaction in propylene glycol under reflux, instead of water, we are able to hydrolyse FeCl3 in the presence of n-octylamine to obtain (repeatedly) soluble, monodisperse approximately 5 nm gamma-Fe2O3 particles that display a tendency to aggregate into superlattices.

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