Open AccessSynergetic effect of size and morphology of cobalt ferrite nanoparticles on proton relaxivity
Author(s) -
N Venkatesha,
Srivastava Chandan,
Hegde Veena
Publication year - 2014
Publication title -
iet nanobiotechnology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.366
H-Index - 38
eISSN - 1751-875X
pISSN - 1751-8741
DOI - 10.1049/iet-nbt.2013.0009
Subject(s) - superparamagnetism , particle size , materials science , nanoparticle , magnetization , transmission electron microscopy , nuclear magnetic resonance , cobalt , particle (ecology) , analytical chemistry (journal) , saturation (graph theory) , nanotechnology , chemical engineering , chemistry , magnetic field , metallurgy , chromatography , oceanography , physics , quantum mechanics , geology , engineering , mathematics , combinatorics
Cobalt ferrite nanoparticles with average sizes of 14, 9 and 6 nm were synthesised by the chemical co‐precipitation technique. Average particle sizes were varied by changing the chitosan surfactant to precursor molar ratio in the reaction mixture. Transmission electron microscopy images revealed a faceted and irregular morphology for the as‐synthesised nanoparticles. Magnetic measurements revealed a ferromagnetic nature for the 14 and 9 nm particles and a superparamagnetic nature for the 6 nm particles. An increase in saturation magnetisation with increasing particle size was noted. Relaxivity measurements were carried out to determine T 2 value as a function of particle size using nuclear magnetic resonance measurements. The relaxivity coefficient increased with decrease in particle size and decrease in the saturation magnetisation value. The observed trend in the change of relaxivity value with particle size was attributed to the faceted nature of as‐synthesised nanoparticles. Faceted morphology results in the creation of high gradient of magnetic field in the regions adjacent to the facet edges increasing the relaxivity value. The effect of edges in increasing the relaxivity value increases with decrease in the particle size because of an increase in the total number of edges per particle dispersion.