We have recently reported on the preparation of iron oxide MNPs
and their surface coatings with tetraethoxysilane (TEOS) and
mercaptopropyl t rimethoxysilane (MPTMS) [9]. One drawback with the
previously used co- precipitation method for preparing the MNPs [9] is
the formation of aggregates in the product, which may limit some of the
biomedical applications. In the present study, we have attempted to
overcome this problem by modifying the MNP preparation procedure. In
the previous study [9], it was also found that different coatings provided
different extents of thermal protection to the MNPs. Further study of the
coating of MNPs with different silane coupling agents (SCAs) should
provide more information about the effects of these coatings and thus
extend their usefulnes s. For example, some biomedical applications of
MNPs require the ability to achieve a good disper sion in liquids. MNP
surface treatment s investigated in this study include the silica, silyl and
aminopropyl silyl coatings. The coated particles have been characterized
by transmission electron microscope (TEM), energy dispersive x- ray (EDX)
spectroscopy, Infrared (IR) and Raman spectroscopy, and thermal
gravimet ric analysis (TGA). The effects of thermal annealing and laser
irradiation on the uncoated and coated MNPs have also been studied by
using vibrational spectroscopy.