Anantharaman, M R; Sasidharan, Smitha; Haseena, V S; Narayanan, T N; Reena Mary, A P; Ajayan, P M; Jayesh, P; Anas, Aziz A; Rebeca, Aburto R; Mani, A S; Joy, P A(American Scientific Publishers, 2012)
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Abstract:
Multimodal imaging agents that combine magnetic
and fluorescent imaging capabilities are desirable
for the high spatial and temporal resolution. In the
present work, we report the synthesis of multifunctional
fluorescent ferrofluids using iron oxide as the
magnetic core and rhodamine B as fluorochrome
shell. The core–shell structure was designed in such
a way that fluorescence quenching due to the inner
magnetic core was minimized by an intermediate
layer of silica. The intermediate passive layer of silica
was realized by a novel method which involves the
esterification reaction between the epoxy group of
prehydrolysed 3-Glyidoxypropyltrimethoxysilane and
the surfactant over iron oxide. The as-synthesized
ferrofluids have a high saturation magnetization in
the range of 62–65 emu/g and were found to emit
light of wavelength 640 nm ( excitation = 446 nm).
Time resolved life time decay analysis showed a
bi-exponential decay pattern with an increase in the
decay life time in the presence of intermediate silica
layer. Cytotoxicity studies confirmed the cell viability
of these materials. The in vitro MRI imaging illustrated
a high contrast when these multimodal nano
probes were employed and the R2 relaxivity of these
∗Author to whom correspondence should be addressed.
Email: smissmis@gmail.com
sample was found to be 334 mM−1s−1 which reveals
its high potential as a T2 contrast enhancing agent