Iron Oxide Nanoparticles and Derivatives for Biomedical Imaging and Application in Cancer Diagnosis and Therapy - Bioanalysis Advanced Materials Methods and Devices - page 8

Fig. 1.3 Schematic representation of the synthesis of a SERS and MRI active contrast agent,
AuMN-DTTC. The process involves sequential reduction of gold onto the parental MN, expansion
of the gold seeds, and incorporation of DTTC and PEG onto the gold seeds

Yigit et al. synthesized MRI-active superparamagnetic iron oxide nanoparticles,
stably complexed with gold nanoparticles (AuMN-DTTC). The gold nanoparticles
serve as a template for a Raman active dye molecule to generate a surface-enhanced
Raman scattering (SERS) effect (Fig. 1.3 ). The synthesized probe was tested for its
utility as a T2 weighted MRI contrast agent and a SERS active contrast agent [ 35 ].
In vivo MR imaging of mice injected intramuscularly with the probe revealed
that AuMN-DTTC indeed could be detected by MRI. SERS measurements using a
portable Raman system showed a distinct SERS signal associated with the injection
site [ 35 ].
This agent presents novel opportunities for noninvasive imaging. By combining
the two modalities, it could allow the high-resolution, high-sensitivity in vivo
detection of biological processes.

1.5 siRNA Therapeutics with Iron Oxide Nanoparticles

RNA interference is a powerful cellular process, which has been explored exten-
sively for therapeutic applications. Administration of synthetic small interfering
RNA molecules (siRNAs) into cellular compartments for degrading disease-
causing mRNAs has shown dramatic therapeutic effects. Due to their initial success
and future potential there are several siRNA-based preclinical and clinical trials for
various diseases [ 15 ]. The biggest hurdles facing in vivo siRNA therapy are
protection from nuclease degradation of the siRNA molecules in the circulation,
their delivery to tissues of interest and intercellular uptake. Nanoparticles serve as a
suitable platform to address these questions. Bioconjugation of siRNA molecules to
nanoparticles not only results in successful delivery of the siRNA payload into the
cellular environment but also protects them from nuclease degradation [ 7 ].
Recently there has been a successful phase I clinical trial of a targeted
siRNA-nanoparticle conjugate for targeting solid tumors [ 5 ]. In addition to