Chemistry Reference
In-Depth Information
3+
3+
nanoparticles were synthesized with NaGdF
: Er
, Yb
/NaGdF
,
4
4
3+
where the Gd
ions in the host matrix act as an MRI contrast agent
[49].
3.5.4
Multifunctional Nanoparticles
Upconversion nanoparticles have been shown to be excellent
fluorescent labels. They have also been shown to achieve other
functions such as delivery of biomolecules. Nanoparticle-based
delivery systems are widely used. They have numerous advantages
since these upconversion nanoparticles can be biofunctionalized
coated with porous materials, which can be utilized for the delivery
of various therapeutic molecules, enabling simultaneous imaging
and therapy. This will be very important in the treatment of various
diseases.
A few examples showing the multifunctionality of these
nanoparticles are elaborated here. Various reports have shown
the supremacy of these nanoparticles in photodynamic therapy.
Photosensitizers such as zinc phthalocyanine or porphyrin were
loaded onto the upconversion nanoparticles and delivered specifically
to cancer cells through targeting agents. The photosensitizers
produced singlet oxygen upon NIR activation. NIR activation
produces upconversion fluorescence, which further activates the
photosensitizer and ultimately causes cell death [50-52]. They can
be simultaneously used for the detection and imaging of tumors.
Multifunctional upconversion nanoparticles were also used for the
delivery and tracking of siRNA to cells. The siRNA was attached
to the silica coating on the nanoparticles, and the upconversion
fluorescence was used to monitor the uptake. Upconversion FRET
was used to study the release of siRNA after entering into the cells
[34, 39]. Thus these particles show good multifunctionality and can
be used especially for simultaneous delivery and imaging.
3.6
Summary and Outlook
This chapter gives an overview of the different types of nanomaterials
synthesized from Ianthanides, their synthesis methods and surface
modifications, which are done before using them for fluorescence
imaging. Lanthanide chelates and rare earth downconversion
