1 research outputs found
Synthesis and Preliminary <i>in Vivo</i> Evaluation of Well-Dispersed Biomimetic Nanocrystalline Apatites Labeled with Positron Emission Tomographic Imaging Agents
In
recent years, biomimetic synthetic apatite nanoparticles (AP-NPs),
having chemical similarity with the mineral phase of bone, have attracted
a great interest in nanomedicine as potential drug carriers. To evaluate
the therapeutic perspectives of AP-NPs through the mechanisms of action
and organs they interact with, the noninvasive monitoring of their <i>in vivo</i> behavior is of paramount importance. To this aim,
here the feasibility to radiolabel AP-NPs (ānakedā and
surface-modified with citrate to reduce their aggregation) with two
positron emission tomographic (PET) imaging agents ([<sup>18</sup>F]ĀNaF and <sup>68</sup>Ga-NO2AP<sup>BP</sup>) was investigated. [<sup>18</sup>F]ĀNaF was used for the direct incorporation of the radioisotope
into the crystal lattice, while the labeling by surface functionalization
was accomplished by using <sup>68</sup>Ga-NO2AP<sup>BP</sup> (a new
radio-metal chelating agent). The labeling results with both tracers
were fast, straightforward, and reproducible. AP-NPs demonstrated
excellent ability to bind relevant quantities of both radiotracers
and good <i>in vitro</i> stability in clinically relevant
media after the labeling. <i>In vivo</i> PET studies in
healthy Wistar rats established that the radiolabeled AP-NPs gave
significant PET signals and they were stable over the investigated
time (90 min) since any tracer desorption was detected. These preliminary <i>in vivo</i> studies furthermore showed a clear ability of citrated
versus naked AP-NPs to accumulate in different organs. Interestingly,
contrary to naked AP-NPs, citrated ones, which unveiled higher colloidal
stability in aqueous suspensions, were able to escape the first physiological
filter, i.e., the lungs, being then accumulated in the liver and,
to a lesser extent, in the spleen. The results of this work, along
with the fact that AP-NPs can be also functionalized with targeting
ligands, with therapeutic agents, and also with metals for a combination
of different imaging modalities, make AP-NPs very encouraging materials
for further investigations as theranostic agents in nanomedicine