Background and Objective: Nanoparticles have special properties,
such as higher surface-to-volume ratio and higher reactivity, which increases
cell penetrability and enhance their applicability in the field of
medicine, especially in the case where other drugs are ineffective. Calcium
phosphate nanoparticles (CPNP) and their encapsulation with therapeutic
and/or diagnostic agents is such an agent synthesized. However, there are
concerns related to the colloidal stability of these nanoparticles, which are
reflected in their tendency to form aggregates in the physiological milieu.
Therefore, successful translation of these nanoparticles from laboratory to
the clinic requires studies of biodistribution and biocompatibility of
nanoparticles for in vivo biomedical applications.
Method: Calcium phosphate nanoparticles synthesized and were tagged with a fluorophore
and surface stabilized with trisilanol for stable aqueous dispersion. The in vivo biodistribution
and sub-acute toxicological studies were done for orally-administered calcium phosphate
Results: The biodistribution studies indicated that these nanoparticles were not prone to rapid
degradation or excretion in the body, were long-circulating, and could appreciably permeate
to the brain. Body/organ weight and biochemical analyses did not reveal much difference between
nanoparticle-administered and saline-administered (control) groups. Finally, histopathological
analyses of major organs such as liver, lungs, heart, stomach and kidney, did not
reveal significant abnormalities in the treatment groups.
Conclusion: Thus, it is evident from these sub-acute toxicity studies that the nanoparticles
appear to be non-toxic to rats following oral administration. These observations can have significant
implications in calcium-phosphate nanoparticle-mediated non-toxic drug delivery to
target organs, such as brain, via non-invasive, oral route.