Photodynamic
therapy is a medical technique, which is gaining increasing attention
to treat various types of cancer. Among the investigated classes of
photosensitizers, the use of Ru(II) polypyridine complexes is gaining
momentum. However, the currently investigated compounds generally show
poor cancer cell selectivity. As a consequence, high drug doses are
needed, which can cause side effects. To overcome this limitation, there
is a need for the development of a suitable drug delivery system to
increase the amount of PS delivered to the tumor. Herein, we report on
the encapsulation of a promising Ru(II) polypyridyl complex into
polymeric nanoparticles with terminal biotin groups. Thanks to this
design, the particles showed much higher selectivity for cancer cells in
comparison to non-cancerous cells in a 2D monolayer and 3D
multicellular tumor spheroid model. As a highlight, upon intravenous
injection of an identical amount of the Ru(II) polypyridine complex, an improved accumulation inside an adenocarcinomic human alveolar basal epithelial tumor
of a mouse by a factor of 8.7 compared to the Ru complex itself was
determined. The nanoparticles were found to have a high phototoxic
effect upon 1-photon (500 nm) or 2-photon (800 nm) excitation with an
eradication of an adenocarcinomic human alveolar basal epithelial tumor inside a mouse. Overall, this work describes, to the best of our knowledge, the first <i>in vivo</i>
study demonstrating the cancer cell selectivity of a very promising
Ru(II)-based PDT photosensitizer encapsulated into polymeric
nanoparticles with terminal biotin groups.
