The concentration of oxygen and its rate of consumption are important factors playing a role in PDT and radiotherapy.
One of the methods for measuring the tissular oxygen partial pressure (pO2) is based on the use of luminophores
presenting an oxygen-dependent quenching of their phosphorescence. The time-resolved luminescence spectroscopy of
palladium (PdTCPP) or ruthenium (RuDPP) porphyrin complexes is used for this purpose. Unfortunately, these
porphyrin derivatives are phototoxic and leak rapidly out of the blood vessels, making them unsuitable for measuring
tissular and or intravascular pO2.
Therefore, this research aimed at developing and testing new biocompatible, non-phototoxic oxygen sensors based on
palladium complexes incorporated into oxygen permeable, polysaccharide-based nanoparticles appropriate for noninvasive
in situ and in vivo measurements of the pO2.
In vitro studies, performed with an optical fiber-based time-resolved spectrophotometer, showed that the incorporation of
such pO2 probes in nanovectors reduces their sensitivity to oxygen as well as their photobleaching by less than one order
However, in vivo biocompatibility studies performed on the chick's embryo chorioallantoic membrane (CAM) model
demonstrated that the luminescence of those oxygen probes tends to be heterogeneously distributed within the
vasculature. In addition, these probes induce a 'clumping tendency', resulting in a more or less decreased viability of the