Novel photosensitizing nanoparticles for PDT and biosensing applications

Abstract Loading of photosensitizing dyes into polymer beads is a meaningful strategy to improve their performance in photodynamic therapies (PDTs) or in sensing applications. In this work we describe a straightforward method for doping 390 nm and 26 nm carboxylated polystyrene nanoparticles with the hydrophobic tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) (RD3) complex. This Ru(II) photosensitizer (PS) efficiently generates singlet molecular oxygen (1O2) upon illumination with blue-green light and displays residual μs-lived red luminescence. its entrapment in the nanoparticles facilitates its use in water and opens up the possibility for bioconjugation without functionalization of the PS dye. After optimization of the doping protocol, we have carried out a photophysical (absorption, steady-state and time-resolved luminescence) and photochemical characterization of the photoactive nanoparticles by investigating the effect of the O2 concentration in water on the RD3 emission features. No leaching of the dye from the nanoparticles was observed. The 1O2 production quantum yield of the encapsulated PS (ΦΔ = 0.50), measured by monitoring the 1O2 emission decay at 1270 nm in D2O, is comparable to that of the free Ru(II) dye in the same solvent (0.49).