Disclosed are nanovectors of formula (I) that can be used simultaneously for the targeting, imaging and treatment, by photodynamic therapy, of cancer cells, and to biodegradable silicon nanoparticles containing a variety of photosensitizing molecules, in particular porphyrins, capable of targeting diseased cells and inducing cell death by excitation in the near-infrared region (>600 nm) in monophotonic and biphotonic modes. In formula (I), (AA) is a porous silicon nanoparticle.