“…In this regard, silica nanoparticles (SN) have attracted attention as carriers for drug delivery due to their properties, which include reduced toxicity, good biocompatibility, high surface area, easy functionalization, optical transparency, and low cost [ 56 , 57 ]. PS-loaded silica nanoparticles have been reported as promising singlet oxygen generator platforms, improving the photoactive drug delivery by enhancing PS poor solubility and selectivity for cancer cells [ 58 , 59 , 60 , 61 , 62 ]. The PS can be physically encapsulated or covalently attached to the internal or external surface of the silica nanoparticles [ 63 , 64 , 65 , 66 , 67 ].…”