| Abstract | Wereport the synthesis, characterization and optical properties of “anionic” drug-based organic nanoparticles. Aqueous-phase ion association between piroxicam (PX) anion and lipophilic phosphazenium cation such as tetrakis[tris(dimethylamino)phosphoranylideneamino]phosphonium (PHS), in the presence of polyvinylpyrrolidone (PVP), produces PX nanoparticles of 200–400nm in diameter. The stability of the nanoparticles is dependent on the molar ratio () of the loaded cation to the drug anion, giving an appropriate synthetic condition of = 1.5. The PX nanoparticles exhibit an enhanced emission with a bathochromic shift compared to that of the PX monomer in water, but their absorption properties do not change. The emission enhancement is due to the effect of immobilization of PX in the hydrophobic solid-state matrices. |