The paper is focused on the formation of hydroxyapatite nanoparticles (HAp) in polyelectrolyte-modified microemulsions, in a microemulsion template phase consisting of cyclohexane, water, cationic surfactant and cosurfactant, in the presence of Na-polyacrylate (PAA) as an anionic polyelectrolyte. It is shown that PAA, can be incorporated into the individual inverse microemulsion droplets. The m...