Figure 1.

(A) Transmission Electron Microscope (TEM) image of aspirin nanoparticles precipitated on a carbon grid. The dark particles in the image range in size between 50 and 200 nm. The particles appear as individual particles or clusters of small particles. The black dots are the crystals of aspirin (separate or in clusters). The gray dots are particles that are not in focus in the image or polymer aggregates (the stabilizing excipients: polyvinylpyrrolidone K-30 and hydroxylpropyl methylcellulose). (B) Transmission Electron Microscope image of Ibuprofen nanoparticles precipitated on a carbon grid. Ibuprofen particles are less dense and therefore appear less dark than aspirin in the image range in size between 30 and 200 nm. The particles appear as individual particles or clusters of small particles. Ibuprofen particles are gray as they are more transparent to the electron beam. The particles that are not in focus are either more transparent or blending in the background.