All nanoparticles are purified by repeated centrifugation, decantation, and redispersion in npropanol, as reported previously. When comparing the drug-loaded nanoparticles without Nmethylimidazole (P1, P2, and P6) with the unloaded Ref particles, we see that incorporation of the prodrug leads to less spherical and uniform particles than the Ref particles (see Figure and Figure ). We suspect that this is due to steric hindrance of the larger prodrug monomer compared to the smaller N-methylimidazole. and Figure ). When comparing the size of the drug-loaded nanoparticles in the SEM images, we recognize a reduction in diameter d from approximately 122 nm to 40 nm when reducing the amount of the prodrug monomer 2 from 50 to 37.5 and down to 25 mol% (see P1, P2, P6 in Table and Figure ). The particle size depends most strongly on the molar percentage of compound 2. A variation of the other two co-monomers at constant concentration of 2 does not lead to a substantial change in d (see P2 -P5 in Figures and).