The PEG and PVA abundance on the surface of the PEGylated nanoparticle systems reveal some interesting information about the morphology and the composition of the nanoparticle surface. Interestingly, PEG cannot exclusively be found on the particle surface, which is observable for all PEGylated nanoparticle species. Comparing the PEG composition of the particle surface to the particle bulk, PEG abundances are only slightly increased on the particle surface, even though PEG itself is highly ZD 7288 and should therefore preferably appear at the interface to the aqueous surrounding of the PLGA nanoparticles. Considering the PVA abundance on the particle surface of PEGylated nanoparticle species, a remarkable effect can be observed. Even though the overexpression of PEG on the surface is lower than expected, there is a strong influence on the PVA abundance at the particle surface with increasing PEGylation degree of the particle species. This enhancing effect can be addressed to strong interactions between PEG and PVA, which both appear to be more hydrophilic polymers than PLGA. The surface of nanoparticles with the highest amount of PEG (15.0% PEG) consists of 33.6% PVA, whereas the surface of comparable, non-PEGylated PLGA nanoparticles (0% PEG) only consists of 7.5% PVA.