In order to synthesize PEG-g-silica NPs, in which PEG was used as the silane molecule modifier, the PEG/TEOS molar ratio
of 4/1 was utilized. In this regard, PEG was added dropwise into the reaction mixture, after the primary particles appeared in
the reaction mixture (about 5 min after adding NH4OH and H2O). Afterwards, the mixture was stirred vigorously for about
1 h and then separated, washed and dried according to the previously described procedure.