A longer treatment time (1 or 2 h) could not further increase the cellular uptake of FA–TiO2nanoparticles, as shown inFig. 4. However,
when CHO cells were treated with unmodified and FA-modified
TiO2nanoparticles for 30 min, there was no big differences between
the amounts of these two kinds of nanoparticles internalized into
cells