Fig. 3 displays TEM images of unmodified and folic acid-modified TiO2. These pictures indicate that all the TiO2 particles were in the nano-sized range. When the FA-to-TiO2 mass ratio was 0.5, particle size was not changed by the folic acid modification. The average particle size remained at ca. 30 nm. When the FA-to-TiO2 ratio increased to 5, however, the particle size increased very slightly and most importantly particles became slightly foggy due to the presence of folic acid