Figure 1.

TEM images show cellular uptake of magnetic nanoparticles. A1 MNP incubated with SH-SY5Y cells, A2 MNP incubated with RAW 264.7 cells, B1 MNP-PEI incubated with SH-SY5Y cells, B2 MNP-PEI incubated with RAW 264.7 cells, C1 MNP-PEI-PEG incubated with SH-SY5Y cells and C2 MNP-PEI-PEG incubated with RAW 264.7 cells. Samples were incubated with cells at 6.25 μg mL^-1 for 24 h, and internalisation of nanoparticles was analysed by TEM as described in the 'Methods' section.