Magnet effect on L-SPIOs and L-SPIO-loaded cancer cells. (A) L-SPIOs in water were placed on the magnetic stand (left); HeLa cells treated with L-SPIOs (1 nmole/ml) for 12 h were on the right. Arrows indicate the position of L-SPIO nanoparticles or the L-SPIO-loaded cells. (B) Long-term viability of L-SPIO-loaded cells. HeLa cells were first seeded in a 24-well plate (5 × 104/well) overnight and treated with 1 nmole/well of L-SPIOs for 12 h in 10% FBS-DMEM. After different time periods of culture, cells were washed, trypsinized and counted with a hemocytometer. (C) Magnetic properties of L-SPIO-loaded cells. HeLa and PC-3 cells were treated with the above L-SPIOs for 12 h in 10% FBS-DMEM and harvested at different time points. L-SPIO-positive cells were separated by a magnet stand and counted with a hemocytometer. All experiments were performed in triplicate. Results are mean ± SEM (n = 3).