title: Morphological effect of oscillating magnetic nanoparticles in killing tumor cells.
abstract: Forced oscillation of spherical and rod-shaped iron oxide magnetic nanoparticles (MNPs) via low-power and low-frequency alternating magnetic field (AMF) was firstly used to kill cancer cells in vitro. After being loaded by human cervical cancer cells line (HeLa) and then exposed to a 35-kHz AMF, MNPs mechanically damaged cell membranes and cytoplasm, decreasing the cell viability. It was found that the concentration and morphology of the MNPs significantly influenced the cell-killing efficiency of oscillating MNPs. In this preliminary study, when HeLa cells were pre-incubated with 100 μg/mL rod-shaped MNPs (rMNP, length of 200 ± 50 nm and diameter of 50 to 120 nm) for 20 h, MTT assay proved that the cell viability decreased by 30.9% after being exposed to AMF for 2 h, while the cell viability decreased by 11.7% if spherical MNPs (sMNP, diameter of 200 ± 50 nm) were used for investigation. Furthermore, the morphological effect of MNPs on cell viability was confirmed by trypan blue assay: 39.5% rMNP-loaded cells and 15.1% sMNP-loaded cells were stained after being exposed to AMF for 2 h. It was also interesting to find that killing tumor cells at either higher (500 μg/mL) or lower (20 μg/mL) concentration of MNPs was less efficient than that achieved at 100 μg/mL concentration. In conclusion, the relatively asymmetric morphological rod-shaped MNPs can kill cancer cells more effectively than spherical MNPs when being exposed to AMF by virtue of their mechanical oscillations.
authors.affiliation: Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China ; Shanghai Institute of Medical Imaging, Shanghai 200032, People's Republic of China.
authors.forename: Dengfeng
authors.initials: D
authors.lastname: Cheng
authors.affiliation: Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China ; Shanghai Institute of Medical Imaging, Shanghai 200032, People's Republic of China.
authors.forename: Xiao
authors.initials: X
authors.lastname: Li
authors.affiliation: Shanghai Institute of Applied Physics, Chinese Academy of Sciences, Shanghai 201800, People's Republic of China.
authors.forename: Guoxin
authors.initials: G
authors.lastname: Zhang
authors.affiliation: Department of Nuclear Medicine, Zhongshan Hospital, Fudan University, Shanghai 200032, People's Republic of China ; Shanghai Institute of Medical Imaging, Shanghai 200032, People's Republic of China.
authors.forename: Hongcheng
authors.initials: H
authors.lastname: Shi
keywords: Alternating magnetic field; Cell viability; Forced oscillation; Magnetic nanoparticles; Mechanical damage; Morphological effect