Electrical Stimulation Promotes Endocytosis of Magnetic Nanoparticles by Cancer Cells

Nanomaterials are increasingly used in biomedical imaging and cancer therapy, and how to improve the endocytosis of nanomaterials by cells is a key issue. The application of alternating current (AC) electrical stimulation to osteosarcoma cells (MG-63) here can increase the cellular endocytosis of Fe₃O₄ nanoparticles (diameter: 50 nm) by 52.46% via macropinocytosis. This can be ascribed to the decrease in F-actin content and the increase in intracellular Ca²⁺ concentration. Transmission electron microscope, immunofluorescence staining, western blot, flow cytometry, and inductively coupled plasma emission spectrometer analyses support this interpretation. The application of electrical stimulation decreases the cell viability in magnetic hyperthermia by 47.6% and increases the signal intensity of magnetic resonance imaging by 29%. Similar enhanced endocytosis is observed for breast cancer cells (MCF-7), glioblastoma cells (U-87 MG), melanoma cells (A-375), and bladder cancer cells (TCCSUP), and also for Fe₃O₄ nanoparticles with the diameters of 20 and 100 nm, and Zn_0.54Co_0.46Cr_0.65Fe_1.35O₄ nanoparticles with the diameter of 70 nm. It seems the electrical stimulation has the potential to improve the diagnostic and therapeutic effects of magnetic nanoparticles by promoting endocytosis.