Delivery of Artificial Materials Into Adhesive Cells by Electromechanical Poration

In order to transmit information from inside cells or living organisms, it is important to embed sensors or artificial objects inside cells or tissues rather than placing them on the surface of the tissue, to accurately extract internal information. However, sensors and artificial objects embedded in living tissues or cells have limitations because of their impact on cell viability and transfection efficiency. Electromechanical poration (EMP) is a promising method for introducing micrometer-scale materials into living cells. Unlike conventional electroporation, EMP combines high-voltage electrical stimulation with mechanical stimulation generated by the volume change of microbubbles at the electrode surface. These microbubbles create transient mechanical stress that facilitates membrane permeabilization while potentially reducing cellular damage. Using EMP, we investigated the delivery of polystyrene beads and silver-coated DNA-functionalized gold nanoparticle crystals (Au@Ag NPCs) into HeLa cells. Polystyrene beads up to 3 µm in diameter were successfully introduced, whereas delivery efficiency significantly decreased for beads larger than 6 µm, indicating a size-dependent limitation of cellular uptake. Importantly, cell viability remained high even 4 hours after bead delivery, regardless of bead size, indicating minimal cytotoxicity. In addition, Au@Ag NPCs (1–1.5 µm) were successfully delivered with a delivery rate of 0.5%, without inducing significant cytotoxicity over 1–4 days. These results demonstrated that EMP enabled efficient intracellular delivery of micrometer-scale materials while preserving cell viability, supporting its potential for intracellular sensing applications.