Gold Nanoparticle-Mediated Depolarization of Membrane Potential is Dependent on Concentration and Tethering Distance from the Plasma Membrane

The photoactivation of plasma membrane-tethered gold nanoparticles (AuNPs) for the photothermally-driven depolarization of membrane potential has recently emerged as a new platform for the controlled actuation of electrically active cells. In this report, we characterize the relationship between AuNP concentration and AuNP-membrane separation distance on the efficiency of photoactivated plasma membrane depolarization. We show in differentiated rat pheochromocytoma (PC-12) cells that AuNPs capped with poly(ethylene glycol) (PEG)-cholesterol ligands localize to the plasma membrane and remain resident for up to 1 h. The efficiency of AuNP-mediated depolarization is directly dependent on the concentration of the NPs on the cell surface. We further show that the efficiency of AuNP-mediated photothermal depolarization of membrane potential is directly dependent on the tethering distance between the AuNP and the plasma membrane, which we control by iteratively tuning the length of the PEG linker. Importantly, th...