Mechanism of plasmon-driven molecular jackhammers in mechanical opening and disassembly of membranes†

Abstract

Plasmon-driven molecular jackhammers (MJHs) are a type of molecular machine that converts photon energy into mechanical energy. Upon insertion into lipid bilayers followed by near-infrared light activation, plasmon-driven MJH mechanically open cellular membranes through a process that is not inhibited by reactive oxygen species (ROS) inhibitors and does not induce thermal heating. The molecular mechanism by which the plasmon-driven MJH open and disassemble cellular membranes has not hitherto been established. Herein, we differentiate the mechanical mechanism in MJHs from the ROS-mediated chemical effects in photodynamic therapy or thermal effects in photothermal therapy. We further present a detailed molecular mechanism for the plasmon-driven MJH disassembly of lipid bilayers. The mechanical studies on plasmon-driven MJH disassembly processes on artificial lipid bilayers were done using ROS-unreactive saturated phytanoyl phospholipids. We were able to capture in real-time the lipid bilayer disassembly by MJHs using fluorescence confocal microscopy on saturated phospholipids in giant unilamellar vesicles.