Altering model cell membranes by means of photoactivated organic functionalized gold nanorods

Abstract

A possible non-invasive photothermal therapy employs photothermal agents with high light-to-heat conversion efficiency. Gold nanorods (Au-NRs) can be applied as photothermal agents because of their optical properties and specific tumor-targeting capability. The potential therapeutic applications and toxicological effects of photothermal agents depend on the interaction of the Au-NRs with the cell membrane, the understanding of which is of great importance. Although studies in this area have been performed, the interactions between model cell membranes and photoactivated Au-NRs have not yet been described. In this study, we explain how local excitation of the Au-NRs caused a local temperature increase in their vicinity that affected the properties of a model membrane composed of dipalmitoylphosphatidylcholine (DPPC). Our results showed that the illumination of the Au-NRs changed the DPPC’s organization in the Langmuir monolayer. Upon photoactivation, the mutual distances between the DPPC molecules increased; however, the conformation of the lipid tails remained unchanged. Moreover, the illumination of the membrane at a surface pressure corresponding to that in a native cellular membrane caused a more stable and elastic behavior of the Langmuir monolayer. The results obtained corroborate the theory that photoactivation of Au-NRs influences the packing and phase behavior of mimetic cell membranes. In the long term, it may allow us to understand how the photoactivation of nanoparticles facilitates the transport of medicinal substances.