Interactions of curcumin-coated silver nanoparticles with sparsely tethered bilayer membranes containing an ion-gate-forming peptide.

Understanding nanoparticle-membrane interactions is important for assessing nanotoxicity and drug delivery mechanisms. This work uses electrochemical analysis to investigate how curcumin-coated silver nanoparticles influence the biophysical properties of a gold-supported sparsely tethered Bilayer Lipid Membrane (stBLM). By monitoring gramicidin-mediated ion flux, we show that the addition of curcumin and its curcumin-coated silver nanoparticles increases the membrane ionic conductivity. A key finding is the chloride-dependent translocation of silver: at high chloride concentrations, the appearance of an Ag+/Ag redox signal indicates that silver species or derived electroactive ions penetrate the phospholipid bilayer. This process is likely driven either by the formation of neutral, passive, permeating sub-nanometer AgCl nanocrystals or by localised passive diffusion of free silver ions interacting with transient membrane boundary faults, leading to localised membrane disruption. This result provides new insights into the mechanical stability of phospholipid bilayers in the presence of metallic nanomaterials.