Nanoparticle-cell interactions are important to many critical applications, such as drug delivery and diagnostics, as well as relevant for determining the safety of nanoparticles to humans and the environment. This study focuses on a unique mechanism of cytotoxicity, namely, membrane destabilization, that is principally dependent on the nanoparticulate nature of the material rather than on the molecular properties. The interactions of 2, 5, 10, and 40 nm-diameter gold nanoparticles with supported lipid bilayers (SLB) of L-α-phosphatidylcholine (PC) were investigated with QCM-D technique. The nanoparticles weres tested in their citric acid stabilized state as well as in the presence of  polymethacrylic acid (PMA). The results show that 2, 5, 10 and 40 nm diameter citric acid stabilized gold nanoparticles caused only a small lipid loss from the bilayer. When the nanoparticles were coated with PMA, the smaller nanoparticles caused a mass increase on the bilayer. We proposed that the increased adhesion between the nanoparticle and the bilayer due to PMA is responsible for increased nanoparticle adsorption overcompensating for the loss of some lipid molecules. We observed significant mass loss in the case of the 40 nm PMA coated nanoparticle. We proposed that the bilayer engulfs the nanoparticle and its removal from the crystal surface is responsible for the observed significant mass loss. We propose a simple model to suggest that the competition between the particle-bilayer adhesion energy, the bilayer bending energy and the interfacial energy at bilayer defect edges allows the larger nanoparticles and more adhesive nanoparticles to be engulfed by the bilayer and leave the crystal surface causing mass loss. This large mass change can certainly be associated with membrane disruption and cytotoxicity. This suggests that even if gold nanoparticles are intrinsically not cytotoxic, they can become cytotoxic in the presence of other organic additives through manipulation of their adhesive interactions with the bilayer.

Size dependence of gold nanoparticle interactions with a supported lipid bilayer: A QCM-D study

249th National Meeting (2015)

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