(623aq) Effect of Surface Functional Groups On Interactions of Engineered Nanomaterials with a Lipid Bilayer

Engineered nanomaterials (ENM) are being introduced into a wide range of commercial products. Recent studies have shown that ENM can induce health risks. ENM could induce toxicity in a variety of ways, several of which involve molecular interactions with cell membranes, including creating pores in the membrane and entering cells or organelles through the membrane. However, the mechanisms underlying ENM’s molecular interactions with cell membranes are poorly understood.  This paper describes electrophysiological studies to explore the effect of surface functional groups on interactions between polymeric nanoparticles and synthetic BLM that mimic cell membranes. Polypropargyl glycolide (PGL) nanoparticles decorated with different surface functional groups (PEG, OH, COOH) were fabricated.  The sizes and aggregation rates of the ENM were then determined using light scattering. Synthetic diphytanoyl phosphocholine BLM were then challenged with the ENM, and resulting current spikes and integral conductance were measured for each particle type.  PGL nanoparticles having PEG and OH surface groups resulted in current spikes, while nanoparticles having COOH groups generated both current spikes and integral conductance. Frequency of current spikes having a relatively high conductance (>100 pS), as well as total charge transferred through the BLM, increased in the order PEG<OH<COOH. Ion selectivity of the ENM-generated conductance was investigated by measuring transmembrane currents at various applied potentials in the presence of a 10:1 ion gradient, before and after reversing the applied potential. The results showed no evidence that the conductance triggered by the surface-functionalized polymeric ENM nanoparticles was ion selective.