(363a) Nanoparticle Binding On Model Phospholipid Membranes Using Liquid Crystals As A Detection Platform

Substantial scientific activities have been developed in elucidating potential toxic effects of nanomaterials on biological cells in the past few years. Goodman et al. observed that cationic 2 nm gold nanoparticles are moderately toxic to mammalian and E. coli cells. The interaction between nanomaterials and cells depends strongly on the type and surface modification of nanomaterials. The latter can bring toxic nanomaterials to less toxic or, in opposite, to make relatively non-toxic nanomaterials more toxic. While almost all past studies pursued for direct exposure of nanomaterials to biological cells, very few studies investigated the physical binding between nanomaterials and cell membrane, which is the first event occurred before nanomaterials entering cells. Here, we report an easily visualized model system to study the interactions between phospholipids and nanoparticles. In this study, 1,2-dilauroyl-sn-glycero-3-phosphocholine (DLPC) was self-assembled spontaneously at planar interfaces between nematic liquid crystal 4'-pentyl-4-cyanobiphenyl (5CB) and aqueous phase. Gold nanoparticles coated with bovine serum albumin (BSA) were then added into the system to study the interaction with the phospholipid monolayer. Based on the optical textures of liquid crystal, the gold nanoparticles interacted with the DLPC and change the orientations of liquid crystals. The nanoparticles without BSA coating exhibited different optical textures, indicating the potential of using liquid crystal systems to identify surface status of nanoparticles. Furthermore, DLPC molecules were more susceptible to protein-coated gold nanoparticles rather than uncoated ones. The interaction rate of DLPC molecules to protein-coated gold nanoparticles depends strongly on the concentration of the protein used. This study offers a promising system to investigate the physical interaction between nanoparticles and phospholipid membrane, where liquid crystal is used as a detector to reflect and amplify the interaction phenomena between phospholipid and nanoparticles. Results obtained from this study may offer new information to aid the design of drug delivery vehicles as well as to understand the mechanism of potential cytotoxicity by nanomaterials, where the interaction between nanoparticles and plasma membrane is an essential step.