Self-standing Nanoparticle Membranes and Capsules

We perform coarse-grained molecular dynamics simulations of self-standing nanoparticle membranes observed in recent experiments (Nat. Mater. 6, 656 (2007)). In order to make our simulations feasible, we model 2 − 3 times smaller gold nanoparticles (core radius of rcore ≈ 0.8 nm) covered with alkanethiol ligands (length of lligand ≈ 0.5−2.6 nm). We study the structure, stability, and mechanical properties of these membranes and show that these characteristics are controlled by the ratio of RLC = lligand/rcore. For RLC ≈ 0.6, the ligated nanoparticles form well ordered mono- layers with hexagonal packing, in agreement with the experiments (RLC ≈ 0.44). For RLC ≈ 1.6, the nanoparticles form less organized multilayers, which are more stable and flexible. We show that these membranes could potentially form stable capsules for molecular storage and delivery.