Self-standing nanoparticle membranes and capsules

Abstract

We perform coarse-grained molecular dynamics simulations of self-standing nanoparticle membranes observed in recent experiments (K. E. Mueggenburg et al., Nat. Mater., 2007, 6, 656). In order to make our simulations feasible, we model 2–3 times smaller gold nanoparticles (core radius of r_core ≈ 0.8 nm) covered with alkanethiol ligands (length of l_ligand ≈ 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 R_LC = l_ligand/r_core. For R_LC ≈ 0.6, the ligated nanoparticles form well ordered monolayers with hexagonal packing, in agreement with the experiments (R_LC ≈ 0.44). For R_LC ≈ 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.