Long-Range Architecture of Single Lipid-Based Complex Nanoparticles with Local Hexagonal Packing

The three-dimensional architecture of single nanoparticles made of inverse micellar lipids templated on polyelectrolytes and exhibiting a local hexagonal packing is elucidated by high-resolution cryoelectron microscopy and coarse-grained Monte Carlo simulations. Cryoelectron microscopy demonstrates that the internal structure of the complexes is less ordered than commonly recognized from X-ray diffraction. We have devised a coarse-grained model of self-avoiding flexible tubes mimicking the lipid-coated polyelectrolytes and interacting via a short-range attractive potential. Consistently with cryoelectron microscopy, the resulting clusters obtained through a Monte Carlo scheme exhibit a varying degree of order ranging from weakly organized aggregates to partially organized spooled and straight bundles, depending on the length and on the persistence length of the tubes. These findings may help in the design of self-assembled lipid-based complexes for biomedical and nanotechnological applications.