Specific binding structures of dendrimers on lipid bilayer membranes.

Dissipative particle dynamics simulations are used to study the specific binding structures of polyamidoamine (PAMAM) dendrimers on amphiphilic membranes and the permeation mechanisms. Mutually consistent coarse-grained (CG) models both for PAMAM dendrimers and for dimyristoylphosphatidylcholine (DMPC) lipid molecules are constructed. The PAMAM CG model describes correctly the conformational behavior of the dendrimers, and the DMPC CG model can properly give the surface tension of the amphiphilic membrane. A series of systematic simulations is performed to investigate the binding structures of the dendrimers on membranes with varied length of the hydrophobic tails of amphiphiles. The permeability of dendrimers across membranes is enhanced upon increasing the dendrimer size (generation). The length of the hydrophobic tails of amphiphiles in turn affects the dendrimer conformation, as well as the binding structure of the dendrimer-membrane complexes. The negative curvature of the membrane formed in the dendrimer-membrane complexes is related to dendrimer concentration. Higher dendrimer concentration together with increased dendrimer generation is observed to enhance the permeability of dendrimers across the amphiphilic membranes.