New insights into interactions between dendrimers and surfactants. 4. fast-exchange/slow-exchange transitions in the structure of dendrimer-surfactant aggregates

The interactions between poly(amidoamine) (PAMAM) dendrimer and surfactant (sodium dodecyl sulfate, SDS) in aqueous solutions were investigated by a combination of ¹H NMR, diffusion measurements (PFG NMR), and NOE techniques. The diffusion studies suggested that different types of dendrimer-surfactant aggregates are formed by varying surfactant concentrations in the dendrimer solution. The ¹H NMR analysis proved that the presence of fast-exchange/slow-exchange transitions in the dendrimer-surfactant aggregates. The supramolecular structure of the aggregate was based on the hydrophobic interactions between the dendrimer scaffold and the surfactant aliphatic chain, as well as electrostatic/hydrogen-bond interactions between dendrimers and SDS monomers, bilayers, or globular micelles. In comparison with previous investigations, the present study provides a new insight into interactions between dendrimers and surfactants, which may be helpful for the design of dendrimer-based microreactors or nanovehicles.