Stoichiometry and Structure of Poly(amidoamine) Dendrimer-Lipid Complexes.
The energetics, stoichiometry, and structure of poly(amidoamine) (PAMAM) dendrimer-phospholipid interactions were measured with isothermal titration calorimetry (ITC), transmission electron microscopy (TEM), atomic force microscopy (AFM), dynamic light scattering (DLS), and molecular dynamics (MD) simulations. Dendrimers of sixth-generation and smaller interacted with the lipids at an average stoichiometry and enthalpy proportional to the number of primary amines per dendrimers (4.5 ± 0.1 lipids/primary amine and 6.3 ± 0.3 kJ/mol of primary amines, respectively). Larger dendrimers, however, demonstrated a decreased number of bound lipids and heat release per primary amine, presumably due to the steric restriction of dendrimer deformation on the lipid bilayer. For example, eighth-generation PAMAM dendrimers bound to 44% fewer lipids per primary amine and released 63% less heat per primary amine as compared to the smaller dendrimers. These differences in binding stoichiometry support generation-dependent models for dendrimer-lipid complexation, which are consistent with previously observed generation-dependent differences in dendrimer-induced membrane disruption. Dendrimers of seventh-generation and larger bound to lipids with an average stoichiometry consistent with each dendrimer having been wrapped by a bilayer of lipids, whereas smaller dendrimers did not.
Kelly
Christopher V
CV
Applied Physics Program.
Liroff
Meghan G
MG
Triplett
L Devon
LD
Leroueil
Pascale R
PR
Mullen
Douglas G
DG
Wallace
Joseph M
JM
Meshinchi
Sasha
S
Baker
James R
JR
Orr
Bradford G
BG
Banaszak Holl
Mark M
MM