Membrane-Based Nanotechnology and Drug Delivery - Membrane Biophysics, Biological and Medical Physics, Biomedical Engineering - page 137

Fig. 6.7 Lipid bilayer formation in the presence of particles larger than the lipid bilayer thickness.
AFM images ( left ) of lipid bilayer formation over a surface with 5-20nm silica nanoparticles (a-d):
a substrate with particles and no lipid, b a surface partially covered by lipid bilayer (shown in silver
color ), c a lipid bilayer formed on the substrate, d an image of the lipid bilayer after “subtraction”
of the particles and the substrate. AFM images ( right ) of lipid bilayer formation over the surface
with mixed 5-140nm silica particles (e-h): e the substrate with particles and no lipid, f partial
coverage of the surface by a lipid bilayer, g a lipid bilayer formed on the substrate, and h an image
of the lipid bilayer after “subtraction” of the particles and the substrate. Schematics in the center
illustrate how the lipid bilayer forms a pore around particles smaller than 22nm ( i ) and how it may
envelop the larger particles ( j ). The structure of the bilayer area encircled in j is speculative because
it cannot be resolved or assumed from AFM experiments. This figure with its description has been
taken with the publisher's permission from [ 22 ]
time, the nanoparticles may use that time-dependent opening to travel to the cellular
interior. Based on this hypothesis we aim to develop a novel nanotechnology-based
drug delivery method. A detailed explanation is presented below.
6.4.1 Membrane Transport of Nanoparticles Through
Lipid-Lined Ion Pores
Chemotherapy drugs are found to induce lipid-lined toroidal pores in lipid mem-
branes. A model diagram has been presented in Chap. 4 . Many other antimicrobial
peptides such as magainin, melittin, colicin, etc., also induce toroidal pores (see