Tip penetration through lipid bilayers in atomic force microscopy

Probing small unilamellar EggPC vesicles on mica surface by atomic force microscopy

“…This suggests that these jump-in and -out gaps correspond to the sudden opening and closing of portions of the vesicle bilayer during approach and retraction force measurements. This finding is consistent with the jump-in point observed on bilayer [28]. The discontinuities on approach force curve on liposomes were also reported [29].…”

“…We refer to the load at which the jump-in occurs as the breakthrough force. The jump-in (4.57 ± 0.27 nm) corresponds to the removal of the bilayer fragment between the tip and substrate, most probably by a lateral push-out mechanism [28]. The maximum steric barrier was reported to be proportional to the surface excess of the film, and can be used to compare the packing density of films with similar adsorption mechanisms [42].…”

“…They discarded the force plots with discontinuities which are important for understanding the structure of liposome. Several papers have described the force curves on different types of bilayer and a jump-in point was observed [28][29][30]. Franz et al [28] interpreted the jump-in point as a penetration of the AFM tip through the bilayer.…”

“…Several papers have described the force curves on different types of bilayer and a jump-in point was observed [28][29][30]. Franz et al [28] interpreted the jump-in point as a penetration of the AFM tip through the bilayer. Recently, Teschke and Souza [31] reported individual approaching force curve on liposome.…”

Force measurements with the atomic force microscope: Technique, interpretation and applications

“…(8.4) directly shows that v is a monotonically increasing function of F j , and vice versa: the mean yield force increases with the loading rate. This was indeed observed [754,755].…”