Nanosociety Meeting Friday @ 12pm, McCullough 115: Lateral Fusion of Lipid Membranes to Nanoscale Functionalized Posts

Brian E Hardin bhardin at stanford.edu
Wed Nov 18 09:22:22 PST 2009


Ben Almquist (Melosh Group) will be presenting his research involving
"biomimetic stealth probes" at 12pm in McCullough 115 this Friday. Pizza
will be served.


*Lateral Fusion of Lipid Membranes to Nanoscale Functionalized Posts*

The ability to specifically and non-destructively incorporate inorganic
structures into or through biological membranes is essential to realizing
full bio-inorganic integration. However, molecular delivery and interfaces
to inorganic objects, such as patch-clamp pipettes, generally rely upon
destructive membrane holes and serendipitous adhesion, rather than selective
penetration and attachment to the bilayer. In fact, materials greater than a
few nanometers have not been shown to penetrate lipid bilayers without
disrupting the continuity of the membrane. I will discuss the development of
nanofabricated probes that spontaneously insert into the hydrophobic
membrane core by mimicking the hydrophobic banding of transmembrane
proteins, forming a well-defined bio-inorganic lateral junction. These
biomimetic ‘stealth’ probes consist of hydrophilic posts with 2-10 nm
hydrophobic bands formed by molecular self-assembly, and are easily
fabricated onto a variety of substrates including silicon wafers,
nanoparticles, and AFM tips. By fabricating this architecture onto AFM
probes, we have directly measured the penetration behavior and adhesion
force of different molecular functionalities within the bilayer. Following
insertion, stealth probes remain anchored in the center of the bilayer,
while purely hydrophilic probes have no preferred location. The strength of
the stealth probe adhesion varies greatly between short and long chain
alkane functionalizations, indicating that chain mobility, orientation, and
hydrophobicity all contribute to stability within the bilayer. In addition,
the consequences of geometric factors such as band thickness and the
presence of multiple bands on interface stability have been established. By
selectively choosing the desired properties of the hydrophobic band, it is
possible to tune the failure tension of the interface from values comparable
to that of pristine lipid vesicles to only a fraction of the strength.
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