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

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.