Dual Friction Force/Fluorescence Microscopy

Friction force microscopy (FFM) is a mode of atomic force microscopy (AFM) that quantifies both normal and horizontal forces against substrates. Recent improvement in its accuracy at nanonewton ranges and the possibility of combining AFM with fluorescence microscopy enabled the simultaneous characterization by FFM and fluorescence microscopy. This Tutorial describes the operation principle of the dual friction force/fluorescence microscopy setup and highlights its emerging applications in mechanochromic materials.

Lipid nanotubes as an organic template for the fabrication of carbon nanostructures by pyrolysis

We demonstrate the fabrication of carbon nanoribbons with a width of 40 nm based on fixation and pyrolysis of an organic template, lipid nanotubes. To our best knowledge, this is the smallest feature size achieved by pyrolysis of surface-patterned organic templates. Such a pyrolytic carbon nanostructure can be used for electronics and sensing applications in future.

Lipid Nanotubes as an Organic Template for an Electrically Conductive Gold Nanostructure Network

We demonstrate an approach to fabricate a gold nanowire network that presents a macroscopic electrical conductivity based on a lipid nanotube (LNT) template with attached gold nanoparticles. The poor electrical conductivity that we have previously faced was overcome by centrifugation and resuspension of gold nanoparticle solution for removing stabilizing agents, which increased the density of gold nanoparticles on the LNTs. An additional electroless metal plating further enhanced their contacts at nanoscale. Thanks to these procedures, the sheet resistance was improved by 11 orders of magnitude. As a proof of principle, transparent conductive films were fabricated with these gold nanowires, which exhibited sheet resistance of maximum 70 Ω/□ and transmittance of 50-75% in visible light.

Artificial tubular connections between cells based on synthetic lipid nanotubes

Open-ended artificial tubular connections between cells were controllably fabricated using synthetic lipid nanotubes.

Freely drawn single lipid nanotube patterns

LNTs are unique 3D structures made only of safe and abundant biomaterials by self-assembly. The current bottleneck for developing applications using LNTs is the lack of an easy technique to pattern them on substrates. We report a method to free-draw single lipid nanotube (LNT) patterns in any shape on surfaces with 1,2-dioleoyl-sn-glycero-3-phosphoethanolamine (DOPE) that takes an inverted hexagonal (HII) phase. We used pre-self-assembled LNTs or HII lipid blocks as a lipid reservoir from which new LNTs were pulled by applying a point load with a micromanipulator. The extreme simplicity of our technique originates from the fundamental nature of DOPE lipids that prefer a HII phase, while all the conventional approaches use PC lipids that form a lamellar phase. By adjusting the surface properties with polyelectrolyte multilayers, the created single LNT objects are able to remain adhered to the surface for over a week. Importantly, it could be shown that two vesicles loaded with caged fluorescent molecules were able to fuse well with a LNT, enabling diffusive transport of uncaged fluorescent molecules from one vesicle to the other.