drawing-hydrophobicity-patterning-long-polydimethylsiloxane-silicone

Drawing and Hydrophobicity-patterning Long Polydimethylsiloxane Silicone Filaments

Polydimethylsiloxane (PDMS) silicone is a versatile polymer that cannot readily be formed into long filaments. Traditional spinning methods fail because ...

Claremont McKenna College

Scripps College

Pitzer College

Single-experiment analysis of phospholipid compositional gradients reveals diffusion coefficients, phase separation parameters, and binding densities as a function of localized lipid mixture. Compositional gradients are formed by directed self assembly where rapid-prototyping techniques (i.e., additive manufacturing or laser-cutting) prescribe lipid geometries that self-spread, heal and mix by diffusion. 

Configurable lipid membrane gradients quantify diffusion, phase separations and binding densities.

We introduce a multi-functional microscope for research laboratories that have significant cost and space limitations. The microscope pivots around the sample, operating in upright, inverted, side-on and oblique geometries. At these geometries it is able to perform bright-field, fluorescence and qualitative ellipsometric imaging. It is the first single instrument in the literature to be able to perform all of these functionalities. The system can be assembled by two undergraduate students from a provided manual in less than a day, from off-the-shelf and 3D printed components, which together cost approximately $16k at 2016 market prices. We include a highly specified assembly manual, a summary of design methodologies, and all associated 3D-printing files in hopes that the utility of the design outlives the current component market. This open design approach prepares readers to customize the instrument to specific needs and applications. We also discuss how to select household LEDs as low-cost light sources for fluorescence microscopy. We demonstrate the utility of the microscope in varied geometries and functionalities, with particular emphasis on studying hydrated, solid-supported lipid films and wet biological samples.

An Assemblable, Multi-Angle Fluorescence and Ellipsometric Microscope.

We introduce a method to produce continuous polydimethylsiloxane (PDMS) silicone filaments on the order of 0.5 m long and 100 μm in diameter. The approach overcomes traditional limitations in silicone drawing by partially precuring the polymer and drawing through a tube furnace. We characterize the filaments' mechanical properties, and their ability to switch hydrophobicity by UV-ozone and corona discharge patterning. The flexible filaments' dynamic properties were evaluated by way of athermal acoustic excitation at the air-water interface, revealing conformational reconfigurability consistent with a wormlike chain model. We envision applications in rapid prototyping and as a platform for model foldamer studies.

Article	Year
Configurable lipid membrane gradients quantify diffusion, phase separations and binding densities. Soft matter\| PubMed ID: 26426824	2015
An Assemblable, Multi-Angle Fluorescence and Ellipsometric Microscope. PloS one\| PubMed ID: 27907008	2016
Gravity-Drawn Silicone Filaments: Production, Characterization, and Wormlike Chain Dynamics. ACS applied materials & interfaces\| PubMed ID: 29111635	2017

Babak Sanii

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