Levy, Stephen
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Stephen Levy

Office: S2 - 263

Phone: 607-777-3066

Email: slevy@binghamton.edu

 

Research

We investigate the statistical mechanical properties of soft materials, like biomolecules, in confined topologies.  We are interested in exploring the scaling laws predicting the conformation and dynamics of polymers, like individual DNA molecules, in nanofluidic structures.  We typically fabricate nanofluidic channels in fused silica wafers using tools available at the Binghamton Nanofabrication Lab or at Cornell's Nanoscale Facility.  We electrophoretically manipulate DNA inside these channels to study their biophysical and transport properties.  DNA molecules are extremely interesting polymers due to their high linear charge, flexibility, aspect ratio, and genetic role in biological organisms.


 Fused Silica Nanochannels   

Top down scanning electron micrograph of an array of nanofluidic channels (bottom) etched in fused silica.

The channels are approximately 150 nm in width and depth and tens of microns in length.  

At the top of the image the outline of a larger microfluidic loading channel can be seen.  

We used similar devices to study the entropic unfolding of DNA molecules within the channels.

 


 Images of a DNA molecule   

Images of a DNA molecule unfolding in time (from top to bottom) inside a nanofluidic channel.

It is important to note that no external potentials are being applied.

Over the time scale of approximately one minute, the T4 DNA molecule unfolds to increase its entropy within the channel.

The final unfolded length of the molecule is approximately thirty microns.


 Silicon Master for Microfluidic Assay  

 

Image of a silicon chip that has been deep etched to serve as a master for a PDMS mold.

 

 

 

 PDMS Chip  

 

PDMS microfluidic chip on an inverted microscope. The chip has several pieces of tubing connected to external valves for flow control.

 

 

 

Magentic Bead Assay  

Images of magnetic beads trapped in the microfluidic device. The beads are functionalized with an antibody to an interleukin-8 protein.  A secondary antibody with a fluorescent label is convected across the bead bed.  By measuring the fluorescent intensity of the beads we can determine the concentration of the interleukin in the sample.  The assay is sensitive to concentrations between 1 and 10,000 pg/mL of interleukin-8.

Last Updated: 10/6/16