Liphardt Lab Research
We're a biophysics and synthetic biology lab. Our research focuses on understanding and controlling energy and information fluxes in biological systems. Our model systems range from E. coli bacteria to eukaryotic cells such as the S. cerevisiae yeast. Current projects include the development and synthesis of light-powered bacteria. We also develop new tools to characterize cells and molecules, such as super-resolution light microscopy and interacting gold nanoparticles ("Plasmon rulers"). The lab is located in Stanley Hall, very close to the Campanile.
Synthetic Biology; Energy and Signals Transduction
Design and synthesis of light-powered forms of E. coli
We synthesize light powered and controlled forms of the E. coli bacterium to help us understand the conversion of light into mechanical work in biological systems. The images above show a single E. coli cell that is stuck to a surface and that rotates when illuminated with green light. The cell uses the Proteorhodopsin light powered pump to harvest photons, creating a proton-motive-force, that in turn drives the flagellar motor.
New Tools and Probes
Plasmon Rulers: a new tool for measuring molecular distances
A key problem in biophysics is the measurement of nm scale distances. In collaboration with the lab of Paul Alivisatos, we have been using characterizing the distance dependence of the plasmon resonance between two gold (or silver) nanoparticles. Unlike conventional dyes, noble metal nanoparticles do not blink or bleach, making it possible to track them, or use them to measure distances, for arbitrary durations. For an overview of our ongoing plasmon resonance work, please see the meeting report in Science 308 (2005).
Optical Trapping and Manipulation of Nanowires
Semiconductor nanowires have unique optical and electronic properties. We're collaborating with the lab of Peidong Yang to find new ways of manipulating nanowires, and assembling them in to 3-D heterostructures. Primarily, we use optical tweezers to grab nanowires and fuse them to other wires and objects.
Nucleic Acids
Mechanical properties of RNA
RNA molecules perform many activities in the cell, including structural scaffolding, information transfer (e.g. mRNA and tRNA), and catalysis (e.g. catalysis of the peptide bond during protein synthesis). We would like to learn how RNA folds, and characterize the mechanical properties of RNA, such as resistance to mechanical stresses and strains.
Forces inside DNA loops
Imagine grabbing a single piece of DNA and trying to bend it. What are the forces needed to do that? We use force sensors with optical readout to directly measure the forces inside small, highly strained DNA loops.
