Jongyoon Han

Biosketch

Research Scientist•2001-2002•Sandia National Laboratories, Livermore, CA
Ph.D. Applied Physics • 2001 • Cornell University, Ithaca, NY
M. S. Physics • 1994 • Seoul National University, Seoul, Korea
B. S. Physics • 1992 • Seoul National University, Seoul, Korea

Research in Computational and Systems Biology

Just as electrical circuits process information in the form of collective motion of electrons that form electrical currents, biological systems transmit and process information mediated by nucleic acids, proteins and small effector molecules. The Han laboratory leverages new advances in microelectromechanical systems (MEMS), microfluidics, and nano- and micro-fabrication to develop new technologies for analyzing complex biological systems.

Nanofluidic channels for biomolecule separation and preconcentration

The goal of this work is to design artificial nanofluidic channels to act as molecular sieves that can separate DNA, proteins and other biomolecules. Gels or polymer monolith structures provide nano-scale pores that can be used for molecular separation, but it is difficult to measure or control the size of these porous structures. However, we can precisely design and fabricate solid-state fluidic nanostructures that provide high efficiency and resolution for molecular separation and filtration. Our technology could be pivotal in developing a micro Total Analysis System (microTAS), which is a single automated micro- or nano-scale device that incorporates several different analytical systems.

We are using this approach to develop a novel separation technique for various biomolecules, including proteins, carbohydrates and small molecules. Our laboratory has developed a novel system to separate various biomolecules with a nanofluidic channel device containing entropic traps, which consist of a series of nano-troughs interspersed between channel constrictions. This method is not only faster than conventional separation methods, but also the device is compact and easy to be integrated with a biosensing units such as mass spectrometry — features that make it amenable to incorporation into an integrated microTAS. In addition, we have developed a very efficient protein / peptide preconcentrator by utilizing a unique ion transport properties of nanofluidic channel. Target concentration enhancement of up to a million fold can be achieved using this device, which would have a significant impact in proteomic analysis.

Multi-dimensional biomolecule separation We also are developing microfluidic devices to preprocess a complex biomolecule sample to enable separation, identification and analysis of its individual components. At present there is no practical approach to combine and integrate several different microfluidic separation techniques into a single integrated device. One critical issue is the need to contend with two-step separation schemes that requires buffers with very different chemical properties. We are developing “smart” separation systems that use microfluidic valves to prevent cross-contamination of buffers required for different steps. We have produced a device that separates a complex protein mixture first by isoelectric focusing, and then transfers protein peaks corresponding to a selected pI range to a second channel for separation by capillary electrophoresis. We are now collaborating with Steve Tannenbaum to couple this integrated chip with a conventional mass spectrometer for streamlined protein identification and analysis. Our ultimate goal is to optimize this device to separate a very complex sample such as a cell extract and identify its constituents.

Primary Collaborators

Steve Tannenbaum (Biological Engineering, MIT)
Patrick Doyle (Chemical Engineering, MIT)
Scott Manalis (Biological Engineering, MIT)
Michael Rubner (DMSE, MIT)

Selected Publications

J. Fu, P. Mao, and J. Han, (2005) "A Nanofilter Array Chip for Fast Gel-Free Biomolecule Separation," Applied Physics Letters, 87, 263902.

Y.-C. Wang, A. L. Stevens, and J. Han, (2005) "Million-fold Preconcentration of Proteins and Peptides by Nanofluidic Filter," Analytical Chemistry, 77, 4293-4299.

P. Mao and J. Han, (2005) "Fabrication and Characterization of 20 nm Nanofluidic Channels by Glass-Glass and Glass-Silicon Bonding," Lab on a Chip, 5, 837-844.

Y.-C. Wang, M. H. Choi, and J. Han, (2004) "Two-Dimensional Protein Separation with Advanced Sample and Buffer Isolation Using Microfluidic Valves," Analytical Chemistry, 76, 4426-4431.

J. Han, "Nanofluidics," in Introduction to Nanoscale Science and Technology , M. D. Ventra, S. Evoy, and J. R. Heflin, Eds.: Kluwer, (2004).

J. Han, and H. G. Craighead. (2002), “Characterization and Optimization of an Entropic Trap for DNA Separation,” Analytical Chemistry, 74, 394-401.

J. Han, and H. G. Craighead. (2000), “Separation of Long DNA Molecules in a Microfabricated Entropic Trap Array,” Science, 288, 1026-1029.

J. Han, S. W. Turner, and H. G. Craighead. (1999), “Entropic trapping and escape of long DNA molecules at submicron size constriction,” Physical Review Letters, 83, 1688-1691.