"Nanofluidic Filters and Membranes for Biomolecule Analysis"

Prof. Jongyoon Han, Massachusetts Institute of Technology

Recent advances in fabrication techniques allow one to create regular nanofluidic pores and channels down to ~10 nm in critical dimension, with excellent uniformity and size control. This creates unique opportunities for advancing both nanoscience and nanotechnology. Study of nanoscale molecular interaction with surrounding nanostructure has many applications in separation science, membrane engineering, and drug delivery. Nanofluidic channels can provide very uniform, well controlled experimental platform for studying these phenomena. In addition, detailed study of nanoscale transport of ions and molecules through confined environment would lead to ideas for novel nanofluidic devices.

One of the important advantages of MEMS-fabricated nanofilter membranes is the flexibility of membrane system design, which is not readily achievable in random nanoporous materials. As an example, a novel biomolecule (protein and DNA) separation device is presented in the talk. We have successfully designed and fabricated an anisotropic sieving structure that can be used for size separation of various biomolecules (Fu, Yoo and Han, 2006). The sieving structure consists of a two-dimensional periodic array of nanofluidic filter (nanofilter). The bidirectional electrophoretic motion of biomolecules in the sieving structure causes molecules of different sizes to follow radically different paths, leading to efficient separation. Using this sieving structure, we have implemented a high-throughput, continuous-flow biomolecule separation device and evaluated its performance on various biologically relevant molecules (Fu, Schoch, Stevens, Tannenbaum and Han, 2006). We also demonstrated nanofluidic biomolecule preconcentrator (Wang, Stevens and Han, 2005), where dilute protein samples can be efficiently concentrated for more efficient downstream detection. In addition to its potential as a signal enhancement strategy for proteomics, the device is a model system for studying nonlinear electrokinetic phenomena and concentration polarization (Kim, Wang, Lee, Jang and Han, 2007), which has relevance in many perm-selective membrane applications such as Nafion®. These nanofluidic tools are expected to be critical in dealing with some of the technical bottlenecks in current bioanalysis processes.

References:

Fu, J., R. R. Schoch, A. L. Stevens, S. R. Tannenbaum and J. Han (2006). "Patterned anisotropic nanofluidic sieving structure for continuous-flow separation of DNA and protein." Nature Nanotechnology 2 (2): 121 - 128.

Fu, J., J. Yoo and J. Han (2006). "Molecular sieving in periodic free-energy landscapes created by patterned nanofilter arrays " Physical Review Letters 97(1): 018103.

Kim, S. J., Y.-C. Wang, J. H. Lee, H. Jang and J. Han (2007). "Concentration Polarization and Nonlinear Electrokinetic Flow near Nanofluidic Channel." Physical Review Letters 99: 044501.

Wang, Y.-C., A. L. Stevens and J. Han (2005). "Million-fold Preconcentration of Proteins and Peptides by Nanofluidic Filter." Analytical Chemistry 77(14): 4293-4299.