Label-free Digital Detection of DNA and MicroRNA Targets

Henrik Persson - Stanford University
Thursday, January 8, 2009, 12:00 pm, Physical Sciences Building, Room 240
Hosted by Assistant Professor Nader Pourmand
Biomolecular Engineering

Abstract

DNA microarrays have enabled high throughput analysis of gene-expression and
genotyping. However, it still suffers from limited dynamic range and relies heavily on
enzymatic manipulations and amplification to create a detectable signal. In this seminar a
novel nanomechanical detection method that may circumvent these disadvantages is
presented. It is based upon a modified atomic force microscope (AFM) that can monitor
changes in torsional harmonic forces on the cantilever. Such changes correlate to the
stiffness of the material and can discriminate between single and double stranded DNA
on a surface. Automated image analysis reveals hybridized molecules with single
molecule precision, thus providing a digital measure of hybridization. This method can
detect target concentrations over 4 orders of magnitude with a limit of detection in the
low attomolar concentration range without any labeling, enzymatic manipulations, and
amplification. Finally, we demonstrate the performance of this technique by measuring
differential expressions of microRNAs in tumor samples, a method which has been
shown to help discriminate tissue origins of metastatic cancer.

Biography

Henrik Persson, Ph.D. is a research associate at Stanford Genome Technology Center,
where his research interest is all surface chemistry aspects in the development of novel
biosensors with optical, electrical, magnetic and nano-mechanical detection schemes.
Prior to joining Stanford Genome Technology Center he held various research positions
at Fortebio, Inc. and Zyomyx, Inc. A native of Sweden, Henrik holds an MS in Chemical
Engineering from Lund University, Sweden. He earned his Ph.D. in Material Science and
Engineering from the Swiss Federal Institute of Technology, ETH Zurich, Switzerland
and completed postdoctoral training in Biochemistry at Stanford University School of
Medicine, Stanford, California.