• Increase font size
  • Default font size
  • Decrease font size
Home Projects 1st call (2008) 5. Studies on the Statistical Analysis of Biomolecule by using Atomic Force Microscopy (AFM)

5. Studies on the Statistical Analysis of Biomolecule by using Atomic Force Microscopy (AFM)

Dr. G. Dietler (EPFL), Dr. J. Vörös (ETHZ) - PhD student: Jae Sun Jeong

Project finished in December 2012.

AFM is a powerful single molecule imaging technique for biomolecule which enables exploration of the detailed topography at the molecular level. Used in conjunction with statistical analyses, the resultant images can reveal the behavior of biomolecule in their native state. We present our study of statistical analysis using AFM for two important types of biomolecules; amyloid β-protein (Aβ) and deoxyribonucleic acid (DNA). These molecules have heterogeneous repeating units which facilitate the deposition on the surface for AFM. The self-assembled Aβ is the major component of amyloid plaques which is a well known manifestation of Alzheimer’s disease in the human brain. However, many investigations in Aβ fibrillogenesis have reported that there is a lack of systematic statistical analysis. We visualize the Aβ 1-42 fibrillogenesis at sequential incubation time and examine their structural behavior using statistical analyses through AFM. We suggest a model for Aβ 1-42 fibril behaviors based on the determination of the flexibilities and dimensions of the fibrils combined with the statistical theory of semi-flexible polymer physics. The proposed model may be of general applicability to Aβ 1-42 fibril formation and highlights the distinct flexibility of fibril. DNA is the bio-polymer carrying the genetic information needed for the development and functioning for all living organisms. It is extremely important to understand the DNA topologies on a flat surface which serves as a template for DNA based sensors and microarray applications, in particular under electric field. There are many reports regarding DNA network film adsorption on a HOPG electrode under controlled potential visualizing with AFM, however, until now there is no report of in-situ single DNA molecule immobilization by applying positive potential through electrochemical system combined with AFM. We observed the conformational change of λ-DNA on the flat electrode according to constant polarized electric potential range with AFM in-situ. This provides insight into the understanding of the DNA topology under electrochemical conditions that has much potential for biological applications such as with bio-sensor devices.

Contact: Jea Sun Jeong