Paper AS2+BI-ThM5
Single Biomolecule Force Spectroscopy Measurements; the Importance of Controlled Surface Chemistry

Thursday, November 12, 2009, 9:20 am, Room K

Over the past decade, considerable interest has focussed on the ability of atomic force microscopy (AFM) and related techniques to record forces on or between single biological molecules. Many elegant examples are evident within the literature where such approaches have been employed, for example, for studies of force induced protein and RNA unfolding processes, and the dissociation of a wide-range of biomolecular complexes, including those involved in cell adhesion. Despite these elegant examples, and the considerable advantages of performing measurements at the single molecule level, such measurements are still far from routine. Indeed, even in the most experienced hands the experiments can suffer various problems which can arise from poor control of the chemistries employed for biomolecular surface attachment e.g. such as non-specific binding, difficulties in single molecule pickup and variability between experiments.

This presentation will provide an overview of the approaches we have employed in recent studies to address such issues. This for example, will include our studies of the mechanical properties of long molecules of DNA (>1000 base pairs) in which we have demonstrated the advantages of the addition specific terminal functionalities for surface attachment [1]. The advantages will be highlighted through our investigations of the effects on DNA mechanical properties of a range of different DNA binding molecules (e.g. drugs and proteins involved in DNA replication [1,2]). For studies of the dissociation of biomolecular complexes, we will highlight the advantages of an alternative approach, in which we have exploited the unique properties of dendron functionalized surfaces. Developed in collaboration with the group of Professor J.W. Park (Pohang University of Science and Technology (POSTECH), we have recently employed such surfaces for studies of DNA hybridization [3], and interactions between intracellular signal transduction proteins [4].

[1] W. Zhang, R. Barbagallo, C. Madden, C.J. Roberts, A. Woolford, S. Allen. (2005) Nanotechnology 16 2325-2333

[2] W. Zhang, C. Machon, A. Orta, N. Phillips, C.J. Roberts, S. Allen, P. Soultanas (2008) Journal of Molecular Biology 377, 706-714

[3] J. Yung, B.J. Hong, W. Zhang, S.J.B. Tendler, P.M. Williams, S. Allen and J.W. Park (2007). Journal of the American Chemical Society, 129(30), 9349-9355.

[4] I.H. Kim, H.Y. Lee, H.D. Lee, Y.J. Jung, S.J.B. Tendler, P.M. Williams, S. Allen, S.H. Ryu, and J.W. Park (2009) Analytical Chemistry 81(9), 3276-3284