Dr Bart Hoogenboom

Biography

• High-resolution atomic force microscopy in liquid
• Solid-liquid interfaces
• Single-molecule biophysics
• Molecular machines
• Membrane proteins
• Nanomechanical resonators

Research Interest

I am fascinated by the opportunities of nanotechnological tools to study and manipulate single atoms and molecules. I believe that there is a particular interest in exploiting these tools to investigate the molecular machines that make the biological cell function in a way similar to a macroscopic factory and yet - because of their nanometre-scale size and the presence of an aqueous environment - so different.

My research has a strong focus on scanning probe techniques. Of all scanning probe microscopes, the atomic force microscope (AFM) is the most popular for biological applications. Using an extremely sharp tip, it allows users to scan a surface just like a person's fingertip reading Braille, “touching” and “feeling” single molecules and/ or atoms. Moreover, since the AFM can be operated in liquid, we can probe and image biomolecules under conditions that are very near to those in a living cell.

Precise control of the AFM cantilever, our miniature "fingertip", is crucial to gently probe molecules without damaging or distorting them. In our laboratory, we develop new techniques to get complete control of the cantilever in aqueous environment, with the aim of probing and imaging biologically relevant samples with sub-molecular or even atomic resolution. We apply these techniques to a variety of samples, preferably to molecules of biomedical relevance.

Biography

• 2007-present, Lecturer in the London Centre for Nanotechnology and the Department of Physics and Astronomy, University College London
• 2005-2007, Post-Doctoral Research Assistant, Biozentrum, University of Basel, Switzerland, Laboratory of Prof. Andreas Engel
• 2002-2005, Post-Doctoral Research Assistant, Department of Physics, University of Basel, Switzerland, Laboratory of Prof. Hans Hug
• 1998-2002, Ph. D. Condensed Matter Physics, University of Geneva, Switzerland, Laboratory of Prof. Øystein Fischer
• 1998, M. Sc. Surface Physics, University of Groningen, the Netherlands, Laboratory of Prof. George Sawatzky

Selected and recent publications (click here for a full list of publications)

• R. R. Grüter, Z. Khan, R. Paxman, J. W. Ndieyira, B. Dueck, B. A. Bircher, J. L. Yang, U. Drechsler, M. Despont, R. A. McKendry, and B. W. Hoogenboom, "Disentangling mechanical and mass effects on nanomechanical resonators", Appl. Phys. Lett. 96, 023113 (2010)
• N. Jenkins, Y. Fasano, C. Berthod, I. Maggio-Aprile, A. Piriou, E. Giannini, B. W. Hoogenboom, C. Hess, T. Cren, and Ø. Fischer, "Imaging the essential role of spin fluctuations in high-Tc superconductivity", Phys. Rev. Lett.103, 227001 (2009) .
• C. Leung, H. Kinns, B. W. Hoogenboom, S. Howorka, and P Mesquida, "Imaging surface charges of individual biomolecules", Nano Lett. 9, 2769 (2009).
• B. W. Hoogenboom, K. Suda, A. Engel, and D. Fotiadis, “Supramolecular assemblies of the voltage-dependent anion channel in the native membrane”, J. Mol. Biol. 370, 246 (2007). [online article]
• B. W. Hoogenboom, H. J. Hug, Y. Pellmont, S. Martin, P. L. T. M. Frederix, D. Fotiadis, and A. Engel, “Quantitative dynamic-mode scanning force microscopy in liquid”, Appl. Phys. Lett. 88, 193109 (2006). [online article]

Teaching

• PHASM800/PHASG800 Molecular Biophysics, term 2 (2009/2010)
• PHAS3255 Solid State Physics, evening course, term 2 (2008/2009)

Research

Figure 1: Atomic and molecular resolution in liquid.
The forces between cantilever tip and sample can be precisely determined from shifts in the cantilever resonance frequency (frequency-modulation AFM). Combined with a highly-sensitive deflection detector, this technique allows atomic-resolution images (left, showing atomic-scale defects) of mica and molecular-resolution images of the membrane protein bacteriorhodopsin (right, here imaged in a 2D lattice), all in physiological buffer solution.

Figure 2: VDAC in the native membrane.
Outer mitochondrial membranes were purified and adsorbed on a mica substrate. Subsequent frequency-modulation AFM images show the VDAC assembling in monomers, dimers, trimers, tetramers, hexamers and higher oligomers. VDAC, appearing as a ring in the image, has an outer diameter of about 5 nm.