Dr Iwan A. T. Schaap
- +44 (0)131 451 4145
Earl Mountbatten Building
We investigate the structure-function relationship of biomaterials; how do mechanics control biological function? Currently, our research is focused on natural composite materials like viruses and cells. These structures often show a remarkable correlation between their life stage and mechanical response. Viruses for example are very robust when they travel between host organisms but once they enter a target cell they undergo structural changes that eventually allow them to open up to release their genetic material. Because we perform our experiments in a controlled liquid environment, we can mimic events that are triggered by temperature, chemicals, pH, or force, which enables us to investigate the mechanical transitions during the unpacking of influenza viruses, CCMV and adenoviruses.
In addition, we use our knowledge about the architecture of natural biomaterials to improve the application of biomolecules in nanotechnology. In recent work we showed that clathrin proteins, normally involved in the formation of transport vesicle in cells, can be applied to form very regular and stable webbings on almost any type of surface. This surface functionalization could be a first step to fabricate more efficient sensors or biosynthetic reactors.
To measure the mechanical response we indent or stretch our samples on a sub-micrometer length-scale. Depending on the composition of the material we expect either an elastic response (regular protein assemblies like viruses), or a more complex visco-elastic behaviour that depends on both the time- and length-scale of the deformation experiment (heterogeneous structures like cells). For the more robust samples we use atomic force microscopy and for fragile samples a vertical laser trap, a special in-house development for very soft materials. Finite element analysis is employed to model the experiments in order to extract the intrinsic mechanical parameters of the tested materials.
Much of our research is carried out as national or international collaborations, in which we provide the nano-mechanical expertise while our partners are experts on a specific biological system.
A. Ortega-Esteban, K. Bodensiek, C. San Martín, M. Suomalainen, U.F. Greber, P.J. de Pablo, I.A.T. Schaap (2015) Fluorescence tracking of genome release during the mechanical unpacking of single viruses. ACS Nano. 11, 10571-10579.
P.N. Dannhauser, M. Platen, H. Böning, I.A.T. Schaap (2015) Durable protein lattices of clathrin that can be functionalized with nano-particles and active bio-molecules. Nat. Nanotechnol. 10, 954-957.
S. Li, C. Sieben, K. Ludwig, C.T. Höfer, S. Chiantia, A. Herrmann, F. Eghiaian, I.A.T. Schaap (2014) pH-controlled two-step uncoating of influenza virus. Biophys. J. 106, 1447-1456.
K. Bodensiek, W. Li, P. Sánchez, S. Nawaz, I.A.T Schaap (2013) A high-speed vertical optical trap for the mechanical testing of living cells at piconewton forces. Rev sci instrum 84, 113707.
S. Nawaz, P. Sánchez, K. Bodensiek, S. Li, M. Simons, I.A.T. Schaap (2012) Cell visco-elasticity measured with AFM and optical trapping at sub-micrometer deformations. PLOS ONE 7, e45297.
Iwan Schaap performed his PhD at the faculty of physics and astronomy of the Vrije Universiteit Amsterdam in the Netherlands where he used atomic force microscopy to probe the mechanical properties from artificial DNA structures and microtubules. In 2006 he moved as an EU funded Marie Curie fellow to the MRC National Institute of Medical Research in London. Here, he studied the structure and mechanics of single influenza viruses and actin filaments using AFM, optical trapping and TIRF microscopy. In 2008 Iwan Schaap took up a junior group leader position at the faculty of Physics at the University of Gӧttingen in Germany. He developed an integrated approach using atomic force microscopy and single molecule fluorescence to study how single viruses unpack themselves in target cells. Furthermore, he developed novel approaches to measure mechanical properties of living cells that resulted in multiple successful collaborations with the local medical community. End 2015 Iwan Schaap took up a position as associate professor at IB3 of the Heriot Watt University where he will continue his work to increase our understanding of the function of biological structures via mechanical measurements on the nm and pN scale.