Biomathematics Seminar: Measuring and designing mechanical properties and interfaces with AFM: from single molecules to live cells and nanomedicine
18 October 2011 14:00 in CM105 (Mathematical Sciences)
Biological systems exploit the physical chemistry of molecules and soft matter-composites to engineer entropy, thermal fluctuations and molecular forces and create functional structures with complex mechanical properties (stiffness, elasticity, adhesion) and tailored interfaces. These structures enable biological function, from the selectivity of a membrane channel, to the binding of a protein to DNA to cell division and morphogenesis and are altered by disease or trauma. Understanding these complex, dynamic structures is one of the main challenges of modern physics and constitutes the basic foundation of nanomedical devices and bioinspired materials.
In the last few years we have developed techniques based on the atomic force microscope (AFM) that have enabled us to measure the interfaces of biological molecules and structures with physiological fluids: we've been able to measure the solid-liquid adhesion energy with sub-nm resolution1 and to quantify the complex electrostatics of membrane proteins measuring ionic effects on the water structure at the interface2. We have quantified the stiffness of a single membrane protein3 and related it to its interface properties2, dynamics4,5, individual function6 and the coupling with neighboring proteins4. Using multifrequency AFM we have been able to quantitatively map the nanomechanical properties of living cells with unprecedented speed and accuracy7; this will make it possible to study the fundamental mechanisms that determine cell mechanics in different contexts. Currently we are exploiting this knowledge to design nanostructures (nanostructure-based drug-delivery systems, and nanocomposites for tissue regeneration) that enable selectivity and biocompatibility by controlling interfaces and mechanical properties.
(1) Voitchovsky et al. Nature Nanotechnology 5, 401–405 (2010).
(2) Contera et al. Nanoscale, 2, 222-229 (2010).
(3) Voitchovsky et al. Biophysical Journal, 90 (6), 2075-2085 (2006)
(4) Voitchovsky et al. Soft Matter 5 (24), 4899-4904 (2009).
(5) Yamashita et al. Journal of Structural Biology, 167 (2), 153-158 (2009).
(6) Voitchovsky et al. Biophysical Journal, 93 (6), 2024-2037 (2007).
(7) Raman, Trigueros, Cartagena, Stevenson, Susilo, Nauman, Contera, Nature Nanotechnology accepted (2011).
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