Nanoscale biology

Friday 26/02/2010 14:30

For next week’s colloquium, on Friday 26th February, we’re delighted that Raphael Levy of the University of Liverpool will talk about ‘Gold nanoparticles, peptides and cells: the dynamic picture’. This colloquium will be of particular interest to those in the quantum/nano/photonics areas. Undergraduates will, as always, be most welcome.

The dynamic interactions and fate of nanomaterials in contact with living systems is thought to be controlled by the structure and chemical properties of its interface. In most cases, the interface is formed by a layer of organic molecules (polymers, proteins or small molecules). This layer is itself dynamic and can evolve due to ligand exchange, enzyme activity and non-specific binding. The layer encodes the specific recognition properties of the particle and also often carries active moieties. It is therefore critical for the progress of the field that the chemical integrity of the layer and the fate of the core materials can be followed independently in real time.

Using a combination of photothermal (imaging of the core material) and fluorescence (imaging of the organic layer) the Liverpool group has shown that peptides and proteins attached to nanoparticles are degraded by the enzyme Cathepsin L upon cell entry (See et al, ACS Nano, 3, 2461). This process is generic: Cathepsin L is ubiquitous and is able to cut a third of the proteome. Such potential degradation has to be taken into account in the design of future bioconjugated nanomaterials.

The degradation mentioned above occurs in the endosomal/lysosomal compartments of the cell. Finding intracellular delivery strategies which reach the cytosol and bypass these compartments is of primary importance for applications of nanomaterials in imaging and nanomedicine. Dr Levy will present a range of approaches currently under investigation in our lab, including the use of targeting peptides and permeabilizing toxins.

Another major challenge in the field is the structural characterization of nanomaterials. This challenge is similar to the one faced by biologists in the early days of structural biology. Dr Levy will report on recent progress on the structural characterization of peptide-capped nanoparticles.

This will be at 2.30pm in the seminar room, Tea and cakes afterwards. Programme online.

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