Andrew.Ridsdale@nrc-cnrc.gc.ca
Andrew Ridsdale
  Ph.D. Biochemistry and Molecular Biology (Manitoba)

My research experience is fairly evenly divided between the engineering-physics and biological research. My Ph.D. was in molecular-cell biology working on chromatin structure with Jim Davie at University of Manitoba in Winnipeg. I first worked non-linear optical (NLO) laser scanning microscopy in 1991. My technical competences include optical, software and electronic engineering, chemical, biochemical and molecular-biology methods, cell and tissue manipulation and image data analysis and visualization. My primary scientific interest (since the mid 1980's) has focused on material-level approaches (rather than molecular-level) to understanding living cells.

After a two and a half year postdoctoral in the laboratory of Professor Watt Webb at Cornell I worked in laser spectroscopy of protein molecules in the Department of Biophysics at Albert Einstein college of medicine (with Dr. Marco Pereira). This was followed by ten years (1997 - 2007) at the Ottawa Health Research Institutes (OHRI). During this time I worked mostly with Dr.Peter Stys who has since moved to Calgary Alberta. From 2002-2007 I was responsible for development multi-modal laser scanning microscopy capabilities at OHRI. This included implementing different laser scanning platforms from the component level. For each microscopy platform different laser sources could be directed to the samples and generated-signals to different detectors. Resolution of spectral, time (fluorescence lifetime) and polarization properties, could be done in imaging modes. Later I collaborated with in the development of the CARS microscope.

I joined Albert Stolow's group at NRC Ottawa at the end of 2007 where I'm involved in the operation of the CARSlab facility. This is a multi-user non-linear optical (NLO) microscopy facility which has two main roles:
1) Development of new NLO microscopy technologies and tools
2) Collaborative and in-support work for researchers in other areas who wish to make use of the unique capabilities of the CARSlab.

Research Interests

I have been interested for a long time in material-level (as opposed to molecular) approaches to measuring and understanding the dynamics of living cells. If we want to get beyond the limiting ideas of the interior of cells being membrane-bound compartments of diffusing molecules we need some alternative physics of cells which is consistent with experiment. The big question is: are there some principles (or laws) that apply to the material architecture of cytoplasm of all living cells that distinguishes it from non-living matter?

If we could, somehow, look at the first proto-cells it would probably be easier to guess an answer; but, all living cells that that we can observe today have undergone considerable evolutionary fine-tuning. Their complex webs on interacting molecules have been optimized, by natural selection, for potentiating individual reproduction (that is: for biological function). Molecular diversity and refinement makes it very difficult to see the subtle commonalities in cell-scale structure.

Still, much recent research on mechanics of cells does indicate that there may be some universal physical properties of living matter: the apparent "soft-glassy" mechanics of cells.

I am interested in developing tools to look at molecular-scale mechanics within living cells. One current project is to develop a fluorescence-lifetime vs. emission wavelength (time-spectra) laser scanning microscopy system. The detector is based on a wire delay-line on a multi-anode photomultiplier. This is combined with multi-channel time correlated single photon counting electronics. Such a device determines time-resolved fluorescence Stoke's shift over a few orders in time (depending of the reporter dye used). These type of experiments fit very well with recent research in glassy materials.