Friday, January 25, 2013

An optical scientist considers the question: what do biologists want from a microscope?

Optics and biology have been intertwined for hundreds of years. Robert Hooke and Antonie van Leeuwenhoek both contributed greatly to the fields of microscopy and microbiology in their infancy, advancing each field by establishing a greater understanding in the other. As optics evolved and technologies derived from it became more refined, the number of discoveries in the realm of microbiology witnessed a concomitant increase. This fact was perhaps recognized in part with the award of the Nobel Prize in Physics in 1953 to Fritz Zernike for the phase contrast microscope, a tool which rendered otherwise invisible cells visible with relatively modest modifications to an existing microscope. Much work in microbiology followed as a result of this along with other developments in optics.

The relationship seemed to change, though, starting in the mid-twentieth century with the advent of molecular biology. During this time, molecular biological technologies evolved and matured to the point where discoveries were facilitated primarily by non-optical means, with microscopes serving as more of a tool for routine lab work than as significant drivers for learning something new. After all, a traditional light microscope is limited to observing structures no smaller than about one wavelength of light across, or about half a micron (one millionth of a meter). DNA, proteins, and all the other biomolecules are just too small to see, even for the most powerful microscope objectives.

Of course one could argue that the development of the targeted fluorescent proteins that reveal the location of a molecule's existence within a cell helped to advance the field of optics, but in this case the role of enabler switched sides; molecular biology led to an increase in the number of optical technologies for imaging fluorescent markers, such as fluorescence correlation spectroscopy. From the viewpoint of a scientist, this reversal is a bit distasteful. We would like for technology to enable new discoveries about the fundamentals of life, not for new discoveries to lead to technology that tells us what we already know.

Now we are well into the twenty first century and are rooted firmly within the scientific age of molecular biology and biotechnology. (The age of physics is now past and now concerns itself primarily with the ultimate limits of space: the infinitesimal quark and the awesomely large cosmos.) Given the history between optics and biology and the recent change in their relationship, I think it's necessary to make an assessment, so to speak, of this relationship.

In the near future I will write posts that explore this topic. I hope to answer questions like
  1. What do biologists want out of a measurement technique?
  2. Will the current trends in improving microscopies lead to answers of the fundamental questions of molecular and microbiology, or are we moving in the wrong direction?
  3. Are optical scientists misguided in the search for improved images? Are there other forms of information carried by light that are more useful than images?
  4. Will it be possible to better control biological processes using light?