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Where physics meets biology

Although science is often taught as if the disciplines were clearly separated, exciting things can happen when the boundaries blur

Athene Donald, Friday 17 August 2012, guardian.co.uk

A beta in vitro2
Aggregates of the protein fragment (A β 1-40) associated with Alzheimer’s disease, grown in a test-tube. Photograph: Danielle Cannon

The Higgs boson and the probability that it’s been found have been much in the news recently; so has the safe landing on Mars of Nasa’s Curiosity. Good times for physicists in making mainstream newspapers, it would seem. But other physicists are quietly beavering away in less visible ways, doing what they’ve always done best: exploring the world around them with curiosity (that’s with a small ‘c’), cunning and creativity and at a wide range of different length- and time-scales. Physicists come in many different guises, and what excites one may leave another cold.

So let me lay my credentials on the table. I am a soft matter-cum-biological physicist and what excites me is the world around me, the soft squidgy stuff that turns up ubiquitously scattered around our houses in food, cosmetics, paint and ointments, in bulk plastics and novel materials for renewable energy devices; but also, pervasively, in the tissues of our own bodies and the rest of the animal kingdom. Yes, physics and biology can sometimes collide and when they do, it can produce something entirely new.

More than half a century ago, physics and biology came together in the work of Crick and Watson – working at my own place of work, the Cavendish Laboratory in Cambridge – with Franklin and Wilkins from Kings College, London. The structure of the DNA double helix was solved by bringing the then relatively new technique of X-ray diffraction to bear on the structure of carefully grown DNA crystals. Out of this and related work grew the whole field of molecular biology and, although physicists often migrated to work in this field, it became divorced from physics as a discipline.

For many years after that mainstream physics concentrated on "simple" systems which could be fully understood and modelled. Biology tended to be seen as messy and complicated, not a fit subject for a physicist (as a senior departmental colleague once made very clear to me as I made my initial forays into the field), and few individuals in physics departments braved the untidy world of biological organisms. As a result, those whose tastes remained biological would more likely be found in some form of biology department calling themselves biophysicists, or perhaps working as medical physicists in a hospital.

But times change and so do the attitudes of physicists towards messy systems. Complexity and emergent phenomena are most definitely now seen as proper domains for a physicist. Emergent phenomena cover processes where the outcome is more than the sum of the component parts, and something new emerges from collective behaviour that could not be predicted by looking at any contributing entity in isolation. This applies to superconductivity in certain complicated inorganic compounds, but also to the synchronised beating of heart cells. Studying biological systems with a physicist’s mindset has, if I can put it this way, become respectable, and as a soft matter physicist I no longer feel that colleagues frown upon my research if I mention that I am studying starch, proteins or cellular biophysics.

There was, in the past, one way that did seem acceptable for a physicist to enter the biological arena and that was by providing a service, typically imaging of some sort. Medical imaging has made great strides during the past decades – MRI, CAT scans and ultrasound being familiar to many from hospital visits, often transforming diagnostics and treatment – and much of their development work can be directly attributed to physicists and engineers.

The many new microscopies which are transforming the way we see cells function also owe a lot to physicists’ understanding of lenses, noise and image analysis algorithms, coupled with the power of lasers. But historically often this wasn’t a true collaboration, more a sort of service agreement, which can end up being frustrating for both sides.

My own interest in biological physics stems from my earlier research on synthetic polymers, the long-chain molecules very familiar from the polyethylene of polythene bags or in double glazing made from uPVC (short for unplasticised polyvinyl chloride). Long chain molecules behave in a particular way simply because they are long chains; they can get tangled up in a way small molecules cannot and this means their motion is severely restricted.

It also means they can interact at different places along their length to form both specific and non-specific junctions. For instance, in the case of proteins this means tangles and aggregates can form when their native, typically globular, structure is lost and they unravel to reveal their macromolecular (literally ‘large molecule’ from the Greek) nature. Such protein tangles may arise when denaturation occurs as you cook proteins and then cool them down again to get jelly or yogurt to set; or, more disastrously, they may form in the brains of patients suffering from the various neurodegenerative diseases of old age such as Alzheimer’s and Parkinson’s. In these cases it seems the native structure is lost just because the control mechanisms in our brain can break down over the years.

The physicist can apply the same basic principles and insights to these two very different situations, and maybe cast new light by looking for universalities rather than the specifics arising from the particular amino acid sequence each different protein possesses. That at least is the hope.

There are two drawbacks of working at this interface with biology. Firstly, there is the challenge of finding space to teach it in the undergraduate curriculum. Curricula are always overfull, and no one wants their pet topic to be ousted to make way for something new. The absence of any exposure of many undergraduates to these exciting new topics has been noted, however, and various reports have highlighted that something needs to be done about it (for instance, the 2005 EPSRC International Review of Physics remarked upon it, as did the 2008 RCUK Wakeham Review of Physics).

In order to help departments who perhaps lack researchers confident to tackle it, the Institute of Physics is preparing new material, which can be slotted in as and when a department feels able to do so. Secondly, because this field is inherently interdisciplinary it can struggle for funding, and may fall down the cracks between research councils. Notably the EPSRC (Engineering and Physical Sciences Research Council) may feel the physics isn’t original enough, the BBSRC (Biotechnology and Biological Sciences Research Council) may not see cutting edge biology being done, or the MRC (Medical Research Council) may think it is too far removed from disease.

Yet the excitement is precisely in bringing the different fields together so that, just as with emergent phenomena, the sum is more than its parts and two apparently "unoriginal" components can add up to something truly innovative and exciting. It certainly comes in considerably cheaper than hunting the Higgs.

So, with that brief overview of the field I work in, welcome to my own corner of the blogs at Occam’s Corner, the outpost on the Guardian blogs of Occam’s Typewriter. I aim to write not only about my science, but about the world I inhabit as a professor in a research-intensive university and the issues that affect me, my colleagues and the students we teach: expect blogging on the human face of science and the challenges for the workforce, as well as the science itself; and about the things that go right and the things that go, just occasionally, rather disastrously wrong.




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