A UCD scientist is leading an international effort to find ways of producingperfect crystals, work that could lead to new drugs and novel materials,writes Dick Ahlstrom
Discovering ways to produce order from chaos is one way of understanding the work being tackled by a new European/US research network. Headed by a Dublin-based scientist, the network involves understanding how particles and molecules join up to make perfectly ordered structures.
A sugar crystal grown in solution is a good example of the kind of structure that can be imposed on molecules as they adopt a shape, but not all substances co-operate in this way, explains Prof Kenneth Dawson of University College Dublin.
Dawson, who holds the chair of physical chemistry at Belfield, was recently elected president of the European Colloid and Interface Society. It represents academics and industry researchers working on a wide range of subjects, from biomaterials and food processing to polymers and new materials.
He is also the co-ordinator of a major new research network with the cumbersome title "Dynamically Arrested Soft Matter and Crystallisation". It involves 14 European labs and two in the US at the Massachusetts Institute of Technology and Harvard.
"It is attempting to understand how to control the ordering of very small particles," explains Dawson. "You start with very small particles and want to do something with them."
Handling small particles to build a larger construct is the essence of new materials development, but a new material isn't much help if you don't know what it looks like or how it is put together, he says. It doesn't matter whether it is a novel new substance or a drug going ahead for clinical use. You have to know what the sample contains before it can be used safely.
Dawson cites as example the preparation of photonic crystals, crystals that respond at light wavelengths.
"In order to make them you have to make a perfect array, a perfect crystal. You have to develop a way to form such crystals," he explains. "If you don't order them you can't specify what they are. If you can't specify exactly what the substance is you can't use it."
This is particularly true for medicines. You might have data to show the drug has an action, but the regulatory authorities also want to know how the drug is put together, how its atoms are arranged. Delivering this information involves trying to get the molecules or particles assembled into an ordered structure so they can be imaged using X-ray crystallography, says Dawson.
"They need to be embedded in a lattice. In doing so, if they are all ordered in this lattice, the X-rays hit off them in the right way."
However, this is also the challenge placed before the new research network. It is easy to make sugar or salt crystals, but how would you form crystals of glass in order to study its molecular structure?
Despite what its name implies, lead crystal has nothing to do with actual crystals. Glass has no internal molecular structure, and Dawson and fellow chemists refer to any substance that has no crystalline structure as a "glass".
"You can think of it as an ultra, ultra thick liquid," says Dawson, referring to the glass in a window-pane or substances that refuse to crystallise. However, atoms and molecules in such substances do adopt a surprising and unlikely pattern when they form.
"It looks like a traffic jam or a pile of sand. I use the term jam advisedly," he says. In the same way that street traffic can jam together to prevent anything getting through, some substances resist crystallisation by jamming in very much the same way, he says. "We are trying to understand where the traffic jams are and what is causing them."
He developed laws to describe how jams can occur as particles slide and jostle around one another while being marshalled into a crystalline structure. These same laws work very well when describing the way cars jam up on a busy street.
"They are the same set of laws in the glass in a window and proteins as they gel and get trapped like in a traffic jam," he says. And, as is with real traffic, the trick, he adds, is to be able to control the space that forms around individual cars - or particles - as you direct them about. "The important thing is actually to understand how the internal space in a system is managed."
Why study such an exotic thing?
"It is one of the last great challenges of the condensed matter state," Dawson answers. Being able to form proper crystals of drugs, proteins and unique new materials is also essential if these are to reach the marketplace.