Low-energy microscope aids pharmaceutical developments

Scientists are using a new kind of low-energy microscope to develop improved vaccines and drugs.

The technology, developed at the Rutherford Appleton Laboratory (RAL) in Harwell, Oxfordshire, allows researchers to observe processes in living cells for long periods of time without interfering with or damaging them.

A team at Imperial College London is using the microscope to develop more effective avian influenza vaccines, while pharmaceutical company UCB hopes to improve cancer drugs by studying ageing cells.

The equipment uses two techniques that involve detecting radiation from the cells and the molecules inside them as they interact with the proteins of vaccines and viruses.

‘Normally we would fire visible light into the cellular system to try to excite a fluorescent probe and to visualise where things are in the cell,’ said RAL’s Dr Stan Botchway, who developed the equipment for the Science and Technology Facilities Council (STFC).

‘But you can’t look at the cells for a long period of time because you would heat up the cell or cause photo damage. By using near-infrared light, which is completely harmless, you can look at the cell for a much longer period of time.’

The second technique provides a way of looking at protein interaction inside cells without breaking them open first.

It relies on a process known as Förster/fluorescence resonance energy transfer (FRET) where energy is transferred between molecules that come within a few nanometres of each other.

This energy transfer puts the receiving molecule into an excited state but for slightly less time than by other means of excitation.

Botchway developed an instrument to measure these tiny time differences (as short as 25 picoseconds) and indicate where FRET is taking place.

‘With this we can tell whether the molecules are interacting or not,’ he said. ‘You tag one protein with one fluorescent molecule [donor] and another protein you’re interested in with another fluorescent molecule [acceptor] and if the two proteins are touching you get the change.’

Botchway originally developed the technology several years ago for studying photodynamic cancer therapy drugs and then moved on to looking at protein interaction.

‘By combining all these problems we now have a methodology that is widely applicable to several questions in biology, so it’s almost a universal tool for looking at how proteins and small molecules behave in cells,’ he said.

The research at Imperial is part of the Biotechnology and Biological Sciences Research Council’s (BBSRC) Combating Avian Influenza initiative. Details were published in a paper in the December 2010 edition of the Journal of Virology.

Pox virus infecting avian cells - image captured using confocal microscopy in the Central Laser Facility
Pox virus infecting avian cells – image captured using confocal microscopy in the Central Laser Facility (STFC and Oxford Brookes University)