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Fluorescent bursts aid nano-imaging
09 May 2006
US chemists have measured nanometre distances previously unattainable by conventional microscopy.
Robin Hochstrasser's team from the University of Pennsylvania claim that the technique, which uses a fluorescent probe, can easily be used with existing microscopes and has potential uses in nanotechnology and biological systems.
The probe, known as Nile Red, is non-fluorescent in water but emits light when bound to a hydrophobic particle. By studying the trajectory of fluorescent bursts emitted by Nile Red molecules when they collided with lipid vesicles, Hochstrasser calculated the inter-vesicle distances.
The resolution of the technique, known as trajectory time distribution optical microscopy, is not limited by diffraction in the same way as conventional microscopy, enabling Hochstrasser to measure inter-vesicle distances as small as 160 nm.
Aiping Zhu, an expert in fluorescence microscopy from the University of Michigan, US, sees the potential of Hochstrasser's technique. 'This method substantially improves spatial resolution of the microscope and is therefore very significant,' he said.
Hochstrasser's team are now working on creating images in living cells. Point-like objects with a separation as small as 40 nm should be distinguishable, if predictions from simulated results are correct, he said.
'The next step is the construction of a high spatial stability imaging microscope based on the principles of this research,' said Hochstrasser.
Joanne L Thomson
E Mei, F Gao and R M Hochstrasser, Phys. Chem. Chem. Phys., 2006, 8, 2077