Watch the video above to see a very recent advance in molecular science — the kind that would take months or years to reach classrooms before the edge of human knowledge moved online.
A Chemistry World post this week explains:
The researchers placed a thin film of water containing single stranded DNA molecules between a glass surface and a metal-coated base. By heating a spot on the base with an infrared laser a thermal gradient is created in the fluid layer, with cooler fluid at the top. This pushes the DNA molecules towards the top of the film. The laser is then scanned in a radial pattern from the centre; as the laser spot moves it heats up the fluid locally causing changes in viscosity which result in contraction and expansion of the fluid either side of the moving spot, which causes the fluid to flow outwards, away from the centre. The layer of fluid above this moving ‘belt’ moves in the opposite direction to conserve mass. In this way, the molecules, which have been drawn to the upper layer of the fluid by the initial heating, are pulled towards the central spot, where they accumulate.
Weinert and Braun showed that high concentrations of DNA can be accumulated within a few seconds when carried on the conveyor. ‘The mechanism does not require microfluidics, electrodes, or surface modifications,’ the researchers say. ‘As a result, the trap can be dynamically relocated. The optical conveyor can be used to enhance diffusion-limited surface reactions, redirect cellular signalling, observe individual biomolecules over a prolonged time, or approach single-molecule chemistry in bulk water.’
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