Redrawing Microscopy’s Boundaries

Two Andor back-illuminated electron-multiplying CCD (EMCCD) cameras have been instrumental in helping Steven Chu, a Nobel laureate and current US Secretary of Energy, redraw the boundaries of optical microscopy.

By developing an active feedback system, Chu and his team repeatedly placed the centroid of a single fluorescent molecule image anywhere on either of two cameras’ CCD arrays and measure its position with subpixel accuracy. This means that, in conjunction with additional optical beams to stabilize the microscopy system, traditional errors caused by nonuniformity of chip manufacture can be reduced to subnanometer scale.

As a result, the team was able to develop a two-color, single-molecule imaging system, which achieved image resolutions with an order of magnitude greater than the current best superresolution techniques (5 nm). The system is described in the July 29 online edition of Nature.

One of the cameras used by the group was an Andor DU860, which is capable of acquiring images at 500 frames per second; the other was a highly sensitive DU897 model that can capture individual photons from single fluorescence emitters.

Gaining the ability to resolve single molecules at this level has significant implications for biological research, where it should allow the structure of large, multisubunit complexes to be analyzed at the single-molecule level.

Chu and his colleagues are planning to harness the new technique to learn more about the human RNA polymerase II system, which initiates the transcription of DNA, and the molecular mechanisms controlling cell-to-cell adhesion processes.

The resolving power of this new superresolution technique may also be of great use in guiding the design of new photometric imaging systems in scientific fields such as nanometrology, atomic physics and astronomy.

For more information, visit: www.andor.com