The new Standing Wave Axial Nanometry (SWAN) microscope technology enables comprehensive 3D measurement of single bio-molecules with unparalleled accuracy and precision. Unlike existing technologies which measure molecules along the x and y axes, SWAN allows height measurements along the z axis down to the nanometer level, without any custom optics or special surfaces for the samples.
Here a commercial atomic force microscope is attached to a single molecule fluorescence microscope. The tip of the atomic force microscope is positioned over a focused laser beam to create a standing wave pattern. A molecule pre-treated to emit light is placed within the standing wave. As the tip of the atomic force microscope moves vertically, the fluorescence emitted by the molecule fluctuates in a way that corresponds to its distance from the surface. That distance can be compared to a marker on the surface and measured. The axial position is determined from the phase of the emission intensity.
It can be used to image the axial location of a single nanoscale fluorescent object with sub-nanometer accuracy and repeatedly measured upto 3.7 nm precision.
Iowa State University and Ames Laboratory researchers- Sanjeevi Sivasankar, Hui Li and Chi-Fu Yen, who devised this technology, used fluorescent nanospheres and single strands of DNA to calibrate, test and prove the new instrument. It has been used to measure the orientation of single DNA molecules of different lengths, grafted on surfaces with different functionalities
Medical researchers and other biology/biotechnology researchers in need of high-resolution data from microscopes, stand to benefit most from this.
Source: Iowa State University