Produção de imagem biológica com microscopia eletrônica de 4D ultra rápida

terça-feira, maio 18, 2010

Biological imaging with 4D ultrafast electron microscopy

David J. Flannigan,  Brett Barwick, and Ahmed H. Zewail1

-Author Affiliations

1. Physical Biology Center for Ultrafast Science and Technology, Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, CA 91125

Contributed by Ahmed H. Zewail, April 26, 2010 (sent for review April 17, 2010)


Advances in the imaging of biological structures with transmission electron microscopy continue to reveal information at the nanometer length scale and below. The images obtained are static, i.e., time-averaged over seconds, and the weak contrast is usually enhanced through sophisticated specimen preparation techniques and/or improvements in electron optics and methodologies. Here we report the application of the technique of photon-induced near-field electron microscopy (PINEM) to imaging of biological specimens with femtosecond (fs) temporal resolution. In PINEM, the biological structure is exposed to single-electron packets and simultaneously irradiated with fs laser pulses that are coincident with the electron pulses in space and time. By electron energy-filtering those electrons that gained photon energies, the contrast is enhanced only at the surface of the structures involved. This method is demonstrated here in imaging of protein vesicles and whole cells of Escherichia coli, both are not absorbing the photon energy, and both are of low-Z contrast. It is also shown that the spatial location of contrast enhancement can be controlled via laser polarization, time resolution, and tomographic tilting. The high-magnification PINEM imaging provides the nanometer scale and the fs temporal resolution. The potential of applications is discussed and includes the study of antibodies and immunolabeling within the cell.

evanescent    nanoscale   biostructure


1To whom correspondence should be addressed. E-mail:

Author contributions: D.J.F., B.B., and A.H.Z. designed research, performed research, contributed new reagents/analytic tools, analyzed data, and wrote the paper.

The authors declare no conflict of interest.


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