Low-dose phase retrieval of biological specimens using cryo-electron ptychography

Dr Judy Kim, Professor Pete Nellist, Professor Angus Kirkland and colleagues from Jiangsu and Nanjing Universities, used cryo-electron microscopy to study frozen-hydrated specimens of rotavirus double-layered particles and HIV-1 virus-like particles under low-dose conditions.  This method was also used to study heterogeneous objects in an Adenovirus-infected cell over large fields of view.

The method relies on the use of phase contrast imaging at high defocus to improve information transfer at low spatial frequencies at the expense of higher spatial frequencies.  This paper, published in Nature Communications, demonstrates that electron ptychography can recover the phase of the specimen with continuous information transfer across a wide range of the spatial frequency spectrum, with improved transfer at lower spatial frequencies, and as such is more efficient for phase recovery than conventional phase contrast imaging.