Graphene-Assisted Electron Microscopy for Advanced Chemical & Biological Analysis

Abstract

In the 1st part, we demonstrate, for the first time, the liquid phase nanobubbles encapsulated by graphene membrane can be visualized by in-situ UHV-TEM, showing the critical radius of nanobubbles determining its long-term stability as well as two different growth processes of merging nanobubbles depending on their relative sizes. Finally, we confirm that the nanobubbles can catalyze the nucleation and growth of nanoparticles. Our result is believed to provide a deeper understanding on the extraordinary behaviors and functions of nanobubbles.

The behaviors of nanobubbles have been predicted by theoretical studies, but their actual observation with graphene liquid cells needs diverse knowledge and technologies ranging from chemical synthesis, electron microscopy and fluid dynamics to electrochemical and biological approaches. Thus, the present study can be accomplished only by wide interdisciplinary collaboration. In addition, many problems in our environment are associated with water. Therefore, our finding on new properties and functions of water and nanobubbles will attract immediate concern from the public, which is believed to match well with the scope of a topical, interdisciplinary journal.

In the 2nd part, we found that graphene-coating alternative to metal coating enables non-destructive high-resolution imaging by scanning electron microscopy (SEM) as well as chemical analysis by EDS, utilizing graphenes transparency to electron beams, high conductivity, outstanding mechanical strength, and flexibility. Comprehensive understanding of biological objects can be effectively achieved through electron microscopy (EM) analysis, more effectively without any auxiliary treatment. However, charge accumulation on non-conductive surface by electron beams has always hampered EM-mediated biological studies.

The outstanding performance of atomically thin graphene membrane as protective coating for EM analysis was theoretically confirmed by Monte Carlo simulations. We believe that the graphene-coated imaging and analysis would provide us a new opportunity to explore various biological phenomena unseen before due to the limitation in sample preparation and image resolution, which will broaden our understanding on the life mechanism of various living organisms.