Graphene-Enhanced 3D Chemical Mapping of Biological Specimens at Near-Atomic Resolution

The direct imaging of individual atoms within the cellular context holds great potential for understanding the fundamental physical and chemical processes in organisms. Here, a novel approach for imaging of electrically insulated biological cells by introducing a graphene encapsulation approach to disguise the low-conductivity barrier is reported. Upon successful coating using a water-membrane-based protocol, the electrical properties of the graphene enable voltage pulsing field evaporation for atom probe tomography (APT). Low conductive specimens prepared from both Au nanoparticles and antibiotic-resistant bacterial cells have been tested. For the first time, a significant graphene-enhanced APT mass resolving power is also observed confirming the improved compositional accuracy of the 3D data. The introduction of 2D materials encapsulation lays the foundation for a breakthrough direction in specimen preparation from nanomembrane and nanoscale biological architectures for subsequent 3D near-atomic characterization.