Infection under the ion beam : focused ion beams and antibacterial properties of biomaterials

Abstract

In this thesis, Helium Ion Microscopy (HIM) imaging and milling on organic and antibacterial materials will be discussed. In addition, I will discuss the antibacterial properties of surface-immobilized bacteriophages. HIM is a recently developed imaging method, which is especially suitable for biological samples because they can be imaged without a metal coating. Because of the state-of-the-art ion source, the microscope has also a higher imaging resolution compared to the scanning electron microscope (SEM). The suitability of HIM imaging for the bacteria-phage interactions is discussed in addition to the more delicate nanocellulose samples. High beam damage on the cellulose was found which has not been reported previously with HIM. Indeed an ion beam can have a milling property, which is demonstrated here with bacteria, bacteria-dragonfly interactions and encapsulated bacteriophages to obtain volumetric information. The antibacterial effectivity of immobilized bacteriophages was analyzed quantitatively with HIM-imaging and biological measures. It was found that detaching phages from the material are likely the major contributor to the infectivity of the phage-biomaterial.