Atomic Force Microscopy of Biofilms—Imaging, Interactions, and Mechanics

Abstract

Atomic force microscopy (AFM) has proven itself to be a powerful and diverse tool for the study of microbial systems on both single and multicellular scales including complex biofilms. This chapter will review how AFM and its derivatives have been used to unravel the nanoscale forces governing the structure and behavior of biofilms, thus providing unique insight into the control of microbial populations within clinical and industrial environments. Diversification of AFM-based technologies has allowed for the creation of a truly multiparametric platform, enabling the interrogation of all aspects of microbial systems. Advances in traditional AFM operation have allowed, for the first time, insight into the topographical landscape of both microbial cells and spores, which, when combined with high-speed AFM's ability to resolve the structure of surface macromolecules, have provided, with unparalleled detail, visualization of this complex environmental interface. The application of AFM force spectroscopies has enabled the analysis of many microbial nanomechanical properties including macromolecule folding pathways, receptor ligand binding events, microbial adhesion forces, biofilm mechanical properties, and antimicrobial/antibiofilm affectivities. Thus, AFM has offered an outstanding glimpse into the biofilm, how its inhabitants create and use this complex adaptive interface, and perhaps most importantly what can be done to control this.

Atomic force microscopy studies of bioprocess engineering surfaces – imaging, interactions and mechanical properties mediating bacterial adhesion

“…Several studies have been completed detailing the effect of surface roughness on bacterial adhesion [10][11][12][13][14][15][16][17][18]. The consensus of the aforementioned studies being that on the micro-scale, bacterial adhesion is at its peak when the arithmetic roughness (R a ) of the surface nears the diameter of the cell.…”

“…However, due to the mobility of some bacterial species and the generally weak forces binding the cells to the surface, immobilization of the cells is often required to prevent destruction of the sample . Comprehensive review of the methods employed in the immobilization of bacterial cells can be found here . However, for the purposes of this review a brief summery shall be supplied.…”

Review on the microbiologically influenced corrosion and the function of biofilms

“…From the MIC point of view, the 3D imaging (providing important information on the form, length, width, outer part of microbial cells) and the force measurements are mostly used. [88,89].…”

Testing Anti-Biofilm Polymeric Surfaces: Where to Start?

“…AFM consists of a tip held in intimate contact with the surface. When the tip is scanned across the surface, it encounters surface forces and the cantilever is deflected, generating force–sample distance curves [349]. As samples can be examined in their native state, sample preparation is minimal, greatly reducing the development of artefacts [350].…”