Quantitative Characterization of Viscoelastic Properties of Environmental Biofilms based on Optical Coherence Elastography

Biofilms are complex biological materials comprised of living bacterial cells that are encased in a dynamic extracellular matrix (ECM). The ECM is a slimy aggregate that contains a variety of biopolymers including polysaccharides, proteins, and extracellular DNA. The arrangement of these biopolymers in a biofilm contributes to its dynamic heterogeneous architecture and mechanical stability, facilitates its adhesion to surfaces, and acts as a source of nutrients for growing bacterial cells. Mechanical properties play a crucial role in the persistence of biofilms on surfaces, and their structural failure allow biofilms to disperse and recolonize new surfaces in the environment. Proliferating biofilms can impact the spread of infectious diseases through bacterial growth on medical devices, food processing equipment's, and drinking water systems, and lead to biofouling of pipelines, ship hulls, and industrial equipment. In this lecture, I will review recent advances in mechanical characterization techniques for probing the heterogeneous mechanical properties of environmental biofilms. In particular, I will describe a new approach called Optical Coherence Elastography (OCE) for viscoelastic characterization of environmental biofilms and partially transparent hydrogels that my research group, in collaboration with Professor George Well's group, developed recently. OCE studies on synthetic biofilm materials may provide a promising pathway to investigate the influence of single or multiple biopolymer components on the mesoscale mechanical properties of the ECM and to understand how these properties control biofilm performance and function in beneficial contexts like waste-water purification systems.