Collaborative Research: Controlled Investigation of Micro- and Nanoscale Contact Interactions Between Microbes and Biomaterials Using Artificial Bacteria

University Of Utah, Salt Lake City UT

Investigators

Abstract

Moving bacteria and cells transport themselves though very dense environments of long molecules during normal biological processes and disease. Examples are sperm that travel through mucus in reproduction, bacteria of the nose, lung or gut penetrating mucus during infection, and soil and oceanic bacteria migrating through a bacterial mat of long-chain molecules. The molecules of mucus and other molecules of the body are often about the same length as a microbe. This means that individual and unpredictable interactions between microbes and molecules change how the microbes move. Experimental evidence suggests that microbial transport though such materials could be dominated by direct contact interactions with the individual molecules. Contact interactions are difficult to measure and their effect on locomotion is difficult to quantify. The overall goal of this research is to quantify the effect of direct contact interactions on the propulsion of bacteria. The research will use novel artificial bacteria, 'microrobots', and manufactured mucus to discover which contact interactions dominate transport. The data will improve our ability to understand, perhaps to control, the movement and spread of microorganisms in real-world environments. The investigators will work with local K-12 students in an outreach program named "Move Like a Microbe." The goal of the outreach is to intrigue the students using new understanding of bacterial mobility and encourage them into a science or technology (STEM) path in their later education. Understanding the nanomechanics of microbe transport also will improve our abilities to control disease and understand normal bacterial behavior. Microstructural interactions with swimming microorganisms have mostly been investigated using hydrodynamic and mechanical models. There has been no in-depth examination of the role of contact interactions mediated by electrostatic forces, van der Waals attraction, and biochemical bonding. This research will advance understanding of bacterial transport by combining new microrobotic artificial bacteria systems and a novel semisynthetic mucus to allow well-controlled and well-characterized experiments. The artificial models allow control of density, stiffness, surface charge, surface chemistry, and micromechanical properties, to clarify the relative importance of hydrodynamic, close-range, and nanoscale contact interactions for microbial transport through biological media. Numerical modeling will be used to integrate the interactions into quantitative models of transport. Finally, natural bacteria will be observed moving through well-defined biomaterials and their behavior will be correlated with that observed in the artificial systems, in order to identify which contact interactions are most important for biologically relevant scenarios, testing the hypothesis that contact interactions dominate the effect of organism-scale microstructure on bacterial swimming. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.