Carbon nanofiber orientation influences bacterial adhesion under flow conditions

Biosensing methods continue to increase in complexity, and together with growing interest in living materials, new options for fixing bacteria under flow conditions are needed. Current methods of cell fixation consist of microfluidic cell trapping, dielectrophoretic immobilization, chemical fixation, or cell encapsulation. However, these methods come with disadvantages, such as chemical alteration, isolation, or exposure to high shear forces. In this work we present electrospun carbon nanofibers as a new cell scaffold material, and explored the potential of this material for bacterial adhesion under normal flow conditions. To characterize immobilization, model organisms E. coli were introduced into carbon nanofiber samples, and after an incubation period, perfusion at different flow speeds was applied. Adhesion was quantified by counting the number of bacteria remaining on the scaffold after a fixed period of flow exposure. The fibers were additionally characterized for their wettability and surface roughness, properties expected to influence adhesion. It was observed that a larger fraction of bacteria remained on the scaffold as flow rates increased in comparison with surfaces without the scaffold. Thus, electrospun carbon nanofibers provide an interesting approach of bacterial fixation given their biocompatibility and tune-able properties ( e.g. electrical conductivity and fiber diameter), opening a variety of applications and enabling tailored scaffolds optimized for a variety of processes and bacteria strains.