(194h) Optical Nanosensors for Monitoring 3D Oxygen Gradients and Oscillations in Biofilms

Bacterial biofilms can form persistent infections on wounds, on implanted medical devices, and are associated with many chronic diseases, such as cystic fibrosis. These infections are medically difficult to treat due to slow antibiotic penetration through the biofilm matrix making biofilms more resistant to antibiotic attack compared to their planktonic counterparts. The development of nanosensors to spatially and temporally monitor the behavior of biofilms via target analytes is a critical component towards improved understanding of biofilms and treatments. To this end, we developed oxygen-sensitive optical nanosensors to measure 3D oxygen gradients and growth oscillations within Pseudomonas aeruginosa biofilms.

Using this approach, we improved on traditional electrode-based 1D methods of measuring oxygen profiles by investigating the spatial and temporal variation of oxygen concentration during biofilm growth and the changes in oxygen consumption rates when biofilms are challenged with antibiotic attack. We observed spatial oxygen oscillations as the biofilm grew due to the dichotomy between the protection of interior cells and the nutrient consumption that occurs during growth. Further, we studied 3D oxygen gradients where oxygen was present at greater biofilm depths under antibiotic attack compared to the untreated controls.