KBC / UCMR Seminar
Adam Olsson
McGill University, Canada
Title:
"Acoustic Sensing of Bacterium-Substratum Interfaces"
Room: KB3B3, KBC
Host: Madeleine Ramstedt
Abstract:
Acoustic Sensing of Bacterium-Substratum Interfaces
Adam L.J. Olsson
McGill University
Bacterial adhesion to surfaces and subsequent biofilm formation is an important phenomenon in many areas including, amongst others, biomedical engineering, food processing and water treatment. Since biofilms essentially originate from only a few initial bacterial colonizers, understanding the mechanisms governing the initial bacterial adhesion event may help designing surfaces with the ability to manipulate biofilm formation.
This presentation explores the possibilities to utilize a quartz crystal microbalance with dissipation monitoring (QCM-D) to acoustically sense the mechanical properties of the bacterium-surface interface. The QCM-D is generally considered a mass balance, where a negative shift in the resonance frequency of a quartz crystal sensor is proportional to attached mass. However, in the case of bacterial adhesion, the surface attached bacterium possesses a resonance frequency that couples to the oscillation of the sensor surface. The resulting frequency shift of this “coupled resonance” is either negative or positive, depending on the ratio between QCM-D resonance frequency and the bacterium resonance frequency which, in turn, is determined by its mass and surface contact stiffness. Thus, analyzing bacterial adhesion in QCM-D within the context of “coupled resonance” offers a unique opportunity to monitor mechanical properties of bacterium-surface contacts.
Since the quartz sensor is mounted in a temperature controlled flow module, and because change in resonance frequency of the sensor is monitored in real time, it possible to follow dynamic changes of the bacterium-surface contact during both the initial adhesion event as well as during subsequent biofilm growth. Another important aspect of the method is that the stiffness, which is related to bond strength, is investigated without detaching the bacteria from the surface; hence the method is non-destructive.