Investigation of in-vitro bacterial surface layer formation by FBARs

We report investigations on the adsorption and in-vitro recrystallization kinetics of the bacterial surface layer protein of Bacillus sphaericus NCTC 9602 on gold surfaces by means of film bulk acoustic resonators. The acoustic resonators were operated in shear mode at about 800 MHz. From the measured changes of frequency and in dissipation, the mass and the viscoelasticity of biomolecular films formed at the top electrode of the device could be derived, respectively. The measured data revealed that protein adsorption is a fast process while the time constant for the recrystallization of the monomers into ordered two-dimensional protein crystals is typically on the order of 1 h.