title: Microrheology of growing Escherichia coli biofilms investigated by using magnetic force modulation atomic force microscopy.
abstract: Microrheology of growing biofilms provides insightful information about its structural evolution and properties. In this study, the authors have investigated the microrheology of Escherichia coli (strain HCB1) biofilms at different indentation depth (δ) by using magnetic force modulation atomic force microscopy as a function of disturbing frequency (f). As δ increases, the dynamic stiffness (ks) for the biofilms in the early stage significantly increases. However, it levels off when the biofilms are matured. The facts indicate that the biofilms change from inhomogeneous to homogeneous in structure. Moreover, ksis scaled to f, which coincides with the rheology of soft glasses. The exponent increases with the incubation time, indicating the fluidization of biofilms. In contrast, the upper layer of the matured biofilms is solidlike in that the storage modulus is always larger than the loss modulus, and its viscoelasticity is slightly influenced by the shear stress.
authors.affiliation: Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, People's Republic of China.
authors.forename: Tiansheng
authors.initials: T
authors.lastname: Gan
authors.affiliation: Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, People's Republic of China.
authors.forename: Xiangjun
authors.initials: X
authors.lastname: Gong
authors.affiliation: Physical Chemistry I, Department of Chemistry and Biology & Research Center of Micro and Nanochemistry and Engineering (Cμ), University of Siegen, Adolf-Reichwein-Str. 2, 57076 Siegen, Germany.
authors.forename: Holger
authors.initials: H
authors.lastname: Schönherr
authors.affiliation: Faculty of Materials Science and Engineering, South China University of Technology, Guangzhou 510640, People's Republic of China.
authors.forename: Guangzhao
authors.initials: G
authors.lastname: Zhang
mesh_terms: D018441:Biofilms / Q000254:growth & development*; D004926:Escherichia coli / Q000502:physiology*; D008280:Magnetics / Q000379:methods; D018625:Microscopy, Atomic Force / Q000379:methods; D012212:Rheology / Q000379:methods; D014783:Viscosity