TITLE:
A Biomimetic Gellan-Based Hydrogel as a Physicochemical Biofilm Model
AUTHORS:
Jan Hellriegel, Steffi Günther, Ingo Kampen, Antonio Bolea Albero, Arno Kwade, Markus Böl, Rainer Krull
KEYWORDS:
Biofilm Mechanics; Gellan Based Hydrogel; Viscoelasticity; Design of Experiments (DoE); Surface Response Methodology
JOURNAL NAME:
Journal of Biomaterials and Nanobiotechnology,
Vol.5 No.2,
March
31,
2014
ABSTRACT: Biofilm-forming microorganisms are ubiquitous,
but continuous cultivation of these microorganisms with predictable biofilm
growth and structural properties remains challenging. The development of a
reliable simulated biofilm has been limited by a lack of information about the
microorganism subpopulations and fluid-structure interactions involved in
biofilm formation and detachment due to mechanical stress. This paper presents
a gellan-based hydrogel as an alternative material for a simulated physicochemical
biofilm. The mechanical properties of the hydrogel in terms of the storage (G')
and loss (G'') moduli can be tuned and adapted to imitate biofilms of different
strengths by changing the concentration of gellan and mono(Na+) or
divalent (Mg2+) ions. The storage modulus of the hydrogel ranges
from 2 to 20 kPa, and the loss modulus ranges from 0.1 to 2.0 kPa. The material constants of the hydrogels
and biofilms of Pseudomonas putida KT2440 were experimentally determined by rheometric analysis. A simplified
biofilm imitate based on highly hydrolyzed gellan hydrogels was established by
using experimental design techniques that permitted independent analyses
regardless of growth. This model system design was compared to real biofilms and was
adapted to mimic the mechanical properties of biofilms by changing the hydrogel
composition, resulting in biofilm-like viscoelastic behavior. The use of a
gellan-based hydrogel enables the imitation of biofilm behavior in the absence
of growth effects, thus simplifying the system. Biofilm characterization tools
can be tested and verified before their application to the measurement of
slow-growing, highly variable biofilms to estimate system errors, which are
often smaller than the biological variations. In general, this method permits
faster and more reliable testing of biofilm mechanical properties.