Journal of Biomaterials and Nanobiotechnology, 2014, 5, 83-97 Published Online April 2014 in SciRes. http://www.scirp.org/journal/jbnb http://dx.doi.org/10.4236/jbnb.2014.52011 How to cite this paper: Hellriegel, J., Günther, S., Kampen, I., Albero, A.B., Kwade, A., Böl, M. and Krull, R. (2014) A Biomi- metic Gellan-Based Hydrogel as a Physicochemical Biofilm Model. Journal of Biomaterials and Nanobiotechnology, 5, 83-97. http://dx.doi.org/10.4236/jbnb.2014.52011 A Biomimetic Gellan-Based Hydrogel as a Physicochemical Biofilm Model Jan Hellriegel 1 , Steffi Günther 2 , Ingo Kampen 2 , Antonio Bolea Albero 3 , Arno Kwade 2 , Markus Böl 3 , Rainer Krull 1 1 Institute of Biochemical Engineering, Technische Universität Braunschweig, Braunschweig, Germany 2 Institute for Particle Technology, Technische Universität Braunschweig, Braunschweig, Germany 3 Institute of Solid Mechanics, Technische Universität Braunschweig, Braunschweig, Germany Email: r.krull@tu-braunschweig.de Received 17 December 2013; revised 5 March 2014; accepted 18 March 2014 Copyright © 2014 by authors and Scientific Research Publishing Inc. This work is licensed under the Creative Commons Attribution International License (CC BY). http://creativecommons.org/licenses/by/4.0/ Abstract Biofilm-forming microorganisms are ubiquitous, but continuous cultivation of these microorgan- isms with predictable biofilm growth and structural properties remains challenging. The devel- opment of a reliable simulated biofilm has been limited by a lack of information about the micro- organism subpopulations and fluid-structure interactions involved in biofilm formation and de- tachment 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 dif- ferent strengths by changing the concentration of gellan and mono- (Na + ) or divalent (Mg 2+ ) 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 tech- niques 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 er- rors, which are often smaller than the biological variations. In general, this method permits faster and more reliable testing of biofilm mechanical properties. Keywords Biofilm Mechanics; Gellan Based Hydrogel; Viscoelasticity; Design of Experiments (DoE); Surface Response Methodology