A Modular Flow Cell System for Studying Biomimetic and BioinspiredAnti-Adhesive and Antimicrobial Surfaces

ABSTRACT

Biofouling causes serious problems in many kinds of technical equipment. Consequently, there is great interest in developing surfaces with anti-adhesive and antimicrobial properties. Many such surfaces exist in nature, and artificial systems that mimic or are inspired by these natural systems could potentially be valuable technical surfaces. Recent studies on the interactions of bacteria with cicada wings revealed that rather than the wings being effective at repelling bacteria, after attachment the wing surface disrupts bacterial cell walls. Inspired by these structures, SmartMembranes GmbH used electrochemical precision etching to produce porous anodized aluminum oxide (AAO) membranes with structurally well-defined surface nanopatterns having pore diameters of 200–300 nm. We investigated the surfaces of these AAO membranes to assess their potential to prevent biofouling, using Escherichia coli as a model microbe. Bacterial adhesion tests were conducted using a modular flow cell system that is designed to enable on-line observation of biofilm formation in continuous flow on opaque surfaces using a fluorescence microscope. The system was adapted to permit testing of multiple samples with various dimensions and material properties simultaneously. Bacterial adhesion tests showed that AAO surfaces with pore diameters of 300 nm exhibit 99% less biofilm growth than widely used electropolished stainless steel.

Acknowlegdment

The authors thank Dr. M. Zschaetzsch for help with flow chamber experiments and Dr. C. Bellmann of the Leibniz Institute for Polymer Research Dresden for performing the contact-angle measurements. We also acknowledge the valuable help in REM provided by Dipl.-Ing. P. Viala of the Institute of Process Engineering and Environmental Technology TU Dresden. This work was financially supported by the Central Innovation Program SME (Zentrales Innovationsprogramm Mittelstand [ZIM]) of the Federal Ministry for Economic Affairs and Energy, Germany.

Additional information

Notes on contributors

Susan Mulansky

Susan Mulansky is a Ph.D. student at the Institute of Food Technology and Bioprocess Engineering at TU Dresden (Biomonitoring Group), Germany, under the supervision of Prof. Dr. Thomas Bley and Assoc. Prof. Dr. Elke Boschke. She received a Diploma of Engineering in bioprocess engineering at TU Dresden in 2012. She is currently working on bacterial adhesion on bioinspired surfaces.

Petra Goering

Petra Göring is a Managing Partner at SmartMembranes GmbH, Germany, the leading manufacture of high-ordered porous materials from alumina and silicon with defined and adjustable membrane properties and structural parameters. She graduated in chemistry at the Martin-Luther-University Halle-Wittenberg in 1994, and completed her Ph.D. in the Department of Physical Chemistry of the same university in 1997. She then worked as a researcher in several scientific institutions, including the Max Planck Institute of Microstructure Physics, University of Paderborn, and MLU Halle-Wittenberg, before founding SmartMembranes GmbH in July 2009. She is currently responsible for production and research and development (R&D), as well as sales and marketing in the company.

Maria Ruhnow

Maria Ruhnow worked at the Institute of Food Technology and Bioprocess Engineering at TU Dresden (Biomonitoring Group), Germany, under the supervision of Prof. Dr. Thomas Bley and Assoc. Prof. Elke Boschke. She received a Diploma of Engineering in bioprocess engineering at TU Dresden in 2013, and is currently working as a validation expert regarding cleaning, process, and packaging activities in the manufacturing and science technology group at Novartis Pharma Produktions GmbH.

Felix Lenk

Felix Lenk is a postdoc at the Institute of Food Technology and Bioprocess Engineering at TU Dresden, Germany, and leader of the SmartLab-Systems group working on the next generation of laboratory devices and systems. He studied Automation & Control and Electrical Engineering at the TU Dresden, Germany, and at the University of Calgary, Calgary, Alberta, Canada, and graduated in 2009. In 2014 he received his Ph.D. in bioprocess engineering at TU Dresden in the field of growth modeling of plant in vitro cultures. He currently works in the field of autonomous sensor systems and laboratory automation for different applications.

Thomas Bley

Thomas Bley has held the Chair of Bioprocess Engineering at the TU Dresden, Germany since 1996. He graduated in mathematics at the TU Dresden in 1975, received his Ph.D. degree in 1981, and qualified as a postdoctoral lecturer in 1990. His research focus is on biomonitoring and biosignals (flow cytometry), modeling and controlling of bioprocesses, biocatalysis in heterogeneous systems, and white biotechnology and plant cells in bioreactors.

Elke Boschke

Elke Boschke is an associate professor (PD) at the Institute of Food Technology and Bioprocess Engineering at TU Dresden, Germany, leading the Biomonitoring Group. She graduated in biology at the Donezk State University, Ukraine, in 1975, received her Ph.D. in the Department of Forest Sciences of the TU Dresden in 1983, and qualified as a postdoctoral lecturer in the Faculty of Mechanical Engineering of the TU Dresden in 2008. Her current research interests include the analysis of bacterial adhesion and biofilm formation, the identification and characterization of target molecules utilizing surface plasmon resonance (SPR), and optimizing procedures for biomagnetic separation using variable magnetic fields.