title: Enzymatically active biomimetic micropropellers for the penetration of mucin gels.
abstract: In the body, mucus provides an important defense mechanism by limiting the penetration of pathogens. It is therefore also a major obstacle for the efficient delivery of particle-based drug carriers. The acidic stomach lining in particular is difficult to overcome because mucin glycoproteins form viscoelastic gels under acidic conditions. The bacterium Helicobacter pylori has developed a strategy to overcome the mucus barrier by producing the enzyme urease, which locally raises the pH and consequently liquefies the mucus. This allows the bacteria to swim through mucus and to reach the epithelial surface. We present an artificial system of reactive magnetic micropropellers that mimic this strategy to move through gastric mucin gels by making use of surface-immobilized urease. The results demonstrate the validity of this biomimetic approach to penetrate biological gels, and show that externally propelled microstructures can actively and reversibly manipulate the physical state of their surroundings, suggesting that such particles could potentially penetrate native mucus.
authors.affiliation: Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany.; Institute for Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: Debora
authors.identifier: 0000-0002-5039-7435
authors.initials: D
authors.lastname: Walker
authors.affiliation: Institute for Medical Engineering and Department of Mechanical Engineering, Technische Universität München, Boltzmannstrasse 11, 85748 Garching, Germany.
authors.forename: Benjamin T
authors.initials: BT
authors.lastname: Käsdorf
authors.affiliation: Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany.
authors.forename: Hyeon-Ho
authors.initials: HH
authors.lastname: Jeong
authors.affiliation: Institute for Medical Engineering and Department of Mechanical Engineering, Technische Universität München, Boltzmannstrasse 11, 85748 Garching, Germany.
authors.forename: Oliver
authors.initials: O
authors.lastname: Lieleg
authors.affiliation: Max Planck Institute for Intelligent Systems, Heisenbergstrasse 3, 70569 Stuttgart, Germany.; Institute for Physical Chemistry, University of Stuttgart, Pfaffenwaldring 55, 70569 Stuttgart, Germany.
authors.forename: Peer
authors.initials: P
authors.lastname: Fischer
keywords: Micropropellers; biomimetic penetration of biological gels; gastric mucus barrier; gel-sol transition; helicobacter pylori swimming mechanism; muco-adhesion; propulsion in viscoelastic media; urease surface immobilization
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