Biomolecules: Enzymatically active biomimetic micropropellers for the penetration of mucin gels

Abstract

In the body, mucus provides an important defensemechanism by limiting the penetration of pathogens. It is therefore also amajor 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 themucus barrier by producing the enzymeurease,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 tomove through gastricmucin gels bymaking use of surface-immobilized urease. The results demonstrate the validity of this biomimetic approach to penetrate biological gels, and showthat externally propelled microstructures can actively and reversibly manipulate the physical state of their surroundings, suggesting that such particles could potentially penetrate native mucus.