title: Entrapment of subtilisin in ceramic sol-gel coating for antifouling applications.
abstract: Enzymes with antifouling properties are of great interest in developing nontoxic antifouling coatings. A bottleneck in developing enzyme-based antifouling coatings is to immobilize the enzyme in a suitable coating matrix without compromising its activity and stability. Entrapment of enzymes in ceramics using the sol-gel method is known to have several advantages over other immobilization methods. The sol-gel method can be used to make robust coatings, and the aim of this study was to explore if sol-gel technology can be used to develop robust coatings harboring active enzymes for antifouling applications. We successfully entrapped a protease, subtilisin (Savinase, Novozymes), in a ceramic coating using a sol-gel method. The sol-gel formulation, when coated on a stainless steel surface, adhered strongly and cured at room temperature in less than 8 h. The resultant coating was smoother and less hydrophobic than stainless steel. Changes in the coating's surface structure, thickness and chemistry indicate that the coating undergoes gradual erosion in aqueous medium, which results in release of subtilisin. Subtilisin activity in the coating increased initially, and then gradually decreased. After 9 months, 13% of the initial enzyme activity remained. Compared to stainless steel, the sol-gel-coated surfaces with active subtilisin were able to reduce bacterial attachment of both Gram positive and Gram negative bacteria by 2 orders of magnitude. Together, our results demonstrate that the sol-gel method is a promising coating technology for entrapping active enzymes, presenting an interesting avenue for enzyme-based antifouling solutions.
authors.affiliation: Interdisciplinary Nanoscience Center, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C, Denmark.
authors.forename: Viduthalai Rasheedkhan
authors.initials: VR
authors.lastname: Regina
authors.forename: Helmer
authors.initials: H
authors.lastname: Søhoel
authors.forename: Arcot Raghupathi
authors.initials: AR
authors.lastname: Lokanathan
authors.forename: Claus
authors.initials: C
authors.lastname: Bischoff
authors.forename: Peter
authors.initials: P
authors.lastname: Kingshott
authors.forename: Niels Peter
authors.initials: NP
authors.lastname: Revsbech
authors.forename: Rikke Louise
authors.initials: RL
authors.lastname: Meyer
mesh_terms: D000900:Anti-Bacterial Agents / Q000737:chemistry* / Q000494:pharmacology*; D018441:Biofilms / Q000187:drug effects*; D002516:Ceramics / Q000737:chemistry*; D020099:Coated Materials, Biocompatible / Q000494:pharmacology; D004800:Enzymes, Immobilized / Q000494:pharmacology; D008422:Materials Testing; D013193:Stainless Steel / Q000737:chemistry*; D020860:Subtilisin / Q000737:chemistry* / Q000494:pharmacology*
chemical_list: D000900:Anti-Bacterial Agents; D020099:Coated Materials, Biocompatible; D004800:Enzymes, Immobilized; D013193:Stainless Steel; D020860:Subtilisin