title: Alternating Current Electrophoretic Deposition for the Immobilization of Antimicrobial Agents on Titanium Implant Surfaces.
abstract: One prominent cause of implant failure is infection; therefore, research is focusing on developing surface coatings that render the surface resistant to colonization by micro-organisms. Permanently attached coatings of antimicrobial molecules are of particular interest because of the reduced cytoxicity and lower risk of developing resistance compared to controlled release coatings. In this study, we focus on the chemical grafting of bioactive molecules on titanium. To concentrate the molecules at the metallic implant surface, we propose electrophoretic deposition (EPD) applying alternating current (AC) signals with an asymmetrical wave shape. We show that for the model molecule bovine serum albumin (BSA), as well as for the clinically relevant antifungal lipopeptide caspofungin (CASP), the deposition yield is drastically improved by superimposing a DC offset in the direction of the high-amplitude peak of the AC signal. Additionally, in order to produce immobilized CASP coatings, this experimental AC/DC-EPD method is combined with an established surface activation protocol. Principle component analysis (PCA) of time-of-flight secondary ion mass spectrometry (ToF-SIMS) data confirm the immobilization of CASP with higher yield as compared to a diffusion-controlled process, and higher purity than the clinical CASP starting suspensions. Scratch testing data indicate good coating adhesion. Importantly, the coatings remain active against the fungal pathogen C. albicans as shown by in vitro biofilm experiments. In summary, this paper delivers a proof-of-concept for the application of AC-EPD as a fast grafting tool for antimicrobial molecules without compromising their activities.
authors.affiliation: KU Leuven Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, 3001 Heverlee, Belgium.
authors.forename: Annabel
authors.identifier: http://orcid.org/0000-0002-4890-0177
authors.initials: A
authors.lastname: Braem
authors.affiliation: KU Leuven Centre of Microbial and Plant Genetics (CMPG), Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.
authors.forename: Katrijn
authors.initials: K
authors.lastname: De Brucker
authors.affiliation: KU Leuven Centre of Microbial and Plant Genetics (CMPG), Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.
authors.forename: Nicolas
authors.initials: N
authors.lastname: Delattin
authors.affiliation: Department of Materials Science and Engineering, Chair for Surface Science and Corrosion, Friedrich-Alexander-University of Erlangen-Nuremberg , Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Manuela S
authors.identifier: http://orcid.org/0000-0003-0892-4614
authors.initials: MS
authors.lastname: Killian
authors.affiliation: KU Leuven Center for Surface Chemistry and Catalysis (COK), Kasteelpark Arenberg 23, 3001 Leuven, Belgium.
authors.forename: Maarten B J
authors.identifier: http://orcid.org/0000-0001-6582-6514
authors.initials: MB
authors.lastname: Roeffaers
authors.affiliation: Biomaterials Laboratory, Graduate School of Natural Science and Technology, Okayama University , 3-1-1, Tsushima, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Tomohiko
authors.initials: T
authors.lastname: Yoshioka
authors.affiliation: Biomaterials Laboratory, Graduate School of Natural Science and Technology, Okayama University , 3-1-1, Tsushima, Kita-ku, Okayama 700-8530, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Hayakawa
authors.affiliation: Department of Materials Science and Engineering, Chair for Surface Science and Corrosion, Friedrich-Alexander-University of Erlangen-Nuremberg , Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Patrik
authors.initials: P
authors.lastname: Schmuki
authors.affiliation: KU Leuven Centre of Microbial and Plant Genetics (CMPG), Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.|Department of Plant Systems Biology, Vlaams Instituut voor Biotechnologie (VIB) , Technologiepark 927, 9052 Ghent, Belgium.
authors.forename: Bruno P A
authors.initials: BP
authors.lastname: Cammue
authors.affiliation: Department of Materials Science and Engineering, Chair for Surface Science and Corrosion, Friedrich-Alexander-University of Erlangen-Nuremberg , Martensstrasse 7, 91058 Erlangen, Germany.
authors.forename: Sannakaisa
authors.initials: S
authors.lastname: Virtanen
authors.affiliation: KU Leuven Centre of Microbial and Plant Genetics (CMPG), Kasteelpark Arenberg 20, 3001 Heverlee, Belgium.
authors.forename: Karin
authors.initials: K
authors.lastname: Thevissen
authors.affiliation: KU Leuven Department of Materials Engineering (MTM), Kasteelpark Arenberg 44, 3001 Heverlee, Belgium.
authors.forename: Bram
authors.initials: B
authors.lastname: Neirinck
mesh_terms: D000890:Anti-Infective Agents; D020099:Coated Materials, Biocompatible; D004560:Electricity; D004586:Electrophoresis; D019736:Prostheses and Implants; D014025:Titanium / Q000737:chemistry*
chemical_list: D000890:Anti-Infective Agents; D020099:Coated Materials, Biocompatible; D014025:Titanium
keywords: alternating current; antifungal activity; biofilm prevention; biofunctionalization; caspofungin; electrophoretic deposition; titanium