Mechanical and microbiological testing concept for activatable anti-infective biopolymer implant coatings

Martin Schulze; Manfred Fobker; Jan Puetzler; Jule Hillebrand; Silke Niemann; Erhard Schulte; Jochen Kurzynski; Georg Gosheger; Julian Hasselmann

doi:10.1016/j.bioadv.2022.212917

Mechanical and microbiological testing concept for activatable anti-infective biopolymer implant coatings

Biomater Adv. 2022 Jul:138:212917. doi: 10.1016/j.bioadv.2022.212917. Epub 2022 May 25.

Authors

Martin Schulze¹, Manfred Fobker², Jan Puetzler³, Jule Hillebrand³, Silke Niemann⁴, Erhard Schulte², Jochen Kurzynski⁵, Georg Gosheger³, Julian Hasselmann⁶

Affiliations

¹ Clinic for General Orthopedics and Tumororthopedics, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany. Electronic address: martin.schulze@ukmuenster.de.
² Central Laboratory, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany.
³ Clinic for General Orthopedics and Tumororthopedics, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany.
⁴ Institute of Medical Microbiology, University Hospital Muenster, Domagkstraße 10, 48149 Muenster, Germany.
⁵ Materials Engineering Laboratory, Department of Mechanical Engineering, University of Applied Sciences Muenster, Stegerwaldstraße 39, 48565 Steinfurt, Germany.
⁶ Clinic for General Orthopedics and Tumororthopedics, University Hospital Muenster, Albert-Schweitzer-Campus 1, 48149 Muenster, Germany; Materials Engineering Laboratory, Department of Mechanical Engineering, University of Applied Sciences Muenster, Stegerwaldstraße 39, 48565 Steinfurt, Germany.

PMID: 35913227
DOI: 10.1016/j.bioadv.2022.212917

Abstract

An anti-infective bilayer implant coating with selectively activatable properties was developed to prevent biofilm formation and to support the treatment of periprosthetic infection as a local adjunct to current treatment concepts. In a first step, Ti6Al4V discs were coated with a permanent layer of Poly(l-lactide) (PLLA) including silver ions. The PLLA could be optionally released by the application of extracorporeal shock waves. In a second step, a resorbable layer of triglyceride (TAG) with incorporated antibiotics was applied. The second layer is designed for resorption within weeks. Prior to approval and clinical application, a comprehensive evaluation process to determine mechanical/physical and microbiological properties is obligate. To date, none of the existing test standards covers both drug-releasing and activatable coatings for orthopedic implants. Therefore, a comprehensive test concept was developed to characterize the new coating in a pilot series. The coatings were homogeneously applied on the Ti6Al4V substrate, resulting in an adhesion strength sufficient for non-articulating surfaces for PLLA. Proof of the extracorporeal shockwave activation of PLLA was demonstrated both mechanically and microbiologically, with a simultaneous increase of biocompatibility compared to standard electroplated silver coating. Wettability was significantly reduced for both layers in comparison to the Ti6Al4V substrate. Thus, potentially inhibiting biofilm formation. Furthermore, the TAG coating promoted cell proliferation and bacterial eradication. In conclusion, the testing concept is applicable for similar biopolymer coating systems. Furthermore, the extracorporeal activation could represent a completely new supportive approach for the treatment of periprosthetic joint infections.

Keywords: Activatable properties; Anti-infective coating; Antibacterial implant coating; Biodegradable polymer coatings; High-energy extracorporeal shock wave (fhESW); Mechanical testing; Microbiological testing.

MeSH terms

Biopolymers / pharmacology
Coated Materials, Biocompatible* / pharmacology
Materials Testing
Prostheses and Implants
Silver* / pharmacology

Substances

Biopolymers
Coated Materials, Biocompatible
Silver