A Cell-Adhesive Plasma Polymerized Allylamine Coating Reduces the In Vivo Inflammatory Response Induced by Ti6Al4V Modified with Plasma Immersion Ion Implantation of Copper.

Uwe Walschus,Andreas Hoene,Birgit Finke,Andreas Podbielski,Rainer Bader,Silke Lucke,J Nebe,Gerold Lukowski,Martin Polak,Carmen Zietz,Maciej Patrzyk,Michael Schlosser

doi:10.3390/jfb8030030

Abstract

Copper (Cu) could be suitable to create anti-infective implants based on Titanium (Ti), for example by incorporating Cu into the implant surface using plasma immersion ion implantation (Cu-PIII). The cytotoxicity of Cu might be circumvented by an additional cell-adhesive plasma polymerized allylamine film (PPAAm). Thus, this study aimed to examine in vivo local inflammatory reactions for Ti6Al4V implants treated with Cu-PIII (Ti-Cu), alone or with an additional PPAAm film (Ti-Cu-PPAAm), compared to untreated implants (Ti). Successful Cu-PIII and PPAAm treatment was confirmed with X-ray Photoelectron Spectroscopy. Storage of Ti-Cu and Ti-Cu-PPAAm samples in double-distilled water for five days revealed a reduction of Cu release by PPAAm. Subsequently, Ti, Ti-Cu and Ti-Cu-PPAAm samples were simultaneously implanted into the neck musculature of 24 rats. After 7, 14 and 56 days, peri-implant tissue was retrieved from 8 rats/day for morphometric immunohistochemistry of different inflammatory cells. On day 56, Ti-Cu induced significantly stronger reactions compared to Ti (tissue macrophages, antigen-presenting cells, T lymphocytes) and to Ti-Cu-PPAAm (tissue macrophages, T lymphocytes, mast cells). The response for Ti-Cu-PPAAm was comparable with Ti. In conclusion, PPAAm reduced the inflammatory reactions caused by Cu-PIII. Combining both plasma processes could be useful to create antibacterial and tissue compatible Ti-based implants.

Highlights

Successful medical use of biomaterials requires a sufficient level of biocompatibility as well as specific physical and chemical properties suitable for the intended application
We examined several surface treatments based on plasma polymerized allylamine (PPAAm), resulting in an amino-group rich, positively charged Ti surface characterized by robust anchoring of the PPAAm film with the Ti substrate due to the formation of carbide and oxycarbide bonds, as recently demonstrated by other authors [8]
Previous in vitro studies showed antibacterial properties for Ti6Al4V (Ti) surfaces either treated with plasma immersion ion implantation of copper (Cu-PIII) alone or with Cu-PIII followed by an additional plasma polymerized allylamine (PPAAm) film [5,6]

Summary

Introduction

Successful medical use of biomaterials requires a sufficient level of biocompatibility as well as specific physical and chemical properties suitable for the intended application. Cu is toxic to mammal cells in a concentration-dependent manner, possibly causing adverse tissue effects in vivo This was, for example, demonstrated in a study using Ti samples with a layer of galvanically deposited Cu which induced stronger acute inflammatory reactions than untreated control samples during the first three days following implantation in rats [7]. Such adverse effects should be minimized in order to reduce impacts in the peri-implant tissue while still maintaining the antibacterial properties

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Conclusion