A promising strategy to prevent infections around orthopaedic titanium implants is to use naturally occurring cationic antimicrobial peptides (CAMPs) such as the human ß-defensin-2 as antibacterial coatings. Human antimicrobial peptides represent a part of the innate immune system and have a broad antimicrobial spectrum against bacteria, fungi, and viruses.Methods:
In the present study, titanium surfaces were functionalized by four different self-assembled monolayers (SAMs) forming methoxy silanes: (1) hexadecyltrimethoxysilane, (2) dimethoxymethyloctylsilane, (3) allyltrimethylsilane, and (4) 3-aminopropyltrimethoxysilane. In addition, calf skin type-I collagen was cross-linked to the SAM surface 3-aminopropyltrimethoxysilane by means of two different treatments: (1) N-hydroxysuccinimide and (2) glutaraldehyde. The functionalized titanium surfaces were coated with recombinant human ß-defensin-2 (rHußD2), an antimicrobial peptide, and were tested for antibacterial activity against Escherichia coli. The release of rHußD2 was quantified by means of enzyme-linked immunosorbent assay (ELISA).Results:
The coating of functionalized titanium surfaces with rHußD2 was successful. Recombinant HußD2 was eluted from the titanium surfaces continuously, yielding antimicrobial activity up to several hours. Antimicrobial activity with a killing rate of 100% was observed for all functionalized titanium surfaces after two hours of incubation. The dimethoxymethyloctylsilane-functionalized titanium surface delivered 0.65 µg of rHußD2 after six hours with a 60% bacterial killing rate. The silane-functionalized surfaces exhibited a faster release of antimicrobially active rHußD2 compared with collagen modifications.Conclusions:
Natural antibiotics such as rHußD2 integrated into the metal surface of titanium implants may be a promising tool to prevent and control infections around orthopaedic implants.Clinical Relevance:
This kind of titanium surface modification may provide an alternative treatment of serious, life-threatening infections related to prosthetic implant surgery.