Antibacterial activity and cytocompatibility of an implant coating consisting of TiO₂ nanotubes combined with a GL13K antimicrobial peptide

Abstract

Prevention of implant-associated infections at an early stage of surgery is highly desirable for the long-term efficacy of implants in dentistry and orthopedics. Infection prophylaxis using conventional antibiotics is becoming less effective due to the development of bacteria resistant to multiple antibiotics. An ideal strategy to conquer bacterial infections is the local delivery of antibacterial agents. Therefore, antimicrobial peptide (AMP) eluting coatings on implant surfaces is a promising alternative. In this study, the feasibility of utilizing TiO 2 nanotubes (TNTs), processed using anodization, as carriers to deliver a candidate AMP on titanium surfaces for the prevention of implant-associated infections is assessed. The broad-spectrum GL13K (GKIIKLKASLKLL-CONH2) AMP derived from human parotid secretory protein was selected and immobilized to TNTs using a simple soaking technique. Field emission scanning electron microscope, X-ray diffraction, Fourier transform infrared spectroscopy, and liquid chromatography–mass spectrometry analyses confirmed the successful immobilization of GL13K to anatase TNTs. The drug-loaded coatings demonstrated a sustained and slow drug release profile in vitro and eradicated the growth of Fusobacterium nucleatum and Porphyromonas gingivalis within 5 days of culture, as assessed by disk-diffusion assay. The GL13K-immobilized TNT (GL13K-TNT) coating demonstrated greater biocompatibility, compared with a coating produced by incubating TNTs with equimolar concentrations of metronidazole. GL13K-TNTs produced no observable cytotoxicity to preosteoblastic cells (MC3T3-E1). The coating may also have an immune regulatory effect, in support of rapid osseointegration around implants. Therefore, the combination of TNTs and AMP GL13K may achieve simultaneous antimicrobial and osteoconductive activities.

Antimicrobial Peptides in Biomedical Device Manufacturing

“…Self-organized and vertically oriented titanium oxide nanotubes loaded with the broad spectrum AMP HHC36 showed in vitro bactericidal activity against S. aureus in liquid surrounding the nanotubular surface and reduced bacterial colonization on the surface ~200-fold (Ma et al, 2012 ). GL13K-eluting coatings on these titanium oxide nanotubes prevented growth of Fusobacterium nucleatum and P. gingivalis in an in vitro disk-diffusion assay (Li et al, 2017 ). In vitro release of Tet213 from microporous calcium phosphate coatings applied on titanium showed bactericidal activity against S. aureus and P. aeruginosa (Kazemzadeh-Narbat et al, 2010 ).…”

Antibiofilm Peptides and Peptidomimetics with Focus on Surface Immobilization

“…As a result, peptide loaded TiO 2 nanotube surface effectively killed S. aureus in vitro, and the release of the AMP from the nanotubes was verified via liquid chromatography coupled mass spectrometry (LC-MS) analysis [ 134 ]. Furthermore, GL13K peptide loaded in TiO 2 nanotubes, on titanium surfaces, by a simple soaking technique demonstrated a sustained and slow drug release profile in vitro and eradicated the growth of Fusarium nucleatum and P. gingivalis within 5 days of exposure [ 133 ].…”

Application of TiO2Nanotubes as a Drug Delivery System for Biomedical Implants: A Critical Overview

“…In the second study, TNTs implants were coated with basic fibroblast growth factor (bFGF) in combination with a biodegradable polymer (PLGA) and analyzed by histomorphometry also after 12 weeks . The results of both studies showed a significant increase in bone cell adhesion and proliferation for the groups containing growth factors when compared to the anodized‐only control groups, suggesting a positive influence of the incorporation of growth factors to the TNTs surfaces in terms of the quality and quantity of the observed bone formation …”

“…tested in vitro the bacterial cultures on TNTs surfaces with GL13K antimicrobial peptides for their known antibacterial spectrum, using a simple soaking technique. The peptide incorporation did not affect the surface biocompatibility, and the previously cultured Fusobacterium nucleatum and Porphyromonas gingivalis bacterial colonies were eradicated from TNTs surfaces after 5 days of antibiotic activation …”