Comparison of the structure and function of a chimeric peptide modified titanium surface

Abstract

Peri-implantitis is a plaque-initiating infectious disease that can be prevented by interfering with the initial bacterial attachment. At present, surface modification of implants using antimicrobial peptides can interfere with the adhesion of streptococci. In this study, the structure and function of chimeric peptides were compared to get a strategy to modify a Ti surface. Compared to the antimicrobial activity with a fragment of hBD-3, the bifunctional and multifunctional chimeric peptides retain their antimicrobial function. All peptides showed antimicrobial activity against streptococcus in biofilm and planktonic conditions. The results demonstrate significant improvement in reducing bacterial colonization onto titanium surfaces. According to the results of structure analysis, the antimicrobial activity of tyrosine in hBD3-3 was stronger than that of the alpha helix in bifunctional or multifunctional chimeric peptides. Rigid connections were proved to avoid functional domain changes due to the interaction of charges. These results indicated that the endogenous peptide fragments modifying the Ti surface could provide an environmentally friendly approach to reduce or prevent the occurrence of peri-implant diseases.

Fig. 1. The molecular characteristics of the peptides show amphipathic properties (top: hydrophilic, bottom: hydrophobic). (A) hBD3-3. (B) TBP-1-hBD3-3. (C) TBP-1-RGDS-hBD3-3.

Fig. 2. Raman spectra results of hBD3-3, TBP-1-hBD3-3, and TBP-1-RGDS-hBD3-3. (A) Raman spectra wave results of hBD3-3 (a), TBP-1-hBD3-3 (b), and TBP-1-RGDS-hBD3-3 (c). (B) Detailed structures and peptide sources (A: hBD3-3, B: TBP-1-hBD3-3, and C: TBP-1-RGDS-hBD3-3).

Fig. 3. XPS wide-scan spectra of Ti surfaces: Ti treated with PBS (control) and Ti treated with TBP-1-hBD3-3 or TBP-1-RGDS-hBD3-3 dissolved in PBS. Elemental composition of Ti disc surfaces with or without chimeric peptides treatment, as determined via XPS.

Fig. 4. Antibacterial effects of hBD3-3, TBP-1-hBD3-3, and TBP-1-RGDS-hBD3-3 against single-species (S. oralis, S. gordonii or S. sanguinis) biofilms. Biofilms treated with the three peptides (1/2 MIC) were incubated for 24 h (A) or 72 h (B). Data are shown as the mean ± SEM; n = 3. *P < 0.01 compared with the control groups.

Fig. 5. (A) SEM images of S. gordonii biofilms formation for 24 h. (B) SEM images of S. gordonii biofilms that were treated with TBP-1-RGDS-hBD3-3 at 320 μg mL⁻¹ for 24 h. (C) TEM micrographs of the inner structures of S. gordonii that were treated with TBP-1-RGDS-hBD3-3 at 320 μg mL⁻¹ for 12 h. White or black arrows: disruption of the cell membrane and release of cellular contents.