Antibiofilm peptides against biofilms on titanium and hydroxyapatite surfaces

Abstract

Biofilms are the main challenges in the treatment of common oral diseases such as caries, gingival and endodontic infection and periimplantitis. Oral plaque is the origin of microbes colonizing in the form of biofilms on hydroxyapatite (tooth) and titanium (dental implant) surfaces. In this study, hydroxyapatite (HA) and titanium (Ti) disks were introduced, and their surface morphology was both qualitatively and quantitatively analyzed by a scanning electron microscope (SEM) and atomic force microscope (AFM). The average roughness of Ti disks (77.6 ± 18.3 nm) was less than that of HA (146.1 ± 38.5 nm) (p < 0.05). Oral multispecies biofilms which were cultured on Ti and HA disks for 6 h and three weeks were visualized by SEM. We investigated the ability of two new antibiofilm peptides, DJK-5 and 1018, to induce killing of bacteria in oral multispecies biofilms on Ti and HA disks. A 6-h treatment by DJK-5 and 1018 (2 or 10 μg/mL) significantly reduced biomass of the multispecies biofilms on both Ti and HA disks. DJK-5 was able to kill more bacteria (40.4-75.9%) than 1018 (30.4-67.0%) on both surfaces (p < 0.05). DJK-5 also led to a more effective killing of microbes after a 3-min treatment of 3-day-old and 3-week-old biofilms on Ti and HA surfaces, compared to peptide 1018 and chlorhexidine (p < 0.05). No significant difference was found in the amount of biofilm killing between Ti and HA surfaces. Both peptide DJK-5 and 1018 may potentially be used as effective antibiofilm agents in clinical dentistry.

Keywords: Antimicrobial; Biofilm; Hydroxyapatite; Peptide 1018; Peptide DJK-5; Titanium.

Graphical abstract

Fig. 1

SEM images of Ti and HA surfaces without saliva coating and biofilm growth. (A) Ti surface under low magnification (1000 ×); (B) HA surface under low magnification (1000 ×); (C) Ti surface under high magnification (3000 ×); (D) HA surface under high magnification (3000 ×).

Fig. 2

AFM images for Ti and HA surfaces. (A) Ti and (B) HA surfaces as 2D image; (C) Ti and (D) HA surfaces as 3D image (X, Y and Z scales are in μm); (E) Comparison of Ra values between Ti and HA, asterisk indicates significant differences between groups (p < 0.05).

Fig. 3

SEM images of biofilms at different stages of development (6 h and 3 weeks) on Ti and HA disks.

Fig. 4

Confocal microscopy images of 24-h-old biofilms on Ti and HA surfaces treated with peptides DJK-5 and 1018 for 6 h. The bar indicates 150 μm.

Fig. 5

Long-term antibiofilm effect of peptides on biofilms on different surfaces. (A) DJK-5 and (B) 1018, dead bacteria proportion as measured by viability staining and CLSM. Different lowercase letters in each treatment group indicate statistically significant difference (p < 0.05). (C) Biovolume of 24-h-old biofilm exposure to peptide for 6 h, asterisks indicate significant differences between groups (p < 0.05).

Fig. 6

Short-term antibiofilm effect of peptides on biofilms on different surfaces. (A) DJK-5, (B) 1018 and (C) CHX, dead bacteria proportion as measured by viability staining and CLSM. Different lowercase letters in each treatment group indicate statistically significant difference (p < 0.05).