Multi-bioactive Peptide Coatings for Dental Implants

Abstract

Functionalization of implants with multiple bioactivities is desired to obtain surfaces with improved biological and clinical performance. The outcome of dental implants depends on the process of "racing for the surface". To assist bone cells to win the race, bacterial colonization of the surface and tissue healing promotion around it need to be accomplished soon after implantation. Therefore, functionalizing titanium (Ti) surfaces with bioactive coatings which can either enhance cellular adhesion and differentiation or inhibit bacteria adhesion, or both, is desired. To enhance cellular performance on Ti surface, we developed a simple route to covalently co-immobilize two different oligopeptides on Ti surfaces. Appropriately designed oligopeptides containing either RGD or PHSRN bioactive sequences were mixed and covalently-bonded on CPTES-silanized surfaces. The obtained peptide coatings showed strong mechanical stability as well as enhanced osteoblast adhesion. To prevent bacteria adhesion on Ti surfaces, we tethered using silanes on Ti surface an antimicrobial peptide, GL13K which is derived from human parotid secretory protein. Our previous work demonstrated that, after immobilization, GL13K displayed antimicrobial effect against Porphyromonas gingivalis, a pathogen closely associated with dental peri-implantitis. In addition, GL13K coating showed adequate cyto-compatibility with osteoblasts and human gingival fibroblasts. This work showed that the covalently bonded GL13K coating resisted mechanical, hydrolytic and proteolytic challenges and displayed sustained bioactivity after cycles of body fluid incubation and autoclaving. GL13K coating prevented biofilm formation by killing S.gordonii at their early developmental stage and the antimicrobial effect of GL13K coating was highly dependent on the secondary structure of the tethered peptides. When we investigated the activity of GL13K coating in simulated dynamic conditions with a drip flow bioreactor, unique cell wall damage was observed. The simple and reliable methodology to tether peptides on Ti surface that was developed in this work can be used to establish a multifunctional coating with both bone-regenerative and bacteria inhibitive bioactivities.