Inflammatory and biocompatibility evaluation of antimicrobial peptide GL13K immobilized onto titanium by silanization

The inflammatory reaction around the implant after implant placement is important not only for osseointegration but also for long-term implant survivals. In our study, GL13K, an antimicrobial peptide, was immobilized onto titanium surfaces to improve its anti-inflammatory properties. The method of silanization was used to immobilize the GL13K, which was confirmed by X-ray photoelectron spectroscopy, scanning electron microscopy, atomic force microscopy, water contact angle measurement. DAPI fluorescence staining and Cell Counting Kit-8 (CCK-8) were used to measure the cell attachment and cell viability of the RAW264.7, which indicated a good cytocompatibility. Cellular morphology of RAW264.7 on modified surfaces showed less cell pseudopod. ELISA and qRT-PCR were performed to measure the inflammatory activity of the modified titanium surfaces. The secretion levels of pro-inflammatory cytokines interleukin (IL)-1β, tumor necrosis factor-alpha (TNF-α) and inducible nitric oxide synthase (iNOS) were downregulated at 12h, 24h, and 48h, while the anti-inflammatory cytokines IL-10 and arginase were upregulated at 12h, 24h, and 48h. All results indicate that the GL13K-coated titanium surfaces make the inflammatory process towards a less pro-inflammatory, which may promote the process of osseointegration.