Assessing the impact of CAP-p15 functionalization on the bioactivity of rough TiO2-coated 316L stainless steel surfaces

Abstract

Stainless steel 316L (316L SS) is frequently used in implants and medical devices because of its low cost, high mechanical strength, and adequate biocompatibility. However, its bioinert nature limits osseointegration, often confining its applications to temporary uses. To address this issue, surface modifications such as oxide coatings and peptide adsorption have emerged as promising strategies to enhance the bioactivity of 316L SS. This study explores the surface modification of 316L SS substrates through sandblasting, followed by the deposition of a TiO₂ layer and subsequent biofunctionalization with a cementum attachment protein-derived peptide (CAP-p15) via physisorption using three different concentrations. The modified surfaces were characterized using X-ray photoelectron spectroscopy (XPS), scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDX), surface roughness analysis, and water contact angle measurements (WCA). Samples were incubated in artificial saliva (AS) for 21 days. The resulting peptide release, surface microstructure, the morphology and chemical composition of the deposits were evaluated. Additionally, human periodontal ligament cells (hPDLCs) were cultured on the modified surfaces to assess cell viability and attachment. Characterization revealed significant changes in surface chemistry, roughness, and wettability following functionalization. In vitro testing in AS demonstrated the formation of carbonated apatite, indicative of enhanced bioactivity. Furthermore, hPDLCs cultured on functionalized surfaces exhibited enhanced viability, improved adhesion, and enhanced cell spreading. These results suggest that peptide-based functionalization with CAP-p15 is a promising strategy for enhancing the osseointegration potential of 316L SS, offering valuable prospects for bone tissue regeneration.