Effect of Surface Roughness and Polyelectrolyte Multilayer Coatings on the In Vitro Cytocompatibility of Additively Manufactured Titanium Implants

BACKGROUND/AIM: Titanium alloys are widely used in orthopedic and dental implants due to their favorable mechanical properties and biocompatibility. Additive manufacturing enables complex implant geometries but results in increased surface roughness, which may influence cellular behavior. Surface coatings are intended to improve cell adhesion and biocompatibility. This study investigates the cytocompatibility of additively manufactured titanium surfaces by assessing combined effects of micrometer-scale roughness and nanometer-thick polyelectrolyte multilayer coatings. Cytocompatibility was examined through fibroblast and osteoblast adhesion, viability, proliferation, and cytotoxicity to determine suitability for biomedical implant applications. MATERIALS AND METHODS: Cell adhesion of MC3T3 osteoblasts and L929 fibroblasts on the different substrates, both uncoated and surface-modified, was quantitatively assessed using live/dead staining. Substrate-induced cytotoxicity was evaluated by measuring lactate dehydrogenase (LDH) release. In addition, cellular viability was determined using the XTT assay, while cell proliferation was analyzed by incorporation of 5-bromo-2'-deoxyuridine (BrdU). RESULTS: The coatings composed of synthetic polyelectrolyte multilayers combined with the lowest roughness level enhanced preosteoblast viability. Fibroblast's viability remained unaffected by surface topography or coating. Proliferation was more strongly influenced by surface structure and coating in fibroblasts than in preosteoblasts. CONCLUSION: Cell adhesion and proliferation showed cell type-specific responses to surface roughness and polyelectrolyte multilayer coatings of titanium implants, with fibroblasts benefiting from synthetic coatings and preosteoblasts responding predominantly to surface topography. All coatings met the requirements for cytocompatibility according to DIN EN ISO 10993-5, with no adverse effects on cell viability, proliferation, or substrate-dependent toxicity. Therefore, polyelectrolyte multilayer coatings appear to be a feasible surface modification strategy for applications in biomedical implant.