Vacuum Ultraviolet (VUV)-Induced Physicochemical Engineering of Titanium: Enhanced Fibroblast Activity, Redox System, and Glycosaminoglycan Binding for Soft Tissue Integration

Bacterial invasion at the titanium-tissue interface causes peri-implant inflammation, posing challenges for implants in orthopedics, maxillofacial prosthetics, and dentistry. This study hypothesized that titanium surface decarbonization improves soft tissue cell adhesion and growth. One-minute vacuum ultraviolet (VUV) light treatment at 172 nm reduced surface carbon from 60% to 29% without altering surface topography, making surfaces hydrophilic and hydro-attractive. Human fibroblasts attached to VUV-treated surfaces 2-4 times more frequently than untreated surfaces, with an even greater increase on tilted and curved surfaces. Fibroblast proliferation rose 2-6 times, with an expedited G1-to-S phase transition. Cell retention under dislodging forces increased 2-5 times on VUV-treated surfaces. RNA sequencing showed upregulation of extracellular matrix production, growth factors, cell cycle progression, antioxidant defenses, and proteoglycan/glycosaminoglycan (GAG)-binding, alongside downregulation of the inflammatory response on VUV-treated titanium surfaces. An oxidative stress test showed minimal adverse effects from hydrogen peroxide on cells on VUV-treated surfaces, attributed to increased intracellular glutathione reserves. Enhanced adhesion on VUV-treated titanium was negated by treating the cells with GAG-cleaving enzymes. These findings demonstrate that VUV-mediated decarbonization enhances fibroblast attachment, proliferation, and adhesion by fostering homeostatic cellular phenotypes involving proteoglycan/GAG interactions and antioxidant defense, offering a strategy to improve the soft tissue sealing around titanium implants.