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.