Upconversion nanocomposite for ROS-responsive diagnosis and hydrogen therapy of osteoarthritis

IntroductionOsteoarthritis (OA) is a common degenerative joint disease for which no definitive effective treatment currently exists. Therapeutic hydrogen (H2) exhibits antioxidant and anti-inflammatory properties and holds promise for alleviating OA; however, targeted delivery and sustained release of H2 remain challenging.MethodsIn this study, we developed an upconversion nanocomposite for integrated diagnosis and therapy of OA. Upconversion nanoparticles (UCNP) were first synthesized and coated with hydrogen-producing TiO2 to form UCNP@TiO2. A H2O2-sensitive thioketal (TK) linker was then conjugated onto the surface of UCNP@TiO2 to attach a black hole quencher (BHQ), yielding the functionalized nanocomposite UCNP@TiO2-TK-BHQ.ResultsIn the presence of hydrogen peroxide (H2O2), cleavage of the TK linker triggers the release of BHQ, thereby restoring the fluorescence of UCNP for real-time reactive oxygen species (ROS) detection. Simultaneously, near-infrared (NIR) light activates UCNP@TiO2 to generate hydrogen, which scavenges ROS and promotes the restoration of chondrocyte health.Discussion/ConclusionThe UCNP@TiO2-TK-BHQ nanocomposite thus represents a promising theranostic platform that combines ROS sensing with on-demand H2 therapy, offering an integrated approach for both diagnosis and treatment of OA.