Osteoarthritis (OA) is the most prevalent chronic joint disease, with its incidence increasing with age (Xia, 2014). It is the leading musculoskeletal disorder contributing to mobility impairments in individuals over 65 years. Although several risk factors – such as advancing age, obesity, and genetic predisposition – have been linked to OA development, its pathogenesis remains poorly understood (Xia, 2014). Recent studies suggest that excessive production of Reactive Oxygen Species (ROS) during OA-associated inflammation disrupts intracellular signaling, compromises chondrocyte survival, and impairs cartilage matrix homeostasis (Lepetsos et al., 2019). ROS have also been implicated in subchondral bone deterioration, further aggravating joint damage. (Zahan, 2020).

Selenium (Se) is a vital micronutrient essential for human health and commonly used as a dietary supplement (Wang, 2017). It plays key roles in immune modulation and antioxidant defense systems (Kielczykowska, 2018). Se supplementation has demonstrated protective effects against various toxic agents, including heavy metals, carcinogens, and pharmaceuticals, with severe adverse effects (Kielczykowska, 2018). However, the clinical application of Se is constrained by its narrow therapeutic index and toxicity at higher doses. Advances in nanotechnology have enabled novel biomedical uses of metal-based nanoparticles. In this regard, Se nanoparticles (SeNPs) have garnered interest due to their reduced toxicity and superior biocompatibility compared to conventional organic and inorganic Se formulations, positioning them as promising candidates for therapeutic interventions (Wadhwani, 2016). Research has explored the therapeutic potential of SeNPs in oxidative stress- and inflammation-mediated disorders, such as arthritis, cancer, and neuropathies (Kielczykowska, 2018, Martinez-Esquivias, 2022, Martinez-Esquivias, 2021).

Polydopamine (PDA), a polymer derived from the oxidative polymerization of dopamine and other catecholamines, has emerged as a versatile material for surface modification (Ball, 2018). Its high catechol and amine content enables strong adhesion to diverse substrates, facilitating the immobilization of biomolecules (Davidsen, 2021). PDA’s distinctive surface chemistry has drawn significant attention in biomedical applications, particularly for enhancing surface properties (Lee, 2007). Furthermore, PDA exhibits radical-scavenging properties, effectively neutralizing ROS in inflammatory conditions. Although its protective mechanisms have been investigated in several disease models (Zhao, 2018), the anti-inflammatory and therapeutic potential of PDA in OA remains largely unexplored. This study aimed to evaluate the therapeutic effects of PDA-coated SeNPs in the treatment of OA.