A New Treatment Modality for Rheumatoid Arthritis: Combined Photothermal and Photodynamic Therapy Using Cu_7.2S₄ Nanoparticles

Abstract

Rheumatoid arthritis (RA) is a worldwide inflammatory disease that seriously threatens human health and needs more effective treatment approaches. Near infrared (NIR) light can efficiently penetrate inflamed joints affected by RA, so phototherapy, including photothermal therapy (PTT) and photodynamic therapy (PDT), may provide new opportunities. In this work, the unique Cu_7.2 S₄ nanoparticles (NPs) are prepared for RA treatment enlightened by the fact that copper (Cu)-based nanomaterials can simultaneously serve as PTT agents and photosensitizers (for PDT). Meanwhile, Cu can promote ostogenesis and chondrogenesis. The Cu_7.2 S₄ NPs combined with NIR (808 nm, 1 W cm^-2 ) irradiation not only achieve better bone preservation, including higher bone mineral density (BMD) and bone volume/total volume, but also inhibit inflamed synovial invasion, cartilage erosion, and expression of proinflammatory cytokines in vivo. Moreover, the Cu_7.2 S₄ NPs can effectively kill clinical pathogenic Staphylococcus aureus and Escherichia coli to prevent bacterial infection during intra-articular injection. Therefore, the combined PTT and PDT using the multifunctional Cu_7.2 S₄ NPs could be a novel RA treatment modality with full potential.