Fluorescent/Circular Dichroic Dual-Mode Chiral Upconversion Nanocomposite for Diagnosis and Treatment of Rheumatoid Arthritis

Chiral nanophotonic materials have emerged as ideal candidates for biosensing applications due to their exceptional sensitivity. However, the inability to directly visualize chiral signals limits their broader application, particularly in disease diagnosis and treatment. In this study, we introduce a chiral nanocomposite based on upconversion nanoparticles (UCNPs), denoted UCNPs@L-POM, that exhibits both upconversion luminescence (UCL) and circular dichroism (CD) signals. This dual-signal system enables ultrasensitive detection and in vivo imaging of ·OH. The detection limits for UCL and CD signals in aqueous solution are 6.258 and 0.912 μM, respectively. This dual-mode sensing approach is also effective at the cellular level. As a demonstration, UCNPs@L-POM enables in situ imaging diagnosis of rheumatoid arthritis (RA), characterized by elevated levels of ·OH expression. Additionally, through the oxidation reaction induced by ·OH, UCNPs@L-POM effectively alleviates paw inflammation and promotes the healing of RA. This work offers new prospects for biological applications of chiral nanocomposites.