Multimodal HOCl-responsive MEH-PPV Nanoparticles for Anti-Inflammatory Imaging and Therapy

Inflammatory disorders often correlate with an unusually high intracellular production of hypochlorous acid (HOCl). Therefore, its rapid, sensitive, and specific detection is crucial for an early diagnosis and treatment evaluation. While nanoparticles for detection have already been reported, multimodal nanoparticles that simultaneously detect and eliminate reactive oxygen species (including the excess of HOCl) are scarce despite their interest. Herein, we developed highly selective fluorescent nanoparticles using the copolymer poly(2-methoxy-5-(2-ethylhexyloxy)-1, 4-phenylenevinylene) (MEH-PPV), with (MEH@CS) and without a chitosan coating (MEH). The conjugated polymer is oxidized in the presence of HOCl, exhibiting a rapid (in less than 30 s) and sensitive fluorescence turn-off response with a log-log linear HOCl relationship within dynamic ranges of ≈ 0.784–83 μM and ≈ 0.384–55 μM for MEH and MEH@CS NPs, respectively, allowing to monitor basal HOCl levels within the standard physiological concentration range (5 – 25 μM) and its differentiation from overproduction. Moreover, the nanoparticles can encapsulate and release quercetin (a powerful natural scavenger for HOCl), leading not only to monitoring but also to a reduction in pro-inflammatory cytokines of inflammation-stimulated macrophage cells.