Lysosome-targeted fluorescent probe for real-time imaging of hypochlorite in rheumatoid arthritis and machine learning-assisted quantification in plant tissues

Rheumatoid arthritis (RA) is a chronic autoimmune inflammatory disease closely associated with excessive oxidative stress. Hypochlorite (ClO^-) are key reactive oxidants in inflammatory microenvironments which contribute to lysosomal dysfunction and inflammatory cascade amplification. However, rapid and selective visualization of ClO^- in complex biological systems remains challenging. In addition, residual ClO^- in plant-derived foods raises safety concerns, while conventional analytical methods are unsuitable for direct in situ detection. To address this issue, we developed a lysosome-targeted fluorescent probe HB-Z, for sensitive ClO^- detection in RA models and plant tissues.

The designed probe HB-Z consists of a 1,8-naphthalimide-based fluorophore, p-aminophenyl ether recognition unit, and morpholine lysosomal-targeting group, enabling remarkable turn-on fluorescence response upon ClO^- triggered cleavage. Spectroscopic studies demonstrated excellent selectivity, rapid response within seconds, high sensitivity, and good pH stability. HB-Z successfully imaged exogenous and endogenous ClO^- in live RAW 264.7 macrophages with distinct lysosomal localization. In a λ-carrageenan-induced acute arthritis mouse model, HB-Z enabled visualization of elevated joint ClO^- levels and real-time monitoring of oxidative fluctuations during disease progression and antioxidant-mediated remission. Furthermore, HB-Z achieved concentration-dependent fluorescence imaging of exogenous ClO^- residues in soybean sprouts. By integrating fluorescence features and soaking time, a stochastic gradient descent machine-learning classifier further enabled three-class discrimination of disinfection status with high accuracy.

This probe provides a versatile platform for dynamic ClO^- imaging in inflammatory diseases and intelligent assessment of food disinfection quality, possessing great potential for exploring the mechanism of inflammatory diseases and realizing intelligent food safety detection.