Spectrally Separated Dual Functional Fluorescent Nanosensors for Subcellular Lysosomal Detection of Hypochlorous Acid and Chloride

Dynamic monitoring of different chemical species at the subcellular level greatly enriches our understanding of various biochemical processes. Hypochlorous acid (HClO), an indispensable disinfecting weapon in immune responses, is synthesized from chloride ions (Cl-) with the enzyme myeloperoxidase (MPO) in lysosomes. Here, we reported a dual-functional fluorescent nanosensor (NS_Cl&HCIO) to simultaneously monitor the subcellular concentration changes of HClO and Cl- in lysosomes. Prepared by nanoprecipitation from biocompatible polymers, NS_ClNS_Cl&HCIO contained a Cl- sensitive dye (Q+), a HClO reactive dye (Cy5), and a reference dye(LRed). Spectral separation ensured no cross-response between the two analytes. The nanosensors exhibited a detection limit of ca. 21 nM for HClO and responded to Cl- in a dynamic range of 0 to 170 mM, with excellent selectivity over a range of other reactive species and common biological ions. The dynamics of HClO in the lysosomes of RAW264.7 cells were successfully monitored by the endocytosed NS_ClNS_Cl&HCIO with high contrast, indicating that the proposed nanosensors are very promising for the detection of subcellular Cl- and HClO.