<i>In Situ</i> Imaging of Cellular Inflammatory\nResponse to Antibiotic Exposure with a DNAzyme Nanorobot

Antibiotic-induced\ninflammation involves the release of myeloperoxidase\n(MPO), an enzyme whose expression in tissues is associated with the\ninflammatory pathway. However, existing methods for detecting MPO\nin cells are limited. In this study, a DNAzyme nanorobot was developed\nusing a scaffold of gold nanoparticles (AuNPs) decorated with functional\nDNAzyme strands and their fluorophore-labeled substrate strands. The\nDNAzyme remains inactive due to a self-assembled hairpin structure,\nwith a phosphorothioate (PT) modification inserted into the stem domain.\nWhen MPO is present, it triggers a halogenation process that generates\nhypochlorous acid (HClO). HClO specifically catalyzes the cleavage\nof the PT-site, releasing free DNAzyme strands to cleave their substrates\nand generating an increasing fluorescent signal. The detection limit\nfor MPO and its primary product, HClO, were determined to be 0.038\nμg/mL and 0.013 μM, respectively. The DNAzyme nanorobot\ncan be readily introduced into cells and function autonomously to\ndifferentiate increased MPO/HClO levels caused by antibiotics. This\napproach was applied to image RAW264.7 cells exposed to four prevalent\nantibiotics found in the environment (phorbol 12-myristate 13-acetate,\nerythromycin, penicillin, and tetracycline) as well as antibiotic\nproduction wastewater. This nanorobot offers novel strategies for\nmonitoring inflammation to evaluate the health impacts of antibiotic\nexposure.