Nitroreductase-Activated Probes for Monitoring Hypoxia

Hypoxia, a hallmark of solid tumors, complicates cancer treatment by reducing the efficacy of radiotherapy and chemotherapy. To optimize strategies for hypoxia detection and targeted cancer therapy, this work explores the development of hypoxia-responsive fluorescent probes. In this study, we compared various nitroaromatic groups and both elimination-based and cyclization-based self-immolative designs to study nitroreductase (NTR) activation. The research highlighted differences in activation response among the probes, with elimination-based probes (8b–8d) showing faster activation compared to cyclization-based probes (8f–8i). Furthermore, analogs with different nitroaromatic linkers exhibited different selectivity profiles for common biomolecules and ions. These subtle differences were also apparent in our cellular hypoxia assays, underscoring the importance of carefully selecting the nitroaromatic moiety and probe/drug design for applications such as diagnostic tools to detect hypoxia or targeted cancer therapies.