Hydrogen peroxide (H₂O₂) is a key redox intermediate generated within cells. Existing probes for H₂O₂ have not solved the problem of detection of the ultra-low concentrations of the oxidant: these reporters are not sensitive enough, or pH-dependent, or insufficiently bright, or not functional in mammalian cells, or have poor dynamic range. Here we present HyPer7, the first bright, pH-stable, ultrafast, and ultrasensitive ratiometric H₂O₂ probe. HyPer7 is fully functional in mammalian cells and in other higher eukaryotes. The probe consists of a circularly permuted GFP integrated into the ultrasensitive OxyR domain from Neisseria meningitidis. Using HyPer7, we were able to uncover the details of H₂O₂ diffusion from the mitochondrial matrix, to find a functional output of H₂O₂ gradients in polarized cells, and to prove the existence of H₂O₂ gradients in wounded tissue in vivo. Overall, HyPer7 is a probe of choice for real-time H₂O₂ imaging in various biological contexts.

过氧化氢 (H ₂ O ₂ ) 是细胞内产生的关键氧化还原中间体。现有的 H ₂ O ₂探针并没有解决检测超低浓度氧化剂的问题：这些报告基因不够灵敏，或依赖于 pH 值，或不够明亮，或在哺乳动物细胞中不起作用，或具有较差的动态范围。在这里，我们展示了 HyPer7，这是第一个明亮、pH 稳定、超快和超灵敏的比率 H ₂ O ₂探针。HyPer7 在哺乳动物细胞和其他高等真核生物中功能齐全。该探针由集成到脑膜炎奈瑟菌超灵敏 OxyR 结构域中的循环排列的 GFP 组成. 使用 HyPer7，我们能够揭示线粒体基质中 H ₂ O ₂扩散的细节，找到极化细胞中 H ₂ O ₂梯度的功能输出，并证明受伤组织中 H ₂ O ₂梯度的存在体内。总体而言，HyPer7 是各种生物环境中实时 H ₂ O ₂成像的首选探针。