Uncovering the Fluctuation of Peroxynitrite during Early Embryonic Development Using an Integrative Nanobeacon

Embryonic development is the beginning of life, and various kinds of bioactive molecules are implicated in this crucial process. Especially in its early stage, some important biochemical reactions regulating physiological balance may be resuscitated. Thus, revealing the dynamic changes of bioactive molecules during early embryonic development is crucial to the elucidation of biological phenomena. Peroxynitrite (ONOO^-) is a typical signaling molecule in intercellular communication. However, up to now, no work has studied the fluctuation of ONOO^- during early embryonic development due to its low content, especially in mammals. Herein, a polymeric nanobeacon that integrates an ONOO^--responsive degradable scaffold and a fluorescence amplification module, named IFN, was designed to selectively sense embryonic ONOO^- with high sensitivity. By virtue of the specific dye, ONOO^- was sensitively detected in the range of 0-4.5 μM with a detection limit of 20.4 nM. From the attractive embryonic results, a sudden increase in ONOO^- content after fertilization was observed in a mammalian model, while the level of ONOO^- decreased slightly at the four-cell and eight-cell stages, finally reaching an equilibrium throughout the morula and blastocyst stages. This phenomenon is due to the resuscitation of ovotids, the activation of some life events by fertilization, and the subsequent establishment of physiological balance. This work not only suggests that ONOO^- plays a positive role in normal embryonic development but also highlights the molecular events occurring at the initial phase of life. Furthermore it opens up new avenues for monitoring chemical changes during mammalian embryonic development.