Unveiling the negative correlation of formaldehyde and hydrogen sulfide in Parkinson’s disease models using a dual-responsive ruthenium(II) complex probe

Parkinson's disease (PD) is one of the most common neurodegenerative diseases caused by various complicated pathological processes. Recent studies have revealed that formaldehyde (FA) and hydrogen sulfide (H2S) are essential signal molecules closely linked to central nervous systems. Therefore, understanding the physiological functions and relationship of FA and H2S in PD is beneficial for the early diagnosis and treatment of PD. However, an effective tool that could detect and visualize FA and H2S simultaneously in PD is still lacking. Herein we report the design and synthesis of a novel dual-responsive ruthenium(II) complex-based luminescent probe, Ru-aza-NBD, for the discriminatory detection of FA and H2S in aqueous media and PD models of living cells and mouse brains. Notably, using Ru-aza-NBD as a probe, the increased level of FA and the decreased level of H2S in PD models were discovered, which revealed the negative correlation of FA and H2S in PD for the first time. Collectively, Ru-aza-NBD could be an excellent tool for further investigating the biological functions of FA and H2S in pathological processes of PD, which offers a promising approach for the exploration of the pathogenic mechanism, diagnosis and treatment of this disease.