Unraveling the Hydrolysis of Merocyanine-Based Probes in Biological Assay

Merocyanine dyes, owing to their unique photochemical properties, are widely used to fabricate probes for the detection of biologically active small molecules and bioimaging. In this paper, merocyanine-based probes were proved of undergoing unwanted hydrolysis. To explore the strategies toward avoiding the hydrolysis, the detailed hydrolysis mechanism was first investigated, which was also confirmed by density functional theory (DFT) calculation. Then a series of merocyanine dyes were rationally designed. Influences of molecular structures of the probes, the analytical media such as pH and components of the solution on the hydrolysis were systematically studied. The experimental results suggest that merocyanine based probes with low electron density are more likely to suffer the hydrolysis, which could be exacerbated by the well-accepted strategy for constructing type-II probes. It is worth noting that chemical surroundings could also exert distinctive influence on the hydrolysis. The hydrolysis could be obviously aggravated when fetal calf serum or DMSO was deployed. Our findings will definitely provide an effective and reliable approach for guiding the rational design of highly robust merocyanine-based probes and the optimization of the analytical media, which is helpful in terms of avoiding the hydrolysis of the probes and hydrolysis caused analytical errors.