Development and application of two-photon fluorescent probe for visual monitoring of isoprene in plants

As the main volatile organic compounds (VOCs), isoprene plays a dual role in plant stress protection and air pollution. However, its spatiotemporal dynamic monitoring in plants is insufficient, which limits environmental risk assessment. In this study, by systematically investigating the effects of the introduction of alkyne groups, maleimide groups and conjugated structures on the performance of probes, a probe (TPCM-π-M), with excellent two-photon properties was prepared. It showed good linear response in 1-240 ppm range with a detection limit of 0.2 ppm, enabling accurate detection of isoprene in various plant samples. In addition, the spatial distribution of endogenous isoprene in deep plant tissues and dynamic visual monitoring of isoprene under abiotic stress were achieved through two-photon imaging, overcoming the shortcomings of traditional single-photon imaging such as insufficient penetration depth. In particular, the dynamic regulation mechanism of plant isoprene metabolism under abiotic stress was revealed through the carotenoid/photorespiration inhibition model, and the correlation between the isoprene content in different flowers and their stress response ability was confirmed. This study provides technical support for analyzing the role of isoprene in plant metabolism and environmental adaptation, and has theoretical and applied value in plant physiology, pollution monitoring and biomedical imaging.