A biocompatible ruthenium-based composite fluorescent probe using bovine serum albumin as a scaffold for ethylene gas detection and its fluorescence imaging in plant tissues

The detection of phytohormone ethylene is significant for extending the shelf-life of postharvest and controlling plant maturity. In this work, we report a biocompatible fluorescent probe for trace detection of the phytohormone ethylene based on the mechanism of the olefin metathesis reaction. The probe was prepared by simply incubating the ruthenium-based complex (FPRu) with bovine serum albumin (BSA). Then the structure of the probe was characterized by Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and circular dichroism circular dichroism (CD). The probe possesses a satisfactory detection of limit (LOD) for ethylene (1.17 ppm) and a decent linear range (4–250 ppm). Moreover, the probe-based test paper could also detect ethylene vapor with the naked eye, completing the visualization effect. Ethylene concentration monitoring at plant maturity could be done in solution and vapor. In particular, due to the protection of the hydrophobic pocket of BSA, the ruthenium-based fluorescent probe was also effectively applied to the fluorescence imaging in plant tissues. This work provides a new strategy to achieve highly selective detection and fluorescence imaging of ethylene in plant tissues without complicated operations and expensive instruments, which is of great significance for plant biology, agriculture and the food industry.