Detection of Ethylene Gas by Fluorescence Turn‐On of a Conjugated Polymer

The detection and monitoring of ethylene is of great interest and importance in the food and agricultural industries. Ethylene as one of the smallest plant hormones is responsible for the ripening of fruit and plays an important role in many more developmental plant processes such as seed germination, fruit ripening, senescence and abscission. As fruits and vegetables start ripening, ethylene is produced and emitted, and the internal ethylene concentration in some fruits is used as a maturity index to determine the time of harvest. In some fruits and vegetables, such as bananas, the ripening process is continued after harvesting by exposure to ethylene gas, and the monitoring of ethylene gas in storage rooms is important to avoid deterioration of ethylene-sensitive produce. The ethylene concentration in ripening rooms is held between 10 and 200 ppm depending on the type of fruit or vegetable, while in storage facilities a value of less than 1 ppm is required. [i] Traditionally, gas chromatography [iia] and photoacoustic spectroscopy [iib] have been used to measure ethylene concentrations. Both techniques suffer from the disadvantage of being operationally impractical and do not allow for real-time measurements. Other sensing systems that have been suggested or quenching. [iif] However, all of these systems have drawbacks such as high cost, impracticability, or insufficient sensitivity towards ethylene. We have a that conjugated as sensory materials. readily transform a chemical signal into an easily measured optical and can achieve large signal amplification relative to small ethylene of the system has to be improved, and we are currently investigating the use of different polymers and small molecule fluorophores. A new ethylene sensor was created from a conjugated polymer-copper (I) composite. The fluorescence of the conjugated polymer is quenched by the presence of copper (I) moieties. Upon exposure to ethylene gas the copper complexes bind to ethylene and no longer quench the polymer fluorescence. This new sensory concept can be used in solution and in thin film.