Carbon dots and ruthenium doped oxygen sensitive nanofibrous membranes for monitoring the respiration of agricultural products

During the storage of agricultural products, the oxygen concentration in the packages represents the level of food respiration and hence indicates its freshness. Herein, self-referenced photoluminescent oxygen sensitive fibrous membranes were prepared, with the inclusion of an oxygen-sensitive probe, i.e. tris (4,7-diphenyl-1,10-phenanthroline) ruthenium (II) dichloride (RuDPP), with an oxygen-insensitive luminophore, i.e. silane-functionalized carbon dots (SiCDs). Silicone was selected as the matrix, obtained via sol-gel process, and was electrospun to get nanofibers containing mesoporous microstructure and with high oxygen permeability. The as-prepared RuDPP@SiCDs/SiO2 fibrous membranes possessed hydrophobicity and exhibited ideal oxygen sensitivity, which realized a remote evaluation of the freshness of packaged fruits, through ratiometric photoluminescence imaging on the concentration change of environmental oxygen. The results indicate that such kind of oxygen-sensitive fiber membranes are capable as an optical oxygen sensor for agricultural applications.