Electrospun colourimetric sensors for detecting volatile amines

Volatile amines are present in our daily life as a result of chemical manufacturing, agriculture and farming, release by rotten food or exhalation under certain medical conditions or diseases. An efficient, fast and low-cost method for detecting these compounds is desired due to their often-toxic nature. The development of a highly sensitive electrospun colourimetric sensor for the detection of volatile amines is reported here. Composite microfibrous meshes were obtained by incorporating activated furan adducts (FAs) into electrospun polymer meshes. Volatile amines penetrate into the amorphous polymer matrix where the ring-opening reaction with FAs yields strongly coloured donor-acceptor Stenhouse adducts (DASAs), resulting in an easily observable visible mesh colour change. Different FAs were evaluated, including a highly reactive FA yielding 3rd generation DASAs. The colourimetric responses were assessed qualitatively and quantitatively by RGB (red, green and blue) colour analysis. The sensors showed a detection range with high sensitivity down to the low-ppb range. Additionally, the covalent attachment of FAs to a polymer backbone anchored them inside the fibres and successfully prevented leaching. Thus, the cytotoxic effect of leached FAs was eliminated, as shown by indirect and direct contact tests with human fibroblasts.