Electrospun fibre colorimetric probe based on gold nanoparticles for on-site detection of 17β-estradiol associated with dairy farming effluents

An on-site colorimetric probe, based on gold nanoparticles incorporated into electrospun polystyrene nanofibres, for the detection of oestrogenic compounds, as represented by 17 beta-estradiol, in dairy effluents is presented. The probe exhibited a significant absorption peak at 542 nm, ascribed to surface plasmon resonance of Au nanoparticles (NPs). With increasing 17 beta-estradiol concentration the surface plasmon resonance (SPR) band shifted to a longer wavelength accompanied by a visual colour change from shades of pink to blue. The visible cut-off concentration was 100 ng/ml. Upon exposure to cholesterol and a series of compounds known to induce oestrogenic activity, p,p'-DDE, deltamethrin, 4-tert-octylphenol and nonylphenol, only 17 beta-estradiol could induce a pink colour observable by the naked eye, which is indicative that the proposed gold nanoparticles-incorporated electrospun polystyrene nanofibres could be employed as highly selective colorimetric strips to detect 17 beta-estradiol, with minor interference from other endocrine-disrupting compounds usually present in dairy effluents. The facile nature of the colorimetric probe and potential application in monitoring water quality was demonstrated.