Colorimetric determination of dopamine using an electrospun nanofibrous membrane decorated with gold nanoparticles

This study reports the preparation of a flexible nanofibrous probe for the rapid colorimetric detection of dopamine. To this aim, gold nanoparticles (AuNPs) were immobilized on the surface of electrospun nanofibrous membrane to obtain a new hybrid material. This hybrid structure would benefit from the properties of both nanofibers and AuNP, being (a) the porosity and high surface area of nanofibers, and (b) the unique optical properties of AuNP. The electrospun poly(ethylene terephthalate) (PET) nanofibrous membrane was alkaline treated in NaOH aqueous solution, followed by immersion in the AuNP solution. The morphology of AuNP-PET membranes was characterized using a field emission scanning electron microscopy. The AuNP-PET probes showed quick, visible color change (from red to dark blue) in the presence of dopamine at the physiological pH values. The visual detection limit was 0.5 μM. The color difference based on the formula of the L*a*b* color space was used to quantify the concentration of dopamine. The color difference increased almost linearly in the 0.5–500 µM concentration range. The presence of electrostatically adsorbed AuNP on the surface of nanofibers, along with the flexibility of the nanofibrous membrane, was responsible for fast, sensitive, and on-site detection of dopamine.