Poly(aspartic acid) Electrospun Nanofiber Hydrogel Membrane-Based Reusable Colorimetric Sensor for Cu(II) and Fe(III) Detection

Electrospun nanofiber membrane (ENM) with huge specific surface area is an ideal solid substrate for sensors. However, only a few ENMs are developed into colorimetric sensors and it is even more challenging to fabricate multiple-ion-responsive ENM-based colorimetric sensor. In this study, benefiting from the excellent metal ion adsorption ability of poly­(aspartic acid) (PASP) and high specific surface area of nanofibers, a reusable colorimetric sensor utilizing PASP electrospun nanofiber hydrogel membrane (ENHM) was designed to detect Cu²⁺ and Fe³⁺ in aqueous solution with simple filtration. The sensor based on PASP–ENHM exhibited high sensitivity and selectivity, and colorimetric responses for Cu²⁺ and Fe³⁺ detection could be observed by the naked eye. Upon exposure to Cu²⁺ aqueous solution, the color of the sensor changed from white to blue with a naked eye detection limit of 0.3 mg/L, while it turned from white to yellow with a detection limit of 0.1 mg/L for Fe³⁺ detection. Furthermore, this sensor was reusable after metal ion extraction by the desorption process.